Nucleus is bound by double membrane (nuclear membrane)
Nuclear membrane has pores in it
The cytoplasm-like material is called nucleoplasm
Nucleoplasm contains chromatin
Small spherical body called nucleolus within nucleus
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Nucleus functions
Control cell's activity
retain chromosomes
Pores allow transportation of mRNA and nucleotides
Nucleoplasm contains chromatin (chromatin is made up of DNA coils bound to proteins).
Nucleolus makes RNA (RNA is needed to make ribosomes)
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Mitochondria
Double membrane seperated by narrow fluid-filled inter-membrane space
Inner membrane is folded inwards to from extensions called cristae
Interior contains organic matrix (containing chemical compounds)
Reactions take place in matrix or on the inner membrane
Muscles contain large numbers of mitochondria because of high metabolic activity.
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Mitochondria functions
Site of anaerobic respiration in the cell
Cristae increases the surface area on which respirtory processes takes place
Produce energy as ATP
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Endoplasmic reticulum (ER)
Elaborate system of membranes forming flattened sacs
Fluid filled spaces between membranes are called cisternae
The ER is connected with the nucleur membrane and may link to the golgi body
Cavities are interconnected
Rough endoplasmic reticulum (RER) -Ribosomes on outer surface
Smooth endoplasmic reticulum (SER) - membranes which lack ribosomes.
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Endoplasmic reticulum functions
Transport of materials throughout the cell
RER - transports proteins made by the ribosomes (present in large amounts in cells that make enzymes that may be secreted out of the cell
SER - synthesis and transport of lipids
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Ribosomes
Made of one large and one small sub-unit
Manafactured in nucleolus from rRNA and protein
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Ribosome functions
Important in protein synthesis
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Golgi body Functions
Produce secretory enzymes
Secretes carbohydrates (example - formation of plant cell walls)
Producing glycoprotein
Transporting and storing lipids
Forming lysosomes
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Golgi body forming
1) Formed by RER being pinched off and forming small vesicles
2) A number of vesicles join up and fuse together forming golgi body
3) Proteins are transported in vesicles and are modified and packaged in golgi body
4) E.g. proteins combined to make glycoproteins
5) Vesicles pinch off other end and the products are secreted by exocytosis when vesicle fuses with cell membrane
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Lysosomes
Small vacuoles formed when portions of the golgi body are pinched off
Contains isolated digestive enzymes from remainder of the cell
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Lysosome functions
Release enzymes and destroy worn out organelles in cell
Some lysosomes discharge contents during digestion carried out in membrane-lined vacuole
Digest material that has been taken into cell, e.g.white blood cells engulf bacteria by phagocytosis and lysosomes discharge contents into the vesicle and digest the bacterium.
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Centrioles
Found in animal cells and most protoctists but not higher plants cells
Located outside nucleus in centrosome
Two hollow cylinders positioned at right angles to one another.
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Centriole function
Cell division -centrioles divide and move to opposite poles and synthesise the microtubules of the spindle
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