BiO Ch.14

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

Meselson and Stahl

What type of repair mechanism 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 regions at the ends of eukaryotic chromosomes?

Telomeres

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

Telomeres

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

eukaryotes

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

how DNA replicates

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

photolyase

During DNA replication, the enzyme _______ synthesizes RNA primers, the enzyme _______ unwinds the double helix, and the enzyme DNA _________ joins two strands of DNA together.

primase, helicase, ligase

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

DNA repair mechanisms have likely evolved because

there is no way for cells to avoid exposure to mutagens

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

2 nm

Polymerase

Attaches a nucleotide to the 3' end of the DNA strand

Gyrase

Relieves coiling in DNA strands ahead of the replication fork

In an aging cell, the activity of telomerase would be

low

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

primase

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 DNA structure proposed by Watson and Crick involves

1. a sugar phosphate backbone 2. a helical structure 3. two grooves (major and minor)

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

Mismatch

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

endonuclease; exonuclease

The two general categories of DNA repair are

nonspecific and specific

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

DNA repair systems

During semiconservative DNA replication,

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

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

polymerase

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

semiconservative replication

What are some basic differences in prokaryotic and eukaryotic replication?

1. Eukaryotes have linear chromosomes. 2. Eukaryotes have multiple, large chromosomes.

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

1. Nitrogenous base 2. Sugar 3. Phosphate group

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

1. Polymerase 2. Nucleotides 3. Template

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

1. RNA-digesting enzymes did not affect its transforming ability. 2. The elemental composition of the substance was very similar to that of DNA. 3. DNA-digesting enzymes destroyed its transforming ability. 4. Protein-digesting enzymes did not affect its transforming ability.

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.

1. Sliding clamp 2. Primase 3. Helicase 4. Clamp loader 5. Polymerases

Features of the Watson and Crick model include

1. a sugar phosphate backbone 2. a double stranded structure 3. a helical structure

The two main eukaryotic DNA polymerases that extend DNA are

1. epsilon 2. delta

DNA primase

1. makes a primer of RNA complementary to the DNA. 2. makes a primer about 10 -20 nucleotides in length.

Place the steps of lagging strand synthesis in the correct order

1. synthesize primers using primase 2. synthesize DNA 3. replace RNA primers with DNA 4. stitch fragments together

The problems in replicating the ends of linear chromosomes are caused by

1. the need for a primer 2. the directionality of polymerases

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

ligase

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

linear chromosomes

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

mutagens

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

primosome

Griffith's experiments were important because they showed

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

The DNA backbone is composed of

1. sugars 2. phosphate groups

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 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

Franklin used x-ray ________ to suggest that DNA has a helical structure.

Diffraction

Which type (or types) of cells has more than one origin of replication per chromosome?

Eukaryotes

The enzyme machinery responsible for mismatch repair must be able to distinguish between the template strand and a newly synthesized strand. How is that achieved in a bacterial cell, such as E. coli?

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

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

Genes

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

Hershey and Chase

Why do eukaryotic cells have multiple origins of replication?

To ensure timely replication of multiple, relatively large chromosomes

Helicase

Unwinds the double helix

A bacterial chromosome is typically replicated as

a single replicon

Nucleotides contain a sugar, a phosphate, and a nitrogenous

base

The enzymes in the replisome are active on

both the leading and the lagging strand

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

determined that DNA is the genetic material

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

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

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

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

_________ 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

Griffith's studies were instrumental in the discovery of DNA as the genetic material because his experiments demonstrated

transformation in bacteria

Primase

Makes a 10-12 bp complementary primer to the DNA

Agents that cause mutation are known as

mutagens

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

phosphodiester backbone

Consider a double-stranded DNA molecule. In complementary base pairing, A pairs with ____, and C pairs with ____.

T, G

Which of these are part of the Watson-Crick model of the structure of DNA molecules?

1. Each DNA molecule is composed of 2 phosphodiester strands. 2. Each DNA molecule is composed of two strands that run antiparallel.

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

Lagging

The enzyme _____ uses ATP to unwind the DNA template.

helicase

The DNA controlled by an origin is called a

replicon

Which type (or types) of cells uses (or use) a primase that is a combination of RNA polymerase and DNA polymerase and makes short RNA primers which are then extended with DNA to produce the final primer?

Eukaryotic

Which of the following bonds, while individually weak, are numerous enough to hold the two strands of a double-stranded DNA molecule tightly together?

Hydrogen bonds between basepairs

Experiments have shown that telomerase is involved in

cellular aging

Genes, which contain trait specifying information, are located on

chromosomes

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