bio ch 14

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

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

Short, repeated sequences of DNA are characteristic of

telomeres

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

DNA digesting enzymes RNA digesting enzymes protein digesting enzymes

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

DNA gyrase

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

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

Mismatch repair

Which of these is not required for DNA replication?

NADPH

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

Telomeres are related to

cellular aging

The enzyme _____ uses ATP to unwind the DNA template.

helicase

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

how DNA replicates.

In an aging cell, the activity of telomerase would be

low

Order the steps in excision repair from first to last, starting at the top.

1. recognition of damage 2. removal of the damaged region 3. resynthesis using the information on the undamaged strand as a template

The experiments used to distinguish between the three potential DNA replication mechanisms were performed by

Meselson and Stahl

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

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

thymine

Chargaff's rule indicates that the amount of A in a sample is equal to the amount of _____ and the amount of C in a sample is equal to the amount of ______.

thymine; guanine

Griffith performed experiments, which demonstrated

transformation in bacteria.

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 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

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

This type of primase is a combination of RNA polymerase and DNA polymerase that makes short RNA primers and then extends them with DNA to produce the final primer:

eukaryotic

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

mutagens

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

sugar phosphate group nitrogenous base

______ are short protective repeats of DNA on the ends on eukaryotic chromosomes which are generated by the enzyme _______

telomeres; telomerase

List the three phases of DNA replication:

termination elongation initiation

Griffith's experiments were important because they showed

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

Agents that cause mutation are known as

mutagens

Genes, which contain trait specifying information, are located on

chromosomes

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

2

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

2 nm

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

5'-GGGCAT-3'

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

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

Eukaryotes

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 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.

Helicase Clamp loader Polymerases Sliding clamp Primase

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

Telomerase

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

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

A phage is a type of _______ that infects ______ cells.

virus; bacterial

Franklin determined that the structure of DNA was helical based on

x-ray diffraction analysis

Bacterial replication (for example in E. coli) begins at

a single origin

Place the steps of lagging strand synthesis in the correct order (start at the top):

1. synthesize primers using primase 2. synthesize DNA 3. replace RNA primers with DNA 4. seal nicks in the DNA

Which enzyme covalently links nucleotides together?

DNA polymerase

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

DNA repair systems

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

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

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

Bacterial DNA is typically replicated as

a single replicon

Indicate the 4 nitrogenous bases used in DNA.

adenine cytosine thymine guanine

Viruses that infect bacteria are known as

bacteriophages

Nucleotides contain a sugar, a phosphate, and a nitrogenous

base

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

endonuclease; exonuclease

the amount of guanine always equals the amount of ________

cytosine

The two main eukaryotic DNA polymerases that extend DNA are

delta epsilon

The major significance of the Hershey and Chase's experiments is that they

determined that DNA is the genetic material

This model of DNA replication suggests that newly synthesized strands of DNA have mixtures of parental and newly synthesized strands of DNA:

dispersive

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.

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

Which of these are used in RNA?

guanine cytosine uracil adenine

Match these enzymes involved in DNA replication with their function.

helicase- unwinds the double helix gyrase-relieves coiling in DNA strands ahead of the replication fork primase- makes a 10-12 bp complementary primer to the DNA polymerase- attaches a nucleotide to the 3' end of the DNA strand

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

DNA primase (choose all that apply)

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

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

mismatch

During semiconservative DNA replication

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

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

phosphate groups. sugars.

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

phosphodiester

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

phosphodiester backbone

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

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

photolyase

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

polymerase

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

polymerase template nucleotides

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

primase

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

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

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

semiconservative replication

Different models for DNA replication include:

semiconservative replication dispersive replication conservative replication

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 two general categories of DNA repair are

specific nonspecific

Match the types of repair mechanisms with how they work:

specific- target a single kind of lesion in DNA and repair that damage nonspecific- repair multiple kinds of lesions in DNA, using a single mechanism

List several differences in prokaryotic and eukaryotic replication.

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

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

the larger amount of DNA organized into multiple chromosomes, and the linear structure of the chromosomes.

The enzymes in the replisome are active on

the leading and the lagging strands

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

the need for a primer the directionality of polymerases

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

the replication fork

DNA repair mechanisms have likely evolved because

there is no way for cells to avoid exposure to mutagens

The DNA structure proposed by Watson and Crick involves

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


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