BIOL Exam 3
What is the function of histone proteins? A. to organize the microtubules that make up the spindle B. to connect chromosomes to the mitotic spindle C. to attach sister chromatids together D. to package DNA in eukaryotic chromosomes
A. to organize the microtubules that make up the spindle
Failure of cell division in anaphase in meiosis can result in a:Select all that apply. A. triploid fertilized egg. B. haploid gamete. C. diploid fertilized egg. D. diploid gamete.
A. triploid fertilized egg. D. diploid gamete.
Restriction enzymes cleave double-stranded DNA at the sites that show a particular type of symmetry; these sequences read the same on both strands and are called palindromes. Which of these sequences is not a palindrome? A. 5'-GGTACC-3' B. 5'-CCTCAGG-3' C. 5'-CGGCCG-3' D. 5'-CCTGCAGG-3' E. 5'-AGATCT-3'
B. 5'-CCTCAGG-3'
How would the loss of p53 activity affect a cell? A. DNA damage could accumulate. B. All of these choices are correct. C. The G1/S checkpoint would not be functional. D. CDK activity would not be appropriately regulated.
B. All of these choices are correct.
Which statement below is false: A. Meiosis creates gametes while mitosis creates somatic cells B. At the end of meiosis I the two daughter cells are diploid C. meiosis is the division of a cell into four genetically different cells D. mitosis is the division of a cell into two genetically identical daughter cells
B. At the end of meiosis I the two daughter cells are diploid
How does meiosis generate genetic diversity? A. random alignment of homologs at metaphase I only B. synapsis C. both crossing over at prophase I and random alignment of homologs at metaphase I D. crossing over in prophase II
C. both crossing over at prophase I and random alignment of homologs at metaphase I
The amount of _____ is fairly constant throughout the cell cycle, but the amount of _____ varies. A. DNA; cyclins B. cyclin-dependent kinases; cyclins C. cyclin-dependent kinase; DNA D. cyclins; DNA
C. cyclin-dependent kinase; DNA
Any mutation that increases the risk of disease in an individual is known as a: A. genetic load. B. predisposition factor. C. genetic risk factor. D. transmission mutation. E. somatic mutation.
C. genetic risk factor.
Name the stages of meiosis below, from cell #1 through #8. Ignore any lines pointing to chromosomes in #3 & #4. Be sure to indicate I or II in each of your answers. Answer options: prophase I, prophase II, metaphase I, metaphase II, anaphase II, anaphase I, cytokinesis, telophase I, telophase II 1. 2. 3. 4. 5. 6. 7. 8.
1. anaphase I 2. anaphase II 3. prophase I 4. metaphase I 5. metaphase II 6. telophase I 7. prophase II 8. telophase II
The picture below illustrates DNA replication. Study the picture carefully and use the dropdown boxes to select the name of each important labeled part of the process. ("DNA polymerase I", "helicase", "Primase", "DNA ligase", "RNA primer", "Single Stranded Binding Protein", "Okazaki fragment", "Topoisomerase", "DNA polymerase III") 1. 2. 3. 4. 5. 6. 7. 8.
1. helicase 2. single stranded binding proteins 3. primase 4. RNA primer 5. DNA polymerase III 6. okazaki fragment 7. DNA ligase 8. DNA polymerase I
If there are 20 centromeres in a cell at anaphase, how many chromosomes are there in each daughter cell after cytokinesis takes place? A. 10 B. 40 C. 80 D. 20
A. 10
A new nucleotide can only be added to the A. ("3'", "5'") end of a growing DNA strand. DNA therefore always grows in the B. ("5' to 3'", 3' to 5'") direction.
A. 3' B. 5' to 3'
Consider a diploid organism with a haploid complement of 4 chromosomes in its gametes. At meiotic prophase I, how many total chromosomes copies will be present in a cell? A. 8; 4 pairs of homologous chromosomes B. 16; 4 pairs of homologous chromosomes and 2 sister chromatids per chromosome C. 4; 1 complete set of chromosomes D. 12; 4 pairs of homologous chromosomes and their haploid complement
A. 8; 4 pairs of homologous chromosomes
Cell cycle checkpoints: A. All of these choices are correct B. can be blocked by the protein p53. C. act as a brake on cell division if something is not right. D. provide opportunities to check if the cell has carried out steps necessary for cell division.
