1. Human genome sequence

2. DNA = DEOXYRIBONUCLEIC ACID RNA = RIBONUCLEIC ACID
Strong acid hydrolyses DNA & RNA into 3 components:
nitrogenous base (4 different ones)
sugar
phosphoric acid
Mild acid hydrolyses DNA & RNA into 2 components:
Nucleoside = base—sugar
Nucleotide = base-sugar-phosphate
DNA & RNA are polymers of nucleotides

3. NUCLEOTIDE structure: nitrogenous bases
PURINE
amino
ADENINE — A
keto (carbonyl)
GUANINE — G
amino

4. NUCLEOTIDE structure PYRIMIDINE CYTOSINE — C THYMINE — T URACIL— U
amino
keto (carbonyl)
methyl
keto (carbonyl)

5. First difference between DNA and RNA:
DNA contains the bases A, G, C and T
RNA contains the bases A, G, C and U

6. NUCLEOTIDE structure D-ribose (RNA) D-2-deoxyribose (DNA)
2. THE SUGARS — pentoses 1 2 4 3 5
D-ribose (RNA) 1 2 4 3 5 H
D-2-deoxyribose (DNA)

7. Second difference between DNA and RNA:
DNA contains 2-deoxyribose
RNA contains ribose

8. NUCLEOTIDE structure pH 7 (H3PO4) (HPO42-) 3. PHOSPHORIC ACID
Phosphate ion

9. NUCLEOSIDE = base—sugar
adenine
ribose
DEOXYADENOSINE = adenine—deoxyribose
deoxy H

10. Adenosine 5'-monophosphate
NUCLEOTIDE structure
Base—sugar—phosphate
adenine
ribose
e.g. ADENOSINE
Adenosine 5'-monophosphate
(5'-AMP) 5'

11. NUCLEOSIDE numbering ' "Prime" mark: '6 5 4 3 2 1 '
"Prime" mark: '
The 3' and 5' positions are very important for understanding DNA and RNA structure and function 5 4 3 2 1

12. Adenosine 5'-monophosphate (5'-AMP)
Adenosine 5'-diphosphate (5'-ADP)
ribose
adenine 5'
Adenosine 5'-triphosphate (5'-ATP)

13. How are mononucleotides linked together to form the polymers DNA and RNA?5' O 3' P -
3',5'-phosphodiester bond

14. POLARITY 5' O 3' A C
Single-stranded polynucleotides have one free 5' end and one free 3' end — they exhibit POLARITY

15. DNA is a double helix

16. What information did Watson and Crick use in 1953 to arrive at their "double helix" structure for DNA?
Studies of DNA hydrolysis showed that the repeating unit was a NUCLEOTIDE
CHARGAFF's "rules"
%A = %T
%G = %C

17. %A = %T %G = %(C + 5-MeC) %G = %C
Plants have a particularly high content of 5-MeC
%A = %T
%G = %(C + 5-MeC)
%G = %C

18. 5-methylCYTOSINE 6-methylADENINE
Note that in addition to the bases A,G, C and T there are some minor bases found in DNA H NH 2 O N
CH3
5-methylCYTOSINE H N
HCH 3
6-methylADENINE
prokaryotes and eukaryotes
prokaryotes

19. Conclusion: DNA MUST be double-stranded
X-ray diffraction patterns obtained by Wilkins, Franklin & Gosling showed:
helical structure with repeats at 0.34 and 3.4 nm
2 nm wide
phosphates on outside of structure
Density of chain suggests the helix contains 2 strands
Conclusion: DNA MUST be double-stranded

20. A G T C GC base pair AT base pair 3 H-bonds 2 H-bonds 1.08 nm N H O C

21. sugar-phosphate backbone
Double helical DNA
Major groove
Minor groove
3.4 nm:
One helical turn
Base pairs "stacked" vertically in interior
sugar-phosphate backbone
2 nm
0.34 nm
10 bp per turn

22. Both strands coiled round a common axis Strands are ANTIPARALLEL5' 3' 5' 3'
One runs 5' to 3'
Other runs 3' to 5'

23. Watson & Crick solved the structure of DNA in 1953
"...A structure this pretty just had to exist."
- James Watson in The Double Helix

24. The implications of the ‘Double Helix’
Based on the fact that DNA is the genetic material:
Stable
Faithful replication and propagation of life
Two strands: one can form the template for DNA replication
Faithful transmission of information to RNA
One strand acts as template
RNA then transfers information to proteins

25. DNA replication

26. Protein Structure

27. R is a chemical group that varies in different amino acids.
Amino acid structure N C O OH H R
R is a chemical group that varies in different amino acids.
C is central “chiral” carbon.

28. Non-polar amino acids

29. Polar amino acids

30. Peptide bonds result from dehydration of A.A.s

31. Primary structure is the sequence of A.A.s

32. Sickle-cell anemia cause

33. Secondary structure

34. Tertiary structure

35. Quaternary structure

36. If all cells come from other cells where did the first ‘life’ come from?
The Miller-Urey experiment
Water is heated in a closed apparatus containing methane (CH4), ammonia (NH3) and hydrogen (H2) and an electric discharge is passed through the mixture.

37. Many precursors can be produced in simple pre-biotic conditions
Some amino acids found (building blocks for proteins)
Some nucleic acids found e.g. adenine
Some sugars found including ribose