Bio 11 & 12
Cell division is regulated by: a) growth factor signals. b) All of these choices are correct. c) signals about the nutritional status of the cell. d) signals that indicate that the cell has reached a sufficient size. e) signals that indicate that DNA has been replicated.
b) All of these choices are correct.
The second meiotic division resembles mitosis because: a) sister chromatids are separated during anaphase II to become the chromosomes of the daughter cells. b) chromosomes decondense during telophase II. c) the daughter cells have the same number of chromosomes as the parent cell. d) All of these choices are correct. e) spindle microtubules attach from opposite directions to the centromere of each sister chromatid pair.
d) All of these choices are correct.
How would the loss of p53 activity affect a cell? a) All of these choices are correct. b) DNA damage could accumulate. c) CDK activity would not be appropriately regulated. d) The G1 /S checkpoint would not be functional.
a) All of these choices are correct.
Recall the experiments of Peyton Rous and his colleagues. If he had found that filtered cancer cell extract could not cause cancer when injected into healthy animals, what could he have deduced? a) All of these choices are correct. b) An intact cancer cell is necessary to cause cancer. c) A large protein may cause cancer. d) Cancer may be caused by bacteria.
a) All of these choices are correct.
Denaturation of DNA is a necessary step in Southern blotting procedure because it separates double stranded DNA into single stranded DNA. a) true b) false
a) true
In circular DNA, the DNA molecule is not shortened during each round of replication. a) true b) false
a) true
Restriction enzymes recognize certain DNA sequences and some of them will cut straight through, and others will leave an overhang at both ends of the cut. a) true b) false
a) true
The alignment of chromosomes at metaphase of meiosis II is most similar to the alignment of chromosomes during metaphase of mitosis. a) true b) false
a) true
The occurrence of nondisjunction during mitosis can result in the development of certain cancers; however, nondisjunction is often thought of in relation to meiosis and the development of certain trisomies. a) true b) false
a) true
Trisomy 21 (Down syndrome) is one of only a few examples of an autosomal trisomy in which the fetus develops to term and is born alive. a) true b) false
a) true
Asexual reproduction occurs in: a) All of these choices are correct. b) animal cells. c) plant cells. d) bacterial cells. e) unicellular eukaryotes.
a) All of these choices are correct.
Sexual reproduction results in an increase in genetic diversity because: a) All of these choices are correct. b) during prophase I, genes that are paternally and maternally derived recombine so that the gametes have chromosomes that are different from the parents' chromosomes. c) during metaphase I, the bivalents line up in a random orientation so that gametes inherit a random set of maternally and paternally derived chromosomes. d) during fertilization, the gametes that fuse are random so that a large number of chromosomal combinations are possible in the new organism.
a) All of these choices are correct.
The prokaryotic protein FtsZ is evolutionarily related to eukaryotic tubulin. What does this mean? a) All of these choices are correct. b) The amino acid sequence for FtsZ is similar to tubulin. c) The overall protein structure of FtsZ is similar to tubulin. d) The two proteins evolved from a common ancestral protein. e) The gene sequence for FtsZ is similar to tubulin.
a) 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) All of these choices are correct. b) The sister chromatids would not separate. c) The chromosome would not line up properly at metaphase. d) One of the daughter cells would have an extra copy of that chromosome.
a) All of these choices are correct.
Which statement regarding cancer, according to Douglas Hanahan and Robert Weinberg, are true? a) All of these choices are correct. b) Cancer cells can sometimes metastasize and travel throughout the body. c) Mutations in growth factor receptors are sometimes required for cancer cell division. d) Cancer cells can resist cell-death signals. e) Cancer cells typically secrete factors that promote blood vessel formation.
a) 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) Because mitochondrial DNA is circular, it does not shorten when it replicates. b) Shortening of the DNA is only a problem with nuclear DNA; shortening of mitochondrial DNA is not catastrophic. c) because they have high telomerase activity d) because they have high telomerase activity, and their DNA is circular, so it doesn't shorten in replication e) Since mitochondrial DNA only contains a few genes, it can last a lot longer.
a) Because mitochondrial DNA is circular, it does not shorten when it replicates.
