Biology 2A- Cells, Organs & Populations

Animal Cells;

 Nucleus; contains genetic material, controls activities of the cell

Cytoplasm; where chemical reactions take place. Contains Enzymes

Cell Membrane; holds cell together controlling what goes in and out.

Mitochondria; where most reactions for respiration take place. Resperation releases energy

Ribosones; where proteins are made in the cell.

PLant Cells; contain most of the above and the few below;

Cell Wall; made of cellulose

Permanant Vacuole; contains cell sap

Chloroplasts, where photosynthesis takes place, and also contain chlorophyll

Yeast Cell;

Yeast is a microorganism. A yeast cell has a NUCLEUS, CYTOPLASM, CELL MEMBRANE AND IS SURROUNDED BY A CELL WALL

they have food pockets

Bacterial Cell

Bacterial Cells do not have a nucleus.

A bacterial cell has a cytoplasm and a cell membrane surrounded by a cell wall

The genetic Matherial floats in the cytoplasm because the cells dont have a nucleus

Contain 2 types of DNA; Plasmid and

Diffusion

'Diffusion is the spreading out of particals from an area of HIGH CONCERNTRATION  to an area of LOW CONCERNTRATION

• is when oxygen is taken into the cell
• Gradual movement of particles from crowed places to more open places meaning they can move around more freely.
• natural tendancy for stuff to spread out
• Happens in solutions and gasses (particles can move around freely&easily)
• The bigger the difference in concerntration the faster the diffusion rate!!
• the concerntation of oxygen inside a cell is kept low because the cell usues it up gradually.

1) Palisade (Leaf) Cells

• Packed with Chloroplasts for photosynthesising
• Tall shape- large surface area-absorbs alot of carbon dioxide
• Thin shape-pack loads into top and bottom of leaf.
• Where most photosynthesis happens

2) Guard Cells (adapted to open and close pores)

• Special kidney shape-open/close pores in a leaf
• When plant has lots of water they fill with it and go plump and turgid. Makes the stomata open so gasses can exchange for photosynthesis.
• When plant is short of water, the guard cells loose water and become flaccid, making stomata close- stops too much water vapour escaping.
• Thin outter walls and thickened inner walls make opening and closing work
• They are sensetive to light and close at night
• Guard cells adapt to their function of allowing gas exchange and controlling water loss within a leaf.

3) Red Blood Cells

• concave disc shape gives large surface area for absorbing oxygen.
• Packed with haemoglobin- the pigment that absorbs oxygen
• They have no nucleus- more room for haemoglobin
• VERY IMPORTANT PART OF THE BLOOD

4) Sperm &Egg Cells-Soecialised for REPRODUCTION

• Egg cells-Carry female DNA and to nourish developing embryo in the early stages- contains huge food reserves to feed embryo.
• When Sperm fuses with Egg, the eggs membrane instantly changes its structure to stop anymore sperm getting in. Makes sure the offspring ends up with the right amount of DNA.
• sperm gets male DNA to the female DNA, it has a long tail and a streamlined head to make it swim to the egg.
• Sperms contain alot of MITROCHONDRIA in the cell to provide the energy needed.
• Sperm also carries enzymes in the head to digest through the egg cell membrane.