1. Molecular Genetics
The Role of the Cell.

2. The Cell Cells are the building blocks of all living things.
Many different shapes and sizes from small, round cells to long whip-like ones like nerve cells.
Most of their organelles are the same.
Ref plant and animal cells.

3. Prokaryotes Pro means before Karyon means nucleus
Includes simple single-celled bacteria and cyanobacteria.
The DNA is not held within a membrane or bound to proteins.
Simple chromosome with its ends joined to form a circle. (no true nucleus.)

4. Prokaryotes
No membrane-bound organelles such as mitochondria or mitotic apparatus.
Genotype is shown by phenotype as these types of cells do not have homologous pairs of chromosomes.

5. Prokaryotic Cell

6. Prokaryote Sex
Bacteria have small accessory chromosomes called Plasmids.
These replicate independently of the main chromosome.
Some can be exchanged with other bacteria. (called conjugative plasmids)
Plasmids can transfer antibiotic resistance to other bacteria.

7. Prokaryote Sex

8. Eukaryotes Eu is good Karyon means nucleus.
All cells other than bacteria and cyanobacteria.
Chromosomes are enclosed within a nuclear membrane.
Chromosome is a length of DNA folded like a concertina.

9. Eukaryotes
DNA is wound around proteins called Histones. There are other proteins present.
Contains membrane-bound organelles and forms a spindle during mitosis and meiosis.
Cells may be haploid or diploid (genotype may not be expressed by their phenotype. (may have hidden genes).

10. Eukaryotic Cells

11. Proteins Comes from the greek proteios meaning “first place”.
They are the main structural chemicals of the body and they help to run the body (enzymes and hormones.)

12. Proteins Enzymes that control metabolism.
Structural e.g. hair, muscle etc.
Oxygen carrier haemoglobin.
Fight disease e.g. antibodies and antitoxins.
Part of cell membranes.
Chemical messengers e.g. hormones.

15. Protein Structure Contain C; N; O; H. Some contain S and P.
The sulfur forms small quantities of Hydrogen sulfide when they are broken down.
Some enzymes have a few molecules of micro-elements, (cobalt, zinc and copper)

16. Proteins Made up of amino acids 20 different amino acids.
These are assembled in different orders to form different proteins.
Can be long and stringy (fibrous protein) or folded into almost circular balls or globs (globular proteins)

17. Protein Structure Polymers (made up of monomers).
Amino acids are joined by removing water (condensation) to form a peptide bond.
2 amino acids join to form a Dipeptide.
Many form a Polypeptide.
Proteins are made up of one or more polypeptide chains.

19. Enzymes Biological Catalysts
They speed up reactions by lowering the activation energy barrier.
Specific
Thought to work by the lock and key model or the induced fit model.

20. Lock and Key Model

21. Induced Fit Model

22. Enzymes
Affected by temperature

23. Enzymes
Affected by pH

24. Enzymes
Affected by enzyme conc

25. Enzymes
Affected by substrate conc.

26. Enzymes
Can act as poisons if they get to the wrong part of the body. (many snake, bee and scorpion venoms are harmful because they contain enzymes that destroy blood cells or other tissues.

27. Enzymes
Coenzymes and cofactors