LS 7A weeks 7-10

The estimated number of genes in the human genome is: 40,000. 250,000. 400,000. 15,000. 25,000.

25,000

Approximately what percentage of the human genome consists of repetitive DNA or transposable elements? 5% 1% 25% 10% 50%

50%

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)None of the other answer options is correct. D)a nucleic acid probe to a complementary RNA.

A

How many pairs of chromosomes does the human genome normally have? A)23 B)38 C)6 D)15 E)46

A

The level of DNA packaging brought about by the formation of _____ looks like beads on a string. A)nucleosomes B)30-nm chromatin fibers C)scaffolds D)1400-nm chromatin fibers E)2-nm chromatin fibers

A

The methylation state of an individual CpG island: A)can change over time in response to environmental cues, allowing genes to be turned on or off as needed. B)is fixed, but this has no effect on whether genes are expressed. C)is random sometimes the cytosines are methylated and sometimes they're not, but the state is independent of the environment or cell type. D)can change over time in response to environmental cues, but this has no effect on gene expression. E)is fixed; such genes are permanently turned off.

A

The transformation step in creating bacteria genetically engineered to produce human proteins involves: A)bacteria taking up the recombinant DNA in the form of the vectors. B)binding of the donor DNA to the vector DNA and ligating the two pieces. C)bacteria expressing the novel proteins encoded by the donor DNA. D)None of the other answer options is correct. E)cleaving the donor and vector DNA so they can be bound into a single molecule.

A

X-inactivation is caused by the accumulation of: A)noncoding RNA produced by the Xist gene, which coats the X chromosome and induces DNA methylation, histone modification, and other changes associated with preventing transcription. B)noncoding RNA produced by the Xist gene, which coats the X chromosome and covalenty crosslinks the DNA strands preventing them from being unwound, "unzipped," and transcribed. C)coding RNA produced by the Xist gene; this RNA, in addition to coding for Xist proteins, binds to and coats the X chromosome undergoing inactivation and physically prevents it from being transcribed. D)proteins produced by the Xist gene; these proteins induce meth

A

What features of DNA make it possible to make recombinant DNA in the lab? (Select all that apply.) The genetic code is the same for all organisms Restriction enzymes cut DNA from all species. Two double helices from different sources can be ligated together.

All

Alternative splicing allows for: A)increased stability of a mature mRNA. B)different polypeptides to be made from a single gene. C)two or more different proteins to be made from a single processed mRNA. D)enhanced recognition of an mRNA by a ribosome. E)multiple genes to be used to code for a single polypeptide chain.

B

In eukaryotes, genetic material is packaged in the nucleus. Which one of the following MOST accurately lists the components in order of increasing size? A)nucleotide, DNA duplex, chromatin, nucleosome, chromosome B)nucleotide, DNA duplex, nucleosome, chromatin, chromosome C)chromosome, chromatin, nucleosome, DNA duplex, nucleotide D)nucleotide, nucleosome, DNA duplex, chromatin, chromosome E)chromosome, nucleosome, chromatin, DNA duplex, nucleotide

B

A skin cell in G2 of interphase has _____ as much DNA as it had in G1. A)1/4 B)half C)twice D)four times E)exactly

C

Alternative splicing means that: A)some transcripts are spliced while others are not. B)alternating introns are removed. C)different spliced forms contain different combinations of exons. D)some transcripts are spliced correctly and others incorrectly.

C

DNA is wrapped around histones, which contain many copies of the positive amino acids lysine and arginine. These positive amino acids neutralize the negative charge of the _____ of the DNA wrapped around the histone. A)hydroxyl group B)nitrogenous base C)phosphate group D)ribose sugar

C

In general, when cytosine bases in CpG islands are methylated: A)transcription is active and rapid. B)translation is active and rapid. C)transcription is repressed. D)translation is repressed. E)transcription is active, but slow

C

Modifications of histone tails can: A)affect chromatin structure. B)activate transcription of some genes. C)All of these choices are correct. D)affect expression of some genes in response to the environment. E)repress transcription of some genes.

C

Nucleosomes are found in: A)mitochondria B)chloroplasts C)nucleus

C

One difference between eukaryotic and prokaryotic DNA packaging is: A)prokaryotic cells have smaller chromosomes and thus fit into the cell unaltered. B)eukaryotic cells have fewer genes than prokaryotic cells. C)DNA wraps around histones in eukaryotic packaging. D)prokaryotic cells have different nucleotides that are smaller than eukaryotic cells.

