Cells,tissues and organs.

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  • Created by: Stephanie
  • Created on: 27-04-13 19:31

Animal cells-structure and function:

  • The nucleus- controls all activities of the cell. It contains the genes on the chromosomes. They carry the instructions for making new cells or new organisms.
  • The cytoplasm- a liquid gel in which most of the chemical reactions needed for life,take place.
  • The cell membrane- controls the passage of substances in and out of the cell.
  • The mitochondria- structures in the cytoplasm where oxygen is used and most of the energy is released during respiration.
  • Ribosomes-where protein synthesis takes place. All the proteins needed in the cell are made here.

Plant cells-structure and function:

Plants are different due to the fact they make their own food by photosynthesis. They do not move. Plant cells have all the features of a animal cell but they also contain adapted features.

All plant and algal cells have:

  • A cell wall made of cellulose that strengthens the cell and gives it support.

The majority but not all plant cells have the following features:

  • Chloroplasts are found in the green parts of the plant. They are green because they contain the green substance Chorophyll. Chlorophyll absorbs light energy to make food by photosynthesis. Root cells do not have Chloroplasts because they are underground and do not need to photosynthesise.
  • A permanent vacuole is a space in the cytoplasm filled with cell sap. This is important for keeping the cells rigid to support the plant.

A short overview:

Both cells contain:  Cell membrane,Ribosomes,Mitochondria, Cytoplasm and a Nucleus.

Plant cells also contain:  Cellulose cell wall,permanent vacuole,chloroplasts.

KEY POINTS: 

  • Most human cells are like most other animal cells and contain a nucleus,cytoplasm,cell membrane,mitochondria and ribosomes.
  • Plant and algal cells contain all the structures seen in animal cells as well as a cell wall. Mant plant cells also contain chloroplasts and a permanent vacuole filled with sap.

Bacteria and yeast

Bacteria are single-celled living organisms that are much smaller than animals and plant cells. In relation to size- you could fit hundreds of thousands of bacteria on to the full stop at the end of a sentence,take this one for example. You cannot view individual bacteria without a powerful microscope. When you culture bacteria on an agar plate,you can grow many millions of bacteria. This enables you to see the bacteria colony without a microscope.

What does a bacteria cell contain? 

  • Cell membrane
  • Slime capsule
  • Cell wall
  • Plasmids
  • Flagella
  • Genetic material
  • Cytoplasm

Bacterial cells.

Each bacterium is a single cell. It is made up of cytoplasm surrounded by a membrane and a cell wall. Inside the bacterial cell is the genetic material. 

Unlike animal,plant and algal cells,the genes are not contained in the nucleus. The long strand of DNA (the bacterial chromosome) is usually circular and found free in the cytoplasm. 

Many bacterial cells also contain plasmids,which are small circular bits of DNA. These carry extra genetic information. Bacteria may have a slime capsule around the outside of the cell wall. Some types of bacterium have at least one flagellum,a long

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