1. Higher Biology
Unit 1:
1.1 Structure of DNA

2. Starter
Make a mind map of the key points you remember about DNA from Nat 5 biology in your jotter

3. Learning Intentions
Name the molecules in a DNA nucleotide and identify them in a diagram
Name the type of bond on the backbone of the DNA molecule
Give the names of the 4 DNA bases
Describe the base pairing rule for DNA bases

4. Deoxyribonucleic acid
The DNA molecule is comprised of two chains of nucleotides.
The nucleotides are comprised of deoxyribose sugar, a phosphate and a base.

5. DNA stands for Deoxyribose Nucleic Acid.
It is as double stranded molecule made up of subunits called nucleotides.
Each nucleotide is made of 3 parts;- A base, a phosphate and a deoxyribose sugar.

7. Nucleotides bond together to form a sugar-phosphate backbone
Nucleotides bond together to form a sugar-phosphate backbone. This is due to chemical bonds between the phosphate group of one nucleotide and the carbon 3 of the deoxyribose on another nucleotide.

8. This is what a nucleotide looks like at the molecular level…

9. Nucleotides bond together to form a sugar-phosphate backbone
Nucleotides bond together to form a sugar-phosphate backbone. This is due to chemical bonds between the phosphate group of one nucleotide and the carbon 3 of the deoxyribose on the next nucleotide.
The double helix is described as having two anti-parallel chains of nucleotides because one side goes from 5’ to 3’ (five prime to three prime) and the opposite side goes from 3’ to 5’.

11. The Code There are 4 different types of base in DNA. Thymine = T
Adenine = A
Guanine = G
Cytosine = C
They have complementary base pairing
T pairs with A
G pairs with C

12. The bases pair up using hydrogen bonds to form the double helix shape.
C and G 3 bonds
T and A 2 bonds

13. These bases are described as being complementary to each other
These bases are described as being complementary to each other. This means their shapes match up.