C

One regulatory step in the process of gene expression and synthesis of proteins is the actual modification of proteins themselves, which is called: A)post-protein modification B)transcriptional modification. C)post-translational modification D)alternative splicing. E)alternative modification

C

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 the following sequences is NOT a palindrome? A)5′-AGATCT-3′ B)5′-CCTGCAGG-3′ C)5′-CCTCAGG-3′ D)5′-CGGCCG-3′ E)5′-GGTACC-3′

C

Select the answer option that lists the levels of genetic information in order from smallest to largest. A)DNA strand; gene; genome; chromosome B)genome; gene; chromosome; DNA strand C)gene; DNA strand; chromosome; genome D)gene; chromosome; DNA strand; genome E)DNA strand; chromosome; gene; genome

C

The two organelles that contain their own genome are: A)ER and mitochondria B)chloroplast and vacuole C)mitochondria and chloroplast D)Golgi and ER E)Golgi and mitochondria

C

Transcription of a gene can be increased or decreased according to the: A)combination of histone proteins found within the nucleosome. B)coding sequences in the messenger RNAs for histone proteins. C)combination of amino acid modifications in the histone tails. D)proportion of arginine and lysine amino acids in the histone proteins.

C

What is the name of the class of enzymes that recognizes and cuts a specific sequence of DNA? A)helicases B)topoisomerases C)restriction enzymes D)DNA polymerases E)primases

C

Which of the following BEST describes the way you would engineer bacterial cells to produce a human protein? A)Use restriction enzymes to cleave the vector DNA and to shear the donor DNA into random pieces. B)Use restriction enzymes to cleave the donor DNA and to shear the vector DNA into random pieces. C)Use restriction enzymes to cleave both the donor DNA and the vector DNA. D)None of the answer options is correct. E)Randomly shear the donor DNA and the vector DNA

C

Which of the following statements concerning cyclin-dependent kinases (CDKs) is NOT true? CDKs are enzymes that attach phosphate groups to other proteins. CDKs are present throughout the cell cycle. CDKs are active, or "turned on," when complexed with cyclins. CDKs are inactive, or "turned off," in the presence of cyclins

CDKs are inactive, or "turned off," in the presence of cyclins.

A graduate student wants to create a recombinant DNA molecule and introduce this molecule into bacteria. What is the CORRECT order of steps that he should follow? A)join plasmid and donor DNA using DNA ligase → cut with restriction enzymes → transform bacteria B)cut plasmid/donor DNA with restriction enzymes → transform bacteria → isolate donor DNA/plasmid → join fragments with DNA ligase C)choose plasmid → cut with restriction enzymes → join fragments with DNA ligase → introduce donor DNA → transform bacteria D)choose plasmid/donor DNA → cut with restriction enzymes → join fragments via DNA ligase → transform bacteria E)transform bacteria → choose plasmid/donor DNA → join fragments with DNA ligase

D

Restriction enzymes recognize certain DNA sequences and: A)cut straight through both strands of DNA. B)cut through the DNA, leaving some overhang at both ends. C)will alternate between cutting straight through both strands of DNA and leaving some overhang at both ends. D)some of them will cut straight through, while others will leave an overhang at both ends of the cut.

D

The CORRECT sequence of steps in the eukaryotic cell cycle is: A)G0 → S phase → G1 → S phase → G2 → cytokinesis → mitosis. B)G0 → S phase → G1 → G2 → cytokinesis → mitosis. C)G1 → S phase → G2 → cytokinesis → mitosis. D)G1 → S phase → G2 → mitosis → cytokinesis. E)G0 → S phase → G1 → S phase → G2 → mitosis → cytokinesis.

D

The division of genetic material in a eukaryotic cell is called: A)genetic fission B)replication C)cytokinesis D)mitosis

D

The enzyme responsible for joining Okazaki fragments together during DNA replication is DNA ligase. topoisomerase II. helicase. DNA polymerase. DNA replicase.

DNA ligase

Why are primers needed for DNA replication? A tiny amount of RNA is needed to tell the cell where genes are located. DNA polymerase can only add nucleotides to an existing chain. The primers help with the proofreading function of DNA polymerase. They help with the joining of Okazaki fragments. They help direct the placement of the telomeres.