A. All of these choices are correct
All of these events happen during M phase except: A. synthesis of DNA. B. condensation of the chromosomes. C. formation of the spindle. D. separation of sister chromatids.
A. synthesis of DNA.
A couple has a baby that only has one X chromosome and no Y chromosome. This could have occurred because: A. All of these choices are correct. B. there was nondisjunction of the sister chromatids in meiosis II in the mother. Meiosis in the father was normal. C. there was nondisjunction of sister chromatids in meiosis II of the father. Meiosis in the mother was normal. D. there was nondisjunction of homologous chromosomes in meiosis I in the mother. Meiosis in the father was normal. E. there was nondisjunction of the paired X and Y chromosomes in meiosis I in the father. Meiosis in the mother was normal.
A. All of these choices are correct.
Genetic risk factors: A. All of these choices are correct. B. can increase the likelihood of diseases. C. can work synergistically with environmental risk factors. D. include mutations in the BRCA1 and BRCA2 genes. E. can be heritable.
A. All of these choices are correct.
What procedure could be used after PCR is complete to make certain that the amplification process worked properly and that the correct sequence was amplified? A. DNA sequencing B. None of the answer options is correct. C. DNA denaturation D. DNA hybridization E. gel electrophoresis
A. DNA sequencing
Here is a list of meiotic events in random order.A-Segregation of homologous chromosomes to opposite poles.B-Segregation of sister chromatids to opposite poles.C-Alignment of homologous pairs on the midplate of the cell.D-Pairing and synapsis of homologous chromosomes.E-Condensation of chromosomes in a diploid nucleus. What is the correct order of events? A. EDCAB B. DCABE C. CDEAB D. EDCBA E. DCEBA
A. EDCAB
Which of the statements are true of both first- and second-division nondisjunction? Select all that apply. A. Gametes are produced with missing chromosomes. B. Homologous chromosomes fail to separate. C. Sister chromatids fail to separate. D. Gametes are produced with extra chromosomes. E. Half of the gametes produced are wild-type, whereas half are mutated.
A. Gametes are produced with missing chromosomes. D. Gametes are produced with extra chromosomes.
Which of the statements are true of mitotic cell division? Select all that apply. A. It is a carefully regulated process that only occurs in certain conditions during the life of a cell. B. It occurs in eukaryotes but not in prokaryotes. C. It does not require DNA replication. D. It is a process that ends once development is complete and no longer occurs in adult organisms. E. It is a form of sexual reproduction.
A. It is a carefully regulated process that only occurs in certain conditions during the life of a cell. B. It occurs in eukaryotes but not in prokaryotes.
Would genetic recombination result if crossing over occurred between sister chromatids? A. No, because many genes are present along the entire length of a chromosome. B. Yes, because any rearrangement of DNA produces new combinations of alleles. C. No, because sister chromatids are genetically identical or nearly identical. D. Yes, because genetic diversity would decrease due to the loss of gene combinations.
A. No, because many genes are present along the entire length of a chromosome.
Which of the statements is true regarding origins of replication? A. None of the answer options is correct. B. Circular DNA always has between 2 and 3 origins of replication. C. Eukaryotic DNA always has one origin of replication. D. Origins of replication are synonymous with replication forks. E. The replication bubbles associated with different origins of replication never fuse.
A. None of the answer options is correct.
How might a single base substitution in the sequence of a gene affect the amino acid sequence of a protein encoded by the gene, and why? A. Only a single amino acid could change, because the reading frame is unaffected. B. It is not possible for a single base substitution to affect protein structure, because each codon is three bases long. C. All amino acids following the substitution would be affected, because the reading frame would be shifted. D. The amino acid sequence would be substantially altered, because the reading frame would change with a single base substitution.
A. Only a single amino acid could change, because the reading frame is unaffected.
Which of the choices is an accurate statement that accounts for why women with the genotype XXX are not phenotypically different from an XX female? A. Only one X chromosome is active in each cell, regardless of how many X chromosomes there are in a cell. B. The extra X chromosome only becomes active in nonreproductive areas of the body. C. None of the answer options is correct. D. Cells normally have enzymes that recognize and degrade extra X chromosomes. E. The X chromosome only carries genes dealing with being a female, so having another one doesn't matter.
