1. Structure and Function
DNA
Structure and Function

2. WHAT IS DNA?
DNA stands for DeoxyriboNucleic Acid
The main job of DNA is
to make PROTEINS

3. DNA contains genes that codes for all of our traits
Function of DNA
DNA contains genes that codes for all of our traits
It’s the blueprint to who you are today
Passed from cell to cell

4. Location of DNA DNA is found in the nucleus of the cell for eukaryotes
DNA is found in the cytoplasm for prokaryotes (ex: bacteria)
Our genes are on our chromosomes.
Chromosomes are made up of a chemical called DNA

6. DNA stays in nucleus of a cell to be protected
Eukaryotes
DNA stays in nucleus of a cell to be protected

7. Building Blocks of DNA
Each nucleotide consists of
Deoxyribose (sugar)
Phosphate group
A nitrogen-containing base (A, G, T, C)

8. Nucleotide Structure O=P-O O CH2 O N C Phosphate Group
Nitrogenous base
(A, G, C, or T)
CH2 O C
Sugar
(deoxyribose)

9. Nitrogen Bases Adenine (A) Guanine (G) Thymine (T) Cytosine (C) T or C
A or G
T or C

10. Structure of DNA Double Helix: Watson-Crick Model
Strands are held together by hydrogen bonds between bases
The sides are a sugar-phosphate backbone, while the “rungs” of the ladder are the nitrogen bases.
The DNA strands run in opposite directions

14. Adenine (A) pairs with Thymine (T) Cytosine (C) pairs with Guanine (G)
Base-Pairing Rules
Adenine (A) pairs with Thymine (T)
Cytosine (C) pairs with Guanine (G)

16. DNA BASE-PAIRING PRACTICE
Make a copy of the following DNA Sequence:
DNA Strand #1: C G G T A
DNA Strand #2: G C C A T
DNA Strand #1: A T C G C G A A
DNA Strand #2: T

17. DNA BASE-PAIRING PRACTICE
Make a copy of the following DNA Sequence:
DNA Strand #1: C G G T A
DNA Strand #2: G C C A T
DNA Strand #1: A T C G C G A A
DNA Strand #2: T A

18. DNA BASE-PAIRING PRACTICE
Make a copy of the following DNA Sequence:
DNA Strand #1: C G G T A
DNA Strand #2: G C C A T
DNA Strand #1: A T C G C G A A
DNA Strand #2: T A G

19. DNA BASE-PAIRING PRACTICE
Make a copy of the following DNA Sequence:
DNA Strand #1: C G G T A
DNA Strand #2: G C C A T
DNA Strand #1: A T C G C G A A
DNA Strand #2: T A G C

20. DNA BASE-PAIRING PRACTICE
Make a copy of the following DNA Sequence:
DNA Strand #1: C G G T A
DNA Strand #2: G C C A T
DNA Strand #1: A T C G C G A A
DNA Strand #2: T A G C G

21. DNA BASE-PAIRING PRACTICE
Make a copy of the following DNA Sequence:
DNA Strand #1: C G G T A
DNA Strand #2: G C C A T
DNA Strand #1: A T C G C G A A
DNA Strand #2: T A G C G C

22. DNA BASE-PAIRING PRACTICE
Make a copy of the following DNA Sequence:
DNA Strand #1: C G G T A
DNA Strand #2: G C C A T
DNA Strand #1: A T C G C G A A
DNA Strand #2: T A G C G C T

23. DNA BASE-PAIRING PRACTICE
Make a copy of the following DNA Sequence:
DNA Strand #1: C G G T A
DNA Strand #2: G C C A T
DNA Strand #1: A T C G C G A A
DNA Strand #2: T A G C G C T T

24. A = T C = G A+T+C+G = 100 Chargaff’s Rule
For example: The DNA is made up of 15% Adenine. Figure out the amount of the other nitrogen bases.
Adenine = Thymine Thymine = 15
(a)G+C+15+15= (b) =G+C (c) = 70
G+C = 70 and Guanine =Cytosine
G= 35 and C=35
Therefore: A=15%, T=15%, G=35%, C=35%

25. Practice Problem
The DNA is made up of 30% Cytosine, calculate the amount of the other nitrogen bases.
Cytosine = Guanine G=30
30+30+A+T=100
A+T=
T+A=40
A=20, T=20
Therefore: G=30, C=30, A=20, T=20