ch.5/16
Which statement expresses a real difference between DNA and RNA? (a) DNA can make a double helix; RNA cannot. (b) DNA is much longer than RNA. (c) DNA has more kinds of bases than RNA. Both (a) and (b). (a), (b), and (c).
(b) DNA is much longer than RNA. RNA is made by copying short segments of DNA.
In a nucleotide, the nitrogenous base is attached to the sugar's _____ carbon and the phosphate group is attached to the sugar's _____ carbon. 1' ... 5' 2' ... 1' 2' ... 3' 1' ... 2' 1' ... 3'
1' ... 5' The nitrogenous base is attached to the sugar's 1' carbon and the phosphate group is attached to the sugar's 5' carbon.
If you were to analyze a DNA sample from a eukaryotic cell, you would find that: (a) the number of purines equals the number of pyrimidines. (b) the number of adenines equals the number of uracils. (c) the number of guanines equals the number of cytosines. Both (a) and (c). (a), (b), and (c).
Both (a) and (c). These are consequences of the base-pairing rules, which are fundamental to life.
Which of these is a difference between a DNA and an RNA molecule? DNA is usually double-stranded, whereas RNA is usually single-stranded. DNA contains five-carbon sugars, whereas RNA contains six-carbon sugars. DNA is a polymer composed of nucleotides, whereas RNA is a polymer composed of nucleic acids. DNA contains uracil, whereas RNA contains thymine. DNA contains nitrogenous bases, whereas RNA contains phosphate groups.
DNA is usually double-stranded, whereas RNA is usually single-stranded. With some exceptions, DNA is a double-stranded molecule and RNA is a single-stranded molecule.
Rank the following base pairs according to their stability.
The base pair adenine-cytosine occurs very rarely in nature. It only happens during a mutation event. When the DNA is replicated, one of the two daughters will contain a guanine-cytosine base pair in the location of the mutation, and the other daughter will contain an adenine-thymine base pair.
If a cell were unable to produce histone proteins, which of the following would be a likely effect? Amplification of other genes would compensate for the lack of histones. Spindle fibers would not form during prophase. The cell's DNA couldn't be packed into its nucleus. There would be an increase in the amount of "satellite" DNA produced during centrifugation.
The cell's DNA couldn't be packed into its nucleus.
When nucleotides polymerize to form a nucleic acid _____. hydrogen bonds form between the bases of two nucleotides a covalent bond forms between the sugar of one nucleotide and the phosphate of a second a hydrogen bond forms between the sugar of one nucleotide and the phosphate of a second covalent bonds form between the bases of two nucleotides
a covalent bond forms between the sugar of one nucleotide and the phosphate of a second
Which of the following would you expect of a eukaryote lacking telomerase? a reduction in chromosome length in gametes an inability to produce Okazaki fragments a high probability of somatic cells becoming cancerous an inability to repair thymine dimers
a reduction in chromosome length in gametes
After allowing phages grown with bacteria in a medium that contained 32P and 35S, Hershey and Chase used a centrifuge to separate the phage ghosts from the infected cell. They then examined the infected cells and found that they contained _____, which demonstrated that _____ is the phage's genetic material. labeled DNA .... protein labeled DNA ... labeled protein labeled DNA ... DNA labeled protein .... protein labeled protein ... DNA
labeled DNA ... DNA Since the phage DNA entered the infected cell, it makes sense that DNA is the genetic material.
The building blocks or monomers of nucleic acid molecules are called _____. nucleotides pyrimidines and purines fatty acids DNA and RNA polysaccharides
nucleotides A nucleotide is a nucleic acid monomer consisting of a nitrogen base, a pentose sugar, and a phosphate group. Nucleotides joined together by covalent bonds called phosphodiester linkages form nucleic acid molecules.
If you measure the amounts of the bases in any sample of DNA, you'll find that ... the amount of A + the amount of G = the amount of T + the amount of C. the amount of A = the amount of G; the amount of T = the amount of C. the amount of A + the amount of T = the amount of G + the amount of C. the amount of A + the amount of C = the amount of G + the amount of U. None of the above.
the amount of A + the amount of G = the amount of T + the amount of C. For every A there's a T; for every G there's a C.
Write the complementary sequence for the following DNA sequence, in order from 3' to 5': 5′−CGATATTGAGCTAAGCTT−3′
3'- GCTATAACTCGATTCGAA -5'
Hershey and Chase used _____ to radioactively label the T2 phage's proteins. 14C 92U 222Ra 35S 32P
35S Hershey and Chase used radioactive sulfur to label the phage's proteins.
Nucleic acids are assembled in the _____ direction. 2' to 3' 4' to 5' 5' to 3' 1' to 5' 5' to 1'
5' to 3' New nucleotides are added to the 3' end of a growing polynucleotide.
Cytosine makes up 42% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine? 8% 58% 42% 16%
8%
The radioactive isotope 32P labels the T2 phage's _____. DNA protein coat base plate tail head
DNA The T2 phage consists of a protein coat and DNA. It is the DNA that contains P.
