BIOS 1700 Chapter 12

DNA replication in human cells occurs at a rate of about 50 base pairs per second, and the length of the longest human chromosome (chromosome 1) is 249 Mb. If DNA replication took place continuously from one end of chromosome 1 to the other, it would take approximately: 2 seconds. 2 hours. 2 months. 2 days. 2 minutes.

2 months

A new nucleotide can only be added to the _____ end of a growing DNA strand. DNA therefore always grows in the _____ direction. 5′; 3′ to 5′ 3′; 3′ to 5′ 3′; 5′ to 3′ 5′; 5′ to 3′

3'; 5' to 3'

A new nucleotide can only be added to the _____ end of a growing DNA strand. DNA therefore always grows in the _____ direction. 5′; 5′ to 3′ 3′; 5′ to 3′ 5′; 3′ to 5′ 3′; 3′ to 5′

3'; 5' to 3'

The leading strand is the daughter strand that has its _____ end pointed toward the replication fork and is therefore synthesized _____. 3′; in a series of segments 5′; continuously 3′; continuously None of the other answer options is correct. 5′; in a series of segments

3'; continuously

The leading strand is the daughter strand that has its _____ end pointed toward the replication fork and is therefore synthesized _____. 5′; continuously None of the other answer options is correct. 3′; in a series of segments 3′; continuously 5′; in a series of segments

3'; continuously

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? 8 24 12 16 32

32

During DNA replication in a cell, RNA primase synthesizes a primer that is complementary to the region in the sequence below shown in bold. 5'-CACAGCAGAAACCTACAACTCATG-3' What is the primer sequence? 5'-CTTTGGATGTTG-3' 5'-CUUUGGAUGUUG-3' 5'-GUUGUAGGUUUC-3' 5'-GTTGTAGGTTTC-3'

5'-GUUGUAGGUUUC-3'

The oligonucleotide primers used in the polymerase chain reaction are typically 20-30 nucleotides in length or longer; however, for purposes of this problem let's assume that 6 nucleotides is long enough. You wish to amplify the fragment shown below (the raised dots indicate several kilobases of DNA sequence not shown) and decide to design primers corresponding to the regions that are underlined. What primer sequences would you use? 5'-ATGCTGAAACTTCTC···GGGATGAAATCAGTTT-3' 3'-TACGACTTTGAAGAG···CCCTACTTTAGTCAAA-5' 5'-GTTTCA-3' and 5'-CTGATT-3' 5'-TGAAAC-3' and 5'-AATCAG-3' 5'-GTTTCA-3' and 5'-AATCAG-3' 5'-TGAAAC-3' and 5'-CTGATT-3'

5'-TGAAAC-3' and 5'-CTGATT-3'

The lagging strand is the daughter strand that has its _____ end pointed toward the replication fork and is therefore synthesized _____. 3′; continuously 5′; continuously None of the other answer options is correct. 5′; in a series of segments 3′; in a series of segments

5'; in a series of segments

Production of a recombinant DNA molecule makes use of which of the following properties of DNA? (Select all that apply.) A restriction enzyme cleaves duplex DNA molecules only at the positions of certain short sequences constituting the enzyme's restrictions site. DNA polymerase elongates a growing DNA strand by the addition of successive deoxynuclotides to the 3' end. Duplex nucleic acid molecules can be separated by size by means of electrophoresis. DNA ligase is an enzyme that can join the ends of single-stranded DNA molecules. Complementary single-stranded nucleic acid sequences can come together to form a duplex molecule.

A restriction enzyme cleaves duplex DNA molecules only at the positions of certain short sequences constituting the enzyme's restrictions site. Duplex nucleic acid molecules can be separated by size by means of electrophoresis. DNA ligase is an enzyme that can join the ends of single-stranded DNA molecules. Complementary single-stranded nucleic acid sequences can come together to form a duplex molecule.

An experiment in DNA editing using CRISPR is carried out in which the editing template DNA contains a G-A mismatch in the region to be edited. At the same nucleotide site in the resulting edited targeted DNA, the base pair is expected to be: C-T. G-C. T-A. None of the answer options is correct. G-A.

