206 terms

Unit 4 Biology Review

In Mendel's time, most people believed that
characteristics of parents were blended in the offspring
Darwin did not know which mechanisms were responsible for the variation he saw
In his experiments with plants, Mendel removed which part of the plant to prevent unwantd fertilizations?
A locus is
the location of an allele on a chromosome
Various forms of a gene at a given locus are called
What indicates homozygous genotypes
AA and aa
What genotypes show dominant phenotypes
Aa and AA
Hybrid organisms produced from a cross between two pure-breeding organisms belong to which generation
F1 (first generation)
According to Mendel, what kind of genes "disappear" in F1 pea plants?
If R is dominant to r, the offspring of the cross of RR with rr will
display the same phenotype as the RR parent
Mendel found that pea plants expressing a recessive trait
were pure-breeding
If tall (D) is dominant to dwarf (d), and two homozygous varieties DD and dd are crossed, then what kind of offspring will be produced?
all tall
If tall (D) is dominant to dwarf (d), and two homozygous varieties DD and dd are crossed, then what kind of offspring will be produced?
all Dd
The F2 phenotypic ratio of a monohybrid cross is
If all offspring of a cross have the genotype Aa, the parents of the crosses would most likely be
AA x aa
Short hair (L) is dominant to long hair (l). If a short-haired animal of unknown origin is crossed with a long-haired animal and they produce one long-haired and one short-haired offspring, the results would indicate that
The short-haired animal was heterozygous
For Mendel's explanation of inheritence to be correct
which gametes combine at fertilazation had to be due to chance
The results of a testcross reveal that all offspring resemble the parent being tested. That parent necessarily is
The theory of segregation
explains the behavior of a pair of alleles during meiosis
If short hair (L) is dominant to long hair (l), then what fraction of the offspring produced by a cross of Ll ´ ll will be homozygous dominant?
none (no chance of this offspring)
Two brown dogs mated. Their offspring were five brown puppies and two white puppies. The most probable genotypes of the two brown dogs are
both Bb
Mendel's principle of independent assortment states that
Each hereditary unit is inherited separately from other hereditary units.
An individual with a genetic makeup of aa BB is said to be
If a child belonged to blood type O, he or she could not have been produced by which set of parents?
type AB mother and type O father
Susan, a mother with type B blood, has a child with type O blood. She claims that Craig, who has type A blood, is the father. He claims that he cannot possibly be the father. Further blood tests ordered by the judge reveal that Craig is AA. The judge rules that
Craig is right and doesn't have to pay child support.
If a child has an AB blood type, the parents
can have different blood types, but neither can be blood type O
Coat color in one breed of mice is controlled by incompletely dominant alleles so that yellow and white are homozygous, while cream is heterozygous. The cross of two cream individuals will produce
equal numbers of white and yellow mice, with twice as many creams as the other two colors
In incomplete dominance
One allele is not dominant to the other allele
In incomplete dominance
The genotype can be determinded by the phenotype
In incomplete dominance
The heterozygote is somewhat intermediate to the two homozygotes
In incomplete dominance
The intermediate phenotype may be the result of enzyme insufficiency
If a pure-breeding long-tail cat (LL) is crossed with a pure-breeding cat with no tail (rumpy, ll), and a cat with a short tail (stumpy) is produced, the simplest explanation is
an incompletely dominant gene
A gene that produces multiple effects is called a(n)
pleiotropic gene
Pleiotropic genes
influence more than one aspect of phenotype
Which of the following is not a known result of Marfan syndrome?
The aortic connective tissue becomes too thick and rigid
All of the genes located on a given chromosome comprise a
linkage group
If two genes are on the same chromosome,
They are in the same linkage group
Genes that are located on the same chromosome
tend to be inherited together
Genes that are located on the same chromosome
usually appear together in the gamete
Genes that are located on the same chromosome
are said to be linked
Genes that are located on the same chromosome
may be separated during crossing over
Genes on the same chromosome are separated from each other by
crossing over
Children born to light-skinned women exposed to high levels of sunlight have a heightened risk of birth defects because
UV radiation breaks down folate
This may be influenced by the enviroment
ability of plants to grow
This may be influenced by the enviroment
shape of Daphnia heads
This may be influenced by the enviroment
how people handle stress
This may be influenced by the enviroment
fur color in Himalayan rabbits
A bell-shaped curve of phenotypic variation is a representation of
continuous variation
Melanin pigment can be present in which eye colors
blue, hazel, brown
Green pod, purple flower, yellow seed coat, dwarf plant, axial flower position - Of these, which is not a dominant trait?
dwarf plant
Homozygous, carrier, heterozygotes, hybrid, Aa - Of these, which is not a heterozygoous condition?
pure breeding, homozygous, heterozygous, carrier, phenotype - Of these, which is not discriptive of gene makeup?
