biology final (7-10)

9. How many pairs of chromosomes does the human genome normally have? a) 23 38 15 46 6

23

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

25,000.

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

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

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

50%

3. 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′-CGGCCG-3′ 5′-CCTCAGG-3′ 5′-AGATCT-3′ 5′-GGTACC-3′ 5′-CCTGCAGG-3′

5′-CCTCAGG-3′

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

All of these choices are correct.

7. Modifications of histone tails can: a) All of these choices are correct. affect chromatin structure. activate transcription of some genes. affect expression of some genes in response to the environment. repress transcription of some genes.

All of these choices are correct.

2. Where is DNA polymerase found to the left of the dotted line? a) Top strand Bottom strand Both strands

Both strands

1. The diagram below represents the replication bubble that has formed at a bidirectional origin of replication. The dotted line shows where replication first began. Use this diagram to answer the questions below. Where does lagging strand synthesis occur to the right of the dotted line? a) Top strand Bottom strand Both strands

Bottom strand

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

DNA ligase.

4. Why are primers needed for DNA replication? a) They help direct the placement of the telomeres. They help with the joining of Okazaki fragments. The primers help with the proofreading function of DNA polymerase. 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.

DNA polymerase can only add nucleotides to an existing chain.

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

DNA wraps around histones in eukaryotic packaging.

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

DNA wraps around histones in eukaryotic packaging.

1. Consider the haplotype for the bacterial lac operon: I-O+Z+. There is also a plasmid with the haplotype: I+OcZ-. For all of the questions below, assume there is no glucose and no inducer. Functional beta-galactosidase will be produced in this cell: True False

False

2. Repressor protein will be bound to both operators in this cell: True False

False

5. Gel set C could result from a mutation that causes methylation of the CpG bases in the promoter region of the gene, assuming that WT is not methylated: True False

False

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

False

2. The CORRECT sequence of steps in the eukaryotic cell cycle is: a) G1 → S phase → G2 → cytokinesis → mitosis. G0 → S phase → G1 → S phase → G2 → cytokinesis → mitosis. G0 → S phase → G1 → S phase → G2 → mitosis → cytokinesis. G1 → S phase → G2 → mitosis → cytokinesis. G0 → S phase → G1 → G2 → cytokinesis → mitosis.

G1 → S phase → G2 → mitosis → cytokinesis.

2. A eukaryotic gene is most likely to be transcribed if it is located where? a) In a region of the genome in which the histones are methylated In a heterochromatic region of teh genome In a region of the genome in which the histones are acetylated In a region of the genome in which the histones are unmodified

In a region of the genome in which the histones are acetylated

5. Which lane contains the DNA fragments produced by digestion of the plasmid with enzymes X and Y and Z? a) Lane Q Lane K Lane L Lane M Lane H

Lane H

1. Below on the left is a diagram of double-stranded DNA of a circular plasmid from a bacterial cell. The positions X, Y, and Z are sites where the plasmid DNA is cleaved by restriction enzymes X, Y, and Z, respectively. The numbers are the size in kilobase pairs (kb) of the DNA regions between the restriction sites. On the right is a diagram of an electrophoresis gel. Lane 1 is the ladder, comprised of DNA fragments that range in size from 1-12 kb showing the position of each band size after electrophoresis. The other lanes are DNA bands observed from digestion of the plasmid with one of more of the restriction enzymes. Which lane contains the DNA fragments produced by digestion of the plasmid with enzyme X only? a) Lane Q Lane L Lane K Lane H Lane M

Lane K

4. Which lane contains the DNA fragments produced by digestion of the plasmid with enzymes Y and Z? a) Lane M Lane K Lane Q Lane H Lane L

Lane L

2. Which lane contains the DNA fragments produced by digestion of the plasmid with enzymes X and Y? a) Lane M Lane K Lane H Lane L Lane Q

Lane M

3. Which lane contains the DNA fragments produced by digestion of the plasmid with enzymes X and Z? a) Lane K Lane L Lane M Lane Q Lane H

Lane Q

2. Imagine that a doctor is culturing cells from a malignant melanoma and from a normal skin sample. How would you expect these two cell populations to differ? a) Malignant melanoma cells would have telomeres that do not shorten during successive rounds of replication. Malignant melanoma cells would have active telomerases that constantly replenish and lengthen telomeres. Normal skin cells would have telomeres that do not shorten during successive rounds of replication. Malignant melanoma cells would have inactive telomerases and so their telomeres would shorten during successive rounds of replication. Normal skin cells would have active telomerases that constantly replenish and lengthen telomeres.

