Download DNA Replication

DNA Replication
Question:
• What would be the
complementary DNA
strand for the following
DNA sequence?
DNA 5’-CGTATG-3’
copyright cmassengale
2
The
“Central Dogma”
Possible Modes of DNA Replication
Phosphate
Group
Remember HOW the Carbons
Are Numbered!
O
O=P-O
O
5
CH2
O
N
C1
C4
Nitrogenous base
(A, G, C, or T)
Sugar
(deoxyribose)
C3
C2
copyright cmassengale
5
Remember the Strands are
Antiparallel
5
O
3
3
P
5
O
O
C
G
1
P
5
3
2
4
4
P
5
P
2
3
1
O
T
A
3
O
3
5
O
copyright cmassengale
5
P
P
6
Replication: 5’ to 3’ Direction ONLY
Continuous replication
on one strand
Discontinuous replication
on one strand
Intro to Genetics:
DNA Structure & Function
• Genetics: the study of heredity
– What determines an organism’s traits (characteristics)?
– How are traits passed on from one cell to another, and
from parents to offspring?
• DNA: the molecule that carries genetic information
• DNA has two important functions:
• Carry instructions for making proteins that determine your
traits
• Replicate – make exact copies of itself so it can be passed on
• DNA is found in all cells (in the nucleus in
eukaryotic cells)
Genetic Info in Cells
Chromosomes
Very long, coiled/bunched
up strands of DNA that
contain many genes
Nucleotide Base Pairs
Building blocks of DNA
DNA
Gene: Instructions for
making a protein that
determines a trait
Another Gene: instructions for
making a different protein that
determines a different trait
DNA Structure
Objectives for Class:
Describe the structure of DNA.
DNA Structure
DNA is made out of
Nucleotides
• Nucleotides have 3 parts:
Deoxyribose Sugar
Phosphate
Nitrogenous Base (A, T, C, or G)
DNA molecule = double helix of
nucleotides
Sides: alternating phosphates
& sugars
Middle/ “Rungs” of ladder:
 Pairs of Nitrogenous Bases
connected by Hydrogen bonds
Objectives for Class:
Describe the structure of DNA.
Base Pairing
A ---- T
G ---- C
Objectives for Class:
Describe the structure of DNA.
Hydrogen bonds
connect them
DNA Replication: Overview
• DNA can make an exact
copy of itself!
• Occurs every time a cell
needs to reproduce
• What is the first thing
that would need to
happen to replicate this
DNA?
Objectives for Class:
Describe the structure of DNA.
Steps of DNA Replication
1. Double helix splits (unwinds and
unzips)
– Hydrogen Bonds break
– Separates into 2 single strands
2. New nucleotides match up with
each side
– DNA Polymerase is the enzyme that
does this
– Matches according to base-pairing
rules
3. Two new strands twist up
Result: Two Double Helices
Each half old, half new.
Objectives for Class:
• List the steps of DNA replication
DNA Replication: Summary
Title: DNA Review
Homework: Optional - Finish Parts 2 and/or 3 of the DNA Review Packet
Silent Do Now: (in notebook w/ title & date)
1. Write the complementary base sequence to this single strand of
DNA
G A A C G T
2. Which of the pictures below best illustrates DNA replication?
A. Why?
B.
C.
Bonus: Who is the
perfect Valentine for
a gentleman named
CTCT?
DNA Replication is
Catalyzed by Enzymes
DNA Polymerase Adds Complementary Bases
DNA Polymerase Sees Errors
DNA Polymerase Repairs Errors