Biology 181: Chapter 14

How many hydrogen bonds are formed between adenine and thymine in the double DNA helix?`

2

______ repair is responsible for removing bases that were incorrectly incorporated into DNA during replication.

Mismatch

__________ repair systems target a single kind of lesion in DNA and repair only that damage, while _________ repair systems use a single mechanism to repair multiple kinds of lesions in DNA.

Specific Nonspecific or non specific

What is the name of the subunit that acts as the sliding clamp, which keeps the replicating enzyme complex attached to the template in eukaryotic cells.

PCNA

The sliding clamp of a DNA polymerase ____________.

holds the polymerase to the DNA template

The topological state of DNA refers to

how the DNA coils

In an aging cell, the activity of telomerase would be

low

The amount of the enzyme ________ declines within cells as they age.

telomerase

DNA replication in E. coli ends at a site called the

terminus

DNA repair mechanisms have likely evolved because

there is no way for cells to avoid exposure to mutagens

In order to determine the density of DNA strands, Meselson and Stahl used this technique so that DNA fragments would migrate to the area in the gradient where they had the same density.

A cesium chloride gradient

Telomerase uses which of the following as a template?

A short internal RNA

What is a thymine dimer?

A site where two adjacent thymine bases become covalently cross-linked to each other

The DNA controlled by an origin is called a

replicon

Interpretation of the Meselson-Stahl data leads to support of this model of DNA replication:

semiconservative

Short, repeated sequences of DNA are characteristic of

telomeres

Griffith's experiments were important because they showed

that the genetic material could be passed from one cell to another

Short fragments of DNA created on the lagging strand of DNA during replication are called ____________.

Short fragments of DNA created on the lagging strand of DNA during replication are called

What class of enzymes relieve torsional strain in DNA strands ahead of the replication fork?

Topoisomerases

In the Meselson-Stahl experiment, what was the expected composition of DNA molecules after one rounds of replication, if the conservative model was correct?

Two densities should be observed: the DNA strands would be either all-heavy or all-light

The DNA fibers Franklin used in her x-ray diffraction studies came from

Wilkins

A bacteriophage contains (choose all that apply)

a protein coat genetic material

Bacterial DNA is typically replicated as

a single replicon

Which of these are used in RNA

adenine cytosine uracil guanine

An ______ cuts DNA internally and an ______ cuts at the ends of DNA.

endonuclease; exonuclease

The two main eukaryotic DNA polymerases that extend DNA are

epsilon delta

Cells have several non-specific repair pathways. Indicate which of the following are two general categories of repair mechanisms:

error-free error-prone

In E. coli, the SOS response is part of the

error-prone repair mechanism

Based on replication proteins, DNA replication in archaea is most similar to that of

eukaryotes

Which of these is not one of the three phases of DNA replication?

extension

The enzyme DNA ____________ is the topoisomerase involved in DNA replication.

gyrase

Cancer cells contain

higher levels of telomerase than normal, non-cancer cells.

DNA replication in eukaryotic cells is complicated by the fact that eukaryotic cells have

linear chromosomes

DNA primase (choose all that apply)

makes a primer of RNA complementary to the DNA. makes a primer about 10 -20 nucleotides in length.

Agents that cause mutation are known as

mutagens

Which origins are more sequence-specific?

oriC

DNA replication that leads to the production of double helices with one parental strand and one newly synthesized strand is consistent with

semiconservative replication

The two general categories of DNA repair are

specific nonspecific

The term ______ refers to the coiling of two DNA strands leading to torsional strain.

supercoiling

The term ___________ refers to the coiling of two DNA strands leading to torsional strain.

supercoiling

The enzyme _______ contains a small internal piece of RNA, which is used as a template to extend the end of a linear DNA molecule.

telomerase

The enzyme __________ contains a small internal piece of RNA, which is used as a template to extend the end of a linear DNA molecule.

telomerase

In nucleic acids, the prime symbol is used to indicate

the carbon in a sugar rather than the atoms in the bases attached to the sugars

If normal fibroblast cells are grown in cell culture and the enzyme telomerase is introduced in them,

the cells show an increased lifespan

The problems in replicating the ends of linear chromosomes are caused by (choose all that apply)

the directionality of polymerases the need for a primer

The enzymes in the replisome are active on

the leading and the lagging strands

The partial opening of a DNA helix to form two single strands is called

the replication fork

Chargaff's experiments showed that the amount of adenine in a sample was always the same as the amount of

thymine

Which E. coli genes encode the proteins required to perform excision repair?

