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IB 204 genetics practice questions exam 1

Terms in this set (64)

recessive traits are only visible in?
homozygous individuals
whose data provided the key piece of evidence that DNA is a helix leading to the discovery of the structure of DNA?
Rosalind Franklin
Which phenotype is not controlled by multiple genes interacting with each other and the environment?

A. depression
B. height
C. Lactose intolerance
C. lactose intolerance
How genetically similar are humans?
99.9% similar.
the other 0.1% are differences due to genetics and the environment.
What types of genetic differences are responsible for human genetic variation?

A. duplications
B. deletions
C. SNPs
D. all of the above
D. all of the above
Genes are?

A. probabilistic
B. deterministic
A. probablistic
What causes identical twins to be different?

A. gene expression
B. they have different alleles
C. SNPs
A. gene expression
Sickle cell anemia ___, is caused by a ____ in the beta-hemoglobin (Hb) ___ that changes a T to an A nucleotide, converting glutamine to a valine. In individuals that are ____ for the HbS (sickle cell) ___, hemoglobin molecules stick together, forming polymers that distort the shape of red blood cells into a "sickle" shape. Abnormally shaped cells can accumulate in blood vessels leading to blockages and severe pain. Anemia results as the abnormal red blood cells are rapidly broken down by the body


1. Allele, SNP, homozygous, trait, gene
trait, SNP, gene, homozygous, allele
Retinoblastoma protein (RB) binds to transcription factor E2F, this interaction

A. activates E2F stimulating transition to S-phase
B. deactivates E2F preventing transition to S-phase
B. deactivated E2F preventing transition to S-phase
Proto-oncogenes usually produce factors which

A. stimulate cell division
B. inhibit cell division
A. stimulate cell division
the most significant and general defect of cancer cells is

A. over-expression of many genes
B. inability to repair DNA damage
C. tendency to undergo programmed cell death (apoptosis)
D. chromosomal deletions
B. inability to repair DNA damage.
Individuals can be carriers of the Sickle cell trait but do not suffer from the disease, What type of trait is this an example of and how do carriers remain disease free?
1. Sickle cell anemia is a recessive disorder.
2. individuals who are heterozygous for sickle cell trait possess a functional copy of the gene so they are able to produce functional hemoglobin.
Gene therapy for Sickle Cell Anemia involves removing the patient's bone marrow stem cells, deleting the BCL11A gene via CRISPR, and re-implanting the edited cells. How does deleting the BCL11A lead to remission from symptoms?
Deleting BCL11A allows for production of healthy gamma hemoglobin (typically only found in babies) in adults which can replace the defective beta hemoglobin gene.
Retinoblastoma (RB) protein is an example of a tumor suppressor gene, this means that under normal conditions its role is to:

A. promotes apoptosis
B. promote cell cycle division
c. prevent cell cycle division
C. prevent cell cycle division
A mutation in the ras gene converts it into a form that is permanently bound to GTP. What does this do to ras activity, how does this impact signaling pathways that control cell division and what type of gene is the mutated ras?
Ras bound to GTP is switched on, therefore mutated ras activates cell division, and is an example of an oncogene.
What is the correct order for DNa packaging inside a eukaryotic cell
DNA --> nucleosome --> chromatin fiber --> chromatosome --> 30 nm fiber --> 300 nm fiber --> chromatid
what physical property of histone proteins allow DNA to tightly bind?

A. supercoiling
B. positive charge
C. negative charge?
B. positive charge
Eukaryotic DNA is packaged into chromatin fibers. What is the basic repeating structural, and functional unit of chromatin?

A. nucleosome
B. histone
C. chromatid
A. nucleosome
What type of DNA is highly condensed and has genes that are silenced or suppressed?

A. heterochromatin
B. euchromatin
A. heterochromatin
DNA looping and supercoiling of bacterial chromosomes is necessary to...

A. compact the DNA so it can fit inside the cell
B. localize the DNA to the end of a cell in order to allow bacteria to divide.
C. increase the size of DNA so that it can be accessed by transcription factors
A. compact the DNA so it can fit inside the cell
Which of the following is not an advantage of DNA storage?

A. it allows for fast repeated access to stored information
B. it allows for storage of vast amount of information in a small space
C. It allows for preservation of data for hundreds of thousands of year
A. it allows for fast repeated access to stored information
How was DNA re-purposed for storage of digital information?

A. individual nucleotides were converted into binary numbers
B. individuals codons were converted into analog signals
C. individuals codons were converted into binary numbers
D. individual nucleotides were converted to analog signals
C. individuals codons were converted into binary numbers
A nucleotide consists of

A. a sugar and nitrogenous base and one or more phosphate groups
B. nitrogenous base
C. a sugar and a nitrogenous base
A. a sugar and nitrogenous base and one or more phosphate groups
DNA secondary structure is formed from two antiparallel strands joined by hydrogen bonds between bases. Which base pairing is correct?

