Ch 14: DNA The Genetic Material

Griffith

showed that there was a transforming principle that could be passed between bacterial cells

replisome

the enzymes involved in DNA replication form a macromolecular assembly called the

DNA polymerase 3

the main replication enzyme

DNA primase

the primers required by DNA polymerase during replication are synthesized by the enzyme ___________

helicase

unwinds the double helix

Nonspecific repair

use a single mechanism to repair multiple kinds of lesions in DNA

exonucleases

which chew away at an end of DNA

endonucleases

which cut DNA internally

excision repair

A common form of nonspecific repair is called

telomeres

Short, repeated sequences of DNA are characteristic of

eukaryotic

_________replication involves multiple origins

DNA polymerase I

erases primer and fills gaps

topoisomerases

act to relieve the torsional strain caused by unwinding and to prevent this supercoiling from happening.

DNA polymerase 1

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

Meselson and Stahl

determined a method for the replication of the genetic material

Hershey and Chase

determined that DNA was the genetic material by studying the T2 bacteriophage

Avery, MacLeod, and McCarty

determined that DNA was the genetic material by studying the transforming principle

RNA polymerases

do not have this requirement, so they are the ones that usually synthesize primers

1'

nitrogenous base

DNA polymerase 2

not involved in replication but used for DNA repair

semi-conservative model

one strand of the parental duplex remains intact in daughter strands; a new complementary strand is built for each parental strand consisting of new molecules. Daughter strands would consist of one parental strand and one newly synthesized strand

5'

phosphate group

telomeres

protect the ends of chromosomes from nucleases and maintain the integrity of linear chromosomes

topoisomerases

Enzymes that can alter the topological state of DNA are called

helicases

Enzymes that use energy from ATP to unwind the DNA template are called

SSBP, helicase, topoisomerase

Which of these are involved in the unwinding of DNA?

Okazaki fragments

DNA fragments synthesized on the lagging strand are called

3'

OH group

tautomers

Structural forms found in DNA are called

phosphate groups and sugars

The DNA backbone is composed of two things:

DNA polymerase

The enzyme that matches the existing DNA bases with complementary nucleotides and links the nucleotides together to make a new strand is

semi-conservative model

The only model that was not rejected was the

replication fork

The partial opening of a DNA helix to form two single strands has a forked appearance, and is called the

Meselson and Stahl

The primary purpose of the _________________ experiment was to determine how DNA replicates

single stranded binding protein

The single strands of DNA produced by helicase action are unstable because the process exposes the hydrophobic bases to water, cells solve this problem by using __________________, to coat exposed single strands

telomeres

The specialized structures found on the ends of eukaryotic chromosomes are called ________

phosphodiester bonds

The two strands of the double helix are made up of long polymers of nucleotides, and as described earlier, each strand is made up of repeating sugar and phosphate units joined by:

supercoiling

The unwinding of the two strains introduces torsional strain in the DNA molecule. When this happens, it is called

replicon

We call the DNA controlled by an origin a ____________

guanine

forms three hydrogen bonds with cytosine

adenine

forms two hydrogen bonds with Thymine

excision repair

in this, a damaged region is removed, and is then replaced by DNA synthesis

DNA primase

is an RNA polymerase that synthesizes short stretches of RNA that function as primers for DNA polymerase

DNA gyrase

is the topoisomerase involved in DNA replication

DNA ligase

joins the ends of DNA segment, DNA repair

DNA polymerase III

synthesizes DNA

primase

synthesizes RNA primers

Specific repair

target a single kind of lesion in DNA and repair only that damage