Chapter 16 - The Molecular Basis of Inheritance

What role does complementary base pairing play in the replication of DNA?

Complementary base pairing ensures that the two daughter molecules are exact copies of the parental molecule.

Identify two major functions of DNA pol III and DNA replication.

DNA pol III covalently adds nucleotides to new DNA strands and proofreads each added nucleotide for correct base pairing.

If a species contains 23% A in its DNA, what is the percentage of guanine it would contain? a) 23% b) 46% c) 25% d) 44% e) 27%

a) 23%

In a nucleosome, the DNA is wrapped around a) histones b) ribosomes c) polymerase molecules d) a thymine dimer

a) histones

The definitive experiment showing that DNA and not protein was responsible for carrying heritable information was provided by a) labeling viral DNA with ³²P, and labeling viral protein with ³⁵S b) labeling viral DNA with ³⁵S, and labeling viral protein with ³²P c) labeling bacterial DNA with ³²P, and labeling bacterial protein with ³⁵S d) labeling bacterial DNA with ³⁵S, and labeling bacterial protein with ³²P

a) labeling viral DNA with ³²P, and labeling viral protein with ³⁵S

The spontaneous loss of amino groups from adenine in DNA results in hypoxanthine, an unccommon base, opposite thymine. What combination of proteins could repair such damage? a) nuclease, DNA polymerase, DNA ligase b) telomerase, primase, DNA, polymerase c) telomerase, helicase, single-strand binding protein d) DNA ligase, replication fork proteins, adenylyl cyclase

a) nuclease, DNA polymerase, DNA ligase

In analyzing the number f different bases in a DNA sample, which result would be consistent with the base-pairing rules? a) A = G b) A + G = C + T c) A + T = G + C d) A = C

b) A + G = C + T

A biochemist isolates, purifies, and combines in a test tube a variety of molecules needed for DNA replication. When she adds some DNA to the mixture, replication occurs, but each DNA molecule consists of a normal strand paired with numerous segments of DNA a few hundred nucleotides long. What has she probably left out of the mixture? a) DNA polymerase b) DNA ligase c) Okazaki fragments d) primase

b) DNA ligase

Which of the following enzymes is responsible for removing the primers from which DNA replication has been initiated? a) DNase b) RNase c) Polymerase d) Helicase e) Ligase

b) RNase

If one strand of DNA has the base sequence AAGCCA, the complementary strand has which of the following sequences? a) UUCGUU b) TTCGGT c) AAGCAA d) UTCGTU e) TTCGTG

b) TTCGGT

Imagine that in the not to distant future life is discovered within the hydro-thermal vents of Saturn's moon Enceladus. After growing these organisms in the presence of heavy 15N, centrifuged results have shown one band of heavy DNA. You then grow the organisms for one round of replication in the presence of light 14N and centrifuge the DNA through a density gradient. Much to your surprise the results show unequivocally that these organisms use "fully-conservative" replication. Which of the follow describes your data? a) one intermediate density band and one light band b) one heavy band and one light band c) two heavy bands d) one intermediate density band and one heavy band

b) one heavy band and one light band The two parental heavy strands separate and onto them are synthesized two light daughter strands. In fully-conservative replication the newly replicated double stranded DNA molecule would then separate and the original parental heavy strands would re-hybridize, as would the newly made daughter strands. This would produce on heavy band and one light band upon being centrifuged through a density gradient.

Frederich Griffith is attributed to being the first person to provide an assay showing that a biological compound could alter the expressed traits of an organism. The definitive part of this assay showed that a) colony morphology such as whether smooth or rough shaped colonies were formed could be used to determine if bacteria were lethal or benign b) organic material extracted from one type of bacterial strain could be used to produce similar traits in a different strain of bacteria c) live S-bacteria transformed live R-bacteria d) live R-bacteria plus heat killed S-bacteria was benign in mice e) mixing smooth shaped colonies of bacteria with rough shaped colonies produced intermediate colonies that were lethal in mice.

b) organic material extracted from one type of bacterial strain could be used to produce similar traits in a different strain of bacteria