Malignant melanoma cells would have active telomerases that constantly replenish and lengthen telomeres.

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

None of the other answer options is correct.

2. What features of DNA make it possible to make recombinant DNA in the lab? (Select all that apply.) a) Restriction enzymes cut DNA from all species. None of the other answer options is correct. Two double helices from different sources can be ligated together. 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. The genetic code is the same for all organisms.

3. Consider a cell in which one of the proteins involved in DNA replication is altered. This alteration results in an increased occurrence of single-stranded DNA breaks in the newly synthesized DNA. Which protein function is most likely nonfunctional in this situation? a) The fragment joining function of ligase The strand separation function of single-stranded binding protein (SSB) The proofreading function of DNA polymerase The winding stress relief function of topoisomerase The unwinding function of helicase

The fragment joining function of ligase

5. To cells that are defective in primer removal, you add fluorescent ribonucleotides when the cells are undergoing DNA replication. In this case, you observe that one strand glows more than the other not only near the replication fork but also at intervals along its length. Which strand glows in this way and why? a) The lagging strand glows in this way because it is synthesized continuously. The leading strand glows in this way because it is synthesized continuously. The leading strand glows in this way because its RNA primers are widely spaced. The lagging strand glows in this way because its RNA primers are closely spaced.

The lagging strand glows in this way because its RNA primers are closely spaced.

7. Suppose you add fluorescent ribonucleotides to a cell undergoing DNA replication so that the RNA primers used in DNA synthesis glow when viewed with a fluorescent microscope. You notice that, near each replication fork, one strand glows more than the other. Which strand is it that glows more, and why? a) The lagging strand glows more because its RNA primer is nearer the replication fork. The leading strand glows more because it is elongated nearest the replication fork. The leading strand glows more because it forms the "trombone loop." The lagging strand glows more because it forms the "trombone loop."

The lagging strand glows more because its RNA primer is nearer the replication fork.

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

3. Which strand is bound to more RNA primers to the left of the dotted line? a) Top strand Bottom strand Both strands

Top strand

3. Consider the three sets of gels below. Each set shows an RNA gel and a protein gel for the products of the same gene. For each gel, "WT" indicates the normal wild type products and "Mut" indicates the mutant products. Use these gels to determine whether each of the following statements is true or false. (google docs for image) Gel set A could result from a mutation that inhibits the function of the SWI/SNF nucleosome remodeling complex: True False

True

4. Gel set B could result from a mutation that causes the gene to be targeted by a histone acetyltransferase (HAT), assuming that WT is not targeted by a HAT: True False

True

CRP-cAMP will be bound to both copies of the lac operon in this cell: True False

True

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

Use restriction enzymes to cleave both the donor DNA and the vector DNA.

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

Variable number tandem repeats

4. A Southern blot is a technique that relies on hybridization of: a) a nucleic acid probe to a complementary DNA. a nucleic acid probe to a complementary RNA. None of the other answer options is correct. proteins to DNA.

a nucleic acid probe to a complementary DNA.

For the lactose operon, the CRP-cAMP is a(n): a) operator. activator. promoter. inducer. repressor.

activator

An activator protein combines with a small molecule and undergoes a change in shape that alters its binding affinity to DNA. This change in shape is an example of: a) allosteric effect. activator effect. induced silencing. position effect. dosage compensation.

allosteric effect.