uvrA, uvrB, and uvrC

A phage is a type of Blank 1Blank 1 virus , Correct Unavailable that infects Blank 2Blank 2 bacteria , Correct Unavailable cells.

virus bacteria

Franklin determined that the structure of DNA was helical based on

x-ray diffraction analysis

How are the origins of replication adjusted in eukaryotic cells, so that early in the embryonic development of eukaryotic organisms DNA can be replicated faster?

Cells can increase the number of origins used in early development.

The enzyme that relieves DNA supercoiling ahead of the replication fork is ________.

DNA gyrase

In which type of repair mechanism a damaged region of DNA is removed and then replaced by DNA synthesis?

Excision repair

In order for mismatch repair to occur in a bacterial cell, the enzyme machinery must be able to distinguish between the template strand and a newly synthesized strand. How is that achieved?

For a short period of time after replication, the sequence GATC is methylated at the A only on the template strand.

Which DNA polymerase acts on the lagging strand to remove primers and replace them with DNA?

I

Which DNA polymerase removes and replaces RNA primer segments in the synthesis of the lagging stand because it has 5' to 3' exonuclease activity.

I

Which DNA polymerase does not seem to play a role in replication but is involved in the DNA repair process?

II

Which of the following enzymes involved in DNA replication are found at the replication fork in all three types of cells (bacterial, archaeal, and eukaryotic)? Choose all that apply.

Polymerases Sliding clamp Clamp loader Helicase Primase

The enzyme DNA _______ synthesizes the RNA primers required by DNA polymerases during replication.

Primase

_________ are short protective repeats of DNA on the ends on eukaryotic chromosomes which are generated by the enzyme _________.

Telomeres Telomerase

Which end of a complementary DNA strand base paired with the strand shown in this figure would be at the top?

The 3' end

During the synthesis of the new DNA molecule, where are the new nucleotides added by DNA polymerase?

The 3' end of the growing strand

Which model for DNA replication suggests that both strands of the double helix remain intact and the new DNA double helix consists of two new DNA strands?

The conservative model

The term used to describe two DNA strands that run in opposite directions from each other is

antiparallel

DNA's phosphodiester ________ is composed of sugars and phosphates.

backbone, spine, or back-bone

In E. coli, oriC is the site at which replication

begins

Telomeres are related to

cellular aging

The enzyme Blank 1Blank 1 ass , Incorrect Unavailable uses ATP to unwind the DNA template.

helicase or DNA helicase

The sliding clamp of a DNA polymerase

holds the polymerase to the DNA template

The primary reason the bacteriophage was an ideal model system for the Hershey Chase experiments was

it is made of only protein and DNA.

An Okazaki fragment is a short fragment of DNA created on the _________strand of DNA.

lagging

During DNA replication, the __________ strand is synthesized continuously while the ___________ strand is synthesized as small fragments that are connected to each other to form a continuous strand.

leading lagging

As the lagging strand is being synthesized, adjacent Okazaki fragments are joined by the enzyme DNA _______.

ligase

The level of telomerase stays high in ______, despite their age.

lymphocytes

Select all of the following that are components of a nucleotide.

nitrogenous base sugar phosphate group

Of the following list, which 3 items are required for DNA replication

nucleotides template polymerase

List several differences in prokaryotic and eukaryotic replication.

number of origins of replication structure of chromosome (linear vs. circular) complexity of enzymology

During semiconservative DNA replication

one of the strands in each new double helix comes from the original molecule, and one is newly synthesized.

In the 1950s, the British researcher Maurice Wilkins contributed to the discovery of DNA's double helix structure by

producing uniformly oriented DNA fibers

Which enzymes did Avery, MacLeod, and McCarty use in order to identify the genetic material?`

protein digesting enzymes RNA digesting enzymes DNA digesting enzymes

A new DNA strand can only be synthesized in a ___________ to ________ direction. Some carbons in the structure of nucleotides are denoted by numbers (e.g., 3), while others are denoted by numbers with a prime (e.g., 3'). In your answer, make sure to use the correct notation (i.e., 2 is not the same as 2'), otherwise, you will not receive credit.

