Chapter 13: The Molecular Basis of Inheritance

The radio isotope 32P labels the T2 phage's _____. base plate head protein coat tail DNA

DNA

What are chromosomes made of? DNA and proteins DNA, RNA, and proteins DNA DNA, heterochromatin, and histone proteins DNA and euchromatin

DNA and protein

What is the function of helicase in DNA replication? -It joins together Okazaki fragments. -It adds nucleotides to the new strand in the 5' to 3' direction. -It checks for errors in the newly synthesized DNA strand. -It relieves strain from twisting of the double helix as it is unwound. -It untwists the double helix and separates the two DNA strands.

It untwists the double helix and separates the two DNA strands

The first step in the replication of DNA is catalyzed by _____. helicase ligase single-strand binding protein DNA polymerase primase

helicase

Which of the following enzymes synthesizes short segments of RNA? helicase DNA polymerase III ligase DNA polymerase I primase

primase

The action of helicase creates _____. -replication forks and replication bubbles -primers and DNA fragments -primers and replication bubbles -DNA fragments and replication bubbles -DNA fragments and replication forks

replication forks and replication bubbles

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

single-strand binding protein

What are the repetitive DNA sequences present at the ends of eukaryotic chromosomes called? chromomeres sarcomeres centromeres polypeptides telomeres

telomeres

An Okazaki fragment has which of the following arrangements? -DNA polymerase I, DNA polymerase III -3' RNA nucleotides, DNA nucleotides 5' -primase, polymerase, ligase -5' RNA nucleotides, DNA nucleotides 3' -5' DNA to 3'

5' RNA nucleotides, DNA nucleotides 3'

In an analysis of the nucleotide composition of DNA, which of the following will be found? A = G and C = T A = C A + C = G + T G + C = T + A

A + C = G + T

In trying to determine whether DNA or protein is the genetic material, Hershey and Chase made use of which of the following facts? -DNA contains nitrogen, whereas protein does not. -RNA includes ribose, whereas DNA includes deoxyribose sugars. -DNA contains purines, whereas protein includes pyrimidines. -DNA contains phosphorus, whereas protein does not. -DNA contains sulfur, whereas protein does not.

DNA contains phosphorus, whereas protein includes pyrimidines

Which enzyme catalyzes the elongation of a DNA strand in the 5' → 3' direction? primase helicase topoisomerase DNA polymerase III DNA ligase

DNA polymerase III

Why is the new DNA strand complementary to the 3' to 5' strands assembled in short segments? -DNA polymerase can assemble DNA only in the 3' to 5' direction -it is more efficient than assembling complete new strands -only short DNA sequences can extend off the RNA primers -the replication forks block the formation of longer strands -DNA polymerase can assemble DNA only in the 5' to 3' direction

DNA polymerase can assemble DNA only in the 5' to 3' direction

A new DNA strand elongates only in the 5' to 3' direction because -DNA polymerase can only add nucleotides to the free 3' end. -DNA polymerase begins adding nucleotides at the 5' end of the template. -Okazaki fragments prevent elongation in the 3' to 5' direction. -replication must progress toward the replication fork.

DNA polymerase can only add nucleotides to the free 3' end

Meselson and Stahl cultured E. coli for several generations in a medium with a heavy isotope of nitrogen, 15N. They transferred the bacteria to a medium with a light isotope of nitrogen, 14 N. After two rounds of DNA replication, half the DNA molecules were light (both strands had 14N) and half were hybrids (15N-14N). What did the researchers conclude from these results? -The nitrogenous bases in DNA molecules incorporate both 15N and 14N. -Opposite DNA strands are complementary to each other. -DNA replication is semiconservative.

DNA replication is semiconservative

During DNA replication, the leading strand is synthesized continuously, whereas the lagging strand is synthesized as Okazaki fragments. Why is this so? -There are thousands of origins of replication on the lagging strand but only one on the leading strand. -DNA synthesis can take place only in the 5' to 3' direction. -DNA polymerases can bind to only one strand at a time.

DNA synthesis can take place only in the 5' to 3' direction

DNA replication is said to be semiconservative. What does this mean? -The old double helix is degraded, and half of its nucleotides are used in the construction of two new double helices. -One of the two resulting double helices is made of two old strands, and the other is made of two new strands. -Each new double helix consists of one old and one new strand. -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.