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

alternative splicing RNA editing

1. The lactose operon is under positive control by the CRP-cAMP complex. In order for the operon to be fully inducible, the CRP-cAMP complex must be: (Select all that apply.) a) at low concentration. absent from the regulatory region of the operon. at high concentration. bound to the regulatory region of the operon.

at high concentration. bound to the regulatory region of the operon.

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

bacteria taking up the recombinant DNA in the form of the vectors.

. In prokaryotes, repressor proteins: (Select all that apply.) a) bind with DNA and prevent transcription. are part of the mechanism of positive regulation. bind with activators and prevent transcription. are part of the mechanism of negative regulation.

bind with DNA and prevent transcription. are part of the mechanism of negative regulation.

5. 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. can change over time in response to environmental cues, but this has no effect on gene expression. is fixed; such genes are permanently turned off. is fixed, but this has no effect on whether genes are expressed. is random sometimes the cytosines are methylated and sometimes they're not, but the state is independent of the environment or cell type.

can change over time in response to environmental cues, allowing genes to be turned on or off as needed.

1. 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) choose plasmid/donor DNA → cut with restriction enzymes → join fragments via DNA ligase → transform bacteria transform bacteria → choose plasmid/donor DNA → join fragments with DNA ligase cut plasmid/donor DNA with restriction enzymes → transform bacteria → isolate donor DNA/plasmid → join fragments with DNA ligase join plasmid and donor DNA using DNA ligase → cut with restriction enzymes → transform bacteria choose plasmid → cut with restriction enzymes → join fragments with DNA ligase → introduce donor DNA → transform bacteria

choose plasmid/donor DNA → cut with restriction enzymes → join fragments via DNA ligase → transform bacteria

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

combination of amino acid modifications in the histone tails.

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

different polypeptides to be made from a single gene.

2. Alternative splicing means that: a) some transcripts are spliced correctly and others incorrectly. different spliced forms contain different combinations of exons. some transcripts are spliced while others are not. alternating introns are removed. Instructional Guidance: What does splicing refer to?

different spliced forms contain different combinations of exons.

7. One characteristic of restriction enzymes is that they cut: a) DNA fragments generated by gel electrophoresis. double-stranded DNA strands at specific sites. single-stranded DNA strands at specific sites. single-stranded DNA strands at random sites. double-stranded DNA strands at random sites.

double-stranded DNA strands at specific sites.

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

eukaryotes

It is necessary for the gene that codes for the repressor of lac operon to be near the structural genes. True False

false

4. Select the answer option that lists the levels of genetic information in order from smallest to largest. a) DNA strand; gene; genome; chromosome gene; DNA strand; chromosome; genome genome; gene; chromosome; DNA strand DNA strand; chromosome; gene; genome gene; chromosome; DNA strand; genome

gene; DNA strand; chromosome; genome

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

germ; stem; somatic

The CRP-cAMP complex binds the lactose operon when: a) glucose levels are low and cAMP levels are high b) glucose levels and cAMP levels are high c) glucose levels are high and cAMP levels are low d) None of the answer options is correct e) glucose levels and cAMP levels are low

glucose levels are low and cAMP levels are high

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

has a single origin of replication

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

helicase

Positive and negative transcriptional regulation differ in that: a) None of the answer options is correct. b) positive regulation requires that a promoter be present; a promoter is not necessary in negative regulation. c) in positive regulation, the binding of a regulatory protein to the DNA is necessary for transcription to occur; in negative regulation, such binding prevents transcription. d) in positive regulation, the absence of a regulatory protein promotes transcription; in negative regulation, the absence of a regulatory protein promotes transcription. e) in positive regulation, the binding of a regulatory protein to the DNA is necessary for transcription to occur; in negative regulation, no such protein is necessary.

in positive regulation, the binding of a regulatory protein to the DNA is necessary for transcription to occur; in negative regulation, such binding prevents transcription.

For the lactose operon, lactose is a(n): a) inducer b) repressor c) operator d) promoter e) activator

inducer

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

is uncorrelated with complexity.

