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Genetics and Molecular Biology > Exam 2 > Flashcards

Exam 2 Flashcards

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AP® Biology flashcards
1
Q

Ribosomopathies often result in:
A. defects in specific traits like the craniofacial skeleton
B. Diamond-Blackfan anemia
C. compensatory translation by RNA pol I instead of RNA pol II
D. transcription of 5S rRNA by RNA pol II instead of RNA pol I
E. enhanced translation of Duffy antigen

A

A. defects in specific traits like the craniofacial skeleton

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1
Q

Leading strand DNA replication involves:
A. polymerase alpha activity
B. addition of nucleotides in a 5’-to-3’ direction
C. synthesis of a single DNA primer per chromosome
D. formation of Okazaki fragments
E. initiation by an unusual 5’-to-2’ phosphate bond

A

B. addition of nucleotides in a 5’-to-3’ direction

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2
Q

The order of some molecular events in meiotic crossing-over is:
A. phosphodiester bond cleavage, strand invasion, branch migration, Holliday junction resolution
B. phosphodiester bond cleavage, branch migration, strand invasion, Holliday junction resolution
C. branch migration, Holliday junction formation, phosphodiester bond cleavage, strand invasion
D. strand invasion, phosphodiester bond cleavage, Holliday junction resolution, branch migration
E. Holliday junction formation, branch migration, strand invasion, phosphodiester bond cleavage

A

A. phosphodiester bond cleavage, strand invasion, branch migration, Holliday junction resolution

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3
Q

Which statement is true about congenital malformations?
A. they are caused by mutations affecting many different genes
B. they are only caused by recessive mutations
C. they are less likely to cause death than Alzheimer’s, stroke, diabetes and flu combined
D. they are often treatable with gene therapy
E. they are most often due to defects in chromatid pairing

A

A. they are caused by mutations affecting many different genes

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4
Q

The nucleolus of a cell is where:
A. mRNAs are transported to the cytoplasm for subsequent translation
B. mRNA translation occurs
C. large and small ribosome subunits attach to one another
D. RNA polymerase I localizes during ribosome assembly
E. defective mRNAs are degraded

A

D. RNA polymerase I localizes during ribosome assembly

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5
Q

Amino-acyl-tRNA synthetases charge tRNAs by
A. forming hydrogen bonds between codon and anticodon
B. forming covalent bonds between codon and anticodon
C. forming hydrogen bonds amino acids and codons
D. forming covalent bonds between amino acids and tRNAs
E. forming hydrogen bonds between amino acids and tRNAs

A

D. forming covalent bonds between amino acids and tRNAs

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6
Q

The centromere is characterized by:
A. acetyltransferase activity during chromatid pairing
B. specification of the DNA replication origin
C. progressive shortening during each cell cycle
D. AT-rich repeated sequence
E. localization of an H1 variant that promotes kinetochore assembly

A

D. AT-rich repeated sequence

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7
Q

Roberts syndrome best illustrates the:
A. critical function of gene conversion following cross-over in prophase I
B. consequences of chromosome non-disjunction during meiosis
C. loss of CDK-dependent cell cycle control in cancers of old age
D. importance of cohesin stabilization for chromatid pairing during mitosis
E. essential role of telomere rejuvenation during the eukaryotic life cycle

A

D. importance of cohesin stabilization for chromatid pairing during mitosis

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8
Q

For two genes on non-homologous chromosomes the expected frequency of crossing over is:
A. 0
B. 0.25
C. 0.5
D. 0.75
E. 1

A

A. 0

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9
Q

RNAs may be targeted for degradation when they
A. lack a polyA tail
B. have a premature termination codon
C. lack a termination codon
D. are misfolded
E. all of the above

A

E. all of the above

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10
Q

Which of the following is NOT likely to be required for chromosome packaging in mitosis?
A. condensin
B. topoisomerase
C. cohesin
D. nucleosomes
E. exosomes

