Structure and functions of dna and rna cell

Structure and functions of dna and rna

1. DNA
STRUCTURE AND
FUNCTION
Learning objective: describe the structure of DNA

2. Nucleic acids
DNA
RNA
Biopolymer Monomers
Nucleotides
Hold genetic
information
Various
functions
Natural
Not synthetic

3. Nucleotide
Nucleoside
Nucleotide
Phosphate Phosphate Phosphate
Nucleoside diphosphate
Nucleoside monophosphate
Sugar
Base
Nucleoside triphosphate

4. 1
2
3
4
5
Sugar
RNA
DNA
stable
Pentose Sugar
5 carbon

5. Phosphate
Phosphate
Phosphorus
Polar
Highly organized
oxygen atoms
ATP
Adenosine tri .phosphate

6. Nitrogenous bases
Molecules that contain nitrogen and
act as a base
Carbon (C)
Hydrogen (H)
Oxygen (O)
Nitrogen (N)
Bases : donate electrons to other
molecules and form new molecules
Purines Pyrimidines
Cytosine Thymine Uracil Adenine Guanine

7. How these components are linked?
1
9
1
Glycosidicbond

8. 1
9
1
Glycosidicbond
P
OH
OH
O¯
O
Strong covalent
bond

9. cell
nucleus
Molecule located in the
nucleus of the cell
Code for genetic
information
Deoxyribonucleic acid

10. Cell division
Can be replicated when the cell is ready for division
DNA is the working molecule
Protected and packaged

11. DNA is a polymer: Monomer.monomer.mo
nomer……………
Polynucleotide:Mononucleotide
Nitrogenous base
5 carbon sugar
Phosphate

12. Nitrogenous base
5 carbon sugar
Phosphate
P
OH
OH
O¯
O
Adenine
Guanine
Thymine
Cytosine
DNA: Deoxyribose sugar
Mononucleotide

13. Components of DNA
Nitrogenous base
Nitrogenous bases in DNA
Purines
and pyrimidines
Adenine Guanine
Thymine Cytosine

14. Components of DNA
5 carbon sugar
Phosphate
P
OH
OH
O¯
O

15. DNA step-ladder model
DNA step-ladder model
G C
T A
G C
T A
T A
T A
G C
G C
5´ 3´
5´3´
G C
T A
G C
T A
T A
T A
G C
G C
5´ 3´
5´3´
Sugar-phosphate backbone
Nitrogenous base

16. Hydrogen bonds between two strands
Thymine
Adenine
Guanine Cytosine
5´
3´

17. Phosphodiester bond
Antiparallel
Thymine
Adenine
Guanine
Cytosine
5´
5´
3´
3´

18. Complimentary base pairing : Manner of alignment for the
nitrogenous bases
Thymine
Adenine
Guanine
Cytosine
5´
5´
3´
3´

19. Minor groove
Major groove
One complete turn 34 A⁰
3.4 A⁰
Diameter 20 A⁰
Nitrogenous base
pair
Sugar phosphate
backbone
Right handed
double helix
5´ 3´

20. B-form A-form Z-form C-form
Helix senseRight
handed
Right
handed
left
handed
Right
handed
% humidity 92% 75% (Pu-Py)n66%
Base
pairs/turn
10 11 12 9.3
Helical
diameter
19A⁰ 23A⁰ 18A⁰ 19A⁰

22. Supercoiled form of DNA
DNA supercoiling describes a higher-order DNA structure and a special property of
circular double stranded DNA
The double-helical structure of DNA entails the interwinding of two complementary strands
around one another and around a common helical axis.