Chapter 14 Practice Questions

virus; bacteria

A phage is a type of _______________ that infects ______________ cells

Error-free and error-prone

Cells have several non-specific repair pathways. What are the two general categories of repair mechanisms?

T; G

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

there is no way for cells to avoid exposure to mutagens

DNA repair mechanisms have likely evolved because

linear chromosomes

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

backbone

DNA's phosphodiester _______________ is composed of sugars and phosphates

A sugar phosphate backbone, a helical structure & a double stranded structure

Features of the Watson and Crick model include

the cells show an increased lifespan

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

phosphodiester; hydroxyl

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

hydrogen

In DNA, the two tautomers in the bases exhibit differences in what type of bonding pattern?

begins

In E Coli oriC is the site at which replication

adenine and thymine

In a DNA double helix, two hydrogen bonds form between

The termination site is opposite to the origin

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

low

In an aging cell, the activity of telomerase would be

Wilkins

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

photolyase

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

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

Meselson and Stahl

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

Hershey and Chase

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

double helix

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

Lymphocytes

The level of telomerase stays high in these cells, despite their age

smooth

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

The need for a primer and the directionality of polymerases

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

protein; DNA

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

supercoiling

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

Synthesize primers using primase -> synthesize DNA -> Replace RNA primers with DNA -> Seal nicks in the DNA

What are the steps of lagging strand synthesis?

Initiation, elongation & termination

What are the three phases of DNA replication?

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

What are the two parts of the Watson-Crick model?

Relieves coiling in DNA strands ahead of the replication fork

What does gyrase do?

Unwinds the double helix

What does helicase do?

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

What does polymerase do?

Makes a 10-12 bp complementary primer to the DNA

What does primase do?

Helicase, sliding clamp, primase, polymerases & clamp loader

What enzymes involved in DNA replication are found at the replication fork in all three types of cells?

Telomeres

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

oriC

What origins are more sequence-specific?

Eukaryotes

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

Smooth, rough, live & heat-killed

What types of streptococcus pneumoniae bacteria did Griffith inject into mice?

primosome

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

5' to 3'

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

replication fork

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

leading; 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

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

During semiconservative DNA replication

exonuclease

E. coli polymerases I, II and III have 3' to 5' ____________ activity, which provides them with a proofreading function.

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

Griffith's experiments were important because they showed

three

Guanine forms ______ hydrogen bonds with cytosine

Cells can increase the number of origins used in early development

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?

DNA-digesting enzymes

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?

Genes

In what chromosomal entities are an individual's traits specified?

Excision repair

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

nitrogen

Meselson and Stahl used two isotopes of __________ in their DNA replication experiments so that the daughter strands could be distinguished from the parental strands

Mutagens

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

A short internal RNA

Telomerase uses what as a template?

gyrase

The enzyme DNA ____________ is the topoisomerase involved in DNA replication

primase

The enzyme DNA ____________ synthesizes RNA primers required by DNA polymerases during replication

polymerase

The enzyme DNA _____________ covalently links nucleotides to synthesize new DNA strand together during DNA replication

helicase

The enzyme _________ uses ATP to unwind the DNA template

delta and epsilon

The two main eukaryotic DNA polymerases that extend DNA are

Nitrogenous base, sugar & phosphate group

What are the components of a nucleotide?

Guanine, Adenine, Thymine & Cytosine

What are the four nitrogenous bases used in DNA?

Recognition of damage -> Removal of the damaged region -> Resynthesis using the information on the undamaged strand as a template

What are the steps in excision repair?

Telomerase

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

The conservative model

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 B subunit

Which subunit of DNA polymerase III forms the sliding clamp?

Telomeres; telomerase

___________ are short protective repeats of DNA on the ends on eukaryotic chromosomes which are generated by the enzyme _____________

introducing its genetic material into the host cell

A bacterial virus replicates by

genetic material and a protein coat

A bacteriophage contains

5'; 3'

A new DNA strand can only be synthesized in a ______ to _______ direction

phosphodiester

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

primer

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

lagging

An Okazaki fragment is a short fragment of DNA created on the _________ strand of DNA

a single origin

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