Plant and animal cells have similarities and differences
Animal Cell (like human cells) consist of:
1. Nucleus - Contains genetic material that controls activities of the cell
2.Cytoplasm - Gel like substance where most of the chemical reactions take place. Contains enzymes
3. Cell membrane
4. Mitochondria - Most of the reactions for respiration take place here
5. Ribosomes - Where proteins are made in the cell
Plant cells contain the above plus:
1 Rigid cell wall - made of cellulose it supports and strengthens the cell
2. Permanent vacuole - contains cell sap which is a weak solution of sugar and salts
3 - chloroplasts - where photosynthesis occcurs they contain a green substance called chlorophyll
Cells 3 (micro-organisms)
There are also single celled organisms such as yeast.
It is a microorganism which contains a nucleus, cytoplasm, cell membrane and has a cell wall.
Bacteria cells have no nucleus
The cells have cytoplasm, cell membrane and a cell wall and the genetic material floats in the cytoplasm due to the absense of a nucleus.
Diffusion is the gradual spreading out of particles from an area of high concentration to an area of low concentration
It happens in both solutions and gases because the particles in these substances are free to move about randomly.
An example of diffusion:
Perfume diffused across the roomm.
Remember - the bigger the difference in concentration the faster the rate of diffusion.
Cell membranes hold the cell together but they let things pass in and out of the cell.
Very small molecules can diffuse through cell membranes such as oxygen, glucose, amino acids and water.