A. Only one X chromosome is active in each cell, regardless of how many X chromosomes there are in a cell.
Which events would happen to a cell if cyclin levels were always high in the cell? Select all that apply. A. The cell would divide rapidly. B. Cyclin-dependent kinases would not be activated. C. The cell cycle would not stop at checkpoints. D. Protein substrates of CDKs would be constantly phosphorylated.
A. The cell would divide rapidly. C. The cell cycle would not stop at checkpoints. D. Protein substrates of CDKs would be constantly phosphorylated.
Which of the answer choices is most likely to result in a nonfunctional polypeptide? A. a nonsense mutation B. a missense mutation C. a silent mutation
A. a nonsense mutation
At which checkpoint would a cell become arrested if a chromosome was not properly aligned in the spindle? A. at a checkpoint early in the mitotic phase B. at a checkpoint late in G2 phase C. at a checkpoint late in G1 phase D. None of the answer options is correct.
A. at a checkpoint early in the mitotic phase
Insertions and deletions of single nucleotides: A. cause frameshift mutations. B. shorten chromosomes. C. cause cancer. D. add or delete amino acids to or from the normal polypeptide. E. cause missense mutations.
A. cause frameshift mutations.
A nonsense mutation: A. changes a codon for an amino acid into a stop codon. B. changes the identity of one amino acid in a polypeptide chain. C. shifts the reading frame of a messenger RNA. D. is usually due to a nucleotide substitution in the third position of a codon.
A. changes a codon for an amino acid into a stop codon.
Which of the answer choices may occur when a transposable element inserts into a gene? Select all that apply. A. errors in RNA processing B. interference with transcription C. disruption to the open reading frame D. the gene duplicates itself
A. errors in RNA processing B. interference with transcription C. disruption to the open reading frame
Which of the statements is true regarding DNA replication of a linear chromosome? A. Both strands get shortened at the same end during replication. B. Both strands get shortened at opposite ends during replication. C. Only the leading strand gets shortened during replication. D. Only the lagging strand gets shortened after every other round of replication. E. Only the lagging strand gets shortened during replication.
B. Both strands get shortened at opposite ends during replication.
The difference between DNA polymerase and RNA polymerase is A. DNA polymerase removes DNA nucleotides from the primer during DNA replication while RNA polymerase adds RNA nucleotides to a growing strand of an RNA transcript B. DNA polymerase adds new DNA nucleotides to a growing daughter strand of DNA while RNA polymerase adds RNA nucleotides to a growing strand of an RNA transcript C. DNA polymerase removes DNA nucleotides from the primer during DNA replication while RNA polymerase adds RNA nucleotides as the primer in DNA replication D. DNA polymerase adds new DNA nucleotides to a growing daughter strand of DNA while RNA polymerase adds RNA nucleotides as the primer in DNA replication
B. DNA polymerase adds new DNA nucleotides to a growing daughter strand of DNA while RNA polymerase adds RNA nucleotides to a growing strand of an RNA transcript
The unlettered circle at the top of the figure shows a diploid nucleus with four chromosomes that have not yet replicated. There are two pairs of homologous chromosomes, one long and the other short. One haploid set is black, and the other is gray. The circles labeled A to E show various combinations of these chromosomes. What is the correct chromosomal condition for one daughter nucleus at telophase of mitosis? A. B B. E C. D D. A E. C
B. E
hich of the statements is true regarding CDKs? A. CDKs are active in cells that enter G0 phase of the cell cycle. B. Loss of CDK activity would lead to cancer. C. CDKs are active except when they bind to cyclins. D. The levels of CDKs change with the cell cycle.
B. Loss of CDK activity would lead to cancer. ??
A woman has her genome sequenced and finds that she carries a mutation in p53. Will she develop cancer? A. No, mutations in p53 do not contribute to cancer. B. Possibly; this mutation is likely to predispose her to developing certain types of cancer. C. Yes, she will certainly develop cancer given the role of p53 in the cell cycle.