A

E. exosomes

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11
Q

Replication in eukaryotic cells involves:
A. activation of condensins to disrupt nucleosomes downstream of the replication fork
B. repeated use of a single origin per chromosome arm
C. kinetochore binding to centromeric factors
D. selection of multiple origins from sites licensed by the Pre-Replication Complex
E. none of the above

A

D. selection of multiple origins from sites licensed by the Pre-Replication Complex

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12
Q

Which of the following is NOT true about meiosis?
A. sister chromatids attach to spindle fibers from opposite poles in metaphase I
B. homologous chromosomes synapse with one another
C. sister centromeres detach from each other in anaphase II
D. its products are haploid
E. crossing over occurs between non-sister chromatids in prophase I

A

A. sister chromatids attach to spindle fibers from opposite poles in metaphase I

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13
Q

The polyA tail of mRNAs functions to
A. protect the transcript from degradation
B. code for essential lysine (AAA) tails in the final protein
C. tether the RNA to the nuclear envelope during maturation
D. both A and B
E. both B and C

A

A. protect the transcript from degradation

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14
Q

Which of the following statements is true about cyclins and CDKs?
A. cyclins remain at constant abundance across the cell cycle and complexes formed between
cyclins and variably abundant CDKs permit phosphorylation of target proteins
B. cyclins change in abundance across the cell cycle and complexes formed between cyclins and
CDKs permit dephosphorylation of target proteins
C. cyclins remain at constant abundance across the cell cycle and complexes formed between
cyclins and variably abundant CDKs permit dephosphorylation of target proteins
D. cyclins change in abundance across the cell cycle and complexes formed between cyclins and CDKs permit phosphorylation of target proteins
E. none of the above

A

D. cyclins change in abundance across the cell cycle and complexes formed between cyclins and CDKs permit phosphorylation of target proteins

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15
Q

A major role of unphosphorylated Retinoblastoma protein is to:
A. promote entry into S phase, thereby leading to cancer progression
B. promote lamin phosphorylation, thereby leading to nuclear envelope dissolution
C. promote the degradation of CyclinD, thereby preventing entry into S phase
D. sequester the E2F transcription factor, thereby preventing entry into S phase
E. sequester CDK4, thereby preventing CyclinD phosphorylation

A

D. sequester the E2F transcription factor, thereby preventing entry into S phase

16
Q

p53 (TP53) induces expression of all of the following EXCEPT:
A. the gene encoding CDK inhibitor p21
B. genes encoding proteins that function in apoptosis
C. genes required for DNA repair
D. genes promoting the G1-to-S transition
E. genes required for programmed cell death

A

D. genes promoting the G1-to-S transition

17
Q

Meiosis contributes to genotypic diversity by:
A. promoting crossing over between maternal and paternal chromosome homologs
B. allowing pairs of homologous chromosomes to segregate independently of one another
C. ensuring that some gametes contain only maternal chromosomes and others contain only
paternal chromosomes
D. both A and B
E. both B and C

A

D. both A and B

18
Q

Which of the following statements about telomeres is accurate?
A. their length typically decreases within families during each passing generation
B. their repeating Leu-Gly codons (TTA-GGG) are binding sites for charged tRNAs
C. they become shorter because repeated sequences cannot be replicated accurately
D. they are rejuvenated by synthesis of DNA from an RNA template
E. they are a major site of transcription initiated by pioneer transcription factor binding

A

D. they are rejuvenated by synthesis of DNA from an RNA template

19
Q

Imagine you are interested in guinea pigs. Really seriously interested in guinea pigs. So you have
accumulated a large number of them. You decide to cross one of your brown, curly hair guinea pigs
with a black, straight hair guinea pig. The pups have four different phenotypes: (i) brown, curly; (ii)
black, straight; (iii) brown, straight; (iv) black, curly. The presence of recombinant phenotypes (ii, iv)
most likely indicates that:
A. there are two genes, both on the same chromosome, with crossing over between them
B. there are two genes, each on a different chromosome
C. there is single gene with different alleles that contribute to hair color and shape
D. A or B
E. A or C

