2. 3.3.2 State the names of the four bases in DNA.
You should be able to…
3.3.1 Outline DNA nucleotide structure in terms of sugar (deoxyribose), base and phosphate.
3.3.2 State the names of the four bases in DNA.
3.3.3 Outline how DNA nucleotides are linked together by covalent bonds into a single strand.
3.3.4 Explain how a DNA double helix is formed using complementary base pairing and hydrogen bonds.
3.3.5 Draw and label a simple diagram of the molecular structure of DNA.

3. Nucleotide Structure 3 components: Pentose sugar Organic base
Phosphate
sugar
base
Stay the same
Changes
Contains nitrogen & carbon
Pentose sugar
(5 Carbon atoms)
3 components:
Pentose sugar
(ribose in DNA)
Phosphoric acid
Organic base
(always contains nitrogen)

4. 4 Bases Purines – Pyrimidines – Double ringed structure
Single ringed structure

5. 2 condensation reactions occur in the formation of a nucleotide:
Phosphate
2 condensation reactions occur in the formation of a nucleotide: H
Ester bond OH
Glycosidic
bond OH H
Base
Sugar

7. Tell me… 4 names of bases in DNA components of a nucleotide
2 types of bonds in a nucleotide
1 difference between purine and pyrimidine bases

8. Complementary Base Pairing
*Purines always pair with pyrimidines*
A joins to T (2 hydrogen bonds)
C joins to G (3 hydrogen bonds)
see

11. 5’
3 hydrogen bonds 3’ C G
0.34nm A T 3’
2 hydrogen bonds 5’
2nm

12. For the DNA strand 5'-TACGATCATAT-3' the correct complementary DNA strand is:B
3'-ATGCTAGTATA-5' C
3'-AUGCUAGUAUA-5' D
3'-GCATATACGCG-5' E
3'-TATACTAGCAT-5'

13. Nucleotide 3 components: Pentose sugar; deoxyribose Phosphate group
Nitrogenous base; 4 types:
Join by condensation
phosphate
base
Stay the same
sugar
Changes
Contains nitrogen & carbon
Ribose sugar in RNA
Deoxyribose sugar in DNA
Pentose sugar (5 Carbon atoms)

14. Build a DNA molecule!

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