B. Possibly; this mutation is likely to predispose her to developing certain types of cancer.
The graph at the bottom is depicting the amount of DNA inside cells. Most of the cells examined during interval A have half as much DNA as those measured in interval C. Therefore, most of the cells at interval B must have been in____ while those in interval D were in____ A. G2; mitosis B. S phase; cytokinesis C. G0; mitosis D. G1; cytokinesis E. S phase; G2
B. S phase; cytokinesis
A crime lab has run DNA samples from a crime scene, the victim, and 3 different suspects. They have tested the DNA to determine who committed the crime and the gel electrophoresis results can be seen in the figure below. Based on the gel, which suspect most likely left their DNA at the crime scene? A. Suspect 1 B. Suspect 2 C. Suspect 3 D. Suspect 1 and 2 E. There is no way to tell. This gel is crazy.
B. Suspect 2
Which of the statements is true when a cell has a mutation in the p53 gene, such that the p53 protein is not able to be phosphorylated? A. The cell would arrest, giving time for the DNA damage to be repaired. B. The cell would proceed through the cell cycle even in the presence of DNA damage. C. Nothing would change in the cell cycle, because the p53 protein is normally not able to be phosphorylated. D. The amount of p53 protein in the nucleus would increase in response to DNA damage.
B. The cell would proceed through the cell cycle even in the presence of DNA damage.
Why are telomeres a necessary component of linear chromosomes? A. They fix mistakes that are made during DNA replication. B. They maintain the length of a chromosome because DNA is shortened every time it is replicated. C. None of the answer options is correct. D. They direct where DNA synthesis will end. E. They direct where DNA synthesis will begin.
B. They maintain the length of a chromosome because DNA is shortened every time it is replicated.
Which of these compounds would be most likely to arrest (stop) cells in S Phase? A. emetine: an inhibitor of ribosome activity (and therefore protein synthesis) B. aphidicolin: an inhibitor of DNA polymerase activity C. all of the above D. colchicine: an inhibitor of microtubule (mitotic spindle) formation E. cytochalasin: an inhibitor of actin microfilament assembly
B. aphidicolin: an inhibitor of DNA polymerase activity
The microtubules that form the mitotic spindle extend out from the centrosome. Where would you expect to find the plus (fast-assembling) end of a spindle microtubule? A. away from the centrosome and away from the kinetochore B. away from the centrosome and toward the kinetochore C. toward the centrosome and away from the kinetochore D. toward the centrosome and toward the kinetochore
B. away from the centrosome and toward the kinetochore
One characteristic of restriction enzymes is that they: A. cut double-stranded DNA strands at random sites B. cut single-stranded DNA strands at specific sites C. cut DNA fragments generated by gel electrophoresis D. cut double-stranded DNA strands at specific sites. E. cut single-stranded DNA strands at random sites
B. cut single-stranded DNA strands at specific sites.
Which of these is necessary for the first step of PCR? A. DNA polymerase B. original template DNA C. DNA primers D. All of these choices are correct. E. the four DNA nucleotides
B. original template DNA
Colchicine is a drug that blocks the assembly of microtubules. If dividing cells are treated with colchicine, at what stage of mitosis would you predict the arrest would occur? A. G2 of interphase B. prophase C. telophase D. late anaphase E. metaphase
B. prophase
Normally, in corn, genes for waxy and virescent kernel appearance are located in the same chromosome. In a certain stock, however, it was found that these two genes are in different chromosomes. Which chromosomal aberration would explain this? A. None of the other answer options is correct. B. translocation C. duplication D. deletion E. inversion
B. translocation
Which of the answer choices explains a flower showing multiple sections with different coloration? A. deletion B. transposable elements C. polyploidy D. reciprocal translocation E. germ-line mutation
B. transposable elements
Which one of the sequences is most likely a restriction enzyme recognition sequence? A. 5' C T G G T C 3' 3' G A C C A G 5' B. 5' A C T T C A 3' 3' T G A A G T 5' C. 5' C T G C A G 3' 3' G A C G T C 5' D. 5' T A C G A T 3' 3' A T G C T A 5'
C. 5' C T G C A G 3' 3' G A C G T C 5'
At the start of mitosis, how many sister chromatids are present in a human cell? A. 46 B. 12 C. 92 D. 23
C. 92
Why don't plant cells use a contractile ring to divide their daughter cells? A. Plant cells don't form daughter cells. B. Plant cells don't have an actin cytoskeleton. C. A contractile ring can't "pinch" a cell wall. D. Plant cells don't have plasma membranes.