Chromosomes other than those involved in sex determination are known as
Sex chromosomes
determine sex
Sex chromosomes
vary from one sex to another
Sex chromosomes
carry some genes that have nothing to do with sex
Sex chromosomes
were unknonw to Mendel
Designates a normal human female
Designates a normal human male
The SRY gene is found on
the human Y chromosome
______ males have two of the same sex chromosomes
A karyotype
is a visual display of chromosomes arranged according to size
Chemical used to keep chromosomes from separating during metaphase
Karyotyping involves taking pictures of chromosomes during
achondroplasia, cysitic fibrosis, huntingtong disease, marfan syndrom, progeria - Of these, which is no an autosomal dominant genetic disorder?
Cysitc Fibrosis (autosomal recessive genetic disorder)
A normal woman mated with a man with achondroplasia whose father was normal. What is the chance that this mating will produce offspring with achondroplasia?
0.50 (50 percent)
is an autosomal recessive inheritance and must be homozygous to be expressed
A normal woman whose father had galactosemia mated with a normal man whose mother also was galactosemic. What is the chance that they will have galactosemic children?
0.25 (25 percent)
Progeria is caused by a(n)
spontaneous dominant mutation
A colorblind man and a woman with normal vision whose father was colorblind have a son. Colorblindness, in this case, is caused by an X-linked recessive gene. If only the male offspring are considered, the probability that their son is colorblind is
0.50 (50 percent)
A colorblind man and a woman with normal vision whose father was colorblind have a daughter. Colorblindness, in this case, is caused by an X-linked recessive gene. The probability that their daughter is colorblind is
0.50 (50 percent)
Red-green colorblindness is an X-linked recessive trait in humans. A colorblind woman and a man with normal vision have a son. What is the probability that the son is colorblind?
100 percent
Red-green colorblindness is an X-linked recessive trait in humans. What is the probability that a colorblind woman and a man with normal vision will have a colorblind daughter?
0 percent
If a daughter expresses an X-linked recessive gene, she inherited the trait from
both parents
A human X-linked recessive gene may be
passed to daughters from their fathers and to sons from their mothers
An X-linked carrier is a
heterozygous female
Colorblindness is an X-linked trait in humans. If a colorblind woman marries a man with normal vision,
Their sons will be colorblind; daughters will be carriers
A woman heterozygous for colorblindness (an X-linked recessive allele) marries a man with normal color vision. What is the probability that their first child will be colorblind?
25 percent
Queen Victoria
was a carrier of hemophilia
is rare in the human population
is more common among men
was common in English royalty
is an X-linked recessive trait
A chromosome's gene sequence that was ABCDEFG before modification and ABCDLMNOP afterward is an example of
A chromosome's gene sequence that was ABCDEFG before modification and ABCDCDEFG afterward is an example of
A chromosome that has been broken and rejoined in a reversal sequence has undergone
A chromosome's gene sequence that was ABCDEFG before damage and ABCFG after is an example of
A chromosome's gene sequence that was ABCDEFG before damage and ABFEDCG after is an example of
Cri-du-chat is caused by a(n)
Human chromosomes differ from chimpanzee chromosomes mainly by
The condition occurring when an organism has a 2n + 1 chromosome composition is known as
Down syndrome involves trisomy
The sex chromosome composition of a person with Turner syndrome is
The sex chromosome composition of a person with Klinefelter syndrome is
A genetic abnormality that may result in low fertility males with mental retardation or breast enlargement is
Males who tend to be taller than average and show mild mental retardation may have the _____ chromosome complement
Nondisjunction involving the X chromosomes may occur during oogenesis and produce two kinds of eggs. If normal sperm fertilize these two types, which of the following pairs of genotypes are possible?
None of these
What would be the least satisfactory organism for genetic research?
