Cell Organelles

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  • Created by: Becky
  • Created on: 19-04-13 10:55

Cell Organelles

Nucleus

Structure of the nucleus (http://www.biology4kids.com/files/art/cell_nucleus1.gif)

  • Its function is to control the cell's activities and retain the chromosomes. 
  • The nucleus is bound by a double membrane, the nuclear envelope. The nuclear envelope has pores in it to allow the transport of mRNA.
  •  The cytoplasm like material is called nucleoplasm which contains chromatin (coils of DNA and histone proteins), it is chromatin that condenses to form chromosomes during cell division.

Chromatin condensing into chromosomes (http://www.biology4kids.com/files/art/cell_nucleus2.gif)

  •  Within the nucleus is a small spherical body called the nucleolus which manufactures RNA to from ribosomes.

Ribosomes

Ribosome subunits (http://www.biology4kids.com/files/art/cell_ribosome2.gif)

  • Are very small organelles but are present in large numbers. 
  • They are made up of two subunits, the large subunit and the small subunit. 
  • 70s ribosomes are found in prokaryotes whilst 80s ribosomes are found in eukaryotes.
  •  They are involved in protein synthesis.
  • They can either be found free in the cytoplasm or on the outer surface of the rough endoplasmic reticulum. 

Mitochondria

Mitochondria simple structure (http://www.biology4kids.com/files/art/cell_mitochondria1.gif)

  • Aerobic respiration occurs here producing ATP (the energy currency of the cell).
  •  They have a highly folded inner membrane which provides a large surface area for the respiration reactions. 
  • Some reactions also take place in the matrix (Kreb's cycle) as well as the cytosol of the cytoplasm. 
  • The number of mitochondria varies from cell to cell. More are found in cells with greater ATP requirements these are; cells that move a lot (sperm, muscle), cells with a high metabolic rate (liver) and cells that carry out active transport (small intestine). 

Endoplasmic reticulum

Is an elaborate system of membrane bound sacs (cisternae) that are often continuous with the Golgi body and the nuclear envelope. There are two types of endoplasmic reticulum (ER)

  • Rough ER (rER) - has ribosomes lining it and is involved in protein synthesis as a transport system

 Smooth Endoplasmic Reticulum (http://www.biology4kids.com/files/art/cell_er2.jpg)

  • Smooth ER (sER) - lacks ribosomes and is involved in the synthesis and transport of lipids

 Rough Endoplasmic Reticulum (http://www.biology4kids.com/files/art/cell_er1.jpg)

Golgi Apparatus

Is a collection of flattened membrane bound sacs that are constantly forming on one side and budding off as vesicles on the other.

Its functions are:

  • to package proteins for secretion
  • to secrete carbohydrates
  • to produce glycoproteins
  • to transport and store lipids
  • to form lysosomes

Process of Golgi forming vesicles (http://www.biology4kids.com/files/art/cell_golgi1.gif)

Lysosomes

Simple Structure of a lysosome (http://www.biology4kids.com/files/art/cell_lysosome1.gif)

They are membrane bound vesicles which contain digestive enzymes. They are especially abundant in secretory cells and phagocytic blood cells.

Its functions are to:

  • digest material from the environment. Useful chemicals are absorbed into cytoplasm and waste is egested by exocytosis e.g white blood cells and…

Comments

chocolategingers

really detailed!x

Swallowtail

A concise and to the point set of notes with useful annotated diagrams to help with revision of the cells/ organelles topic found in most GCE Biology specifications. Team these up with some  photographs /electron micrographs to ensure that you can recognise the organelles in real 'life" and then use the stated magnification to practise calculating the size of the organelles.

marwaalfaraj

best thing ever thanks

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