C-T

Which of the following enzymes is the FIRST to bind to the DNA sequences at the origin of replication? DNA ligase DNA primase DNA polymerase DNA helicase single-strand binding protein

DNA helicase

The enzyme responsible for proofreading a growing DNA strand and for replacing mismatched nucleotides is: DNA ligase. DNA polymerase. DNA replicase. topoisomerase II. helicase.

DNA polymerase

The enzyme responsible for proofreading a growing DNA strand and for replacing mismatched nucleotides is: DNA polymerase. DNA ligase. helicase. DNA replicase. topoisomerase II.

DNA polymerase

The enzyme responsible for replacing RNA primers with DNA is a type of: helicase. topoisomerase II. DNA polymerase. DNA ligase. DNA replicase.

DNA polymerase

Which of the following make(s) amplification of a DNA fragment by means of the polymerase chain reaction possible? (Select all that apply.) DNA ligase is an enzyme that can join the ends of single-stranded DNA molecules. A restriction enzyme cleaves duplex DNA molecules only at the positions of certain short sequences constituting the enzyme's restrictions site. DNA polymerase elongates a growing DNA strand by the addition of successive deoxynuclotides to the 3' end. Duplex nucleic acid molecules can be separated by size by means of electrophoresis. Complementary single-stranded nucleic acid sequences can come together to form a duplex molecule.

DNA polymerase elongates a growing DNA strand by the addition of successive deoxynucleotides to the 3' end complementary single-stranded nucleic acid sequences can come together to form a duplex molecule

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? DNA polymerase III DNA polymerase I helicase RNA primase DNA ligase

DNA polymerase |

The enzyme responsible for replacing RNA primers with DNA is a type of: DNA ligase. DNA polymerase I. helicase. topoisomerase II. DNA polymerase III.

DNA polymerase |

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? 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. Normal skin cells would have telomeres that do not shorten during successive rounds of replication. Malignant melanoma 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.

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

Which of the following make(s) sequencing by the Sanger chain-termination method possible? (Select all that apply.) New nucleotides are added only to the 3' end of a growing DNA strand. Duplex nucleic acid molecules can be separated by size by means of electrophoresis. Single-stranded nucleic acid molecules can be immobilized on certain types of filter paper. Complementary single-stranded nucleic acid sequences can come together to form a duplex molecule. A DNA strand whose 3' end terminates in a dideoxynucleotide cannot be elongated.

New nucleotides are added only to the 3' end of a growing DNA strand. Duplex nucleic acid molecules can be separated by size by means of electrophoresis. Complementary single-stranded nucleic acid sequences can come together to form a duplex molecule. A DNA strand whose 3' end terminates in a dideoxynucleotide cannot be elongated.

You are interested in studying human ß-globin and decide to produce the protein in bacterial cells. The ß-globin gene is a relatively simple gene with a single intron. You insert the entire gene, including the gene's promoter, in a plasmid and transform the recombinant plasmid into E. coli. You are disappointed to discover that your bacterial culture does not produce the correct protein. What are some possible explanations? (Select all that apply.) The bacterial cell produces the protein but it is rapidly degraded. The bacterial cell does not recognize the eukaryote promoter. The bacterial cell is missing RNA polymerase. The bacterial cell cannot splice introns.

The bacterial cell produces the protein but it is rapidly degraded. The bacterial cell does not recognize the eukaryote promoter. The bacterial cell cannot splice introns.

In replication of a linear double-stranded DNA molecule, one end of each strand becomes shorter in each round of replication. This happens because: All of these choices are correct. each replicated DNA strand requires an RNA primer. the RNA primer cannot be replaced at the very end of a DNA strand. DNA polymerase elongates a growing DNA strand at only the 3′ end.

all of these choices are correct

In replication of a linear double-stranded DNA molecule, one end of each strand becomes shorter in each round of replication. This happens because: each replicated DNA strand requires an RNA primer. All of these choices are correct. the RNA primer cannot be replaced at the very end of a DNA strand. DNA polymerase elongates a growing DNA strand at only the 3′ end.

all of these choices are correct

The transformation step in creating bacteria genetically engineered to produce human proteins involves: bacteria expressing the novel proteins encoded by the donor DNA. cleaving the donor and vector DNA so they can be bound into a single molecule. bacteria taking up the recombinant DNA in the form of the vectors. 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