In a pedigree chart, a male showing the specific trait being studied is indicated by
darkened square
In a pedigree chart, a female who does not deomonstrate the trait being studied is represented by
clear circle
What is not inherited as an autosomal recessive
Marfan's syndrome
More common in males
How soon after conception is the best time for amniocentesis
8-12 weeks
Amniocentesis involves sampling
the fetal cells floating in the amniotic fluid
Amniocentesis is
used in prenatal diagnosis to detect chromosomal mutations and metabolic disorders in embryos
Chroionic villus sampling can be performed as early as _____ weeks after conception
Preimplantation diagnosis
relies on in-vitro fertilization
What membrane helps form the placenta and can yield cells for early prenatal diagnosis
symptoms of phenylketonuria (PKU) may be minimized or suppressed by a diet low in
Phenotypic treatments
may increase the number of defective genes in the population
What does not provide evidence that genes are located on chromosomes
enviromental factors may influence gene expression
What is not a related condition in which abnormal numbers of chromosomes are present
complete chromosome set
What organism is not widely used in genetic research
What condition is not caused by chromosomal nondisjunction
Huntington disorder
Inhibits microtuble assembly; prevents chromosome movement
a piece of the chromosome is inadvertently left out during the repair process
a repeat of a particular DNA sequence in the same chromosome or in nonhomologous ones
a chromosome segment that has been cut out and rejoined at the same place, but backward
(2n-1) a gamete deprived of a chromosome
a chromosome segment is permanently transferred to a nonhomologous chromosome
(2n+1) three chromosomes of the same kind are present in a set of chromosomes
Nondisjunction of the twenty first chromosomal pair
Down syndrome
autosomal recessive inheritence
x-linked recessive inheritance
nondisjunction of the sex chromosome
turner syndrome
autosomal recessive inheritance
autosomal dominant inheritance
huntingtons disease
x-linked recessive inheritance
autosomal recessive inheritence
sickle cell
Johann Miescher is credited with
discovering nucleic acids
The significance of Fred Griffith's experiment in which he used two strains of Streptococcus pneumoniae is that
it demonstrated that harmless cells had become permanently transformed through a change in the bacterial hereditary system
What is NOT true about Fred Griffiths experiment
mice injected with heat-killed S bacteria die
Which scientisits identified the transforming substance involved in changing R bacteria to S
Bacteriophages are
the significance of the experiments in which 32p and 35s were used is that
it demonstrated that radioactively labeled bacteriophages transfer their DNA but not their protein coats to their host bacteria
Nucleic acid contains
Hershey and Chase discovered that 35s and not 32p had been incorporated into the hereditary system of the bacteria
this statement is False
Experiment that determined DNA, not protein, was the hereditary material
Hershey and Chase
Sulfur is
found in proteins but not nucleic acids
The building blocks of nucleic acids are
amino acids, nucleotides, 5-carbon sugars, phosphate, nitrogenous bases - Of these, which does not belong?
amino acids
In the pairing of two nucleotides within the double helix
hydrogen bonds are used, adenine and thymine bind together, purines bind with pyrimidines, double ring nitrogenous bases connect to single ring bases - all of these
a nucleotide may contain
purine, pentose, phosphate group, pyrimidine
Rosalind Franklins research contribution was essential in
establishing most of the principal structural features of DNA
James Watson and Francis Crick
established the double-stranded nature of DNA
established the principle of base pairing
explained how DNA's structure permitted it to be replicated
proposed the concept of the doube-helix
In the bonding of nitrogenous bases
guanine is paired with cytosine
The DNA molecure could be compared to a
In DNA complementary base pairing occurs between
adenine and thymine
Adenine and guanine are
double ringed purines
Rosalind Franklin used which technique to determine many of the physical characteristics of DNA
x-ray diffraction
From x-ray diffraction data, what was determined about DNA
the molecule had two chains
phosphate groups formed the backbone
each turn of the helix contains 10 bases
the molecule could be a double helix
Each DNA strand has a backbone that consists of alternating
sugar and phosphate molecule
Rosalind Franklin's work established
the diameter of DNA
the distance between bases
the distance between chains
the angle of the helix
The best adjective to describe DNA replication is
Replication of DNA
produces two molecules, each of which is half new and half old DNA joined lengthwise to each other
DNA polymerase
is an enzyme
adds new nucleotides to a strand
proofreads DNA strands to see that they are correct
derives energy from nucleotide triphosphates for synthesis of DNA strands
DNA ligase
joins together fragments of DNA
Artificial twinning is a form of ______ cloning
Nuclear transfer
is used in adult cloning and helps convert a nucleus to a less differentiated state
This is not used to construct nucleic acids
A-C, C-G, A-T, T-A, Purine-pyrimidine: of these, which is incorrectly paired?