A

D. A or B

20
Q

For an mRNA transcribed from a single-exon gene, a premature stop codon would most likely
result in:
A. nonstop decay
B. a shorter protein
C. mis-splicing
D. lack of 40S scanning
E. degradation by nuclear TRAMP complex

A

B. a shorter protein

21
Q

As DNA replication proceeds:
A. old histones are degraded and replaced with new histones that lack post-translational
modifications
B. old histones are returned to chromatin and new histones may be methylated to ensure local heterochromatic states in daughter cells
C. old histones are returned to chromatin and new histones are acetylated to ensure a
euchromatic state in daughter cells
D. old histones are degraded and new histones may be methylated to ensure a heterochromatic
state in daughter cells
E. old histones are returned immediately to chromatin and new histones and nucleosomes are
added in G1

A

B. old histones are returned to chromatin and new histones may be methylated to ensure local heterochromatic states in daughter cells

22
Q

Ribosomopathies are typically
A. found in homozygous individuals
B. found in heterozygous individuals
C. repaired by DNA ligase
D. more severe in each generation
E. mutations of the gene encoding the 60S subunit

A

B. found in heterozygous individuals

23
Q

An important function of serine/arginine-rich (SR) proteins is to:
A. bind polyA tails to promote ribosome dissociation
B. bind DNA to prevent splicing at adjacent sites
C. bind RNA to prevent splicing at adjacent sites
D. bind histone-3 tails to methylate CpG islands
E. bind premature termination codons to target defective mRNAs for degradation

A

C. bind RNA to prevent splicing at adjacent sites

24
Q

Which statement is false:
A. miRNAs often target transcripts of more than one gene
B. miRNAs can block ribosome translocation
C. miRNAs code for several different proteins
D. miRNAs regulate mRNA abundance
E. miRNAs are transcribed initially as longer transcripts

A

C. miRNAs code for several different proteins

25
Q

Without genomic alterations in tumor suppressor number, life-time cancer risk for an organism
would be expected to increase as:
A. body size increases
B. lifespan increases
C. cell number increases
D. all of the above
E. none of the above

A

D. all of the above

26
Q

The “wobble position” allows
A. recognition of different intron splice acceptor and splice donor sequences
B. promiscuous base-pairing and fewer tRNAs than codons
C. the usage of alternative Kozak sequences
D. transcriptional read-through of premature stop codons
E. tRNAs to remain upright at all times

A

B. promiscuous base-pairing and fewer tRNAs than codons

27
Q

mRNAs with upstream open reading frames (ORFs) typically have:
A. improved recruitment of the 40S subunit, thereby facilitating recognition of the main ORF
initiator codon and increasing translation of the main ORF
B. dissociation of 40S and 60S subunits before the main ORF initiator codon, thereby reducing translation of the main ORF
C. incorrect Kozak sequences causing misassembly of 40S and 60S subunits and reduced
translation of the main ORF
D. translation of short polypeptides that improve function of the low-activity protein encoded by
the main ORF
E. polyadenylation motifs within the 5’ UTR, allowing improved stability and longer perdurance of
the mRNA overall

A

B. dissociation of 40S and 60S subunits before the main ORF initiator codon, thereby reducing translation of the main ORF

28
Q

Lagging strand DNA replication involves:
A. an RNA primer
B. activity of a DNA ligase
C. strand synthesis in the 5’-3’ direction
D. all of the above
E. none of the above

A

D. all of the above

29
Q

Humans have remarkably high rates of aneuploidy that can lead to developmental abnormalities
causing spontaneous abortions or severe congenital defects at birth. The likelihood of aneuploidy
increases with:
A. the smaller the size of the chromosome being considered
B. the faster the rate of DNA replication
C. increased CENP-A synthesis in younger individuals
D. the longer it takes to complete meiosis
E. reduced telomerase activity in older individuals

A

D. the longer it takes to complete meiosis

Genetics and Molecular Biology (12 decks)

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