C. A contractile ring can't "pinch" a cell wall.
What is polymerase chain reaction? A. A method to amplify a message inside the cell B. A type of restriction enzyme C. A method to amplify a sequence of DNA D. The elongation of DNA during replication
C. A method to amplify a sequence of DNA
RNA is involved in which of the cellular processes? A. translation B. DNA replication C. All of these choices are correct. D. transcription
C. All of these choices are correct.
The flower in the figure shown has this color pattern because there is a transposable element inserted into the gene that causes purple pigment to be deposited in the flower petal cells. How could the movement of the transposable element cause the purple sectors? A. The transposable element could be in an intron of the flower-color gene and could prevent proper RNA splicing. When the transposable element jumps out, correct RNA processing can occur. B. The transposable element could occur in the promoter of the purple color gene blocking transcription. When the transposable element jumps out, it restores proper transcription. C. All of these choices are correct. D. The transposable element could cause a frameshift mutation in the coding sequence of the purple color gene. When the transposable element jumps out of the gene, the normal reading frame is restored.
C. All of these choices are correct.
What would happen if a pair of sister chromatids only connected to the mitotic spindle at one of their kinetochores? A. The chromosome would not line up properly at metaphase. B. The sister chromatids would not separate. C. All of these choices are correct. D. One of the daughter cells would have an extra copy of that chromosome.
C. All of these choices are correct.
The unlettered circle at the top of the figure shows a diploid nucleus with four chromosomes that have not yet replicated. There are two pairs of homologous chromosomes, one long and the other short. One haploid set is black, and the other is gray. The circles labeled A to E show various combinations of these chromosomes. What is the correct chromosomal condition at prometaphase of mitosis? A. A B. D C. B D. E E. C
C. B
If a mutation occurs that blocks the function of RNA primase, which synthesis of which strand is affected, and why? A. The leading strand is affected because it leads DNA synthesis. B. The lagging strand is affected because it requires an RNA primer for each Okazaki fragment produced. C. Both strands are affected because all DNA polymerase can only add new nucleotides to a 3′-OH present at the end of the RNA primer.
C. Both strands are affected because all DNA polymerase can only add new nucleotides to a 3′-OH present at the end of the RNA primer.
Which of the following enzymes is the first to bind to the DNA sequences at the origin of replication to begin DNA replication? A. single-strand binding protein B. DNA ligase C. DNA helicase D. DNA primase E. DNA polymerase
C. DNA helicase
In observing DNA replication in the lab, you notice that in some cells, a defect occurs where DNA replication proceeds, but the RNA primers are not removed and replaced with DNA. Which enzyme is most likely to be defective in this system? A. DNA ligase B. DNA polymerase III C. DNA polymerase I D. primase
C. DNA polymerase I
Which of the statements is true regarding chromosome replication in eukaryotes? A. In humans, it takes several days to replicate an entire chromosome. B. Replication bubbles remain distinct, isolated structures during chromosome replication and never fuse with one another. C. During chromosome replication, multiple origins of replication form for all DNA in a cell. D. Replication begins at one end of the chromosome and proceeds until it reaches the opposite end. E. None of the answer options is correct.
C. During chromosome replication, multiple origins of replication form for all DNA in a cell.
In the polymerase chain reaction _____ is/are used to take the place of helicase in the DNA replication process. A. None of these B. Restriction enzymes C. Taq polymerase D. Heat E. DNA primers
C. Heat
What is a major difference between meiosis II and mitosis in a diploid animal? A. Sister chromatids separate in mitosis, and homologues separate in meiosis II. B. Crossover takes place in meiosis II. C. Meiosis II occurs in a haploid cell, while mitosis occurs in diploid cells. D. Homologues align on the metaphase plate in meiosis II.
C. Meiosis II occurs in a haploid cell, while mitosis occurs in diploid cells.
What would happen if telomerase stopped working in a cell in which it normally functions at high levels? A. The cell would die immediately because DNA could not be replicated. B. Nothing, telomerase does not have a major function in the cell C. The cell would eventually die because the chromosomes would shortened with each replication. D. The cells would be able to divide indefinitely because the chromosomes would never shorten E. Cancer would be the result because cells would grow uncontrollably.