The flow of genetic information in a cell goes from _____. protein to RNA to DNA DNA to lipid to protein DNA to RNA to glucose DNA to RNA to protein DNA to ribosomes to RNA
DNA to RNA to protein The information in DNA is transcribed into RNA and then translated into protein.
Who demonstrated that DNA is the genetic material of the T2 phage? Franklin Hershey and Chase Meselson and Stahl Darwin and Wallace Watson and Crick
Hershey and Chase did a series of classic experiments demonstrating that DNA is the genetic material of the T2 phage.
Which of the following statements describes chromatin? Which of the following statements describes chromatin? Both heterochromatin and euchromatin are found in the cytoplasm. Euchromatin is not transcribed, whereas heterochromatin is transcribed. Heterochromatin is composed of DNA, whereas euchromatin is made of DNA and RNA. Heterochromatin is highly condensed, whereas euchromatin is less compact.
Heterochromatin is highly condensed, whereas euchromatin is less compact.
Why do histones bind tightly to DNA? Histones are covalently linked to the DNA. Histones are positively charged, and DNA is negatively charged. Histones are negatively charged, and DNA is positively charged. Both histones and DNA are strongly hydrophobic.
Histones are positively charged, and DNA is negatively charged.
What holds the strands of the DNA double helix together? Hydrogen bonds between purines and pyrimidines. Proteins that bind to DNA bases. Covalent bonds between A and T, and between C and G. Attractions between polar sugars. Attractions between the ionized phosphates.
Hydrogen bonds between purines and pyrimidines. A and G are purines; C and T are pyrimidines. Hydrogen bonds link them.
How are the components of DNA paired in the helix structure?
In a DNA sequence, the purine adenine always pairs with the pyrimidine thymine, and the purine guanine always pairs with the pyrimidine cytosine.
How does the enzyme telomerase meet the challenge of replicating the ends of linear chromosomes? It adds numerous GC pairs, which resist hydrolysis and maintain chromosome integrity. It causes specific double-strand DNA breaks that result in blunt ends on both strands. It adds a single 5' cap structure that resists degradation by nucleases. It catalyzes the lengthening of telomeres, compensating for the shortening that could occur during replication without telomerase activity.
It catalyzes the lengthening of telomeres, compensating for the shortening that could occur during replication without telomerase activity.
What is the role of DNA ligase in the elongation of the lagging strand during DNA replication? It stabilizes the unwound parental DNA. It synthesizes RNA nucleotides to make a primer. It joins Okazaki fragments together. It unwinds the parental double helix.
It joins Okazaki fragments together.
In his transformation experiments, what did Griffith observe? Mixing a heat-killed nonpathogenic strain of bacteria with a living pathogenic strain makes the pathogenic strain nonpathogenic. Mice infected with a pathogenic strain of bacteria can spread the infection to other mice. Infecting mice with nonpathogenic strains of bacteria makes them resistant to pathogenic strains. Mixing a heat-killed pathogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells into the pathogenic form.
Mixing a heat-killed pathogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells into the pathogenic form.
In E. coli, there is a mutation in a gene called dnaB that alters the helicase that normally acts at the origin. Which of the following would you expect as a result of this mutation? Replication will occur via RNA polymerase alone. Additional proofreading will occur. No replication fork will be formed. Replication will require a DNA template from another source.
No replication fork will be formed.
Replication in prokaryotes differs from replication in eukaryotes for which of the following reasons? Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many. The rate of elongation during DNA replication is slower in prokaryotes than in eukaryotes. Prokaryotic chromosomes have histones, whereas eukaryotic chromosomes do not. Prokaryotes produce Okazaki fragments during DNA replication, but eukaryotes do not.
Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many.
Which of the following help(s) to hold the DNA strands apart while they are being replicated? single-strand DNA binding proteins ligase DNA polymerase primase
single-strand DNA binding proteins
You can tell that this is an image of a DNA nucleotide and not an RNA nucleotide because you see a _____. phosphate group, not a uracil thymine nitrogenous base, not a uracil nitrogenous base sugar with two, and not three, oxygen atoms double-stranded molecule, not a single-stranded molecule uracil nitrogenous base, not a thymine nitrogenous base
sugar with two, and not three, oxygen atoms DNA nucleotides are composed of deoxyribose sugars, whereas RNA nucleotides are composed of ribose sugars.
Which of these nitrogenous bases is found in DNA but not in RNA? guanine cytosine uracil adenine thymine
thymine DNA contains thymine; RNA does not.
In a DNA double helix an adenine of one strand always pairs with a(n) _____ of the complementary strand, and a guanine of one strand always pairs with a(n) _____ of the complementary strand. thymine ... cytosine uracil ... cytosine cytosine ... uracil guanine ... adenine cytosine ... thymine
thymine ... cytosine This is referred to as specific base pairing.