1. Nucleic Acids

2. Role of nucleic acids in cells

3. A nucleic acid is composed of a long string of nucleotides
A NUCLEOTIDE consists of
a N containing base
a 5C sugar (pentose)
an inorganic phosphate group

4. nucleotide chemical structure

5. nucleotide simplified structure
sugar
base P P
sugar
base

6. There are 5 different bases: adenine, cytosine, guanine, thymine and uracil

7. Nucleotides join together by a condensation reaction
An ester bond forms between the phosphate group of nucleotide and the sugar group of another forming a polynucleotide

8. DNA
DNA nucleotides are made up of
1 phosphate group
5C sugar deoxyribose
1 base of 4 thymine cytosine guanine adenine

9. DNA is a double helix
It is made up of 2 strands joined together by H-bonds between the bases
They join A-T & C-G

10. A forms 2 H bonds with T
G forms 3 H bonds with C
The specific pairing of bases is called complementary base pairing.
There will always be the same number of complementary bases: A=T; G=C
So the number of purines (A, G) will always be equal to the number of pyrimidines (C,T)

11. The strands are ANTI-PARALLEL This means the 2 strands run in opposite directions The sequence of bases makes up the genetic code

12. RNA
RNA nucleotides are made up of
1 phosphate group
5C sugar Ribose
1 base of 4 uracil cytosine guanine adenine

13. RNA polynucleotides are single stranded
There is no relationship between the number of purines and pyrimidines.

14. More detail to follow at A2!!!
There are three main types of RNA
mRNA messenger RNA
formed in nucleus during transcription, carries genetic code into the cytoplasm
rRNA ribosomal RNA
Made in nucleolus , forms ribosomes, site of protein synthesis
tRNA transfer RNA
found in the cytoplasm, transports amino acids to the ribosomes during translation
More detail to follow at A2!!!

15. Differences between DNA & RNA