C. The cell would eventually die because the chromosomes would shortened with each replication.
Which of the reasons explains why bacteria can continually divide while they maintain the length of their chromosome? A. because they only have one chromosome B. because they are so simple C. because their DNA is circular, it never shortens after replication D. because they have plasmids E. because DNA replication is much quicker in bacteria than in eukaryotes
C. because their DNA is circular, it never shortens after replication
The accompanying table gives hypothetical data on the average length of telomeres among groups of people that differ in the lifestyle variables of stress, level of vigorous exercise, and daily caloric intake. To test the hypothesis that "high levels of stress have an effect on average length of telomeres," which groups would you compare? A. group 3 and group 4 B. group 1 and group 2 C. group 2 and group 3 D. group 1 and group 3 E. group 1 and group 4
C. group 2 and group 3
A DNA molecule is cut with two different restriction enzymes known to cleave it only once each. After gel electrophoresis, three different DNA fragments are detected. This result means that the original DNA molecule was: A. It is not possible to make this determination from the information provided. B. circular. C. linear.
C. linear.
Prokaryotic cells and eukaryotic cells reproduce by asexual cell division. Regardless of the type of cell, all cells must __________________ before they divide. A. reconstruct their nucleus B. none of these are correct C. make a copy of their genetic information D. complete meiosis E. complete mitosis
C. make a copy of their genetic information
Sister chromatids separate from each other during _____. A. mitosis and meiosis I B. meiosis II only C. mitosis and meiosis II D. meiosis I only
C. mitosis and meiosis II
An allele is: A. the particular combination of genes for a given trait in a given organism B. the expression of a trait in an individual C. one of several forms of a gene D. one of several types of genes E. the region of a chromosome that encodes a protein
C. one of several forms of a gene
Several years ago, a man noticed a small mole on his wrist. Years later, the mole grew in size and the man was diagnosed as having metastatic melanoma. This was likely the result of: A. a single mutation inactivating a tumor suppressor gene. B. None of the other answer options is correct; cancers arise spontaneously, independent of mutations. C. several mutations affecting proto-oncogenes and/or tumor suppressor genes. D. a single mutation affecting one proto-oncogene in a cell.
C. several mutations affecting proto-oncogenes and/or tumor suppressor genes.
If you were able to find a drug that could inhibit the reactivation of telomerase activity in cancer cells, the cancer cells would: A. eventually die from lack of energy. B. become less invasive. C. slowly erode their chromosome ends. D. gradually revert to normal cells. E. stop dividing immediately.
C. slowly erode their chromosome ends.
One possible result of chromosomal breakage is for a fragment to join a nonhomologous chromosome. What is this alteration called? A. inversion B. deletion C. translocation D. duplication
C. translocation
At a specific area of a chromosome, the sequence of nucleotides below is present where the chain opens to form a replication fork: 5' C C T A G G C T G C A A T C C 3' An RNA primer is formed starting at the underlined T (T) of the template. Which of the following represents the primer sequence? A. 3' A G C C U A G G 5' B. 5' A G C C U A G G 3' C. 5' G G A U C C G A 3' D. 3' A C G U U A G G 5'
D. 3' A C G U U A G G 5'
Failure to recover a specific band in a gel made after PCR can be attributed to: A. inappropriate annealing temperature for used primers. B. inappropriate design of primers. C. inappropriate numbers of cycles for amplification. D. All of these choices are correct.
D. All of these choices are correct.
Proto-oncogenes: A. can be mutated by cigarette smoke to become triggers for cancer. B. can encode growth factors, cell surface receptors, or members of a signal transduction pathway. C. are the normal forms of genes that can mutate to cause cell division to be hyperactive. D. All of these choices are correct.
D. All of these choices are correct.
Which of these events includes a checkpoint in the cell cycle? A. the transition from S phase and the completion of DNA synthesis to G2 phase B. the transition from anaphase to telophase C. All of these events include a checkpoint in the cell cycle. D. the transition from G1 to S phase
D. the transition from G1 to S phase
What feature is shared by restriction fragments produced by the restriction enzymes BclI (T↓GATCA) and Mph1103 (AGATC↓T)? The downward arrow denotes the site of cleavage in each strand. A. These fragments do not have anything in common. B. Both fragments have blunt ends. C. Both fragments have the same 5-base overhang only at the 3′-end. D. Both fragments have the same 4-base overhang, but one at the 5'-end and the other at the 3'-end. E. Both fragments have the same 5-base overhang only at the 5′-end.