What is the name of the enzyme that separates the two strands of DNA during replication? a) helicase b) DNA ligase c) DNA polymerase d) topoisomerase e) primase
a) helicase
A malignant cancer differs from a benign tumor in that: a) malignant cancers invade surrounding tissue and benign cancers do not. b) malignant cancers are caused by viruses and benign cancers are not. c) malignant cancers are lethal and benign cancers are not. d) benign cancers are lethal and malignant ones are not.
a) 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) many, one b) one, one c) one, many d) many, many
a) many, one
The assembly of what cytoskeletal structures are initiated by the M cyclin-CDK complex? a) microtubules b) microfilament c) All of these choices are correct. d) intermediate filaments
a) microtubules
One of the important cell cycle checkpoints occurs during M phase. It inhibits progression to anaphase until all of the chromosome kinetochores are correctly attached to microtubules of the spindle apparatus. If anaphase of mitosis occurred when the kinetochore microtubule connected to only one of the two spindle poles but not the other, what could result? a) nondisjunction b) trisomy c) Turner syndrome d) Down syndrome
a) nondisjunction
The point at which DNA synthesis is initiated is called the: a) origin of replication. b) replication fork. c) primase. d) start codon. e) primer.
a) origin of replication.
Nondisjunction results when: a) pairs of chromosomes fail to separate during anaphase. b) tetrads fail to cross over during prophase of mitosis. c) pairs of chromatids fail to align during metaphase. d) pairs of chromosomes fail to synapse during prophase I of meiosis.
a) pairs of chromosomes fail to separate during anaphase.
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) several mutations affecting proto-oncogenes and/or tumor suppressor genes. b) a single mutation inactivating a tumor suppressor gene. c) a single mutation affecting one proto-oncogene in a cell. d) None of the other answer options is correct; cancers arise spontaneously, independent of mutations.
a) several mutations affecting proto-oncogenes and/or tumor suppressor genes.
In gel electrophoresis, DNA fragments are separated based on their: a) size. b) how many adenine bases are in the fragment. c) charge. d) how many thymine bases are in the fragment. e) sequence.
a) size.
Energy is required in order to add a nucleotide to the growing strand of DNA during replication. From where does that energy come? a) the incoming nucleotide b) DNA ligase c) helicase d) primase e) DNA polymerase
a) the incoming nucleotide
During PCR, where does the energy come from that adds the nucleotide to the growing DNA strand? a) the incoming nucleotides b) ATP c) Taq polymerase d) the primers e) the elevated temperature of the PCR reaction
a) the incoming nucleotides
What is the function of histone proteins? a) to package DNA in eukaryotic chromosomes b) to attach sister chromatids together c) to connect chromosomes to the mitotic spindle d) to organize the microtubules that make up the spindle
a) to package DNA in eukaryotic chromosomes
A daughter strand of DNA produced during chromosome replication can be composed of leading and lagging strands from different replication bubbles. a) true b) false
a) true
An example of second-division nondisjunction is when sister chromatids fail to separate during anaphase of meiotic cell division. a) true b) false
a) true
DNA polymerase requires both a template and a free 3′ end to elongate a nucleotide chain. a) true b) false
a) true
It is estimated that a human cell in G1 phase of the cell cycle contains 6 picograms of DNA in its nucleus. If you measure the DNA content at various stages of mitosis and meiosis, what amounts of DNA can be expected in nuclei at the following stages? prophase mitosis: _____; prophase I meiosis: _____; prophase II meiosis: _____; telophase mitosis: _____; telophase meiosis II: _____. (All amounts are in picograms (10-12 g.) a) 12; 24; 6; 12; 6 b) 6; 6; 3; 6; 3 c) 12; 12; 6; 6; 3 d) 6; 12; 3; 6; 3 e) 12; 12; 3; 6; 3
c) 12; 12; 6; 6; 3
You run a PCR reaction for five cycles starting with a single DNA duplex. Theoretically, how many copies of your sequence would you now have? a) 16 b) 12 c) 32 d) 24 e) 64
c) 32
RNA is involved in which cellular processes? a) translation b) transcription c) All of these choices are correct. d) DNA replication
c) All of these choices are correct.