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

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

Which of the following statements is TRUE regarding DNA replication? Both strands get shortened at opposite ends during replication. Both strands get shortened at the same end during replication. Only the leading strand gets shortened during replication. Only the lagging strand gets shortened during replication. Only the lagging strand gets shortened after every other round of replication.

both strands get shortened at opposite ends during repliaction

The technique of Sanger sequencing takes advantage of the fact that dideoxynucleotides (nucleotides in which the 3′ hydroxyl group is absent) act as: probes. None of the other answer options is correct. chain terminators. palindromic sites. restriction sites.

chain terminators

In gel electrophoresis, DNA fragments migrate toward the negative pole of the electric field. False True

false

Organisms that have been modified to contain DNA from other species are known as: (Select all that apply.) Sanger recombinants. recombinant DNA organisms. DNA hybrids. genetically modified organisms (GMOs). transgenic organisms.

genetically modified organisms (GMOs) transgenic organisms

In contrast to linear DNA replication, circular DNA replication typically: 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.

has a single origin of replication

Gel electrophoresis separates DNA fragments based on: mutations. primers. nucleotide sequence. length. replication rate.

length

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

one leading strand and one lagging strand

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; many one; one many; one one; two

one; many

Which of these is necessary for only the FIRST step of PCR? DNA polymerase DNA primers All of these choices are correct. the four DNA nucleotides original template DNA

original template DNA

Which of these is necessary for only the FIRST step of PCR? DNA polymerase DNA primers the four DNA nucleotides original template DNA All of these choices are correct.

original template DNA

The type of genetic engineering that often involves isolating genes from one species and introducing them into another is called _____ technology. Sanger sequencing recombinant DNA palindromic DNA hybridization Sanger recombination

recombinant DNA

In a long DNA molecule, each origin of replication produces a _____ with a _____ on each side. None of the other answer options is correct. replication bubble; DNA ligase replication bubble; replication fork replication fork; replication bubble replication fork; DNA ligase

replication bubble; replication fork

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

slowly erode their chromosome ends

The enzyme _____ compensates for chromosomes shortening at the tips after each round of DNA replication. DNA polymerase DNA replicase topoisomerase II telomerase DNA ligase

telomerase

What would happen to the variation between organisms in a population if their DNA polymerase did NOT have a proofreading function? The amount of variation would decrease. The amount of variation would increase. The amount of variation would stay the same.

the amount of variation would increase

What feature of double-stranded DNA makes it necessary to have a leading strand and a lagging strand during replication? the antiparallel orientation of the strands the hydrogen bonding between bases the base stacking of the bases the negative charge on the sugar-phosphate backbone

the antiparallel orientation of the strands

What would happen if telomerase stopped working in a cell in which it normally functions at high levels? The cells would be able to divide indefinitely. Cancer would be the result. The cell would die immediately. None of the other answer options is correct. The cell would eventually die as the DNA continued to shorten.

the cell would eventually die as the DNA continues to shorten

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? The leading strand glows in this way because its RNA primers are widely spaced. The lagging strand glows in this way because it is synthesized continuously. The lagging strand glows in this way because its RNA primers are closely spaced. The leading strand glows in this way because it is synthesized continuously.

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

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? The lagging strand glows more because its RNA primer is nearer the replication fork. The leading strand glows more because it forms the "trombone loop." The leading strand glows more because it is elongated nearest the replication fork. 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

A lack of telomerase activity limits what? the number of Okazaki fragments that can be linked together the number of times a cell can divide the rate of DNA replication the rate of meiosis the number of replication bubbles that form during replication

the number of times a cell can divide

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? the proofreading function of DNA polymerase the unwinding function of helicase the strand separation function of single-stranded binding protein the fragment joining function of DNA ligase the winding stress relief function of topoisomerase II

the proofreading function of DNA polymerase

In circular DNA, the DNA molecule is not shortened during replication. True False

true

The presence of Okazaki fragments demonstrates the antiparallel nature of the double helix. True False

true

Which of the following BEST describes the way you would engineer bacterial cells to produce a human protein? 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 both the donor DNA and the vector DNA. 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

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. None of the other answer options is correct. 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. 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