Download DNA Replication

DNA
Structure and Replication
DNA Rap Song
http://www.youtube.com/watch?v=d1UPf7lXeO8
Student Expectations
B 6.A1
Identify components of DNA.
DNA Structure
 DNA stands for Deoxyribonucleic Acid
 Shape: Double helix
 Monomers: Nucleotides (has 3 parts)

Sugar, (deoxyribose),
phosphate
nitrogenous base

Bases are held together by hydrogen bonds.


Four Nitrogenous Bases




Adenine (A)
Guanine (G)
Cytosine (C)
Thymine (T)
 Purines (double ring) Adenine and Guanine
 Pyrimidines (single ring) – Cytosine and Thymine
 Chargaff’s rule:


Adenine pairs with thymine. A –T T – A
Guanine pairs with cytosine. G – C C – G
Nucleotides:
Purines
Adenine
Pyrimidines
Guanine
Phosphate
group
Thymine
Cytosine
Cytosine
Thymine
Sugar:
Deoxyribose
Build a DNA molecule
http://learn.genetics.utah.edu/content/begin/dna
/builddna/
A Closer Look at DNA:
Page 294
Nucleotide
Hydrogen
bonds
Sugar-phosphate
backbone
Key
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
A closer look at DNA:
How DNA condenses
Chromosome
Centromere
Supercoils
DNA
Histones
Chromatin
double
helix
Student Expectation
B 5.A1
Describe the stages of the
cell cycle, including
deoxyribonucleic acid (DNA)
replication.
What is Replication?
 The process of copying DNA during S phase of
interphase in the nucleus
 Makes sure that a daughter cell will have a
complete set of chromosomes
 Original strand of DNA serves as a template for 2
new strands

Template: a pattern; an original model
 Each new strand will be identical to the original
strand because of Chargaff’s rule.
How does replication work?
 1) Helicase unwinds the double helix, forming a
“replication fork,” where replication takes place
 2) DNA polymerase bonds the necessary
nucleotides to the original DNA strand to complete
2 new DNA molecules
 3) DNA polymerase also “proofreads” the new
DNA strand to make sure it is an exact copy of the
original DNA
DNA Replication Facts:
 DNA polymerase can only work in one direction
so:
 2 new strands of DNA are made in opposite
directions
 One strand is made in sequence of nucleotides
 The other strand is what we call the “lagging
strand” because nucleotides are added in
fragments
DNA Replication:
Page 298
Original
DNA
New strand strand
polymerase
DNA
polymerase
Growth
Growth
Replication fork
Replication Nitrogenous
fork
bases
New strand Original
strand
Videos
 http://www.youtube.com/watch?NR=1&featur
e=fvwp&v=bW5JnYZImJA
 http://www.youtube.com/watch?v=5VefaI0Lrg
E&feature=related