Cells

Includes cells, diffusion,specialised cells and cell organisation

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  • Created by: lxxura
  • Created on: 15-03-14 20:47

What are the parts of an animal cell/functions

Nucleus - Genetic material which controls the cell

Cytoplasm - Gel-like substance where most of the chemical reactions happen in the cell, it contains enzymes which control the reactions

Cell membrane - Holds the cell together and controls what enters and leaves

Mitochondria - Where the reactions for repiration happen

Ribosomes - Where proteins are made

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What are the parts of a plant cell/ functions

Cell wall - Rigid wall made of cellulose which supports the cell and strengthens it

Permanant vaculoe - Contains cell sap which is a weak sollution of sugar and salts

Chloroplasts - Where photosynthesis occurs, they contain a green substance called chlorophyll

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Micro-organisms

Yeast - Yeast is a single cell organism which has a cell membrane, nucleus, cytoplasm and a cell wall

Bacteria - cells have no nucleus, the bacteria cell has a cell membrane,cell wall and cytoplasm. The bacteria genetic information floats in the cell membrane

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Diffusion and Diffusion in cells

DIFFUSION- THE GRADUAL MOVEMENT OF PARTICLES FROM A HIGH CONCENTRATION TO A LOW CONCENTRATION

  • This happens in both liquids and gases
  • The simplist form is in a gas e.g perfume in a room
  • The bigger the difference in concentration the fast diffusion happens

Cells

  •  Dissolved substance move in and out of cells
  • Small molecules like oxygen,glucose,amino acids and water can pass through the cell membrane
  • starch and protein cant fit through
  • particles move randomly
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Specialised cells

Palisade leaf cell - Allow photosynthesis

  • It is packed with chloroplasts for photosynthesis. There's more in the top, closer to the light.
  • Tall shape allows for alot of surface area to be exposed down the side,ready to absorb CO2 from the air.
  • Thin shape means lots can be packed in the top of the leaf.
  • They are grouped together at the top of the leaf.

Guard cells - Allow gas exchange and control water lose in the leaf

  • Kidney shape which opens and closes the stomata in the leaf.
  • When the plant has lots of water the guard cells fill up and go plump and turgid causing the stomata to open to exchange gases for photosyntheis.
  • When the plant is short on the water the guard cells lose water and become flacid which closes the stomata, minimising the lose of water vapour.
  • Thin outer walls and thick iner walls allow for opening and closing.
  • Light sensitive and close at night to save water when photosynthesis isnt happeneing.
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Specialised cells

Red blood cells - Carry oxygen

  • Concave shape gives a large surface area to carry the maximum about of oxygen and allows them to pass smoothly through capillaries.
  • Packed with haemoglobin which is the pigment which absorbs the oxygen.
  • No nucleaus to allow for more haemoglobin.

Sperm and Egg cells

Egg cell - carries female DNA and nourishs the developing embryo in the early stage, also contains huge food reserves to feed the embryo.

Sperm cell - Carries male DNA to the egg, it has a long tail and streamline head to help it swim to the egg. It contains alot of mitochondria to provide lots of energy. Sperm carries enzyme in its head to digest through the egg cell membrane.

Sperm fuses with the egg membrane and instantly changes it's structure to stop other sperm entering,this makes sure the offspring have the right amount of DNA.

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Cell organisation

  • Large multicellular organisms have organ systems.
  • Speciallised cells - tissues - organs - organ system
  • Similar cells are organsism into tissues so they can work together to carry out a function
  • Muscular tissue - Contracts to move
  • Glandular tissue - Makes and secrets enzymes and hormones
  • Epithelial tissue - Covers parts of the body e.g. inside of the gut

Tissues are organised into organs

Stomach is an organ made of

  • Muscle tissue which moves the wall to turn up food
  • Glandular tissue which makes digestive juices
  • Epithelial tissues which lines the inside and outside of the stomach.

Organs are made into organ systems - E.G. Digestive system

The digstive system is made up of the stomach and small intestine (digest food) Liver (Produces bile) Small intestine (Absorbes soluble food molecules) Large intestine (Absorbes water from undigested food)

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