Ch. 14- DNA structure, replication, organization

The genetic material of all living organisms is ____.

deoxyribonucleic acid

Prior to the 1940s, many biologists believed ____, which is composed of 20 different types of ____, was most likely the genetic material.

protein; amino acids

What happens when living R strain Streptococcus pneumoniae bacteria are mixed with heat-killed S strain Streptococcus pneumoniae bacteria?

The R strain bacteria are transformed into S strain bacteria.

The alteration of a cell’s hereditary type by the uptake of DNA released by the breakdown of another cell is called ____.

transformation

The transforming principle described by Griffith in his work with Streptococcus pneumoniae is ____.

DNA

Avery, MacLeod, and McCarty concluded that DNA was the hereditary material. If protein was instead, what would happen to mice after protease treatment?

The mice would live.

In their experiments to identify the transforming principle, Avery, MacLeod, and McCarty used enzymes that break down ____.

protein, DNA, and RNA

In the Hershey and Chase experiment, why were phage-infected bacteria radioactive after infection with 32P-labeled viruses?

Bacteria and viral progeny had incorporated 32P into their DNA.

When Hershey and Chase labeled viruses with radioactive phosphorus, why did they conclude DNA is injected?

Most of the radioactive DNA was inside the bacteria.

The T2 bacteriophages used in the Hershey and Chase experiment contain ____.

DNA and protein

In the Hershey and Chase experiment, 32P labeled ____ and 35S labeled ____.

DNA; protein

After two generations of cell divisions with 32P-labeled viral DNA, you should find 32P-labeled DNA in ____ of cells.

about 1/2

James Watson, Francis Crick, Rosalind Franklin, and Maurice Wilkins are recognized for discovering the ____.

three-dimensional structure of DNA

Nucleic acids are long chains of ____.

nucleotides

Each DNA nucleotide is composed of ____.

a five-carbon sugar, a phosphate group, and one of four nitrogenous bases

Adjacent nucleotides on a strand of DNA are connected by a(n) ____.

phosphodiester bond

If a stretch of human double stranded DNA contains 47% G and C bases, then ____.

it contains 53% A and T bases

The genome of an organism contains 14% guanine; therefore, it's genome also contains ____% thymine and ____% cytosine.

36; 14

The genome of an organism contains 30% adenine. Based on this, it also contains 30% ____.

thymine

Purines and pyrimidines are ____.

nitrogenous bases

How are purines distinguished from pyrimidines?

Purines are derived from a pair of fused C-N rings, while pyrimidines are derived from a single C-N ring.

In DNA, the purines are ____.

adenine and guanine

In DNA, the pyrimidines are ____.

thymine and cytosine

Which nucleotide sequence is complementary to 5'-GACGTT-3'?

3'-CTGCAA-5'

Wilkins and Franklin studied the structure of DNA using ____.

X-ray diffraction

A DNA double helix has two strands held together by ____.

hydrogen bonds

The width of a DNA double helix ____.

is constant

The two strands of a DNA double helix are antiparallel. This means that ____.

the 5' end of one strand is paired with the 3' end of the other strand

The polynucleotide chain of DNA has polarity: the 5' end has a bound ____, while the 3' end has a bound ____.

phosphate group; hydroxyl group

Which statement correctly describes DNA base pairing?

Two hydrogen bonds bind A and T; three hydrogen bonds bind G and C.

DNA replication is semiconservative because ____.

each new DNA molecule is composed of one old strand and one new strand

In the Meselson-Stahl experiment, only mixed DNA was observed after one generation. The conclusion was ____.

DNA replication is either semiconservative or dispersive

Based on the experiment image, after replication, each new DNA molecule contains ____.

one old DNA strand and one new DNA strand

DNA polymerase ____.

adds nucleotides to the 3' end of an existing strand

Topoisomerase functions by ____.

creating cuts in the DNA to relieve over-twisting and strain ahead of the replication fork

The active site of DNA polymerase is similar in ____.

archaea, bacteria, and eukaryotes

DNA ligase closes nicks between ____ by forming ____ bonds.

DNA fragments; covalent

Helicase ____.

unwinds the double-stranded DNA helix

A short RNA chain is synthesized by ____ to provide a ____ for DNA elongation.

primase; 3¢ hydroxyl group

Why is DNA ligase most active on the lagging strand?

The lagging strands contain more short DNA segments than the leading strand, which are joined together by DNA ligase.

Adding nucleotides in DNA replication occurs in ____.

the 5' → 3' direction only

Okazaki fragments are ____.

short lengths of new DNA on the lagging strand

During DNA replication, the ____ strand is assembled in the ____ direction and synthesized by ____ replication.

leading; same; continuous

In eukaryotes, the DNA molecule that comprises a chromosome is ____ and has ____ replication origin.

linear, more than one

The energy to form new bonds between nucleotides is provided by ____.

hydrolysis of pyrophosphate

If primase is nonfunctional, how much of DNA replication would occur?

The DNA helix would be unwound by helicase, but no new strands will be produced.

Telomeres are found ____.

at the ends of chromosomes

In humans, telomerase ____.

adds telomere repeats in some human cells

During DNA replication, part of chromosome ends are not copied because ____.

RNA primers at the beginning of a new strand cannot be replaced with DNA

If telomerase is not functioning in a cloning cell, what happens?

The clone's cells may divide, but after a certain number of generations, cell division will stop.

Chromatin consists of ____.

DNA and protein

Nucleosomes are best described as ____.

eukaryotic DNA associated with histone proteins

The nucleosome core particle consists of ____.

DNA wrapped around an 8-protein histone complex

During DNA replication, nucleosomes must ____ ahead of the replication fork and ____ after replication.

disassemble; reassemble

When DNA is replicated, ____.

the histone proteins are also replicated

In prokaryotes, the chromosome is ____ and has ____ origin.

circular; one

Proofreading by ____ corrects errors during DNA replication.

DNA polymerase

Without proofreading, the rate of replication errors is as high as one for every ____ nucleotides.

1,000 to 10,000

After repair enzymes remove an incorrect nucleotide, ____ are needed to complete repair.

DNA polymerase and DNA ligase

Individuals with xeroderma pigmentosum easily develop skin cancer because ____.

they easily develop skin cancer when exposed to sunlight

Variability in offspring is largely a result of ____.

mutations

After two cell divisions, how many of four daughter cells contain an uncorrected mutation?

four

Cancer cells ____.

maintain telomerase function

What is the function of the sliding clamp in DNA replication?

anchor DNA polymerase to the template strand

The structure of the sliding clamp is ____ across life, which indicates ____.

highly conserved; the function of the sliding clamp is similar in these organisms

Some research shows exercise increases telomere length because ____.

Telomerase activity was higher in individuals who exercised.

Cancer treatments may target rapidly dividing cells by ____.

inhibit DNA replication or DNA repair enzymes