Meiosis _____ is sometimes called reductional division because _____. a) I; the sister chromatids are separated b) II; the amount of DNA per chromatid is reduced by half c) I; the number of chromosomes is reduced by half d) II; the sister chromatids are separated e) II; the number of chromosomes is reduced by half
c) I; the number of chromosomes is reduced by half
Why would a compound that interferes with bacterial cell wall synthesis be useful for treating a bacterial infection? a) It would prevent the cells from becoming larger. b) It would prevent replication of DNA, and it would limit the spread of the infection. c) It would limit growth of the bacterial population through cell division. d) It would prevent replication of DNA.
c) It would limit growth of the bacterial population through cell division.
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) Yes, she will certainly develop cancer given the role of p53 in the cell cycle. c) Possibly; this mutation is likely to predispose her to developing certain types of cancer.
c) Possibly; this mutation is likely to predispose her to developing certain types of cancer.
If a human has the genotype XXXY, they would: a) have 3 inactivated X chromosomes and be female. b) have 3 inactivated X chromosomes and be male. c) have 2 inactivated X chromosomes and be male. d) have 2 inactivated X chromosomes and be female. e) have 1 inactivated X chromosome and be male.
c) have 2 inactivated X chromosomes and be male.
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) circular. b) It is not possible to make this determination from the information provided. c) linear.
c) linear.
What type of gene is c-src (cellular-src)? a) oncogene b) growth factor c) proto-oncogene d) tumor suppressor
c) proto-oncogene
The name of the technique used to amplify specific sequences of DNA is: a) electrophoresis. b) Southern blot. c) the polymerase chain reaction (PCR). d) hybridization. e) restriction.
c) the polymerase chain reaction (PCR).
Suppose you are observing some cells with a microscope, and you see a cell that appears to be dividing. You can see that as the cell starts to pinch in half, the DNA seems to be attached to the plasma membrane via a membrane protein. On further analysis, you find that this organism's DNA is circular - that is, it consists of a closed loop. What can you conclude about this organism and its mode of cell division? a) It is a prokaryote that is dividing by mitosis. b) It is a eukaryote that is dividing by binary fission. c) It is a eukaryote that is dividing by mitosis. d) It is a prokaryote that is dividing by binary fission.
d) It is a prokaryote that is dividing by binary fission.
Which statement is true regarding telomeres? a) Telomeres contain non-essential genes that are not necessary for cell survival. b) Telomeres are typically only a few base pairs in size. c) Telomeres are enzymes that repair telomerases, which cap the end of linear chromosomes. d) Telomeres can contain repeated base sequences. e) Telomeres are repaired to the same extent in germ cells and somatic cells.
d) Telomeres can contain repeated base sequences.
Telomerase activity in stem cells is very low. a) true b) false
b) false
What type of protein is being activated by the G1 /S cyclin-CDK complex to promote the expression of histone genes? a) a synthase b) a transcription factor c) a polymerase d) a helicase
b) a transcription factor
Genes that promote cancer are called: a) proto-oncogenes. b) tumor suppressors. c) p53. d) sarcomas. e) oncogenes.
e) oncogenes.
Which reason explains why bacteria can continually divide while they maintain the length of their chromosome? a) Because their DNA is circular, it never shortens after replication. b) because they have plasmids c) because they are so simple d) because DNA replication is much quicker in bacteria than in eukaryotes e) because they only have one chromosome
a) Because their DNA is circular, it never shortens after replication.
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) Both fragments have the same 4-base overhang, but one at the 5'-end and the other at the 3'-end. b) Both fragments have the same 5-base overhang only at the 5′-end. c) Both fragments have blunt ends. d) Both fragments have the same 5-base overhang only at the 3′-end. e) These fragments do not have anything in common.
a) Both fragments have the same 4-base overhang, but one at the 5'-end and the other at the 3'-end.
Muscle cells in the mammalian heart are multinucleate, meaning that multiple nuclei are present in the cytoplasm of individual large cells. Predict what is different about the cell cycle in a muscle cell. a) Cytokinesis does not occur. b) M phase is inhibited. c) S phase happens twice. d) The G1 and G2 phases are extended.
a) Cytokinesis does not occur.