2. A mutant strain of E. coli is found that produces both β-galactosidase and permease constitutively. What are the MOST likely mutations in this strain? (Select all that apply.) a) lacI- lacOc lacP- lacZ- and lacY- mutation in CRP-cAMP binding site

lacI- lacOc

The lacZ and lacY genes are transcribed when: a) glucose levels are high and lactose levels are low. lactose is present, regardless of the level of glucose in the cell. lactose is absent and glucose levels are high. lactose is present and glucose levels are low. glucose levels are low, regardless of the level of lactose in the cell.

lactose is present and glucose levels are low.

2. 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: It is not possible to make this determination from the information provided. circular. linear.

linear

3. A eukaryotic chromosome has _____ origin(s) of replication, and a bacterial chromosome has _____ origin(s) of replication. a) one; one many; two many; one one; many many; three

many; one

6. The two organelles that contain their own genome are: a) mitochondria and chloroplast. endoplasmic reticulum and mitochondria. chloroplast and vacuole. Golgi apparatus and endoplasmic reticulum. Golgi apparatus and mitochondria.

mitochondria and chloroplast.

1. The division of genetic material in a eukaryotic cell is called: a) cytokinesis. mitosis. genetic fission. replication

mitosis

1. X-inactivation is caused by the accumulation of: a) proteins produced by the Xist gene; these proteins induce methylation, histone modification, and other changes associated with preventing transcription. 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. 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. None of the answer choices accurately describes the process of X-inactivation. noncoding RNA produced by the Xist gene, which coats the X chromosome and covalently crosslinks the DNA strands preventing them from being unwound, "unzipped," and transcribed.

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.

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

nucleosomes

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

nucleosomes are repositioned to expose different stretches of DNA to the nuclear environment.

3. 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 chromosome, nucleosome, chromatin, DNA duplex, nucleotide chromosome, chromatin, nucleosome, DNA duplex, nucleotide nucleotide, DNA duplex, nucleosome, chromatin, chromosome nucleotide, nucleosome, DNA duplex, chromatin, chromosome

nucleotide, DNA duplex, nucleosome, chromatin, chromosome

1. Which of the following is circled in this electron micrograph? a) two double-stranded DNA molecules one double-stranded DNA molecule one single strand of a DNA molecule

one double-stranded DNA molecule

6. Each DNA parent strand within a replication bubble acts as a template strand that produces: a) only lagging strands. either a leading strand or a lagging strand. one leading strand and one lagging strand. only leading strands. two leading strands or two lagging strands.

one leading strand and one lagging strand.

7. 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). a) one; two one; one many; one many; many one; many

one; many

8. 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). a) one; many one; two many; one one; one many; many

one; many

A region of prokaryotic DNA consisting of an operator, promoter, and coding sequence for several functionally related genes is called a(n): a) opera. closed reading frame. operon. organized genomic region. operation.

operon

5. 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) ribose sugar All of these choices are correct. phosphate group hydroxyl group nitrogenous base

phosphate group

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

polyploidy.

3. 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 post-translational modification transcriptional modification. alternative splicing. alternative modification

post-translational modification

8. Within a nucleoid, the supercoiled DNA loops are held together by: a) nucleoidal RNAs. proteins. nucleosomes. homologous chromosomes. tubulin.

proteins

An operon is: a) single molecule of RNA coding for more than one protein. region of DNA consisting of the operator and coding sequences for structural proteins. gene coding for a repressor protein. region of DNA consisting of the promoter and operator sequences needed to regulate one or more structural genes. region of DNA consisting of the promoter, the operator, and coding sequences for structural proteins.

region of DNA consisting of the promoter, the operator, and coding sequences for structural proteins.

In prokaryotes, inducers are small molecules that bind to _____ and _____ transcription. a) activators; inhibit b) repressors; promote c) None of the answer options is correct d) activators; promote e) repressors; inhibit

repressors; promote

6. What is the name of the class of enzymes that recognizes and cuts a specific sequence of DNA? a) DNA polymerases topoisomerases helicases restriction enzymes primases

restriction enzymes

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

ribosomes

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

size

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

slowly erode their chromosome ends.

