ch 16 bio
What is the major difference between bacterial chromosomes and eukaryotic chromosomes? () Bacterial chromosomes have much more protein associated with the DNA than eukaryotes. There is no difference between bacterial and eukaryotic chromosomes. The DNA of bacterial chromosomes has a slightly different structure. Bacteria have a single circular chromosome whereas eukaryotes have several linear chromosomes. Eukaryotes have a single circular chromosome whereas bacteria have several linear chromosomes.
Bacteria have a single circular chromosome whereas eukaryotes have several linear chromosomes.
The overall error rate in the completed DNA molecule is approximately _____. () 1 error per 100 nucleotides 1 error per 1,000 nucleotides 1 error per 1,000,000 nucleotides 1 error per 10,000,000,000 nucleotides 1 error per 1,000,000,000 nucleotides
The Correct Answer: 1 per 10,000,000,000 nucleotides
DNA polymerase adds nucleotides to the _____ of the leading strands, and to the _____ of the lagging strands (Okazaki fragments). () sugar group ... phosphate group 5′ end ... 5′ end 5′ end ... 3′ end 3′ end ... 3′ end 3′ end ... 5′ end
The Correct Answer: 3' end ... 3' end
Open Hint for Question 10 in a new window Which of the following is correct? () Adenine forms three covalent bonds with thymine; guanine forms two covalent bonds with cytosine. Adenine forms three hydrogen bonds with thymine; guanine forms two hydrogen bonds with cytosine. Adenine forms two hydrogen bonds with guanine; thymine forms three hydrogen bonds with cytosine. Adenine forms two hydrogen bonds with thymine; guanine forms three hydrogen bonds with cytosine. Adenine forms two covalent bonds with thymine; guanine forms three covalent bonds with cytosine.
The Correct Answer: Adenine forms two hydrogen bonds with thymine; guanine forms three hydrogen bonds with cytosine.
What enzyme joins Okazaki fragments? () DNA polymerase primase helicase DNA ligase topoisomerase
The Correct Answer: DNA ligase
The removal of the RNA primer and addition of DNA nucleotides to the 3' end of Okazaki fragments in its place is carried out by _____. () DNA polymerase III primase ligase DNA polymerase I nuclease
The Correct Answer: DNA polymerase I
Which description of DNA replication is correct? () Ligase separates the two strands of the DNA double helix. Then, DNA polymerase synthesizes the leading strand and primase synthesizes the lagging strand. The two strands separate, and each one receives a complementary strand of RNA. Then this RNA serves as a template for the assembly of many new strands of DNA. Helicases separate the two strands of the double helix, and DNA polymerases then construct two new strands using each of the original strands as templates. Ligase assembles single-stranded codons, then polymerase knits these codons together into a DNA strand. The two strands of DNA separate, and restriction enzymes cut up one strand. Then, the DNA polymerase synthesizes two new strands out of the old ones.
The Correct Answer: Helicases separate the two strands of the double helix, and DNA polymerases then construct two new strands using each of the original strands as templates.
Which of the following statements about replication origins is correct? () Bacterial chromosomes have a single origin, but eukaryotic chromosomes have many origins. In bacteria, the DNA sequence at the origin is recognized by specific proteins that then bind to the origin. The two strands of DNA at the origin are separated, allowing the formation of a replication bubble. In both prokaryotes and eukaryotes, replication proceeds in both directions from each origin. All of the listed responses are correct.
The Correct Answer: None of the above.
Which of the following components is required for DNA replication? () sucrases RNA primer transfer RNA proteases ribosomes
The Correct Answer: RNA primer
Once the DNA at the replication fork is unwound by helicases, what prevents the two strands from coming back together to re-form a double helix? () The helicase pushes the two strands so far apart that they have no chance of finding each other. DNA polymerase follows the helicase so closely that there is no chance for the strands to come back together. Single-strand binding proteins bind the unwound DNA and prevent the double helix from re-forming. The helicase modifies the DNA in such a way as to eliminate the affinity between the two strands. One of the strands is rapidly degraded, preventing the double helix from re-forming.
The Correct Answer: Single-strand binding proteins bind the unwound DNA and prevent the double helix from reforming.
One strand of a DNA molecule has the base sequence 5′-ATAGGT-3′. The complementary base sequence on the other strand of DNA will be 3′-_____-5′. () ATAGGT TATCCA UAUCCA TGGAUA TGGATA
The Correct Answer: TATCCA
Who is credited with explaining the structure of the DNA double helix? () Griffith Avery, McCarty, and MacLeod Jacob and Monod Hershey and Chase Watson and Crick
The Correct Answer: Watson and Crick
At each end of a DNA replication bubble is _____. () an origin of replication a replication fork a gene a telomere a ribosome
The Correct Answer: a replication fork
The role of DNA polymerases in DNA replication is to _____. () synthesize an RNA primer to initiate DNA strand synthesis separate the two strands of DNA link together short strands of DNA attach free nucleotides to the new DNA strand All of the listed responses are correct.