DNA polymerase can only add nucleotides to an existing chain

_____ is the process where new genes evolve from duplicates of old ones. Deletion Duplication and divergence Inversion Reciprocal translocation Centromere dosage

Duplication and divergence

Chromatin remodeling refers to the process by which: A)DNA strands are "unzipped" to allow access to the proteins that carry out transcription. B)mutations change DNA structure and therefore chromatin structure. C)DNA strands are "straightened out" to allow access to the proteins that carry out transcription. D)nucleosomes are repositioned to expose different stretches of DNA to the nuclear environment. E)methylation occurs in CpG islands.

E

Enhancer sequences are bound by: A)histone-modifying complexes. B)cytosine methylation enzymes. C)RNA splicing complexes. D)RNA editing complexes. E)transcription factors

E

One characteristic of restriction enzymes is that they cut: A)DNA fragments generated by gel electrophoresis. B)single-stranded DNA strands at specific sites. C)single-stranded DNA strands at random sites. D)double-stranded DNA strands at random sites. E)double-stranded DNA strands at specific sites.

E

Within a nucleoid, the supercoiled DNA loops are held together by: A)tubulin B)homologous chromosomes C)nucleoidal RNAs D)nucleosomes E)proteins

E

If a restriction site of AatII is 5'-GACGTC -3' then 3'-GACGTC-5' is also an AatII restriction site. True or False

False

What is the difference between mismatch repair and nucleotide excision repair? In mismatch repair, several nucleotides are replaced, whereas in nucleotide excision repair the sugar phosphate backbone is fixed. In mismatch repair, one nucleotide is replaced, whereas in nucleotide excision repair several nucleotides are replaced. In mismatch repair, several nucleotides are replaced, whereas in nucleotide excision repair it is just one. In mismatch repair, the sugar phosphate backbone is fixed, whereas in nucleotide excision repair, several nucleotides are replaced.

In mismatch repair, one nucleotide is replaced, whereas in nucleotide excision repair several nucleotides are replaced.

Which of the following statements regarding tumor suppressors is TRUE? Tumor suppressors act synergistically with proto-oncogenes. None of the other answer options is correct. Mutations affecting tumor suppressors can contribute to the development of cancers. Tumor suppressors include PDGF and cyclins. Tumor suppressors promote cell division.

Mutations affecting tumor suppressors can contribute to the development of cancers.

When in the cell cycle would you find sister chromatids? S G1 S and G2 G2

S and G2

_____ mutations affect only the individual in which they occur; _____ mutations are passed from parent to offspring. Germ-line; somatic Germ-line; heritable Somatic; point Point; germ-line Somatic; germ-line

Somatic; germ-line

How do new cyclin proteins appear in the cytoplasm? All of these choices are correct. They are imported from outside the cell. They are made through protein synthesis. They are recycled.

They are made through protein synthesis.

Why are telomeres a necessary component of linear chromosomes? They fix mistakes that are made during DNA replication. They maintain the length of a chromosome because DNA is shortened every time it is replicated. They direct where DNA synthesis will end. They direct where DNA synthesis will begin. None of the answer options is correct.

They maintain the length of a chromosome because DNA is shortened every time it is replicated.

Which of the following statements concerning cancer and mutations is CORRECT? Cancer can only occur with a mutation in a germ cell. Usually, multiple mutations are required in different genes to cause cancer. Cancer can only occur with a mutation in a somatic cell. Usually, a single mutation is all that is required to cause cancer. None of the other answer options is correct.

Usually, multiple mutations are required in different genes to cause cancer.

What is a cyclin? a kinase a protein whose levels change with the cell cycle a protein that activates kinases and a protein whose levels change with the cell cycle a protein that activates kinases

a protein that activates kinases and a protein whose levels change with the cell cycle

The development of cancer requires both the _____ of an oncogene and the _____ of a tumor suppressor. inhibition; activation activation; activation activation; inhibition inhibition; inhibition

activation; inhibition

CDKs are important in the regulation of the cell cycle. They carry out their function by: preventing the progression of a cell from one stage of the cell cycle to the next. adding phosphate groups to target proteins. degrading cyclin proteins. removing phosphate groups from target proteins.

adding phosphate groups to target proteins.

