DNA REPLICATION MASTERING BIO PART 2

4

What are the repetitive DNA sequences present at the ends of eukaryotic chromosomes called? See Concept 16.2 ( page 328) Hints 1. chromomeres 2. sarcomeres 3. polypeptides 4. telomeres 5. centromeres

4

A hydroxyl is present at the 3' end of the growing DNA strand. What is at the 5' end? 1. a nitrogenous base 2. a deoxyribose 3. a ribose 4. a phosphate group

4

Addition of a nucleotide onto a DNA strand is an endergonic reaction. What provides the energy to drive the reaction? 1. The dehydration reaction between the 5'-phosphate of the incoming nucleotide and the 3'-OH of the growing strand of DNA 2. Complementary bases on the template and the incoming nucleotide are attracted to each other, releasing free energy. 3. Binding of the pre-existing new strand, the template strand, and the incoming nucleotide to the active site of the DNA polymerase 4. Release of pyrophosphate from the incoming nucleotide, and then hydrolysis of the pyrophosphate to inorganic phosphate

4

DNA replication is said to be semiconservative. What does this mean? See Concept 16.2 ( page 322) Hints 1. One of the two resulting double helices is made of two old strands, and the other is made of two new strands. 2. One strand of the new double helix is made of DNA and the other strand is made of RNA. Half of the old strand is degraded and half is used as a template for the replication of a new strand. 3. Each new double helix consists of one old and one new strand. 4. The old double helix is degraded and half of its nucleotides are used in the construction of two new double helices.

4

Early, flawed DNA models proposed by Watson and Crick and by Linus Pauling correctly described which property of DNA? 1. Bases pair with complementary bases. 2. DNA is a double helix. 3. Bases face the center of the molecule, with a phosphate backbone on the outside. 4. DNA is composed of sugars, phosphates, and bases.

1

Erwin Chargaff observed that the proportions of adenine (A) and thymine (T) bases were always equal, as were the proportion of guanine (G) and cytosine (C). Chargaff's observation suggests which of the following statements? 1. The data suggest that A would always pair with T and G would always pair with C in a DNA molecule. 2. Chargaff's observation suggests that identical bases on the two DNA strands would pair with each other--for example, A would pair with A. 3. Chargaff's observation suggests a mechanism by which DNA can replicate itself. 4. Chargaff's observation suggests that all animals have the same amount of A, T, C, and G in their cells.

2

Given a template strand of 3'-ATGCTTGGACA-5' and a partially-made complementary strand containing only 5'-TAC-3', what would be the sequence of the new strand of DNA (including the 5'-TAC-3') if the only additional nucleotides available to DNA polymerase were those containing the bases G, A, and C? 1. 3'-TACGAACCTGT-5' 2. 5'-TACGAACC-3' 3. 5'-TAC-3'; All four nucleotides are required for DNA polymerase to function. 4. 5'-GAACC-3'

2

How does the enzyme telomerase meet the challenge of replicating the ends of linear chromosomes? 1. It adds numerous GC pairs, which resist hydrolysis and maintain chromosome integrity. 2. It catalyzes the lengthening of telomeres, compensating for the shortening that could occur during replication without telomerase activity. 3. It causes specific double-strand DNA breaks that result in blunt ends on both strands. 4. It adds a single 5' cap structure that resists degradation by nucleases.

4

In E. coli, to repair a thymine dimer by nucleotide excision repair, in which order do the necessary enzymes act? 1. DNA ligase, nuclease, helicase 2. nuclease, DNA polymerase, RNA primase 3. helicase, DNA polymerase, DNA ligase 4. nuclease, DNA polymerase, DNA ligase

3

In E. coli, which enzyme catalyzes the elongation of a new DNA strand in the 5' → 3' direction? 1. helicase 2. primase 3. DNA polymerase III 4. DNA ligase

3

In nucleotide excision repair, damaged DNA is excised by what enzyme(s)? See Concept 16.2 ( page 327) Hints 1. primase 2. helicase 3. nuclease 4. ligase 5. DNA polymerases

2, 3, 4

In the 1950s, when Watson and Crick were working on their model of DNA, which concepts were well accepted by the scientific community? Select all that apply. 1. Genes are made of DNA. 2. Genes are located on chromosomes. 3. Chromosomes are found in the nucleus. 4. Chromo1somes are made up of protein and nucleic acid.