The Correct Answer: attach free nucleotides to the new strand
The DNA structures of prokaryotes and eukaryotes are different in several ways, but one way in which they are the same is that _____. () both have a sugar-phosphate backbone most of the DNA is in the form of plasmids histones are present in the nucleosomes the DNA is packaged into several linear chromosomes both have a single circular chromosome
The Correct Answer: both have a sugar-phosphate backbone
During the replication of DNA, _____. () errors never occur both strands of a molecule act as templates the reaction is catalyzed by RNA polymerase the cell undergoes mitosis only one strand of the molecule acts as a template
The Correct Answer: both strands of a molecule act as templates
The incorporation of an incorrect base into the DNA during replication _____. () cannot be repaired, and a new mutation will invariably result is virtually impossible, as the accuracy of DNA polymerase is such that errors almost never occur will almost certainly lead to the death of the cell will trigger the cell to destroy the new strand, and replication will begin again can be repaired by the mismatch repair system
The Correct Answer: can be repaired by the mismatch repair system
Unlike prokaryotic DNA replication, replication of eukaryotic chromosomes _____. () cannot be completed by DNA polymerase is semiconservative is error free involves two leading strands and no lagging strands has a single origin
The Correct Answer: cannot be completed by DNA polymerase
After the formation of a replication bubble, which of the following is the correct sequence of enzymes used for the synthesis of the lagging DNA strand? () ligase, primase, DNA polymerases, helicases helicases, primase, DNA polymerases, ligase helicases, primase, ligase, DNA polymerases helicases, DNA polymerases, primase, ligase primase, helicases, DNA polymerases, ligase
The Correct Answer: helicases, primase, DNA polymerase, ligase
The rate of elongation in prokaryotes is _____ the rate in eukaryotes. () about the same speed as The rates are not comparable, because elongation only occurs in prokaryotes. much faster than sometimes faster and sometimes slower than much slower than
The Correct Answer: much faster than
Monomers for the synthesis of DNA are called _____. () nucleotides disaccharides fatty acids monosaccharides amino acids
The Correct Answer: nucleotides
The two strands of a DNA double helix are antiparallel. This means that _____. () one strand runs in the 5' to 3' direction, and the other runs in the 3' to 5' direction they both run in the 3' to 5' direction the two strands are mirror images one strand is actually composed of RNA only one of the two strands can be used as a template for replication, because DNA polymerase only works in one direction
The Correct Answer: one strand runs in the 5' to 3' direction, and the other runs in the 3' to 5' direction
The experiments of Meselson and Stahl showed that DNA _____. () replicates in a semiconservative fashion codes for the sequence of amino acids in proteins contains complementary base pairing is composed of nucleotides is the genetic material
The Correct Answer: replicates in a semiconservative fashion
Chargaff found that for DNA _____. () A + T = 50% of the total bases the ratio of A to T is close to 1:1 and the ratio of G to C is close to 1:1 the ratio of A to C is close to 1:1 and the ratio of G to T is close to 1:1 A + T = G + C the ratio of A to G is close to 1:1 and the ratio of T to C is close to 1:1
The Correct Answer: the ratio of A to T is close to 1:1 and the ratio of G to C is close to 1:1
The information in DNA is contained in _____. () the sequence of amino acids that makes up the DNA molecule the variation in the structure of nucleotides that make up the DNA molecule the types of sugars used in making the DNA molecule the sequence of nucleotides along the length of the two strands of the DNA molecule All of the listed responses are correct.
The Correct Answer: the sequence of nucleotides along the length of the two strands of the DNA molecule
The unwinding of DNA at the replication fork causes twisting and strain in the DNA ahead of the fork, which is relieved by an enzyme called _____. () primase ligase relievase topoisomerase ribosomes
The Correct Answer: topoisomerase
In what way(s) is our traditional representation of DNA polymerase molecules moving like locomotives along a track inaccurate? () The proteins involved in replication do not move; instead, DNA is drawn through the complex. DNA polymerase acts as part of a large complex of proteins, not like a single locomotive. Like a train on a track, DNA polymerase must add nucleotides sequentially. It cannot jump around. Both the first and second answers are correct. DNA polymerase completes replication of one strand and then begins the other.
The proteins involved in replication do not move; instead, DNA is drawn through the complex. DNA polymerase acts as part of a large complex of proteins, not like a single locomotive.
The two sugar-phosphate strands that form the rungs of a DNA double helix are joined to each other through _____. () covalent bonds between nitrogen atoms in adenine and in thymine ionic bonds between guanine and cytosine covalent bonds between carbon atoms in deoxyribose molecules 5' deoxyribose and phosphate bonds hydrogen bonds between nucleotide bases
hydrogen bonds between nucleotide bases
Which of the following attributes of DNA is most crucial to its accurate duplication? () its specific base pairing and hydrogen bonding its helical nature and hydrogen bonding its deoxyribose sugar and phosphate groups its specific sequence of bases its phosphodiester linkages and complementary strands
its specific base pairing and hydrogen bonding
Which set of enzymes is involved in nucleotide excision repair? () DNA polymerase, helicase, primase hydrolase, nuclease, and ligase nuclease, DNA polymerase, and ligase ligase, nuclease, and primase nuclease, DNA polymerase, primase
nuclease, DNA polymerase, and ligase
