1. The Nucleic Acids
An Introduction

2. DNA
An Introduction

3. What does DNA stand for? De oxy-ribose Nucleic Acid
Type of monosaccharide
Found in the nucleus (eukaryote) or nucleoid (prokaryote) of cells
As in acids and bases
DNA can also be written as Deoxyribonucleic Acid

4. Where do you find DNA?
All mature cells contain DNA except the red blood cells
DNA is found in the nucleus
Small amounts of DNA are also present in the chloroplasts and mitochondria
Chloroplast
Nucleus
Mitochondrion
Source:

5. Building blocks
A single unit of DNA is called a nucleotide it is made up of:
A Sugar Molecule (Deoxy-ribose)
A Phosphate molecule
A Nitrogenous Base P

6. Building blocks P
The nucleotides are bound together via covalent bonds between the phosphate groups, forming a strand of DNA
These covalent bonds are very strong and difficult to break P P P P

7. DNA DNA is made up of 2 strands.
The strands are held together by weak bonds between the nitrogen bases
The bonding between the strands is so weak that the two strands will easily separate at 100˚C
There are four types of nitrogen bases:
Cytosine (C), Guanine (G), Adenine (A) and Thymine (T)
What pairs with C?
What pairs with A?

8. DNA
Once the 2 strands of DNA are bound together, the strands coil to form a helical shape
This is why DNA is often called a double helix
In this diagram, the 2 DNA strands have backbones that are shown in blue and red
The nitrogen bases are shown in yellow

10. The Gene Code
The order of the nitrogenous bases A, T, G & C is very important.
The sequence provides cells with templates for the production of every protein in the body
These proteins play many different roles in the body
Each segment of DNA which determines the structure of one protein is called a gene

11. The DNA in the nucleus of your cells is tightly wound up to form chromosomes so as to take up less space and avoid being tangled

12. Chromosomes
Each chromosome carries approximately 30,000 genes

13. RNA
An Introduction

14. What does RNA stand for? Ribose Nucleic Acid
Type of monosaccharide
Found in the nucleus or nucleoid of cells
As in acids and bases
RNA can also be written as Ribonucleic Acid

15. Building blocks
Like DNA, a single unit of RNA is called a nucleotide. It is made up of:
A Sugar Molecule (Ribose)
A Phosphate molecule
A Nitrogenous Base
Notice that the sugar molecule in RNA is different than in DNA

16. RNA
There are 2 other major differences in the make up of RNA compared with DNA:
RNA is made up of only 1 strand of nucleotides
In RNA, the four types of nitrogenous bases are: Cytosine (C), Guanine (G), Adenine (A) and Uracil (U)
Note that RNA does not contain the base thymine but contains uracil instead.
So in RNA:
Cytosine pairs with Guanine
Adenine pairs with Uracil

17. RNA There are 3 different types of RNA:
Messenger RNA (mRNA) – copies and carries the genetic code from the DNA in the nucleus to the ribosomes
Ribosomal RNA (rRNA) – makes up ribosomes which are responsible for assembling the proteins according to the instructions on mRNA
Transfer RNA (tRNA) – molecules which carry the amino acids to the ribosomes where they are used to construct the protein

18. Where do you find RNA? All mature cells contain RNA
RNA is found in the nucleus as messenger RNA
In the ribosomes as ribosomal RNA
In the cytoplasm as transfer RNA and messenger RNA
Ribosomes
Nucleus
Cytoplasm
Source:

19. Protein Production
1. Transcription: DNA code on genes copied to mRNA template
2. mRNA is able to pass through nuclear pores and travel to ribosomes
3. Translation: Amino acids are carried to the ribosomes by tRNA where they are assembled into a polypeptide chain according to the mRNA sequence

20. Protein Modification
4. Bending and folding: The polypeptide is then able to enter the RER where it is folded, bended and further modified. Small parts of RER containing the protein then pinch off, forming vesicles which then travel to the Golgi Body

21. Protein Export
5. Finishing touches: In the Golgi body, the protein may be further modified
6. Export: Part of the Golgi body containing the finished product will then pinch off, forming a vesicle which is transported to the cell membrane where it fuses with the membrane and expels its contents outside the cell. This is called exocytosis.

22. Summary DNA RNA Double Stranded, helical
Single stranded, 3 different forms – mRNA, rRNA, rRNA
Nucleotides: C, G, A, T
Nucleotides: C, G, A, U
Sugar: Deoxyribose
Sugar: Ribose
Function: Carries code for protein production
Function: Assembles proteins using DNA code