Which statement is true regarding binary fission? a) DNA replication of the circular bacterial chromosome during binary fission is a bidirectional process, starting at one point but progressing in opposite directions. b) In binary fission, cell division is typically asymmetrical, with one daughter cell appearing much smaller than the other. c) Tubulin, rather than FtsZ, is responsible for cell division during binary fission. d) Proteins only anchor the original circular genome to the plasma membrane; the copy produced by DNA replication is free-floating.
a) DNA replication of the circular bacterial chromosome during binary fission is a bidirectional process, starting at one point but progressing in opposite directions.
Which statement is true regarding chromosome replication in eukaryotes? a) During chromosome replication, multiple origins of replication form for all DNA in a cell. b) Replication bubbles remain distinct, isolated structures during chromosome replication and never fuse with one another. c) None of the answer options is correct. d) Replication begins at one end of the chromosome and proceeds until it reaches the opposite end. e) In humans, it takes several days to replicate an entire chromosome.
a) During chromosome replication, multiple origins of replication form for all DNA in a cell.
At which stage of the cell cycle could you see sister chromatids with a microscope? a) M b) G2 c) G1 d) S
a) M
Which of the answer 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 X chromosome only carries genes dealing with being a female, so having another one doesn't matter. c) The extra X chromosome only becomes active in nonreproductive areas of the body. d) Cells normally have enzymes that recognize and degrade extra X chromosomes. e) None of the answer options is correct.
a) Only one X chromosome is active in each cell, regardless of how many X chromosomes there are in a cell.
What is the first enzyme to synthesize a nucleic acid at a replication fork? a) RNA primase b) helicase c) topoisomerase II d) DNA polymerase
a) RNA primase
How must spindle microtubules attach to chromosomes during prometaphase of meiosis I? a) Spindle microtubules from one pole must attach to both kinetochores in a pair of sister chromatids. b) Spindle microtubules from one pole attach to one kinetochore, and spindle microtubules from the other pole attach to the other kinetochore in a pair of sister chromatids, just like in mitosis. c) Microtubules attach to the chiasma. d) Microtubules attach using their minus (slow assembling) ends. e) Microtubules attach at the centrosomes.
a) Spindle microtubules from one pole must attach to both kinetochores in a pair of sister chromatids.
Suppose you analyze a time-lapse video of a cell under a microscope and you observe what appears to be crosslike structures within a bivalent. Which of the answer choices is an interpretation of this observation? a) These structures represent crossing over between non-sister chromatids. b) The cell has completed S phase and is ready to begin cell division. c) The chromatids are the result of crossing over prior to initiation of Prophase 1 of meiosis. d) The cell is probably from a plant that has four sets of chromosomes, rather than only two sets.
a) These structures represent crossing over between non-sister chromatids.
How do new cyclin proteins appear in the cytoplasm? a) They are made through protein synthesis. b) They are recycled. c) They are imported from outside the cell. d) All of these choices are correct.
a) They are made through protein synthesis.
How do CDKs promote cell division? a) They phosphorylate proteins that allow passage through cell cycle checkpoints. b) They cause cyclin levels to increase and decrease. c) They change the ability of microtubules to polymerize. d) They regulate the activity of cyclins. e) They bind to DNA.
a) They phosphorylate proteins that allow passage through cell cycle checkpoints.
A Southern blot is a technique that relies on hybridization of: a) a nucleic acid probe to a complementary DNA. b) proteins to DNA. c) a nucleic acid probe to a complementary RNA. d) None of the answer options is correct.
a) a nucleic acid probe to a complementary DNA.
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
The process of cell division in a prokaryotic cell is called: a) binary fission. b) mitosis. c) cytokinesis. d) binary fusion.
a) binary fission.
What characteristics do you expect to observe with a microscope if you investigate the division of mitochondria and chloroplasts in eukaryotic cells? a) circular DNA attached to the plasma membrane and binary fission b) non-circular DNA and division by mitosis c) circular DNA attached to the plasma membrane and division by mitosis d) mitochondria and chloroplasts replicating by a process unlike binary fission or mitosis
a) circular DNA attached to the plasma membrane and binary fission
Why don't plant cells use a contractile ring to divide their daughter cells? a) Plant cells don't form daughter cells. b) A contractile ring can't "pinch" a cell wall. c) Plant cells don't have an actin cytoskeleton. d) Plant cells don't have plasma membranes.
b) A contractile ring can't "pinch" a cell wall.