A. A with T
B. A with C
C. A with G
A. A with T
Nucleotides in a DNA strand are arranged in what orientation

A. 3' to 3'
B. 3' to 5'
C. 5' to 3'
D. 5' to 5'
C. 5' to 3'
Which is the most common form of DNA helix?

A. B
B. A
C. Z
A. B
Core histones make up the histone octamer around which DNA wraps to form a nucleosome. Which protein families are core histones?

A. H1 and H5
B. H1, H2A, H2B, H3, H4, H5
C. H2A, H2B, H3, H4
D. H1, H3
C. H2A, H2B, H3, H4
Centromeres are made up of short repetitive sequences of DNA, what type of chromatin fiber is formed?

A. euchromatin
B. facultative heterochromatin
C. constitutive heterochromatin
C. constitutive heterochromatin
histone acetylation results in chromatin that is

A. loosely packed
B. tightly packed
C. supercoiled
A. loosely packed
list three pieces of evidence that support the endosymbiotic theory:
1. Chloroplasts and mitochondria are the same size as prokaryotic cells, both divide by binary fission, and some have Fts proteins/homologous at their division plane

2. Mitochondria and chloroplasts have their own DNA that is circular not linear

3. Mitochondria and chloroplasts have their own ribosomes that have 30s and 50s subunits instead of 40s
mitochondrial proteins are encoded

A. in both mitochondrial and nuclear genomes
B. only in the mitochondrial genome
C. only in the nuclear genome
A. in both mitochondrial and nuclear genomes
Mitochondrial DNA is inherited from
A. mothers
B. fathers
C. both
A. mothers
Mitochondrial Eve lived 200,000 years ago, she was:

A. the partner of Y-chromosome Adam
B. the mother of all humans alive
C. The first human
B. the mother of all humans alive
The impact of mitochondrial mutations can vary between cells in a body, this is because

A. mitochondrial mutations are only detrimental at certain stages of development
B. different cells can have different numbers of defective mitochondria
C. mitochondrial mutations impact the function of specific tissues.
B. different cells can have different numbers of defective mitochondria
Which of the following statements is true? membrane bound organelles:

A. promote mixing of the cellular machinery to speed up reactions
B. separate cellular machinery to provide conditions for specific activities.
B. separate cellular machinery to provide conditions for specific activities.
Do mitochondrial (mtDNA) and chloroplast (cpDNA) DNa interact with histones?

A. Yes
B. no
B. No
Three person babies are a treatment for heritable mitochondrial disease, how are they created?

A. by fertilizing a mothers egg with donor sperm from a healthy man
B. by fertilizing a donor egg from a healthy woman with a father's sperm
C. by transplanting the nucleus of an impacted mother into a healthy donor egg for fertilization with the father's sperm.
C. by transplanting the nucleus of an impacted mother into a healthy donor egg for fertilization with the father's sperm.
what organism are mitochondria thought to be most closely related to?

A. protozoa
B. N2 fixing cyanobateria
C. Rickettesia bacteria
C. Rickettesia bacteria
Which one of the following situations is not likely to lead to mitochondrial disease?

A. all mitochondria in a cell are defective
B. the percentage of defective mitochondria is above 60-70%
C. a single mitochondria cell is defective
C. a single mitochondria cell is defective
During replication, the DNA double helix is unwound by the action of

A. topoisomerase
B. helicase
C. primase
B. helicase
during replication, supercoiling can cause over-winding of the DNA, this is prevented by the action of

A. topoisomerase
B. helicase
C. primase
A. topoisomerase
DNA synthesis proceeds from

A. 3' to 3'
B. 3' to 5'
C. 5' to 3'
D. 5' to 5'
C. 5' to 3'
The end replication problem refers to difficulties in copying linear chromosomes, this is overcome by the activity of telomerase, which:

A. synthesizes an RNA primer at the 3' end to start DNA replication
B. elongates the parental strand at the 3' end using an RNA template
C. completes synthesis of the lagging strand using a primase
B. elongates the parental strand at the 3' end using an RNA template
DNA replication is described as "semi-conservative" this means that. after every round of replication

A. half of the new DNA double helices are composed of entirely old DNA, and the other is completely new
B. double helices are hybrids of old and new DNA, with greater amounts of new DNA following each round
C. Double helices consist of one strand of old DNA bound to one strand of newly synthesized DNA
C. Double helices consist of one strand of old DNA bound to one strand of newly synthesized DNA
How would DNA replication be affected in a cell lacking DNA gyrase (topoisomerase)

A. DNA replication would occur, but at a slower rate
B. supercoiling would be reduced
C. DNA replication would halt
C. the leading and lagging strands would switch
C. DNA replication would halt
What would be the result of a mutation that increases MCM expression?

