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Genetics Final

Terms in this set (228)

RNA is:
- involved in transcription
- involved in translation
- normally single stranded
A nucleoside may be composed of
-deoxyribose sugar
-ribose sugar
-uracil
-guanine
Which of the following bases is not typically found in DNA?
uracil
The antiparallel nature of DNA refers to
the opposite direction of the two strands of nucleotides
Hairpins are found in RNA as a result of
sequences on the same strand that are inverted and complementary
Which of the following statements are true about chromosomal organization?
-Nucleosomes interact with each other to form a 30 nm fiber
-DNA wraps around a cluster of histone proteins to form a nucleosome
-Loops of DNA fibers attach themselves to scaffold proteins
Which components of a DNA nucleotide are found along the DNA backbone?
deoxyribose and phosphate
Which of the following modifications do not occur to eukaryotic pre mRNA?
The addition of the Kozak sequence
An in vitro transcription system that contains a bacterial gene does not initiate transcription. What is one possible problem?
There is a mutation at -35, where a promoter consensus sequence is located.
Minimal media...
- can have supplements added to it that would allow auxotroph's to grow.
- contains the raw materials needed to synthesize a multitude of biomolecules.
- contains everything that a prototrophic organism needs to grow.
Which of the following best explains why only pre-mRNA is recognized and receives a 5' cap?
The enzyme that initiates the capping step is known to associate with RNA polymerase II, which generate mRNAs.
A gene encodes a pre mRNA with 5 exons and 4 introns. If a mutation eliminates the 5' splice site at the beginning of intron 3, which sequences will be found in the fully spliced mature mRNA.
Exon 1, 2, 3, Intron 3, Exon 4, and Exon 5
What is mean by the term consensus sequence?
The most commonly occurring sequence amongst a group of related sequences.
In a transcription reaction, two phosphate groups are cleaved from the incoming ________________________ the remaining phosphate group is attached to the growing RNA molecule by a ___________________
NTP; phosphodiester bond
A gene encodes a pre mRNA with 5 exons and 4 introns. If a mutation eliminates the 3' splice site at the end of intron 3, which sequences will be found in the fully spliced mature mRNA
Exon 1, 2, 3, and 5
Complete media...
- contains a multitude of preassembled biomolecules
- contains everything that a prototrophic organism needs to grow.
- contains everything that an auxotrophic organism needs to grow.
In the diagram below, which gene(s) would use the bottom strand as the template for transcription?
A
What is the function of peptidyl transferase activity?
It forms peptide bonds.
The 5¢ and 3¢ untranslated regions (UTRs) of processed mRNA molecules are derived from?
exons
The Shine-Dalgarno sequence is
the sequence in the mRNA where the small ribosomal subunit binds to begin translation
The ribosome is involved in all of the following except
charging the tRNA
An artificial piece of RNA is synthesized that has the sequence 5' GGC 3'. It is mixed with a cell free translation system and the entire mixture is passed through a filtration unit. Which of the following would you expect to find attached to the filter?
glycine
EF - Tu plays a role in the following:
- It consumes GTP
- It stimulates the action of peptidyl transferase
- It helps to insure that the proper amino acid enters the A site of the ribosome
Which of the following is observed in prokaryotes but not in eukaryotes?
The 5' end of a prokaryotic mRNA can be translated while the 3' end is still being transcribed.
Which region of mRNA contains the Shine-Dalgarno sequence?
5' UTR
In eukaryotes, tRNAs are
transcribed in the nucleus, but function in the cytoplasm.
Because of the wobble rules of tRNA-mRNA pairing, which of the following statements are false?
- It occurs with the 3' nucleotide of the anticodon
- It allows one mRNA codon to pair with multiple tRNA anticodon
Assume that you have discovered a new chemical mutagen that modifies guanine so that is mispairs with adenine when adenine is in the template DNA strand during DNA replication. However, this mispairing is limited to when the modified guanine is being added to the newly replicating DNA strand. When the modified guanine is in the template DNA strand it always pairs normally with cytosine being added to the growing newly synthesized strand. What type of mutation would you predict would be caused by the new chemical mutagen?
A-to-C base substitutions
Which of the following statements are true regarding mutations and their repair?
- Many mutations are caused by incorrect pairing between bases during replication, which may be due to wobble, chemical damage, or DNA polymerase being forced to randomly insert nucleotides.
- The 3' to 5' exonuclease activity of DNA polymerase I and III helps to prevent base substitutions
Which of the following is not a cause of spontaneous mutations?
uv light
Which of the following is most likely to lead to a loss of gene function?
A deletion of 1 nucleotide in an exon
How do germ-line mutations differ from somatic mutations?
Germ-line mutations result in mutant gametes, while somatic mutations do not.
Heterozygotes exhibit the dominant phenotype because
They still have one one copy of the gene producing a functional protein
Which of the following base changes in DNA is an example of a transition?
A-to-G
What do alkylating agents do?
They add methyl or ethyl groups to bases.
When an activator interacts with mediator of a eukaryote, what is the result?
RNA polymerase can transition from a closed to open complex, which allows it to move into the elongation stage of transcription
Which of the following statements about gene regulation concerning an operon is INCORRECT?
For a gene under negative repressible control, an environmental stimulus` is required to prevent the gene's repressor from binding to DNA.