D. Both fragments have the same 4-base overhang, but one at the 5'-end and the other at the 3'-end.
If a cell underwent mitosis, and its daughter cells were immediately exposed to chemicals that damaged the DNA, at which stage of the cell cycle checkpoint would you predict the cell would arrest? A. G2 checkpoint B. G1, G2, or the M checkpoints C. M checkpoint D. G1 checkpoint
D. G1 checkpoint
At which stage of the cell cycle could you see sister chromatids with a microscope? A. S x B. G1 C. G2 D. M
D. M
Which of the statements is true regarding a chromosome deletion? A. If a deletion eliminates the centromere, the chromosome is still passed on normally during cell division. B. Chromosome deletions do not affect gene dosage. C. Small chromosomal deletions usually have serious and often fatal consequences for an organism. D. None of the other answer options is correct. E. Small chromosomal deletions are easily detected by microscopy.
D. None of the other answer options is correct.
Trisomy of the X chromosome has little effect on the health, whereas trisomy of any of the autosomes has significant detrimental developmental effects. What could account for this difference in effect of trisomy between the X chromosome and any of the autosomes? A. X chromosomes end up in the polar bodies during meiosis and are not contained in the egg. Autosomes are contained in the egg. B. The X chromosome is very small and contains very few genes. Autosomes are much bigger and contain many genes. C. The X chromosomes don't contain any genes required for basic development or health. Autosomes do contain such genes. D. The X chromosomes undergo X inactivation and thereby correct for the copy number difference. Autosomes do not undergo dosage compensation (the equalization of the numbers of each gene).
D. The X chromosomes undergo X inactivation and thereby correct for the copy number difference. Autosomes do not undergo dosage compensation (the equalization of the numbers of each gene).
A researcher is evaluating the expression of p53 in cells she is culturing in the laboratory. She notices that in a small group of cells, high levels of phosphorylated p53 occur in the nuclei. What can she deduce about these cells? A. These cells are normal. B. Within these cells, the cell cycle has been halted at M-phase. C. These cells have entered mitosis. D. These cells likely contain damaged DNA. E. These cells have entered meiosis.
D. These cells likely contain damaged DNA.
The difference between a single-nucleotide polymorphism (SNP) and a point mutation is that: A. a point mutation can be corrected by various repair mechanisms, whereas a SNP cannot. B. a point mutation becomes permanently incorporated into the genome, whereas a SNP does not. C. a SNP becomes permanently incorporated into the genome whereas a point mutation does not. D. a point mutation is when a base pair is changed to a different base pair, whereas a SNP is when the base pair differs among individuals in a population. E. a SNP can be corrected by various repair mechanisms, whereas a point mutation cannot.
D. a point mutation is when a base pair is changed to a different base pair, whereas a SNP is when the base pair differs among individuals in a population.
Chromosomal mutations that are most likely to cause serious damage to an organism are those that affect the: A. short arm of the chromosome. B. long arm of the chromosome. C. None of the other answer options is correct. D. centromere. E. telomere.
D. centromere.
A human cell with a total of 23 chromosomes is: A. diploid B. polyploid C. aneuploid D. haploid
D. haploid
An individual is heterozygous for a gene if: A. his or her mother is heterozygous for the gene. B. only one allele is present in the population. C. he or she developed from a sperm and egg that carried the same allele. D. he or she developed from a sperm and egg that carried different alleles. E. his or her father is heterozygous for the gene.
D. he or she developed from a sperm and egg that carried different alleles.
These enzymes play important roles in DNA replication: DNA polymerase, primase, ligase, helicase. In what order do they work during replication? A. primase, helicase, ligase, DNA polymerase B. ligase, helicase, DNA polymerase, primase C. DNA polymerase, primase, ligase, helicase D. helicase, primase, DNA polymerase, ligase E. DNA polymerase, helicase, primase, ligase
D. helicase, primase, DNA polymerase, ligase
The lethality of most monosomies and trisomies in humans shows the: A. rarity of variation in the number of copies of each gene in the genome. B. deleterious (harmful) effects of a variable number of tandem repeat sequences. C. advantage of sexual reproduction. D. importance of gene dosage (the number of copies of a gene).