Each new double helix consists of one old and one new strand

Who conducted the X-ray diffraction studies that were key to the discovery of the structure of DNA? Meselson and Stahl McClintock Griffith Franklin Chargaff

Franklin

Who demonstrated that DNA is the genetic material of the T2 phage? Meselson and Stahl Darwin and Wallace Hershey and Chase Franklin Watson and Crick

Hershey and Chase

Nucleotides are added to a growing DNA strand as nucleoside triphosphates. What is the significance of this fact? -Nucleoside triphosphates are more easily transported in the cell than are nucleotides. -Hydrolysis of the two phosphate groups (P-Pi) and DNA polymerization are a coupled exergonic reaction. -Nucleoside triphosphates are more abundant in the cell than nucleotides.

Hydrolysis of the two phosphate groups and DNA polymerization are a coupled exergonic reaction=

Which of the following is true of DNA during interphase? -It is in the form of highly condensed chromosomes and is unavailable for gene expression. -It is in the form of highly condensed chromosomes; it is called heterochromatin. -It exists as chromatin and is less condensed than mitotic chromosomes. -It exists as chromatin; it is completely uncoiled and loose. -It exists as chromatin and is unavailable for gene expression.

It exists as chromatin and is less condensed than mitotic chromosomes

What process repairs damage to a preexisting double helix? transformation nucleotide excision repair operon repair mismatch repair proofreading

Nucleotide excision repair

Which of the following statements describes one difference between DNA replication in prokaryotes and DNA replication in eukaryotes? -Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many. -Prokaryotes have telomeres, and eukaryotes do not. -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

The synthesis of a new strand begins with the synthesis of a(n) _____. Okazaki fragment RNA primer complementary to a preexisting DNA strand short pieces of DNA poly(A) tail single-strand binding protein

RNA primer complementary to a preexisting DNA strand

What is meant by the description "antiparallel" regarding the two strands of nucleic acids that make up DNA? -Base pairings create unequal spacing between the two DNA strands. -The twisting nature of DNA creates nonparallel strands. -The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand. -One strand contains only purines and the other contains only pyrimidines.

The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand

The leading and the lagging strands of DNA formed during DNA replication differ in that -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. -the lagging strand is synthesized continuously, whereas the leading strand is synthesized in short fragments that are ultimately stitched together. -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. -the leading strand is synthesized at twice the rate of the lagging strand.

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

DNA is a self-replicating molecule. What accounts for this important property of DNA? -Its two strands are held together by easily broken covalent bonds. -The nitrogenous bases of the double helix are paired in specific combinations: A with T and G with C. -Replication is thermodynamically spontaneous and requires no enzymes.

The nitrogenous bases of the double helix are paired in specific combinations: AT & GC

Individuals with the disorder xeroderma pigmentosum are hypersensitive to sunlight. This occurs because their cells are impaired in what way? -They do not recombine homologous chromosomes during meiosis. -They cannot repair thymine dimers. -They cannot exchange DNA with other cells. -They cannot undergo mitosis. -They cannot replicate DNA.

They cannot repair thymine dimers

What is the function of DNA polymerase III? -to add nucleotides to the 3' end of a growing DNA strand -to unwind the DNA helix during replication -to degrade damaged DNA molecules -to rejoin the two DNA strands (one new and one old) after replication -to seal together the broken ends of DNA strands

To add nucleotides to the 3' end of a growing DNA strand

After DNA replication is completed, _____. -each new DNA double helix consists of one old DNA strand and one new DNA strand -each new DNA double helix consists of two new strands -each of the four DNA strands consists of some old strand parts and some new strand parts -one DNA double helix consists of two old strands and one DNA double helix consists of two new strands -there are four double helices

each new DNA double helix consists of one old DNA strand and one new DNA strand

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 ... labeled protein labeled protein .... protein labeled DNA ... DNA labeled protein ... DNA labeled DNA .... protein

labeled DNA....DNA

Short segments of newly synthesized DNA are joined into a continuous strand by _____. single-strand binding protein helicase primase DNA polymerase ligase

ligase