Regardless of the environmental conditions, which of the following would always result in expression of the lac operon?
- IsP+OcZ+Y+
- I+P+OcZ+Y+
E. coli lac operon control by CAP is
positive repressible
Which of the following statements about histone and gene expression is correct?
In a general sense, highly condensed DNA bound with histone proteins represses gene expression.
What modification netralizes the charge of histones that promote ionic interaction with DNA molecules?
acetylation
If a bacterium has wild type alleles of all of the components of the lac operon and the cell is growing in media that contains only the sugars lactose and glucose, which of the following statements are true?
- The repressor protein will bind to lactose, preventing it from binding to the operator
- The cell will not be producing functional beta galactosidase enzyme
- cAMP levels in the cell will be low
If an individual has the following genotype of the lac operon: I+P+OcZ+Y-, which of the following statements are correct:
- Transcription will occur if lactose is present in the cell
- The cell will produce functional beta galactosidase enzyme when lactose is present in the cell
- mRNA coding for beta galactosidase will be present if lactose is present in the cell
-mRNA coding for permease will be present if lactose is not present in the cell
The lagging strand of DNA
-requires discontinuous DNA synthesis
- is synthesized by the DNA polymerase moving in the opposite direction as helicase
- is broken up into many Okazaki fragments
DNA replication can be described as ________
semi conservative
In the diagram below, which letter indicates the 5' end of the leading strand?
C
If a deletion occurs in a gene that encodes DNA polymerase I and no functional DNA polymerase I is produced. What will be the most likely consequence of this mutation?
The DNA strands would contain pieces of RNA.
Telomerase is most likely to be active in which of these types of human cells?
Cells that give rise to gametes
suppose Meselson and Stahl had obtained the following results in their experiment. These results are constant with which model of replication?
- Dispersive Replication
- Semiconservative replication
Okazaki fragments
- are found on the lagging strand
- are due to discontinous DNA synthesis
If ribonucleotides were depleted from a cell during S phase, how would DNA synthesis be affected? (Ignore energetic considerations.)
Replication would cease because ribonucleotides are required to initiate DNA synthesis.
A dividing eukaryotic cell is treated with a drug that inhibits the molecular motors associated with kinetochores. At which cell cycle stage would it stop?
M (metaphase)
The phenomenon of "independent assortment" refers to:
unlinked transmission of genes in crosses resulting from being located on different chromosomes, or far apart on the same chromosome.
Which of the following statements are true of mitosis:
- sister chromatids are separated during anaphase
- the nuclear membrane breaks down during prophase
- replication occurs during interphase
During anaphase I of meiosis
- sister chromatids remain connected at the centromere
- homologous chromosomes migrate towards opposite poles of the cell
- the cell transitions from being diploid to haploid
Which of the following genotypes would produce the greatest number of genetically distinct gametes?
Aa bb Cc Dd Ee
True-breeding tall plants with purple flowers are crossed to true-breeding dwarf plants with white flowers. The F1 plants were tall with purple flowers. The genes that affect these traits independently assort. If the F1 plants were bred to dwarf plants with white flowers,the expected ratio of the F2 generation would be
1 tall/white flowers : 1 tall/purple flowers : 1 dwarf/white flowers : 1 dwarf/ purple flowers
Which of the following statements is true?
- The phenotype of a recessive trait disappears in the F1 progeny of a monohybrid cross
- A testcross can be used to determine whether an individual is homozygous or heterozygous.
Hemophilia is an example of an X linked recessive trait. If a normal male mates with a female hemophiliac, what is the probability that a male child will be phenotypically normal?
0%
Traits that are X linked
show up in males and females with equal probability
Joan is phenotypically normal, but had a child with the autosomal recessive disease cystic fibrosis (CF) from a previous marriage. Joan's father has hemophila A, a sex-linked recessive condition where the blood fails to clot properly. Her father has survived due to recent treatment advances. Joan now intends to marry Bill, who is also phenotypically normal but who has a sister, Jill, with CF. Bill's parents are phenotypically normal, and there is no history of hemophilia A in his family. Assume that Joan and Bill do marry and have a child. What is the probability that this child will have CF, but will not have hemophilia A?
1/8
Which of the following statements are false?
For a given chromosome, it carries one gene.
Hemophilia, type A, is an X-linked recessive trait. A mother without hemophilia and a father with hemophilia have a daughter with hemophilia. They have a son named Rodger. If we tested Rodger's blood, the likelihood that he has hemophilia, type A is
1/2
Imagine an individual that is AaBbCcDd. If this individual is selfed what is the probability of producing offspring that have the genotype AaBbCcDD.
1/32
The phenomenon of "independent assortment" refers to:
unlinked transmission of genes in crosses resulting from being located on different chromsomes, or far apart on the same chromosome.
In a cross between AaBbCc and AaBbcc, what proportion of the offspring would be expected to be A_bbcc? (A_ means AA or Aa.)
3/32
If two individuals with the genotype AaBbCc are mated, what proportion of the offspring will be AABBCC
1/64
You are studying body color in an African spider and have found that it is controlled by a single gene with four alleles: B (brown), br (red), bg (green), and by (yellow). B is dominant to all the other alleles, and by is recessive to all the other alleles. The bg allele is dominant to by but recessive to br. You cross a pure-breeding brown spider with a pure-breeding green spider. Predict the phenotype of the progeny.