A. enhanced DNA replication
B. Stalled DNA replication
C. Cell proliferation
D. Disproportionate replication rate of the leading and lagging strand
E. A and C
E. A and C
How does telomere length change through a cell lineage? what telomere treatment is proposed to alter longevity? is it proven and what are the risks?
Throughout a cell's lineage, the telomere length shortens. Gene therapy can reverse normal telomere shortening in order to reverse aging and increase lifespan. This has not been proven in humans, although studies using mice have shown good results. The risk of lengthening telomeres is cancer. Lengthened telomeres can make cancer cells immortal and telomerase is expressed in 90% of cancer cells.
a point mutation causes the following change to DNA:

A. change in the orientation of a chromosomal fragment
B. change in a single nucleotide
C. change in the number of tandem copies of a specific locus
B. change in a single nucleotide
one type of beta-thalassemia is caused by

A. an insertion
B. a substitution
C. a deletion
A. an insertion
de-amination can circumvent DNA repair mechanisms and lead to base pair substitutions because

A. deamination results in base pair excision leading to a deletion
B. deamination converts methylated cytosine to thymine
C. deamination convers cytosine to uracil causing a base-pair mismatch
B. deamination converts methylated cytosine to thymine
Damage to DNA by UV light can cause adjacent nucleotides to stick together, this is repaired by

A. nucleotide repair
B. homologous recombination
C. base excision repair
A. nucleotide repair
dsDNA breaks are the most damaging types of mutation. Which type of repair mechanism can introduce mutations, deletions, and fusions in an effort to fix dsDNA breaks?

A. direct reversal
B. homologous recombination
C. Non-homologous end-joining
C. Non-homologous end-joining
What is the genetic cause of thalassemia?

A. mutation in the HBA and HBA2 genes
B. mutations in the HBB gene on chromosome 11
B. mutations in the HBB gene on chromosome 11
A codon that specifies the amino acid glutamine in the beta hemoglobin gene undergoes a single base substitution to become a mis-sense mutation GAG --> GTA. This mutation is

A. transition
B. transversion
B. transversion
Which general transcription factor recognizes and binds to the TATA box?

A. TFIID
B. TFIIA
C. TBP
C. TBP
mRNA stands for messenger RNA which is produced during transcription, this is made up of the bases

A. A T C G U
B. A C G U
C. A T C G
B. A C G U
Write the consensus sequence for the following set of nucleotide sequences:
A G G A G T T
A G C T A T T
T G C A A T A
A C G A A A A
T C C T A A T
T G C A A T T

hint pyrimidines= Y purines= R no base is more common= N
A/TGCARTT
Sex-determination in turtles involves alternate splicing of a transcription factor. Why would intron inclusion result in a truncated protein?

A. intron inclusion results in 5' de-capping of the transcript
B. intron inclusion results in a shorter transcript
C. intron inclusion results in a longer transcript
D. intron inclusion results in a premature stop codon.
D. intron inclusion results in a premature stop codon.
Which site is the growing amino acid chain bound to within the ribosome, before the transfer of an amino acid?

A. P
B. E
C. A
A. P
In bacteria the ribosome is positioned to allow binding of the initiator tRNA by

A. the Shine-Dalgarno sequence
B. The 5' mRNA cap
C. The AUG start codon
A. the Shine-Dalgarno sequence
in eukaryotes the initiator tRNA

A. catalyzes translocation along the mRNA chain
B. Identifies the start codon during scanning of mRNA
C. Starts the process of translation
B. Identifies the start codon during scanning of mRNA
GTPase activity of initiation factor eEF2 catalyzes

A. Translocation of the ribosome along the mRNA
B. selection and release of an aminoacyl-tRNA into the A site of the ribosome
C. Proofreading of the aminoacyl-tRNA to ensure high fidelity of translation
A. Translocation of the ribosome along the mRNA
in eukaryotes translation termination occurs when

A. The ribosome subunits dissociate from the mRNA and the remaining tRNA molecules are released
B. eRF1 binds in the A site and catalyzes hydrolysis of the peptidyl tRNA
C. The ribosome reaches the end of an mRNA and falls off
B. eRF1 binds in the A site and catalyzes hydrolysis of the peptidyl tRNA
Tetracycline antibiotics target both gram positive and gram negative bacteria by inhibiting initiation of translation. Using your knowledge of the process, infer which of the following mechanisms they use

A. attaching to the m7G cap preventing binding of the pre-initiation complex
B. attaching to the 30s subunit and preventing aa-tRNA binding at the A site
C. attaching to the P site, preventing peptide bond formation
B. attaching to the 30s subunit and preventing aa-tRNA binding at the A site
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