Failure to recover a specific band in a gel made after PCR can be attributed to: a) inappropriate design of primers. b) All of these choices are correct. c) inappropriate annealing temperature for used primers. d) inappropriate numbers of cycles for amplification.
b) All of these choices are correct.
Which statement regarding the S cyclin-CDK complex is true? a) It is responsible for the phosphorylation of nuclear proteins. b) It ensures that DNA is not replicated multiple times. c) It is responsible for the degradation of nuclear membranes. d) It is regulated solely by the action of p53. e) It regulates the expression of histone proteins.
b) It ensures that DNA is not replicated multiple times.
A person has the genotype XXY. What syndrome does this person have and what sex is the person? a) Turner; female b) Klinefelter; male c) no syndrome; male d) Klinefelter; female e) Turner; male
b) Klinefelter; male
Which of the answer choices is a characteristic of meiotic cell division? a) Meiotic cell division ultimately results in the formation of two cells. b) Meiotic cell division results in halving the number of chromosomes. c) The cells produced by meiosis are genetically identical. d) Meiotic cell division requires two rounds of DNA replication.
b) Meiotic cell division results in halving the number of chromosomes.
Suppose a research team does a detailed analysis of the DNA sequence of all three copies of chromosome 21 from an individual with trisomy 21 (Down syndrome). They discover that two of the three chromosomes are essentially identical in sequence, whereas the third chromosome has a significant number of sequence differences. Which of the answer choices is consistent with this observation? a) The extra chromosome 21 resulted from first-division nondisjunction in one of the parents' gametes. b) The extra chromosome 21 resulted from second-division nondisjunction in one of the parents' gametes. c) The extra chromosome 21 resulted from either first- or second-division nondisjunction in one of the parents' gametes. d) The chromosome 21 homologous pair failed to separate during meiosis I in the mother. e) Both the mother and the father had nondisjunction events at chromosome 21 during meiosis to form their gametes.
b) The extra chromosome 21 resulted from second-division nondisjunction in one of the parents' gametes.
DNA polymerase is the enzyme that separates the two strands of DNA during DNA replication. a) true b) false
b) false
First-division nondisjunction will only yield gametes with an extra chromosome, whereas second-division nondisjunction will only yield gametes missing a chromosome. a) true b) false
b) false
If a restriction site of AatII is 5′-GACGTC -3′ then 3′-GACGTC-5′ is also an AatII restriction site. a) true b) false
b) false
Massive parallel sequencing techniques can reliably determine the sequence of hundreds of base pairs but require more time than Sanger sequencing. a) true b) false
b) false
Okazaki fragments are ligated to form a continuous DNA molecule after replication is completed. a) true b) false
b) false
The first step of PCR, called annealing, is performed by DNA polymerase. a) true b) false
b) false
The following 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) helicase, primase, DNA polymerase, ligase c) ligase, helicase, DNA polymerase, primase d) DNA polymerase, helicase, primase, ligase e) DNA polymerase, primase, ligase, helicase
b) helicase, primase, DNA polymerase, ligase
Which of the following is not needed for DNA replication? a) enzymes b) ribosomes c) DNA d) nucleotides e) None of the answer options is correct.
b) ribosomes
What is the function of the enzyme DNA polymerase? a) to synthesize a strand of mRNA using mRNA as a template b) to synthesize a strand of DNA using DNA as a template c) to synthesize a strand of DNA using a polypeptide as a template d) to synthesize a polypeptide using DNA as a template e) to synthesize a strand of mRNA using DNA as a template
b) to synthesize a strand of DNA using DNA as a template
What would happen to the daughter cells if the G2 phase of the parent cell is shortened? a) The cells would be larger than normal. b) The cells would not undergo cytokinesis. c) The cells would be missing chromosomes. d) The cells would be smaller than normal.
d) The cells would be smaller than normal.
Which of the answer choices is true regarding CDKs? a) Loss of CDK activity would lead to cancer. b) CDKs are active in cells that enter G0 phase of the cell cycle. c) CDKs are active except when they bind to cyclins. d) The levels of CDKs change with the cell cycle.
d) The levels of CDKs change with the cell cycle.