All brown
Which of the following statements is always true?
- Genes on different chromosomes will assort independently
- Alleles segregate during the formation of gametes
Coat color is determined by two loci in large cats. Two pink panthers fall in love and produce a large litter of baby panthers with the following phenotypic ratios: 12/16 pink; 3/16 black; and 1/16 white. What is the genotype of the pink progeny?
A_B_ and A_bb
The R locus determines flower color in a new plant species. Plants that are genotype RR have red flowers, and plants that are rr have white flowers. However, Rr plants have pink flowers. What type of inheritance does this demonstrate for flower color in these plants?
incomplete dominance
In the endangered African watchamakallit, the offspring of a true-breeding black parent and a true-breeding white parent are all gray. When the gray offspring are crossed among themselves, their offspring occur in a ratio of 1 black:2 gray:1 white. Upon close examination of the coats, each hair of a gray animal is gray. What is the mode of inheritance?
One gene pair with incomplete dominance
In a certain species of plant, flowers occur in three colors: blue, pink, and white. A pure-breeding pink plant is mated with a pure-breeding white plant. All of the F1 are blue. When the blue F1 plants are selfed, the F2 occur in the ratio 9 blue:3 pink:4 white. How many gene pairs control the flower color phenotype?
2
In chickens, comb shape is determined by genes at two loci (R, r and P, p). A walnut comb is produced when at least one dominant gene R is present at one locus and at least one dominant gene P is present at a second locus (genotype R_ P_). A rose comb is produced when at least one dominant gene is present at the first locus and two recessive genes are present at the second locus (genotype R_ pp). A pea comb is produced when two recessive genes are present at the first locus and at least one dominant gene is present at the second (genotype rr P_). If two recessive genes are present at the first and the second locus (rr pp), a single comb is produced. Give genotypes for comb shape of the parents in the following cross: Rose crossed with pea produces 20 walnut offspring.
RR pp × rr PP
Hair color is determined in Labrador retrievers by alleles at the B and E loci. A dominant allele B encodes black pigment, whereas a recessive allele b encodes brown pigment. Alleles at a second locus affect the deposition of the pigment in the shaft of the hair; dominant allele E allows dark pigment (black or brown) to be deposited, whereas recessive allele e prevents the deposition of dark pigment, causing the hair to be yellow. A black female Labrador retriever was mated with a yellow male. Half of the puppies were black and half were yellow. If the genotype of the black female parent was Bb Ee, then what was the genotype of the other parent?
eeBB
Coat color is determined by two loci in large cats. Two pink panthers fall in love and produce a large litter of baby panthers with the following phenotypic ratios: 12/16 pink; 3/16 black; and 1/16 white. What is the genotype of the white progeny?
aabb
A mother with blood type A has a child with blood type AB. Give all possible blood types for the father of this child.
B and AB
Genes C and D are linked on the same chromosome and 14 map units apart from each other. An individual CCDD is mated with an individual ccdd. The F1 offspring are mated with a tester and 400 offspring are produced. How many of these offspring should be CcDd?
172
The map distances for genes that are close to each other are more accurate than map distances for genes that are quite far apart because
with genes that are far apart, double crossovers and other multiple-crossover events often lead to nonrecombinant or parental offspring and thus reduce the true map distance.
True breeding fruit flies with singed bristles (s) and long wings (L) were mated with pure breeding flies with normal bristles (S) and vestigial (l) wings. The F1 offspring all had normal bristles and long wings. These F1 were mated with flies with singed bristles and vestigial wings. Which phenotypic classes will be recombinant?
- normal bristles and long wings
- singled bristles and vestigial wings
A low coefficient of coincidence indicates that
far fewer double-crossover recombinant progeny were recovered from a testcross than would be expected from the map distances of the genes involved.
True breeding fruit flies with singed bristles (s) and long wings (L) were mated with pure breeding flies with normal bristles (S) and vestigial (l) wings. The F1 offspring all had normal bristles and long wings. These F1 were mated with flies with singed bristles and vestigial wings. Which phenotypic classes will be nonrecombinant?
- singed bristles and long wings
- normal bristles and vestigial wings
When doing a chi square analysis to determine if genes are linked on the same chromosome, which of these statements is correct?
Your hypothesis is that independent assortment is taking place because it allows you to predict the expected number in each phenotypic group.
If genes A and B are coupled and 25 cM apart from each other, which of the following statements are true:
- There will be more (A B) gametes than there are (a B)
- 12.5 % of the gametes will carry (a B)
In Genetics the term "linkage" means
- two or more genes are transmitted as a unit
- two or more genes are on the same chromosome
Genes A and B are linked on the same chromosome. An aaBB individual is crossed to AAbb to produce AaBb offspring. These F1 offspring are crossed with aabb. What would be the genotypes of nonrecombinant offspring?
- Aabb
- aaBb
Interference
- causes us to underestimate the distance between two genes
- is more likely to occur near the centromere
Which of the following statements are true of triploids?
- An example is domesticated banannas
- They are sterile.
A newly discovered species of dung beetle has 2n = 16 chromosomes. It mates with a closely related beetle species that has 2n = 12 chromosomes. How many chromosomes would there be in an allotriploid beetle produced from this cross?