D. importance of gene dosage (the number of copies of a gene).
A malignant cancer differs from a benign tumor in that: A. malignant cancers are lethal and benign cancers are not. B. benign cancers are lethal and malignant ones are not. C. malignant cancers are caused by viruses and benign cancers are not. D. malignant cancers invade surrounding tissue and benign cancers do not.
D. malignant cancers invade surrounding tissue and benign cancers do not.
A eukaryotic chromosome has _____ origin(s) of replication, and a bacterial chromosome has ______ origin(s) of replication. A. one; one B. one; many C. many; many D. many; one
D. many; one
Genotype is A. the individual's observable characteristics or traits B. the genetic changes that occur from transcription C. any genetic difference among individuals that is present in multiple individuals in a population D. the genetic makeup of a cell or organism
D. the genetic makeup of a cell or organism
Consider a cell in which one of the proteins or enzymes involved in DNA replication is altered in a way that results in an increased rate of single-base changes in the newly synthesized DNA strand. Which function of which protein is most likely disrupted in this situation? A. the winding stress relief function of topoisomerase II B. the fragment joining function of DNA ligase C. the unwinding function of helicase D. the proofreading function of DNA polymerase E. the strand separation function of single-stranded binding protein
D. the proofreading function of DNA polymerase
When we say that DNA replication is semiconservative, we mean that: A. only half of an organism's DNA is replicated during each cell division. B. parental DNA stays in the parent cell and daughter DNA ends up in the daughter cell. C. None of the other answer options is correct. D. when DNA is replicated each new double helix contains one parental strand and one newly synthesized daughter strand.
D. when DNA is replicated each new double helix contains one parental strand and one newly synthesized daughter strand.
Sexual reproduction results: A. in a new generation that is not genetically identical to its parents. B. in offspring that are not genetically identical. C. in a new generation with the same number of chromosomes as each parent. D. from combining genetic material from two gametes. E. All of these choices are correct.
E. All of these choices are correct.
Mitochondria contain their own double-stranded, circular DNA and replicate on their own. Why don't they suffer the same consequences as our cells in terms of limited division? A. Shortening of the DNA is only a problem with nuclear DNA; shortening of mitochondrial DNA is not catastrophic. B. Since mitochondrial DNA only contains a few genes, it can last a lot longer. C. Because they have high telomerase activity, and their DNA is circular, so it doesn't shorten in replication. D. Because they have high telomerase activity. E. Because mitochondrial DNA is circular, it does not shorten when it replicates.
E. Because mitochondrial DNA is circular, it does not shorten when it replicates.
Imagine that a doctor is culturing two types of cells: one from a malignant melanoma and one from a normal skin sample. How would you expect these two cell populations to differ? A. Malignant melanoma cells would have inactive telomerases, so their telomeres would shorten during successive rounds of replication. B. Normal skin cells would have telomeres that do not shorten during successive rounds of replication. C. Malignant melanoma cells would have telomeres that shorten during successive rounds of replication. D. Normal skin cells would have active telomerases that constantly replenish and lengthen telomeres. E. Malignant melanoma cells would have active telomerases that constantly replenish and lengthen telomeres.
E. Malignant melanoma cells would have active telomerases that constantly replenish and lengthen telomeres.
The most frequent kind of mutation, a point mutation, occurs when: A. open reading frames are altered. B. DNA repair mechanisms fail. C. a block of nucleotides is rearranged. D. None of the other answer options is correct. E. a single base pair is replaced by another.
E. a single base pair is replaced by another.
If a population has only one allelic form of the gene, every individual is: A. heterozygous. B. conserved C. identical D. polymorphic. E. homozygous
E. homozygous
The gel diagram shows the bands obtained for a single tandem repeat in evidence obtained at a crime scene (W) and genomic DNA from four suspects (A-E). Which suspect cannot be ruled out as the source of the DNA in the sample? A. suspect A B. suspect C C. suspect E D. suspect B E. suspect D
E. suspect D
The parallel lines shown represent the paired strands of a DNA double helix. If this molecule undergoes one round of replication, which ends are shorter in the daughter molecules than in the parental molecules? A. y and z B. w and x C. y and x D. w and y E. w and z
E. w and z