5', five prime, five', 5 prime, or 5′ 3', three prime, three', 3 prime, or 3′

A segment of DNA has the sequence 5'-ATGCCC-3'. The complementary sequence would be

5'-GGGCAT-3'

Which enzyme covalently links nucleotides together?

DNA polymerase

In their experiments, Avery, MacLeod, and McCarty isolated a substance, which had a transforming activity. Which of the following destroyed that substance's ability to transform bacterial cells?

DNA-digesting enzymes

The experiments with radioactively labeled phage that showed that DNA was the genetic material were performed by

Hershey and Chase

Which of these is not required for DNA replication?

NADPH

The DNA structure proposed by Watson and Crick involves

a helical structure a sugar phosphate backbone two grooves (major and minor)

The appearance of colonies of Streptococcus pneumoniae is related to the presence or absence of

a polysaccharide coat

Viruses that infect bacteria are known as

bacteriophages

Genes, which contain trait specifying information, are located on

chromosomes

Different models for DNA replication include:

conservative replication semiconservative replication dispersive replication

E. coli polymerases I, II, and III have 3' to 5' _______ activity, which provides them with a proofreading function, i.e. they can remove a mispaired base.

exonuclease

E. coli polymerases I, II, and III have 3' to 5' ____________ activity, which provides them with a proofreading function, i.e. they can remove a mispaired base.

exonuclease

The primary purpose of the Meselson and Stahl experiments was to determine

how DNA replicates.

Regarding Meselson and Stahl's experiment, the primary difference between the proposed models of DNA replication was related to

how the parental strands were incorporated into the daughter strands

List the three phases of DNA replication:

initiation termination elongation

A bacterial virus replicates by

introducing its genetic material into the host cell

Adjacent nucleotides in the same DNA strand are held together by covalent bonds known as ____________ bonds.

phosphodiester or phosphoester

The enzyme DNA ____ covalently links nucleotides to synthesize new DNA strands together during DNA replication.

polymerase

The purpose of the Hershey Chase experiments was to determine whether a bacteriophage injected ______ or ______ into bacteria.

protein DNA

The results of the Hershey and Chase experiments suggested that DNA was the genetic material because

radioactive bacteriophage DNA was found in the cytoplasm of bacterial cells

A ______________ __________ is the partial opening of a DNA helix to form two single strands.

replication fork

When the double stranded DNA helix is unwound, two single strands of DNA are formed. These strands have to be stabilized because their hydrophobic bases are exposed to water. The proteins that stabilize the two single strands are called

single-strand binding proteins

The normal virulent form of Streptococcus pneumoniae is known as the S form because it forms _________ colonies on solid media.

smooth

The normal virulent form of Streptococcus pneumoniae is known as the S form because it forms colonies on solid media.

smooth

The DNA backbone is composed of (choose all that apply)

sugars. phosphate groups.

During DNA replication, the strand is synthesized continuously while the strand is synthesized as small fragments that are connected to each other to form a continuous strand.

supercoiling

The basic design of the Meselson-Stahl experiment is

to label DNA and follow it through 2 rounds of replication.

How many hydrogen bonds are formed between adenine and thymine in the double DNA helix?

two or 2

Which types of cells have more than one origin of replication?

Eukaryotes

Indicate the 4 nitrogenous bases used in DNA.

cytosine guanine thymine adenine

Choose all characteristics of the transforming substance isolated by Avery, MacLeod and McCarty.

- Protein-digesting enzymes did not affect its transforming ability. - RNA-digesting enzymes did not affect its transforming ability. DNA-digesting enzymes destroyed its transforming ability. The elemental composition of the substance was very similar to that of DNA.

Which of these best describes the density of the bacterial DNA after the second round of replication in the Meselson-Stahl experiments?

2 density classes - one intermediate and one 14N DNA

Consider a double stranded DNA molecule. In complementary base pairing, A pairs with Blank 1Blank 1 t , Correct Unavailable and C pairs with Blank 2Blank 2 g , Correct Unavailable. Please fill the blanks with the single letter abbreviations of the different nucleotides.