20 or 22
Trisomic individuals can be produced when
- nondisjunction has occurred in one parent
- a trisomic is mated with an individual that is euploid
Assuming that these individuals could survive and make gametes, which would be the most infertile?
a triploid tulip
Which of the following is not true of chromosomal deletions?
When heterozygous for the deletion, recombination still occurs with the deleted region.
You have carried out experiments that indicate that gene A is linked to gene B. However in some some individuals you find that A and B are no longer linked. A _________ must have occurred.
translocation
Which of the following plants is the most likely to be fertile?
an allotetraploid
What would be the consequence of a diploid gamete (resulting from meiotic nondisjunction) being fertilized by a haploid gamete from the same species?
autotriploid
Which of the following oligonucleotides is the least likely to bind to template DNA multiple times?
GGCCATTCGGCA
A gene present on a vector that allows researchers to eliminate all individuals that do not carry the vector is known as
dominant selectable marker
You identify an RFLP in mice by digesting genomic DNA with HindIII enzyme and radiolabeling a piece of probe DNA. Southern blot analysis shows that the probe detects a 2kb fragment in one strain of mice and a 4-kb fragment in another strain of mice. The two mice strains are crossed to produce an F1 generation. Two F1 siblings are mated to produce a dozen F2 progeny. You isolate genomic DNA from several F1 and F2 individuals, digest with HindIII, and perform a Southern blot with the same probe.How many bands would be seen in the Southern blot of an F1 individual?
2
Molecular markers can be used to
- determine an individuals genetic fingerprint
- carry out paternity testing
- make a dense linkage map
- identify individuals that may have the genotype responsible for a specific genetic disorder
The technique used to transfer nucleic acids to a nylon or nitrocellulose membrane is known as
Southern blotting
One way to determine if a segment of DNA has been inserted into a vector is to grow the cells carrying the vector in growth media containing X-Gal. Following overnight growth
the white colonies will be carrying the insert DNA because the reporter gene has been inactivated.
You identify an RFLP in mice by digesting genomic DNA with HindIII enzyme and radiolabeling a piece of probe DNA. Southern blot analysis shows that the probe detects a 2kb fragment in one strain of mice and a 4-kb fragment in another strain of mice. The two mice strains are crossed to produce an F1 generation. Two F1 siblings are mated to produce a dozen F2 progeny. You isolate genomic DNA from several F1 and F2 individuals, digest with HindIII, and perform a Southern blot with the same probe.What size bands may be seen in the F2 progeny Southern blot?
Some may have 2 kb, others 4 kb, and others 2 and 4 kb at the same time
In the Avery Experiment, DNase ______ the transforming factor
eliminated
In the Avery Experiment, RNase ______ the transforming factor.
did nothing to
If protein were the genetic material, then protease would ______ the transforming factor in the Avery Experiment.
eliminate
A nucleoside is composed of
- a pentose sugar
- a nitrogenous base
Which of the following bases is not found in DNA?
uracil
A double stranded molecule of DNA is known to 22% cytosine. It must have _____% adenine.
28
Experiments by ________ led to the rejection of the Tetranucleotide Hypothesis
Chargaff
The two strands of DNA are
- twisted around each other in a helix
- held together by hydrogen bonds
- antiparallel
Chromatin structure
- is fluid and capable of changing
- is most highly organized and compacted in heterochromatin regions of the chromosome.
- can influence the expression of genes
Chromosomes are always X shaped structures of DNA and protein.
false
Complete media
- contains everything that a prototrophic organism needs to grow.
- contains everything that an auxotrophic organism needs to grow.
- contains a multitude of preassembled biomolecules
Given the following biochemical pathway, in which the letters represent chemical substances in the pathway and numbers represent enzymes that catalyze the reactions represented by the arrows. Additionally, substance D is required for the proper growth of a cell:A -- 1 --> B -- 2 --> C -- 3 --> DIf a cell has a mutation that prevents enzyme #2 from functioning then you would expect
- the addition of C to result in growth
- the addition of D to result in growth
- the addition of large amounts of A to result in the accumulation of large amounts of B
Our modern understanding of the "gene" includes:
- a gene may code for a single RNA
- a gene may code for multiple RNA
- a gene may code for a protein
- a gene may code for an enzyme
All mature mRNA produced in eukaryotes are the same length as the gene that coded for them.
False
Beadle and Tatum's idea of one gene = one protein is not exactly correct because.
- some genes code for rRNA or tRNA which are never converted into proteins
- some eukaryotic genes can have their exons spliced together in different ways, producing different RNA's which code for different proteins
- some eukaryotic mRNA are cleaved at different spots, changing the ORF of the mRNA
Eukaryotic promoters
- may include sequences more than 1000 nucleotides upstream from the transcriptional start site.
- are composed of a core promoter and regulatory promoter
- may include sequences downstream of the transcriptional start site
Eukaryotic RNA polymerase I is responsible for synthesizing
large rRNA
Which of the following features is primarily responsible for rho protein to cause termination of transcription?
Helicase activity
Termination of transcription in prokaryotes
- involves the formation of a stem loop terminator structure
- relies upon internal base pairing within a RNA strand
Which of the following statements are TRUE regarding transcription in most organisms?
Different genes may be transcribed from different strands of DNA.