In which phase of mitosis do spindle microtubules shorten? a) telophase b) prophase c) metaphase d) anaphase
d) anaphase
A protein that has regular up-and-down pattern of abundance during the cell cycle and that triggers progress of the cell cycle by activating kinases is called a: a) protein kinase. b) cyclin-CDK complex. c) cyclin dependent kinase. d) cyclin.
d) cyclin.
A human cell with a total of 23 chromosomes is: a) polyploid. b) diploid. c) aneuploid. d) haploid.
d) haploid.
Reproduction by mitotic cell division: a) reduces the number of chromosomes by half. b) involves the formation of gametes. c) does not require the replication of chromosomes. d) results in two daughter cells that are genetically identical.
d) results in two daughter cells that are genetically identical.
The role of dideoxynucleotides in Sanger sequencing is: a) the removal of specific bases from DNA. b) the detection of protons during DNA synthesis. c) the inhibition of restriction enzyme activity. d) the termination of DNA synthesis at specific bases. e) the addition of specifically labeled phosphates to the DNA.
d) the termination of DNA synthesis at specific bases.
What is the benefit of using Taq polymerase in PCR? a) Because it is taken from bacteria that live in high temperatures, it does not have a proofreading function. b) Because it is taken from bacteria, it makes fewer mistakes. c) Because it is taken from bacteria, this enzyme works much more efficiently than other types of DNA polymerase. d) None of the answer options is correct. e) Because it is taken from bacteria that live in high temperatures, it stays active during denaturation steps of the reaction.
e) Because it is taken from bacteria that live in high temperatures, it stays active during denaturation steps of the reaction.
Which of the following is true regarding DNA replication of a linear chromosome? a) Only the leading strand gets shortened during replication. b) Both strands get shortened at the same end during replication. c) Only the lagging strand gets shortened during replication. d) Only the lagging strand gets shortened after every other round of replication. e) Both strands get shortened at opposite ends during replication.
e) Both strands get shortened at opposite ends during replication.
What is the result of DNA ligase's action? a) DNA is condensed to chromosomes. b) DNA transcription occurs. c) DNA translation occurs. d) DNA is broken up at specific sites. e) DNA fragments are joined together.
e) DNA fragments are joined together.
Why are primers needed for DNA replication? a) They help direct the placement of the telomeres. b) The primers help with the proofreading function of DNA polymerase. c) They help with the joining of Okazaki fragments. d) A tiny amount of RNA is needed to tell the cell where genes are located. e) DNA polymerase can only add nucleotides to an existing chain.
e) DNA polymerase can only add nucleotides to an existing chain.
Meiosis _____ is similar to mitosis in that _____ separate. a) I; sister chromatids b) I; homologous chromosomes c) I; non-sister chromatids d) II; homologous chromosomes e) II; sister chromatids
e) II; sister chromatids
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 telomeres that shorten during successive rounds of replication. b) Normal skin cells would have active telomerases that constantly replenish and lengthen telomeres. c) Malignant melanoma cells would have inactive telomerases, so their telomeres would shorten during successive rounds of replication. d) Normal skin cells would have telomeres that do not shorten during successive rounds of replication. 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.
Which statement about the strands of a newly replicated DNA molecule is correct? a) Both strands contain some nucleotides from the original molecule. b) Both strands are made up of newly assembled nucleotides. c) The sugar-phosphate chains are conserved, and new bases are inserted between them. d) The base pairs are conserved, and new sugar-phosphate backbones are built up on them. e) One strand is new, and the other is from the original molecule.
e) One strand is new, and the other is from the original molecule.
What would happen if telomerase stopped working in a cell in which it normally functions at high levels? a) None of the answer options is correct. b) The cells would be able to divide indefinitely. c) The cell would die immediately. d) Cancer would be the result. e) The cell would eventually die as the DNA continued to shorten.
e) The cell would eventually die as the DNA continued to shorten.
Select the correct order of steps during PCR. a) denaturation, extension, termination b) initiation, extension, termination c) initiation, denaturation, extension d) annealing, initiation, termination e) denaturation, annealing, extension
e) denaturation, annealing, extension