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DNA and Replication
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2. DNA Structure and Function
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DNA
DNA is a complex molecule.
It is found in all living things BOTH prokaryotic and eukaryotic.
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DNA Double Helix
Nitrogenous
Base (A,T,G or C)
“Rungs of ladder”
“Legs of ladder”
Phosphate &
Sugar Backbone
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DNA
DNA is a Nucleic Acid so it is made up of nucleotides (monomers)
Look at the picture to the left of your notes – label the different points based on your notes from YESTERDAY.
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DNA
Stands for Deoxyribonucleic acid
Made up of subunits called nucleotides
Nucleotide made of:
1. Phosphate group
2. 5-carbon sugar
3. Nitrogenous base
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DNA Nucleotide
O=P-O O
Phosphate
Group N
Nitrogenous base
(A, G, C, or T) O
CH2 O C1 C4 C3 C2 5
Sugar
(deoxyribose)
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DNA P O 1 2 3 4 5 P O 1 2 3 4 5 G C T A
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Nitrogenous Bases
Double ring PURINES
Adenine (A)
Guanine (G)
Single ring PYRIMIDINES
Thymine (T)
Cytosine (C)
A or G
T or C
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10. Two hydrogen bonds are required to bond Adenine & Thymine
Three hydrogen bonds are required to bond Guanine & Cytosine
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DNA Function
Stores genetic information
Carries the genetic code (instructions) for making proteins.
DNA determines an organism’s genes by controlling the synthesis of proteins.
EX: hair color, eye color, height.
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DNA Function
Proteins Traits
Hereditary information is passed on to offspring.
Blueprint for LIFE.
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DNA Replication
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Replication Facts
DNA has to be copied before a cell divides
New cells will need identical DNA strands
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DNA Replication Video
Click on the link above to watch the video introducing DNA Replication
Turn on closed captioning and use headphones to listen.
Fill in the blanks and stop where you see a stop sign to make sure all blanks above are filled in.
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DNA Replication
Enzyme helicase unwinds and unzips DNA by breaking weak Hydrogen bonds
“Replication Fork” forms
Replication
Fork
Parental DNA Molecule 3’ 5’
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DNA Replication
An enzyme (polymerase) adds free-floating nucleotides (base pairs) .
The enzyme (ligase) joins the nucleotides together .
GLUE – matching up.
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19. Direction of Replication
DNA Replication
Two new genetically identical DNA molecules are formed.
1/2 – New
1/2 – from Original
RNA
Primer
DNA Polymerase
Nucleotide 5’ 3’
Direction of Replication
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20. Synthesis of the New DNA Strands
Two NEW genetically identical DNA molecules formed/synthesized.
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21. Synthesis of the New DNA Strands
Test Your Skills – match the base pairs to replicate the DNA!
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Check your work with Ms. Harris – this is your grade for today!
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