Cell division is regulated by: growth factor signals. All of these choices are correct. signals that indicate that DNA has been replicated. signals that indicate that the cell has reached a sufficient size. signals about the nutritional status of the cell.

all

Only 2.5% of the human genome actually codes for proteins. The other 97.5% includes: introns. All of these choices are correct. repetitive DNA. noncoding RNA.

all

Which of the following processes produce different proteins in different cells from the same primary transcript? (Select all that apply.) chromatin remodeling combinatorial control histone modification alternative splicing RNA editing

alternative splicing and RNA editing

In which phase of mitosis do sister chromatids separate? anaphase prophase metaphase telophase

anaphase

In which phase of mitosis do spindle microtubules shorten? prophase telophase anaphase metaphase

anaphase

The C-value paradox applies to: All of these choices are correct. eukaryotes. bacteria. archaea. viruses.

eukaryotes

Any DNA "damage" is considered to be a mutation, even if it is immediately corrected by the action of DNA polymerase. true or false

false

The complexity of an organism is proportional to the number of genes in its genome. False or True

false

Telomerase is fully active in _____ and _____ cells, but almost completely inactive in _____ cells. stem; blood; germ somatic; blood; germ germ; somatic; stem germ; stem; somatic somatic; germ; stem

germ; stem; somatic

In contrast to linear DNA replication, circular DNA replication typically: All of these choices are correct. has a single origin of replication. does not produce Okazaki fragments. does not produce a replication bubble. occurs only at a single replication fork.

has a single origin of replication

What is the name of the enzyme that separates the two strands of DNA during replication? helicase DNA ligase primase DNA polymerase topoisomerase

helicase

When a transposable element inserts into a gene, it can: (Select all that apply.) interfere with transcription. cause errors in RNA processing. cause the gene to duplicate itself. cause the gene to delete itself. disrupt the open reading frame.

interfere with transcription, cause errors in RNA processing, and distrupt the open reading frame

A chromosomal mutation where a segment breaks off, flips, and then reattaches itself is called a(n): duplication. inversion. translocation. reciprocal translocation. deletion.

inversion

The C-value paradox states that genome size: is positively correlated with complexity. is uncorrelated with complexity. differs in reproductive cells and nonreproductive cells. is negatively correlated with complexity.

is uncorrelated with complexity.

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: linear or circular

linear

A malignant cancer differs from a benign cancer in that: benign cancers are lethal and malignant ones are not. malignant cancers are caused by viruses and benign cancers are not. malignant cancers are lethal and benign cancers are not. malignant cancers invade surrounding tissue and benign cancers do not.

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. one; many many; two many; one many; three one; one

many;one

In which phase of mitosis do chromosomes line up at the middle of the cell? anaphase telophase prophase metaphase

metaphase

Which type of repair is a backup for the DNA polymerase proofreading function? base excision repair mismatch repair DNA ligase nucleotide excision repair

mismatch repair

The definition of mutation is "any heritable change in the genetic material." The qualifier "heritable" is necessary because: changes in the genetic material occur at random along the genome. most changes in the genetic material are harmful to the organism. changes in the genetic material occur without regard to the needs of the organism. most changes in the genetic material are repaired soon after they occur.

most changes in the genetic material are repaired soon

The relatively large number of new mutations that occur in the human genome in each generation is tolerable because: most of the mutations occur in somatic cells, not germ cells. compared to other organisms, changes in our proteins have relatively little effect on our cells' structures and functions. we have excellent DNA repair mechanisms. most of our genome is noncoding DNA, so few mutations affect our proteins. we have excellent protein repair mechanisms.

most of our genome is noncoding DNA, so few mutations affect our proteins.

In organisms with large genomes, inversions are more likely to be tolerated if the breakpoints occur in: coding DNA. reciprocal translocations. open reading frames. noncoding DNA. closed reading frames

noncoding DNA

Complex organisms can be characterized as having a: large genome with many protein-coding genes. small genome with few protein-coding genes. None of the other answer options is correct. small genome with many protein-coding genes. large genome with few protein-coding genes.

none

Point mutations that cause amino acid replacements are called: nonsense mutation. transition mutation. nonsynonymous (missense) mutation. stop mutation. synonymous (silent) mutation.

nonsynonymous (missense) mutation.

As a piece of linear DNA is replicated, the leading strand will have _____ RNA primer(s) and the lagging strand will have _____ RNA primer(s). many; many one; two many; one one; one one; many

one;many

Having more than two sets of chromosomes in the genome is called: diploidy. aneuploidy. polyploidy. extraploidy. haploidy.

poluploidy

In which phase of mitosis do chromosomes condense? anaphase telophase prophase metaphase

prophase

A gene associated with promoting normal cell division is called a(n): proto-oncogene or a tumor suppressor. tumor suppressor. proto-oncogene. oncogene.

proto-oncogene.