RNA polymerase
- is composed of more than one protein
- can be nonspecific in its initiation
- synthesizes new strands of RNA beginning at its 5' end
- pairs RNA nucleotides with complementary DNA nucleotides in the template strand
- synthesizes RNA molecules
Transfer RNA
- carry amino acids to the ribosome
- are less than 100 nucleotides long
What is the function of peptidyl transferase activity?
- It cleaves the polypeptide from the last tRNA during termination
- It forms peptide bonds
Which of the following does NOT enhance the binding of the ribosome to the 5′ end of the eukaryotic mRNA?
Kozak sequence
Termination of translation requires
- peptidyl transferase
- a stop codon in the A site
- release factor
Translation
- is influenced by the methyl guanosine cap and poly A tail of eukaryotic mRNA
- begins at the start codon and ends at the stop codon
- consumes a lot of energy
What is the minimum number of different aminoacyl-tRNA synthetases required by a cell?
20, one for each amino acid
Which of the following is NOT required during the process of tRNA charging?
GTP
If a base substitution in one codon changed multiple amino acids in the resulting protein, this would provide evidence that the genetic code was not
nonoverlapping
A _____ bond is used to link together amino acids in a protein.
peptide
Prokaryotic and eukaryotic tRNA
- have a specific three dimensional shape recognized by the enzyme responsible for attaching a specific amino acid to their acceptor stem
- are able to pair with other strands of RNA
- contain many chemically modified nitrogenous bases such as pseudouridine and inosine
- are composed of at least three stem loops
Which of the following statement about the formation of the peptide bond between amino acids is incorrect?
The amino group of the first amino acid and the carboxyl group of the second amino group are involved in forming a peptide bond
Which of the following statements about somatic mutations is FALSE?
They may be inherited in the offspring of mutated individuals.
Which of the following correctly describes nonsense mutations?
They convert a codon for a particular amino acid within a gene into a stop codon.
Which of the following types of mutations does NOT lead to a change in the amino acid sequence of the gene product?
Silent
Loss of function mutations tend to be _______ because half the normal enzyme activity usually _______.
recessive; is sufficient to produce the wild type phenotype.
Spontaneous causes of mutation would include
- segments of DNA that randomly insert themselves at various places along the chromosome
- reactions of nitrogenous bases with water that alter the base pairing rules for the molecule
- strand slippage that occurs when a repeated sequence of nucleotides gets replicated
- mistakes that occur during replication due to wobble pairing between nitrogenous bases
Substances that are mutagenic
- may alter the ability of a base to pair with another base in the opposite DNA strand
- would generate more his+ revertants growing on minimal media in an Ames Test
-are more likely to cause cancer
Assume that you have discovered a new chemical mutagen that modifies guanine so that is mispairs with adenine when adenine is in the template DNA strand during DNA replication. However, this mispairing is limited to when the modified guanine is being added to the newly replicating DNA strand. When the modified guanine is in the template DNA strand it always pairs normally with cytosine being added to the growing newly synthesized strand. What type of mutation would you predict would be caused by the new chemical mutagen?
A-to-C base substitutions
In a double stranded DNA molecule a G is paired with a T. Which of the following statements are true
- This could be corrected by Mismatch Repair if the DNA is hemimethylated
- This could be due to DNA polymerase making a mistake during replication
- This could be due to the deamination of a methylated cytosine.
- This could be corrected by DNA polymerase proofreading
Mutations may be prevented by
- breaking the covalent bond that has formed between adjacent thymines
- cutting out chemically damaged bases like uracil and resynthesizing that segment of DNA
- relying upon the ability of DNA polymerase to proofread during the process of replication
What is the function of DNA glycosylases?
Recognize and remove modified bases from the sugar component of DNA
Choose the type of control illustrated by GAL4 in the control of genes for yeast galactose-metabolizing enzymes.
- Positive inducible
When a structural gene is under positive inducible control, what would be the result of a mutation that eliminates the activator protein?
As the transcription will require an activator protein, the transcription will be turned off.
When a structural gene is under positive repressible control, what would be the result of a mutation that eliminates the repressor protein?
As the transcription does not require a repressor protein, the transcription will be turned on constitutively.
The repressor and catabolite activator protein of the lac operon are both
- proteins encoded by specific genes
- trans acting
- diffusible
- allosteric, meaning that they change shape when they bind to other molecules in the envirionment
Given the following genotype of the lac operon, which of the following statements are true? I+ P+ O+ Z+ Y-
- when allolactose is present in the cell, the enzyme necessary for the break down of allolactose will be present
- when allolactose is present in the cell, mRNA for Beta galactosidase will be made
Given the following genotype of the lac operon, which of the following statements are true?Is P+ Oc Z+ Y+
- when allolactose is absent in the cell, mRNA for permease will be made
- when allolactose is present in the cell, the enzyme necessary for the break down of allolactose will be present
- the repressor protein will never bind to the operatory and therefore gene expression will occur all the time
- when allolactose is present in the cell, mRNA for Beta galactosidase will be made
- when allolactose is absent in the cell, the transporter protein that is needed to move lactose across the plasma membrane will be abundant
Which of the following facts about eukaryotic gene regulation is TRUE?
Mediators are protein complexes involved in regulating transcription rates.
A eukaryotic DNA sequence that affects transcription at distant promoters is called a(n)
enhancer.
After translation, eukaryotic proteins can be modified by
- the addition of phosphate groups.
- the addition of methyl group
- acetylation.
- the removal of amino acids.
