DNA: The Genetic Material

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

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

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

DNA repair systems

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

Meselson and Stahl.

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

Mismatch

_______ repair is responsible for removing bases that were incorrectly incorporated into DNA during replication. Listen to the complete question

Mismatch

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

Mismatch repair

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

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

T, G

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

The DNA structure proposed by Watson and Crick involves

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

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

a single origin

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

Match these enzymes involved in DNA replication with their function. helicase gyrase primase polymerase

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

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

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

In an aging cell, the activity of telomerase would be

low

During semiconservative DNA replication

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

Select all of the following that are components of a nucleotide. phosphate group lipid sugar nitrogenous base triglyceride

phosphate group sugar nitrogenous base

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

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

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

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 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

Griffith's experiments were important because they showed

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

The enzymes in the replisome are active on

the leading and the lagging strands

DNA repair mechanisms have likely evolved because

there is no way for cells to avoid exposure to mutagens

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 -Primase -Helicase -Clamp loader

List several differences in prokaryotic and eukaryotic replication.

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

DNA primase (choose all that apply)

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

The problems in replicating the ends of linear chromosomes are caused by (choose all that apply) Multiple select question. -a lack of telomerase -the directionality of polymerases -the need for a primer -the presence of repeated sequences

-the directionality of polymerases -the need for a primer

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

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

DNA gyrase

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 model organism used by Meselson and Stahl was

Escherichia coli.

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.

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

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

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

Lagging

Choose all characteristics of the transforming substance isolated by Avery, MacLeod, and McCarty. 1.The elemental composition of the substance was very similar to that of DNA. 2.RNA-digesting enzymes did not affect its transforming ability. 3.DNA-digesting enzymes destroyed its transforming ability. 4.Extracting DNA from the substance did not affect its transforming ability. 5.Protein-digesting enzymes did not affect its transforming ability.

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

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 sugar phosphate backbone a double stranded structure a helical structure

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

backbone

Nucleotides contain a sugar, a phosphate, and a nitrogenous ________.

base

Telomeres are related to

cellular aging

Genes, which contain trait specifying information, are located on

chromosomes

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

determined that DNA is the genetic material

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

diffraction

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

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

endonuclease; 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 enzyme ____ uses ATP to unwind the DNA template.

helicase

Match the following strands with the type of synthesis. leading strand lagging strand

leading strand-synthesized continuously lagging strand-synthesized in small fragments that are later connected

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

Agents that cause mutation are known as

mutagens

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

mutagens

The two general categories of DNA repair are

nonspecific specific

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

nucleotides template polymerase

The function of telomeres is to

protect the ends of chromosomes

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

protein digesting enzymes RNA digesting enzymes DNA digesting enzymes

The DNA controlled by an origin is called a

replicon

Different models for DNA replication include:

semiconservative replication conservative replication dispersive 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

_________ 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, nonspefic

Griffith performed experiments, which demonstrated

transformation in bacteria.