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