Download DNA Replication - Northwest ISD Moodle

Pyrimidine, hydrogen bond, DNA polymerase, base
pair, helicase.
DNA Replication
Warm-up Questions:
• Scientists have discovered that certain cells with a defect in a gene called p53 can
cause a serious disease. Gene p53 normally prevents the cell cycle from
continuing until proper chromosome replication has occurred. Defective p53
genes can cause cells to undergo uncontrolled growth. Which type of disease is
most likely to be caused by a defect in p53?
a.
cancer
b.
chicken pox
c.
strep throat
d.
pneumonia
• “Thymine—guanine—thymine—cytosine” describes — (6A)
a.
nucleotides within an RNA strand
b.
a sequence of bases within a DNA section
c.
points of DNA separation during protein synthesis
d.
tRNA codons for specific amino acids
DNA Structure Cont.
DNA is composed of purine and
pryrimidine bases. Adenine and guanine
are purines. Purines are the larger of the
two types of bases found in DNA. Cytosine and thymine are
pyrimidines.
The bases in DNA are connected
by hydrogen bonds. The sequence
of base pairs carries the genetic
information.
The backbone of DNA is made up
of alternating sugar (deoxyribose)
and phosphate groups.
DNA Replication
DNA replication is the process of
producing two identical replicas
The first step in DNA replication
from one original DNA
is the separation of the two DNA
molecule.
strands that make up the helix.
An enzyme, DNA helicase
unwinds and unzips the DNA
strand.
The unzipped DNA forms a Yshape called the replication
fork.
DNA Replication Cont.
Each separate DNA strand now has its
sequence of bases exposed and unpaired.
DNA polymerase enzymes match up each
one of these exposed bases, in turn, with
free nucleotide triphosphates; A with T, and
G with C.
DNA polymerase then uses energy
and joins the new sections together
with new hydrogen bonds.
DNA Replication Cont.
Each end of the genetic sequence in each
side of the split DNA strand has a 3’ and
a 5’ end.
DNA polymerase works in the 5’ to
3’ direction.
In the genetic code, a stop codon is
a nucleotide triplet within mRNA
that signals a termination of
translation.
DNA Replication Video
We will watch the following video.You will be responsible
for taking notes on the video in your journal.
DNA Replication Video.
Replication and Mitosis Memes 