Who was Ms Rosalind Franklin? a) my grade three teacher b) the woman who provided the most crucial data toward solving DNA's structure c) the first British female astronaut d) Nicole Kidman's aunt on her fathers side

b) the woman who provided the most crucial data toward solving DNA's structure

What is the basis for the difference in how the leading and lagging strands of DNA molecules are synthesized? a) The origins of replication occur only at the 5' end b) Helicases and single-strand binding proteins work at he 5' end c) DNA polymerase can join new nucleotides only to the 3' end of a pre-existing strand

c) DNA polymerase can join new nucleotides only to the 3' end of a pre-existing strand

DNA strands (chromosomes) get shorter at each replication cycle. Consequently short repeated sequences called 'telomeres' are required in order to conserve and protect the essential gene coding regions and keep chromosomes viable. The fundamental reason that chromosomes experience this shortening is a) the ligase will only join together Okazakis fragments on the lagging strand b) The helicase enzyme only proceeds in the 3'->5' direction c) DNA-polymerase requires priming and can only proceed in a 5'-> 3' direction d) The leading strand is the long continuous strand that follows a helicase enzyme.

c) DNA-polymerase requires priming and can only proceed in a 5'-> 3' direction

If you grew bacteria in the presence of a heavy isotope of nitrogen could you use this method to distinguish between nucleic-acids and amino-acids? a) Yes, because nucleic acids contain nitrogen but amino acids do not. b) Yes, because both nucleic acids and amino acids contain nitrogen. c) No, because both nucleic acids and amino acids contain nitrogen. d) Yes, because nucleic acids contain phosphate groups and amino acids contain nitrogen. e) No, because nucleic acids contain phosphate groups and amino acids contain sulfur.

c) No, because both nucleic acids and amino acids contain nitrogen.

The best description of 'Okazaki's fragments is, a) All of the DNA fragments produced during DNA synthesis, that must be linked together in the final phase of Sythesis b) The longer DNA fragments on the leading strand, that must be linked together in the final phase of Sythesis c) The shorter DNA fragments on the lagging strand, that must be linked together in the final phase of Sythesis d) The fragments of primers that must be removed prior to the final phase of Sythesis

c) The shorter DNA fragments on the lagging strand, that must be linked together in the final phase of Sythesis

Eukaryotic DNA replication is initiated at a) the 5' end of DNA strands b) the 3' end DNA strand c) numerous origins of replication d) in the middle of each chromosome

c) numerous origins of replication

In his work with pneumonia-causing bacteria and mice, Griffith found that a) the protein coat from pathogenic cells was able to transform from nonpathogenic cells b) heat-killed pathogenic cells caused by pneumonia c) some substance from pathogenic cells was transferred to nonpathogenic cells, making them pathogenic d) the polysaccharide coat of bacteria caused pneumonia

c) some substance from pathogenic cells was transferred to nonpathogenic cells, making them pathogenic

If an RNA sample contains 35% Adenine a) then it will contain 35% pyrimidines b) then it must contain 35% Uracil, and therefore 30% Guanine and Cytosine c) the relative amounts of other ribonucleotides cannot be determined d) then it must contain 15% Cytosine e) none of the choices apply

c) the relative amounts of other ribonucleotides cannot be determined

Information from X-ray crystallographic data collected by _______ was used by Watson and Crick in their development of the model of DNA. a) Chargaff b) Griffith c) McClintock d) Franklin e) Hershey and Chase

d) Franklin

The elongation of the leading strand during DNA synthesis a) progresses away from the replication fork b) occurs in the 3' → 5' direction c) does not require a template strand d) depends on the action of DNA polymerase

d) depends on the action of DNA polymerase

E. Coli cells grown on ¹⁵N medium are transferred to ¹⁴N medium and allowed to grow for to more generations. DNA extracted from these cells is centrifuged. What density distribution of DNA would you expect in this experiment? a) one high-density and one low-density band b) one intermediate-density band c) one high-density and one intermediate-density band d) one low-density and one intermediate-density band

d) one low-density and one intermediate-density band

What is the difference between the ³⁵S and ³²S?

³⁵S has three more neutrons