Bio Chapter 14

Chromosomes are primarily composed of DNA and----

proteins

The DNA controlled by an origin is called a-----

replicon

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

semiconservative 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

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

template nucleotides polymerase

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

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

Franklin determined that the structure of DNA was helical based on

x-ray diffraction analysis

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

11

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

2nm

By convention, the sequence of DNA bases is usually written in the ----to--- direction.

5' to 3'

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

5'-GGGCAT-3'

What is a thymine dimer?

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

Why do we say that a DNA or RNA strand has an intrinsic polarity?

Because it has a free 5' phosphate at one end and a free 3' OH group at the other end

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

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

extension

Bacterial DNA is typically replicated as

a single replicon

Features of the Watson and Crick model include

a sugar phosphate backbone a double stranded structure a helical structure

Indicate the 4 nitrogenous bases used in DNA.

adenine guanine cytosine thymine

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

List several differences in prokaryotic and eukaryotic replication.

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

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

lagging

The two main eukaryotic DNA polymerases that extend DNA are

delta epsilon

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

diffraction

List the three phases of DNA replication:

elongation termination initiation

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

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

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

mutagen

Agents that cause mutation are known as

mutagens

The two general categories of DNA repair are

nonspecific specific

During semiconservative DNA replication

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

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

phosphodiester backbone.

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.

photolyse

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

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

1

Match the function of each DNA polymerase in E. coli.

1- acts on the lagging strand to remove primers and replace them with DNA 2. not involved in replication but used for DNA repair 3. the main replication enzyme

Match the following strands with the type of synthesis.

1. Synthesized continuously 2. synthesized small fragments that are later connected.

A chromosome is primarily composed of (chose all that apply)

DNA proteins

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

DNA gyrase

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

DNA repair systems

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

Eukaryotes

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

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

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

The 3' end of the growing strand

Why do eukaryotic cells have multiple origins of replication?

To ensure timely replication of multiple, relatively large chromosomes

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')

five prime, three prime

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

genes

Which of these are used in RNA?

guanine uracil cytosine adenine

The enzyme---- uses ATP to unwind the DNA template.

helicase

Match these enzymes involved in DNA replication with their function.

helicase---unwinds the double helix gyrase--- relieves coiling DNA stands ahead of the replication fork Primase--- makes a 10-12 bp complementary primer to the DNA. Polymerase--- attaches to a nucleotide to the 3' end of the DNA strand

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.

-----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

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

sugar nitrogenous base phosphate group

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

sugars. phosphate groups.

Short, repeated sequences of DNA are characteristic of

telomeres