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

some of them will cut straight through, while others will leave an overhang at both ends of the cut.

In the lacotse operson of the E. coli, the lacZ and lac Y genes are: a) structural genes. operators. promoters. repressors. inducers.

structural genes

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

template; daughter

2. 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: a) VNTRs have multiple alleles and many possible genotypes. the DNA in the sample must match its origin. an individual could show an extra VNTR band merely by chance. the sample might have been contaminated. any band in the sample could have been degraded by nucleases.

the DNA in the sample must match its origin.

Nucleosomes are found in: a) mitochondria. the nucleus. All of these choices are correct. chloroplasts.

the nucleus.

3. 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: a) restriction fragment length polymorphisms there are in the genome. times a short noncoding sequence is repeated in tandem along the DNA. times a gene is repeated in tandem along the DNA. genes. base pairs.

times a short noncoding sequence is repeated in tandem along the DNA.

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

6. Enhancer sequences are bound by: a) RNA editing complexes. histone-modifying complexes. transcription factors. RNA splicing complexes. cytosine methylation enzymes.

transcription factors.

4. In general, when cytosine bases in CpG islands are methylated: a) translation is active and rapid. transcription is repressed. transcription is active, but slow. transcription is active and rapid. translation is repressed.

transcription is repressed.

3. A skin cell in G2 of interphase has _____ as much DNA as it had in G1. a) four times exactly one-fourth twice half

twice

4. The parallel lines shown here 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) w and x y and z w and z w and y y and x

w and z

6. When we say that DNA replication is semiconservative, we mean that: a) when DNA is replicated, each new double helix contains one parental strand and one newly synthesized daughter strand. 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. only half of an organism's DNA is replicated during each cell division. parental DNA stays in the parent cell and daughter DNA ends up in the daughter cell.

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

A strain of E. coli is genetically engineered in which the lacZ and lacY genes are removed and replaced with a gene encoding a fluorescent protein. A copy of the operon in which the protein product fluoresces green is inserted into the chromosome, and a copy in which the protein product fluoresces red is inserted into a plasmid. Both copies carry a wild-type lacO gene, and the cells of the strain have a single copy of the lacI repressor gene. If both fluorescent proteins are expressed, the cells fluoresce yellow (because a combination of red and green fluorescence appears as yellow), and if neither of the fluorescent proteins is expressed, the cells show no fluorescence. 4. If the lacI gene in the genetically engineered fluorescent strain were nonmutant but the lacO sequence on the chromosome mutated to lacOc, how would the cells fluoresce in the presence of inducer? In the absence of inducer? a) yellow; no fluorescence None of the other answer options is correct. yellow; green yellow; red yellow; yellow

yellow; green

5. If the lacI gene in the genetically engineered fluorescent strain were nonmutant but the lacO sequence on the plasmid mutated to lacOc, how would the cells fluoresce in the presence of inducer? In the absence of inducer? a) yellow; no fluorescence yellow; yellow None of the other answer options is correct. yellow; red yellow; green

yellow; red

3. In order to analyze how different components of the lac operon work, scientists created special strains of E. coli, called partial diploids. A partial diploid has one full copy of the lac operon in the bacterial chromosome plus another copy of the lac operon in a plasmid. Hence, for the lac operon (and only the lac operon) the bacterial cell is a diploid. Below is one possible genotype of a partial diploid. The genotype written to the left of the slash (/) is that of the lac operon in the bacterial chromosome, and the genotype written to the right of the slash is that of the lac operon in the plasmid. I+ P- O+ Z+/ I- P+ O+ Z- For the partial diploid genotype shown here, determine whether functional β-galactosidase is synthesized in the absence and in the presence of lactose (and the accompanying allolactose that is the actual inducer). a) β-galactosidase is produced when lactose is present but is not produced when lactose is absent. β-galactosidase is not produced whether lactose is present or absent. β-galactosidase is not produced when lactose is present but is produced when lactose is absent. β-galactosidase is produced whether lactose is present or absent.

β-galactosidase is not produced whether lactose is present or absent.