Prokaryotes- simple organisms; organelles NOT bound by membrane
Eukaryotes- complex organisms; membrane-bound organelles
The nucleus
- stores genetic information of the cell
- controls and regulates the activities of the cell
- responsible for inheritance
DNA is packed with basic (alkaline) proteins. These proteins neutralise the deoxyribonucleic acid and prevents the acid from reacting with other parts of the cell.
DNA is organised into structures known as chromosomes. Chromosomes are condensed into chromatin threads just before cell division. Theres are in total 23 PAIRS of chromosomes. Each pair of chromosomes is given a number (big to small)
Sex chromosomes- Female XX, Male XY
Gametes- Spermatozoa (23 chromosomes not paired), egg (23 chromosomes not paired). Therefore during fertilisation, the 23 pairs of chromosomes is regained.
Plasma membrane
- regulates substances entering/ leaving the cell
- compartmentalise reactions/ functions
Biology Notes 