2, 4, 5

What are the chemical components of a DNA molecule? Select all that apply. 1. proteins 2. phosphate groups 3. amino acids 4. sugars 5. nitrogenous bases

4

What are the chemical components of a DNA molecule? Select all that apply. 1. proteins 2. phosphate groups 3. amino acids 4. sugars 5. nitrogenous bases

4

What did Rosalind Franklin's famous photo 51 show? 1. DNA is replicated by making identical copies of each strand. 2. Chromosomes are made of DNA and proteins. 3. Complementary DNA bases pair with one another (A with T and G with C). 4. DNA is a helix.

1, 2, 3

What did the structure of DNA's double helix suggest about DNA's properties? Select all that apply. 1. DNA can be replicated by making complementary copies of each strand. 2. DNA can change. Errors in copying can result in changes in the DNA sequence that could be inherited by future generations. 3. DNA stores genetic information in the sequence of its bases. 4. DNA is found in the nucleus.

2

What is meant by the description "antiparallel" regarding the two strands that make up the DNA double helix? 1. One strand contains only purines and the other contains only pyrimidines. 2. The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand. 3. The double helix structure of DNA creates nonparallel strands. 4. Base pairings create unequal spacing between the two DNA strands.

5

What is the function of helicase in DNA replication? See Concept 16.2 ( page 322) Hints 1. It relieves strain from twisting of the double helix as it is unwound. 2. It adds nucleotides to the new strand in the 5' to 3' direction. 3. It checks for errors in the newly synthesized DNA strand. 4. It joins together Okazaki fragments. 5. It untwists the double helix and separates the two DNA strands.

3

What is the function of the enzyme topoisomerase in DNA replication? 1. elongating new DNA at a replication fork by adding nucleotides to the existing chain 2 building RNA primers using the parental DNA strand as a template 3. relieving strain in the DNA ahead of the replication fork caused by the untwisting of the double helix 4. reattaching the hydrogen bonds between the base pairs in the double helix

2

What is the role of DNA ligase in the elongation of the lagging strand during DNA replication? 1. It synthesizes RNA nucleotides to make a primer. 2. It joins Okazaki fragments together. 3. It stabilizes the unwound parental DNA. 4. It unwinds the parental double helix.

3

What is the role of DNA polymerase during DNA synthesis? 1. DNA polymerase catalyzes the synthesis of the template strand of DNA. 2. DNA polymerase provides the free energy to catalyze the endergonic addition of a nucleotide onto the 3' end of a growing DNA strand. 3. DNA polymerase is the enzyme that catalyzes the addition of a nucleotide onto the 3' end of a growing DNA strand. 4. DNA polymerase removes inorganic phosphate from the template strand of DNA to catalyze the polymerization reaction.

2, 4, 5

What materials does DNA polymerase require in order to synthesize a complete strand of DNA? Select all that apply. 1. Inorganic phosphate 2. All four deoxyribonucleotides triphosphates (containing A, C, T, or G) 3. ATP 4. Single-stranded DNA template 5. 3'-OH end of the new DNA strand

4

What process repairs damage to a preexisting double helix? See Concept 16.2 ( page 327) Hints 1. proofreading 2. operon repair 3. transformation 4. nucleotide excision repair 5. mismatch repair

4

Which of the following statements accurately describes the differences between DNA replication in prokaryotes and DNA replication in eukaryotes? 1. Prokaryotic chromosomes have histones, whereas eukaryotic chromosomes do not. 2. The rate of elongation during DNA replication is slower in prokaryotes than in eukaryotes. 3. Prokaryotes produce Okazaki fragments during DNA replication, but eukaryotes do not. 4. Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many.

2

Which of the following statements correctly describes the difference between ATP and the nucleotides used during DNA synthesis? 1. ATP is found only in human cells; the nucleotides are found in all animal and plant cells. 2. The nucleotides have the sugar deoxyribose; ATP has the sugar ribose. 3. ATP contains three high-energy bonds; the nucleotides have two. 4. The nucleotides have two phosphate groups; ATP has three phosphate groups.

2

Which of the following statements correctly describes the difference between the leading and the lagging strands of DNA during DNA replication? 1. The leading strand is synthesized at twice the rate of the lagging strand. 2. The leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction. 3. The lagging strand is synthesized continuously, whereas the leading strand is synthesized in short fragments that are ultimately stitched together. 4. The leading strand is synthesized by adding nucleotides to the 3' end of the growing strand, and the lagging strand is synthesized by adding nucleotides to the 5' end.

1

Which of the following types of molecules help to hold the DNA strands apart while they are being replicated? single-strand DNA binding proteins primase ligase DNA polymerase