Blank 1: T or thymine Blank 2: G or guanine

Which of the following facilitates the reversal of damage to our hereditary material before a permanent mutation can occur?

DNA repair systems

In a bacterium, where does termination of replication occur, relative to the origin?

The termination site is opposite to the origin

The density of the bacterial DNA following the first round of DNA replication in the Meselson-Stahl experiment can best be described as

an intermediate between 14N and 15N DNA.

All DNA polymerases require a short strand of DNA or RNA, called a , to begin their synthesis

primer

In the replisome, the ___________ is composed of primase, helicase, and accessory proteins that prime the lagging strand.

primosome

The function of telomeres is to

protect the ends of chromosomes

Guanine forms Blank 1Blank 1 two , Incorrect Unavailable hydrogen bonds with cytosine.

three or 3

Griffith performed experiments, which demonstrated

transformation in bacteria.

X-ray diffraction was used to determine that the diameter of a DNA molecule is

2 nm

How many hydrogen bonds form between cytosine and guanine in the DNA double helix?

3

In the Meselson-Stahl experiment, what was the expected composition of DNA molecules after two rounds of replication, if the dispersive model was correct?

3/4 of each DNA molecule would be light and 1/4 would be heavy, leading to a single density.

A DNA strand runs 3' to 5'. The complementary strand runs

5' to 3'

A phage is a type of Blank 1Blank 1 virus , Correct Unavailable that infects Blank 2Blank 2 khj , Incorrect Unavailable cells.

Blank 1: virus or viruses Blank 2: bacterial or bacteria

The model organism used by Meselson and Stahl was

Escherichia coli.

In which of the following chromosomal entities are an individual's traits specified?

Genes

In prokaryotes, the two daughter molecules (each a double strand) produced at the end of replication are intertwined, similar to two links in a chain. What is the name of the enzyme that unlinks the two daughter DNA molecules?

Gyrase

The enzyme ____________ uses ATP to unwind the DNA template.

Helicase

What is the function of the UvrABC complex in excision repair in E. coli?

It binds to the damaged DNA and removes damaged DNA by cleaving a single strand on each side.

On this strand, the removal of the last primer leaves a gap that cannot be primed at the ends of the chromosome.

Lagging

________ repair is responsible for removing bases that were incorrectly incorporated into DNA during replication.

Mismatch

What type of repair mechanism is responsible for removing bases that were incorrectly inserted into DNA during replication?

Mismatch repair

Which enzyme prevents chromosomal shortening by attaching a repeat sequence to the ends of chromosomes?

Telomerase

What is the name of the regions at the ends of eukaryotic chromosomes?

Telomeres

Which of the following are short repeats of DNA on the ends of eukaryotic chromosomes?

Telomeres

Which subunit of DNA polymerase III forms the sliding clamp?

The β subunit

Why do eukaryotic cells have multiple origins of replication?

To ensure timely replication of multiple, relatively large chromosomes

Features of the Watson and Crick model include

a double stranded structure a helical structure a sugar phosphate backbone

In a DNA double helix, two hydrogen bonds form between

adenine and thymine

A heavy isotope of nitrogen was used in the Meselson-Stahl experiment so that

different DNA molecules could be separated via ultracentrifugation.

In order for mismatch repair to occur in a bacterial cell, the enzyme machinery must be able to

distinguish between the template strand and a newly synthesized strand.

RNA polymerases

do not require primers to begin synthesis.

The interaction of two strands of DNA via hydrogen bonds is the

double helix

The level of DNA structure that resembles a spiral staircase is the

double helix

Radiation, UV light, x-rays, and chemicals in the environment can cause mutations in DNA and are therefore referred to as _________.

mutagens

In DNA, consecutive nucleotides are linked via _______ bonds, which are made between the 5' phosphate of one nucleotide and the 3' _________ group of another nucleotide.

phosphodiester hydroxyl or OH

Repeating sugar and phosphate units in a single DNA strand make up the

phosphodiester backbone.

Adjacent nucleotides in the same DNA strand are held together by covalent bonds known as _________ bonds.

phosphodiester or phosphoester

Damage caused by UV light leading to thymine dimers is corrected during photorepair by the enzyme ______.

photolyase

The enzyme ______ can repair UV damage by binding to a thymine dimer and cleaving it, therefore restoring two thymines.

photolyase