Biology 2A- Cells, Organs & Populations

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Plant and Animal Cells

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

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Yeast and Bacterial Cell

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

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Diffuson

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.
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Specialized Cells

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.
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Specialized Cells.. (2)

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.
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