Antibodies are to Western blots as _____ are to Northern blots
RNA
DNA probes
If DNA replication was a dispersive mechanism, Messelson and Stahl should have seen this result after one cycle of DNA replication
There should be one band of DNA. This band should be present in the middle of the gradient, indicating that it is composed of an equal portion of heavy and light nitrogen.
If DNA replication was a semiconservative mechanism, Messelson and Stahl should have seen this result after one cycle of DNA replication
There should be one band of DNA. This band should be present in the middle of the gradient, indicating that it is composed of an equal portion of heavy and light nitrogen.
During DNA replication
- DNA polymerase III is responsible for synthesizing the majority of the DNA
- DNA polymerase I is able to remove incorrectly inserted nucleotides
- DNA polymerase I is able to remove the RNA primer at the beginning of each Okazaki fragment
- DNA polymerase III is able to remove incorrectly inserted nucleotides
- DNA polymerase III repeatedly starts and stops synthesizing DNA on the lagging strand
The leading strand of DNA
- requires continuous DNA synthesis
- is one continuous piece of DNA
- is synthesized by the DNA polymerase moving in the same direction as helicase
What type of synthesis occurs on the leading strand?
Continuous
If a deletion occurs in a gene that encodes DNA polymerase I and no functional DNA polymerase I is produced. What will be the most likely consequence of this mutation?
The DNA strands would contain pieces of RNA.
DNA polymerase I and DNA polymerase III both have ______ but only DNA polymerase I has _______.
3′→5′ exonuclease activity; 5′→ 3′ exonuclease activity
The enzyme helicase
- will be loaded twice at each origin of replication. Once for each replication fork.
- is responsible for unwinding and separating the two strands of DNA to allow each to serve as a template for replication
Suppose that some cells are grown in culture in the presence of radioactive nucleotides for many generations so that both strands of every DNA molecule include radioactive nucleotides.C The cells are then harvested and placed in new medium with nucleotides that are not radioactive so that newly synthesized DNA will not be radioactive. What proportion of DNA molecules will contain radioactivity after three rounds of replication?
1/4
During prophase II of meiosis
- replicated chromosomes begin to become more compact
- the spindle begins to form
- the centrosomes migrate to the poles of the cell
During anaphase II of meiosis
sister chromatids migrate towards opposite poles of the cells
The following statement can be correctly applied to which of the following stages of cell division:
Sister chromatids separate during _____.
- Meiosis II anaphase
- Mitosis anaphase
The following statement can be correctly applied to which of the following stages of cell division:
Chromosomes are randomly partitioned during _____, contributing to genetic diversity.
Meiosis I anaphase
Suppose that a diploid cell contains 8 chromosomes (2n = 8). How many different combinations in the gametes are possible?
16
A diploid somatic cell from a rat has a total of 42 chromosomes (2n = 42). As in humans, sex chromosomes determine sex: XX in females and XY in males. What is the total number of telomeres in a rat cell in G2?
168
The attachment point on the chromosome for spindle microtubules is the
centromere.
Sex determination in animals
- may change at different points in the life an individual
- may be due to the presence of a single gene that results in the development of male characteristics
- can be determined by environmental factors
Hemophilia is an example of an X linked recessive condition. If a female that is heterozygous for this trait mates with a male that does not have the trait.
- None of their daughters can have hemophilia
- They have a 1/4 chance of having a child with hemophilia
- Each of their sons has a 50% chance of having hemophilia
You suspect that wing color in a species of butterfly is a sex linked trait. Yellow wings are only observed in males. Blue wings are only observed in females
- The wing color gene could be on a W chromosome
- The wing color gene could be on a Y chromosome
- It is impossible to say what is dominant in this case.
Which of the following statements are true of autosomal recessive traits.
- Recessive traits can skip generations
- If two individuals with the trait mate, all of their offspring must also have the trait.
Which of the following statements are true of X linked recessive traits.
- X Linked Recessive traits can skip generations
- If two individuals with the trait mate, all of their offspring must also have the trait.
- Mutant traits tend to exhibit themselves in males more often than females
Assume that a trait is autosomal recessive. If you assume that individuals that marry into the family are purebreeding unaffected, and your grandfather is known to be heterozygous for the trait.
You have a 1/4 chance of being heterozygous for the trait
Assume that a trait is autosomal recessive. Assume that a female parent has a 1/2 chance of being heterozygous and the male parent has a 2/3 chance of being heterozygous. Their first child does not have the mutant trait. What is the chance that their second child will have the mutant trait?
1/12
Cystic fibrosis is an autosomal recessive condition. John has a brother with cystic fibrosis, but there is no other history of the condition in his family. John's wife has cystic fibrosis. What is the chance that they will have a child with this condition?
1/3
In a cross between pure-breeding tall plants with pure-breeding short plants, all of the F1 are tall. When these plants are allowed to fertilize themselves, the F2 plants occur in a ratio of 3 tall:1 short. Which of the following is not a valid conclusion from these results?
The tall and short traits assort independently of each other in this cross.
Which of the following statements is true?
- A testcross can be used to determine whether an individual is homozygous or heterozygous.
- The phenotype of a recessive trait disappears in the F1 progeny of a monohybrid cross
In dogs, black coat color (B) is dominant over brown (b), and solid coat color (S) is dominant over white spotted coat (s). A cross between a black, solid female and a black, solid male produces only puppies with black, solid coats. This same female was then mated with a brown, spotted male. Have of the offspring from this cross were black and solid, and half of the offspring were black and spotted. What is the genotype of the female?