Who was not instrumental in the discovery of DNA's structure?
In 1944, reported that DNA was the "transforming principle"
Avery and colleagues
Obtained excellent x-ray diffraction photographs that suggested that DNA was a long, thin molecule with regularly repeating structures; also said that DNA had to be helical like a circular stairway
Rosalind Franklin
discovered that the hereditary system of one strain of bateria could be transformed by materials from another strain of bacteria
Fred Griffith
the first to demonstrae throught the use of radioactive isotopes that DNA not protein was the substance transmitted through generations of cells
Hershey and Chase
first to discover DNA and isolate it from fish sperm
Friedrich Miescher
Golden rice could alleviate blindess caused by deficiency in which vitamins?
vitamin A
New genetic combinations result from
crossing over
sexual reproduction
the exchange of genes between different species
Enzymes used to cut DNA molecules in recombinant DNA research are
restriction enzymes
The natural use of restriction enzymes by bacteria is to
destroy viral DNA
Restriciton enzymes
-often produce staggered cuts in DNA that are useful in slicing genes
-are like most enzymes in being very specific in their action
-are natural defense mechanisms evolved in bacteria to guard against or counteract bacteriophages
-are used along with ligase and plasmids to produce a DNA library
Enzymes that joing the sticky ends of DNA fragments
DNA ligase
Small circular molecules of DNA in bacteria are called
-are self reproducing circular molecules of DNA
-are sites for inserting genes for amplification
-may be transferred between different species of bacteria
-may confer the ability to donate genetic material when bacteria conjugate
Because it ahs no introns, researchers prefer to use ____ when working with human genes
RNA can manufacture DNA via the action of
reverse transriptase
cDNA is copied from
A collection of cells containing DNA fragments produced by restriction enzymes and incorporated into plasmids is called
a gene library
multiple copies of DNA can be produced by
-cloning a DNA library
-genetic amplifications
-the use of reverse transcriptase
-the action of DNA polymerase
The laboratory technique used to separate the DNA fragments produced by automated DNA sequencing is
gel electrophoresis
Who did NIH hire in 1988 to head the human genome project?
James Watson
About ___% of an individual's genes are the same as inthe general population
Disabling a gene to determine its action is called a(n) ___ experiment
knock out
E. Coli that contains the genes for human insulin is
-genetically engineered
-a GMO
Bacteria have been engineered to
-produce chymotrypsin
-digest crude oil
-take in heavy metals
-produce enzymes that improve the taste and clarity of beer
These plants have been engineered
-herbicide resistant cotton
-insecticide producing cotton
-drought resistant beans
-low lignin aspen
Scientists have actually changed mice to rats by genetic engineering
When the gene for rat somatotropin was injected into mouse eggs
the mice grew larger than normal
Genetically motified organs from what organism may be used to replace defective human organs
Gene therapy
offers the possibility of replacing defective alleles with normal ones
What human problem has been cured using gene therapy
In the SCID-X1 gene therapy trials, what problem later surfaced in three of the patients
this is not an aspect of the process of splicing
crossing over
this enzyme is not used in genetic engineering
cloned DNA is manufactured in bacterial cells
This plant has not been engineered
soybeans that grow human tissue
These are genetically identical organisms
When one uses the techniques of genetic engineering to move a novel or foreign piece of DNA into the DNA of an organism, these new DNA regions are known by this name
When pieces of DNA are moved by a genetic engineer from one organism to another, they are first incorporated into these entitles
the sole function of these is to cut apart foreign DNA molecules
restriction enzymes
these are specific sequences of DNA that can form sticky ends when cut
restriction sites
this is from a viral source and catalyes reaction to construct DNA strands from mRNA
reverse transcriptase
any DNA copied from mRNA transcripts is known by this name
this is the name of a nuclease whose only function is to cut apart foreign DNA entering a cell
restriction enzyme
collections of DNA fragments produced by restriction enzymes and incorporated into cloning vectors are known by this name
a DNA library