Replicon

The DNA controlled by a origin is called a

How DNA replicates

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

-complexity of enzymology
-structure of chromosome (linear - eukaryotic, circular - prokaryotic)
-number of origins of replication

Differences in pro and eukaryotic replication

Helicase

Causes DNA strand separation at the origin or replication. It uses ATP to unwind the DNA template.

Topoisomerase

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

Steps of lagging strand synthesis

1. Synthesize primers using primate
2. Synthesize DNA
3. Replace RNA primers with DNA
4. Seal nicks in the DNA

Semiconservative replication

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

Telomeres, telomerase

____________ are short protective repeats of DNA on the ends on eukaryotic chromosomes which are generated by the enzyme _________.

Single-strand binding proteins

When double helix unwound, 2 single strand of DNA are formed. These strands must be stabilized b/c hydrophobic bases are exposed to water. The proteins that stabilize the two single strands are called

1. Template
2. Nucleotides
3. Polymerase

3 items required for DNA replication

DNA polymerase

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

Polymerase I

Which polymerase removes and replaces RNA primer segments in the synthesis of the lagging strand because it has 5' to 3' exonuclease activity? I, II, or III?

Leading

_________ strand synthesize continuously

Lagging

__________ strand synthesize in small fragments that are later connected

3 phases of DNA replication

1. Initiation
2. Elongation
3. Termination

A single replicon

Bacterial DNA is typically replicated as

Photolase

What enzyme can repair UV damage by binding to a thymine dimer and cleaving it, therefor restoring 2 thymines?

Telomeres

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

Error-free, error-prone

Two general categories of non-specific repair mechanisms

A single origin

Bacterial replication begins at

Okazaki, lagging

An ____________ fragment is a short fragment of DNA created on the _________ lagging strand of DNA.

The need for primer & the directionality of polymerases

Problems in replicating the ends of linear chromosomes are caused by

Mutagens

Radiation, UV light, x-rays, and chemicals in the environment that can cause mutations in DNA are called

-sliding clamp
-primase
-polymerases
-helicase
-clamp loader

The enzymes involved in DNA replication found at the replication fork of bacterial, archaeal, and eukaryotic cells?

Low

In an aging cell, the activity of telomerase would be

Gyrase

The enzyme ________ is the topoisomerase involved in DNA replication.

Polymerase II

This polymerase is not involved in replication, but is used for DNA repair

Polymerase III

Which polymerase is the main polymerase enzyme?

Polymerase I

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

Eukaryotes

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

Orci

Which origins are sequence specific?

DNA primase

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

DNA repair systems

What facilitates the reversal of damage to our hereditary material before a permanent mutation?

Epsilon, delta

Two main eukaryotic DNA polymerases that extend DNA are

Topoisomerase

What enzyme relieves torsional strain in DNA strands ahead of the replication fork?

Cellular aging

Telomeres are related to

Okazaki, lagging

An ___________ fragment is a short fragment of DNA created on the ___________ strand of DNA

Telomerase

What enzyme contains a small internal piece of RNA which is used as a template to extend the end of a linear DNA molecule?

Cells can increase the number of origins used in early development

How are the origins or replication adjusted in eukaryotic cells so that early in embryonic development DNA can be replicated faster?

To ensure timely replication of multiple, large chromosomes

Why do have multiple origins of replication?

FALSE

TRUE/FALSE
RNA polymerase require primers to begin synthesis.

Terminus

DNA replication in E. coli ends at a site called the

Eukaryotic

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

Exonuclease

E. coli polymerases I, II, III have 3' to 5' __________ activity, which provides them with proofreading function (can remove misprinted base)

Absent

The ends of chromosomes shorten when telomerase is

Replication fork

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

To label DNA and follow it through 2 rounds of replication

The basic design of the Meselson-Stahl experiment is

The lagging and leading strands

Enzymes in the reply some are active on

uvrA, uvrB, uvrC

These E. coli genes encode the proteins required to perform excursion repair

2 densities should be observed: the DNA strands would be either all heavy or all light

In the Meselson-Stahl exeperiment, what was the expected composition of DNA molecules after one round of replication, if the CONSERVATIVE model was correct?

Nitrogen

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

Intermediate between 14N & 15N DNA

The density of the bacterial DNA following the first round of DNA replication in the Meselson-Stahl experiment can beatbox be described as

Holds the pymerase to the DNA template

The sliding clamp of a DNA polymerase does what?

Primosome

In the reply some, the _______________ is composed of primase, helicase, and accessory proteins that prime the lagging strand

High

In cancer cells as compared to normal cells, telomerase is present in what sort of levels?

Lymphocytes

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

Cesium chloride gradient

To determine the density of DNA strands, Meselson and Stahl used this technique so that DNA fragments would migrate to the area in the gradient where they had the same density

Supercoiling

Coiling of two DNA strands leading to torsional strain

The cells will show an increased lifespan

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

Short internal

Telomerase uses a ________ ___________ RNA

Beta subunit

Which subunit of DNA polymerase II forms the sliding clamp?

Termination site is opposite to the origin

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