BBSs
In a cross between AABbCcDD and AaBbccdd, what proportion of the offspring would be expected to be A_B_C_D_? (A_ means AA or Aa.)
3/8
Which of the following statements is true?
- The probability of two or more independent events occurring together is calculated by multiplying their independent probabilities.
- The probability of a woman giving birth to three girls in a row is 1/8.
- The chi-square test is used to determine if observed outcomes are consistent with expected outcomes.
When the chi square value is greater than the critical value, you accept the proposed hypothesis.
False
Coat color is determined by two loci in large cats. Two pink panthers fall in love and produce a large litter of baby panthers with the following phenotypic ratios: 12/16 pink; 3/16 black; and 1/16 white. What is the genotype of the black progeny?
aa B_
Fur color in mice is controlled by two genes (A and B) that interact in a recessively epistatic manner. Mice that are aa are always albino. While mice that carry one copy of the A allele can be agouti or black, depending upon their genotype for B... with black being the recessive trait. Parent #1 has the genotype AaBb and is crossed to parent #2 with the genotype aaBb.
- Parent #1 is agouti
- We should expect 3 agouti : 1 black : 4 albino offspring in the progeny of the cross
- Parent #2 is albino
A mother with blood type A has a child with blood type AB. Give all possible blood types for the father of this child.
- AB
- B
A mother with blood type A has a child with blood type A. Give all possible blood types for the father of this child.
- B
- O
- A
- AB
In rabbits, an allelic series helps to determine coat color: C (full color), cch (chinchilla; gray color), ch (Himalayan; white with black extremities), and c (albino; all white). The C allele is dominant to all others, cch is dominant to ch and c, ch is dominant to c, and c is recessive to all the other alleles. This dominance hierarchy can be summarized as C > cch > ch > c. Indicate the phenotypic ratios expected if rabbits with the cross Ccch × Cch.
3 full color:1 chinchilla
A trait like Hebreden Nodes, where two individuals with the same genotype do not have the same phenotype is an example of
the influence of the environment upon traits
An example of incomplete dominance in snap dragons is flower color. In this case, homozygous dominant individuals have red flowers and homozygous recessive individuals have white flowers. Pink flowers are produced in heterozygous individuals. Which of the following crosses could be used to produce seeds that may have pink flowers?
- Crossing a pink with a pink
- Crossing a pink with a white
- Crossing a red with a white
- Crossing a pink with a red
A gardener has two different white rose bushes in her garden, instead of the normal red. In an effort to breed a better rose bush, she crosses the two white roses to produce F1 offspring. When the F1 are planted, all of the offspring have white flowers.
- There is not enough information to determine which trait is dominant. In order to do that you would have to cross together a pure breeding red with a pure breeding white rose
- The original white rose parental plants must have mutations in the same gene
One type of gene interaction is dominant suppression. Which of the following accurately describes this type of interaction?
Individuals that have at least one copy of a dominant allele for one gene, regardless of their genotype for the second gene, will have the same phenotype as those individuals that are homozygous recessive for both genes.
A testcross is performed on an individual to examine three linked genes. The most frequent phenotypes of the progeny were Abc and aBC, and the least frequent phenotypes were abc and ABC. What was the genotype of the heterozygous individual that is testcrossed with the correct order of the three genes?
bAc/BaC
Why are the progeny of a testcross generally used to map loci? Why not the F2 progeny from an F1 × F1 cross?
It is easier to classify recombinant and parental offspring of a testcross than with the progeny of an F1 × F1 cross.
Assume that an individual of AB/ab genotype is testcrossed and four classes of testcross progeny are found in equal frequencies. Which of the following statements is TRUE?
- The genes A and B are likely located on different chromosomes.
- The genes A and B are on the same chromosome and very far apart.
A low coefficient of coincidence indicates that
far fewer double-crossover recombinant progeny were recovered from a testcross than would be expected from the map distances of the genes involved.
Recombination frequencies can be calculated by
counting the number of recombinant and parental offspring when an individual who is heterozygous for two genes is testcrossed.
Genes may appear to be unlinked if
- They are more than 50 cM apart from each other
- they are on separate chromosomes
You are doing lab work with a new species of beetle. You have isolated lines that breed true for either blue shells and long antenna, or green shells and short antenna. Crossing these lines yields F1 progeny with blue shells and long antenna. Crossing F1 progeny with beetles that have green shells and short antenna yield the following progeny:
Blue shell, long antenna82
Green shell, short antenna78
Blue shell, short antenna37
Green shell, long antenna43
Total240
Assuming that the genes are linked, what is the map distance between them in cM?
33.3 cM
Imagine an individual with the following genotype: A B C / a b c. If a is 10 map units from b and c is 20 map units from b... and assuming that there is no interference... what is the chance that this individual will produce a gamete carrying alleles a b c.
36%
Genes A and B are 18 cM apart from each other on the same chromosome. Parent #1 has the genotype A B / a b. Parent #2 has the genotype a B / A b.
- The genes are in repulsion in parent #2
- The genes are coupled in parent #1
- If the parents are crossed, 3.69% of the offspring will be homozygous recessive for both genes
Which type of polyploidy is synonymous with amphidiploid?