Chronic myelogenous leukemia (CML) is caused when a segment of chromosome 9 and a segment of chromosome 22 both break off and switch places. How is this mutation classified? deletion duplication inversion reciprocal translocation transposition

reciprocal translocation

Which of the following is NOT needed for DNA replication? enzymes ribosomes None of the other answer options is correct. DNA nucleotides

ribosomes

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 single mutation affecting one proto-oncogene in a cell. several mutations affecting proto-oncogenes and/or tumor suppressor genes. a single mutation inactivating a tumor suppressor gene. None of the other answer options is correctcancers arise spontaneously, independent of mutations.

several mutations affecting proto-oncogenes and/or tumor suppressor genes.

The two molecules of double-stranded DNA in a replicated chromosome are called: homologous chromosomes non-sister chromatids bivalent chromosomes sister chromatids

sister chromatids

When DNA with variable number tandem repeats (VNTRs) is visualized on a gel, the resulting fragments separate according to their: shape. G-C content. size. A-T content. color.

size

If you were able to find a drug that could inhibit the reactivation of telomerase activity in cancer cells, the cancer cells would: eventually die from lack of energy. gradually revert to normal cells. become less invasive. slowly erode their chromosome ends. stop dividing immediately.

slowly erode their chromosome ends.

A point mutation that causes no change in the amino acid sequence of a protein is called a: stop mutation. transition mutation. synonymous (silent) mutation. nonsynonymous (missense) mutation.

synonymous (silent) mutation.

Although a match between the DNA in a sample and the genomic DNA of a particular individual for a single variable number tandem repeat (VNTR) is not sufficient to establish identity, a mismatch is definitive. The primary reason is that: an individual could show an extra VNTR band merely by chance. any band in the sample could have been degraded by nucleases. the sample might have been contaminated. VNTRs have multiple alleles and many possible genotypes. the DNA in the sample must match its origin.

teh DNA in the sample must match its origin

In which phase of mitosis does the nuclear envelope reform? prophase anaphase metaphase telophase

telophase

In DNA replication, each individual parent strand acts as a _____ strand for the synthesis of a _____ strand. daughter; duplicate template; duplicate daughter; template template; daughter duplicate; daughter

template;daughter

Imagine a region of DNA containing a variable number tandem repeat (VNTR) that is found in the genome of koalas. The possible number of VNTR alleles in the population equals the number of: base pairs. restriction fragment length polymorphisms there are in the genome. times a gene is repeated in tandem along the DNA. times a short noncoding sequence is repeated in tandem along the DNA. genes.

times a gene is repeated in tandem along the DNA.

What is the function of the enzyme DNA polymerase? to synthesize a strand of DNA using DNA as a template to synthesize a strand of mRNA using mRNA as a template to synthesize a strand of DNA using a polypeptide as a template to synthesize a polypeptide using DNA as a template to synthesize a strand of mRNA using DNA as a template

to synthesize a strand of DNA using DNA as a template

A chromosomal segment that breaks off and attaches to another chromosome is what type of mutation? deletion inversion translocation duplication reciprocal translocation

translocation

A chromosomal mutation in which a segment is missing is called a deletion. true or false

true

Insertion of one nucleotide in a gene will lead to a frameshift mutation. true or false

true

Mutagens increase the amount of damage to DNA. true or false

true

Mismatch repair, base excision repair, and nucleotide excision repair are similar in that each: (Select all that apply.) repairs a short strand of mismatched nucleotides. uses an undamaged segment of DNA as the template to repair a damaged segment of DNA. repairs a single mismatched base. None of the answer options is correct. repairs multiple mismatched or damaged bases across a region.

uses an undamaged segment of DNA as the template to repair a damaged segment of DNA.

_____ are short, repeated sequences of DNA that vary in number from one chromosome to the next. Point mutation repetitions Restriction fragment length polymorphisms Variable number tandem repeats Recombination repeats DNA types

variable number tandem repeats

When we say that DNA replication is semiconservative, we mean that: parental DNA stays in the parent cell and daughter DNA ends up in the daughter cell. only half of an organism's DNA is replicated during each cell division. when DNA is replicated, one double helix contains both parental strands and one contains two newly synthesized daughter strands. None of the other answer options is correct. when DNA is replicated, each new double helix contains one parental strand and one newly synthesized daughter strand.

when DNA is replicated, each new double helix contains one parental strand and one newly synthesized daughter strand.

Which of the following causes breaks in one or both of the sugar-phosphate backbones? UV radiation tobacco smoke X-rays exposure to oxidizing agents such as household bleach or hydrogen peroxide

x-rays