Allotetraploid
Two chromosomes have the following segments, where • represents the centromere:
K L M • N O P Q RS T U V • W X Y Z
What type of chromosome mutation would result in the following chromosomes:
K L M • N O P Q RS T U V • W Z
Deletion
Two chromosomes have the following segments, where • represents the centromere:
K L M • N O P Q RS T U V • W X Y Z
What type of chromosome mutation would result in the following chromosomes:
K L M • N O P Q R Y ZS T U V • W X
Non Reciprocal Translocation
Which of the following statements are true about deletions?
- Being homozygous for a large deletion is likely to be lethal to the organism
- If homozygous for a small deletion, the chromosomes pair normally during prophase I of meiosis
- They may be created when a segment of a chromosome is broken away from the rest and the damage is not repaired.
______ can cause the linear order of genes to change within a linkage group.
Inversion
The centromere is located approximately in the middle of which type of chromosome?
Metacentric
The centromere is at or very near the end in which type of chromosome?
Telocentric
Aneuploidy can result from
- nondisjunction that occurs during anaphase of mitosis
- nondisjunction that occurs during anaphase I
- nondisjunction that occurs during anaphase II
Species A has a diploid number of chromosomes equal to 12. Species B has a diploid number of chromosomes equal to 14. Species C, with 18 chromosomes, is thought to have arisen as a result of polyploidy of the other two species. Which of the following statements are true.
- C is likely a triploid version of species A
- C is likely to reproduce in an asexual manner
An plant is heterozygous for two genes (A and B) on the third chromosome. The alleles are in a coupled linkage arrangement. Normally genes A and B are 32 map units apart from each other. This plant has undergone an inversion on the third chromosome that occupies 1/2 of the space between genes A and B. If this plant is selfed, what is the percent chance that the offspring will have both recessive traits?
17.6 (with margin: 0.5)
0 (with margin: 0)
0 (with margin: 0)
0 (with margin: 0)
A section of a genome is cut with three enzymes: A, B, and C. Cutting with A and B yields a 10kb fragment. Cutting with B and C yields a 2kb fragment. What is the expected result from a digest with A and C, if the C site lies in between the A and B sites?
8kb
A linear DNA fragment is cut with a restriction enzyme to yield two fragments. How many restriction sites are there for the enzyme in this fragment?
1
The specificity of a PCR reaction is determined by
the sequence of the oligonucleotides
You identify an RFLP in mice by digesting genomic DNA with HindIII enzyme and radiolabeling a piece of probe DNA. Southern blot analysis shows that the probe detects a 2kb fragment in one strain of mice and a 4-kb fragment in another strain of mice. The two mice strains are crossed to produce an F1 generation. Two F1 siblings are mated to produce a dozen F2 progeny. You isolate genomic DNA from several F1 and F2 individuals, digest with HindIII, and perform a Southern blot with the same probe.How many bands would be seen in the Southern blot of an F2 individual?
Two of these answers could be correct
Selectable markers are usually used in studies involving transformation in large part because
transformation is usually very inefficient.
Which of the following is NOT true regarding the basic components required for a bacterial cloning vector?
Unique restriction enzyme sites allow for larger pieces of foreign DNA to be inserted into the bacterial cloning vector.
You are interested in a particular segment of rhinoceros DNA and would like to clone it into a cloning plasmid. You have the following restriction map of the region that includes the DNA of interest and the plasmid (E = EcoRI, H = HindIII, X = XbaI, S = SphI, N = NotI).
Which restriction enzymes would you choose to clone the DNA of interest into the cloning vector?
- X
- N
The function of DNA ligase in the generation of recombinant DNA is to
join DNA.
Which of the following oligonucleotides is the least likely to bind to template DNA multiple times?
ATCGGCTTAT
In a population of animals p = 0.7. The introduction of a predator to the environment causes the fitness of homozygous recessive individuals to have a fitness of 0.7 and homozygous dominant individuals to have a fitness of 0.1. Heterozygous individuals have a fitness = 1. One generation after introduction of the predator, what proportion of the population will be heterozygous?
50%
100 individuals whose genetic makeup is composed of 20% recessive alleles join an established population. The established population was composed of 600 individuals whose frequency of their recessive allele was 10%. When the population reaches Hardy Weinberg equilibrium, ____ of indviduals should have the dominant phenotype.
98.7%
Mutations
- generate the new alleles that make evolution possible
- by themselves only slightly change the frequency of alleles within a population
- can have no effect upon the functional ability of a protein
Which of the following statements are true concerning natural selection?
- Selection against a dominant allele can lead to complete elimination of that allele within a population.
- Genotypes with a w = 0 have no chance of passing their genes on to the next generation.
When carrying out a survey of butteflies on a remote island, you notice that 1/400 individuals have yellow wings, which is a recessive trait relative to the dominant trait blue wings. Assuming that this population is in Hardy Weinberg equilibrium, what is the allelic frequency of the recessive allele?
5%
In a population, 220 individuals are AA, 130 are Aa, and 50 are aa. If this population were in Hardy Weinberg equilibrium, you woud expect the frequency of homozygous dominant individuals to be ____
~ 0.508
In a population, 220 individuals are AA, 130 are Aa, and 50 are aa. The genotypic frequency of homozygous dominant individuals is _____
0.55
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