Cytoplasm
BIOCHEMISTRY 3(2+1)
Cytoplasm
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- Collective term for cytosol and organelles contained within
- Colloidal suspension
- Cytosol mainly composed of water with free-floating molecules
- Viscosity constantly changes
- Centrioles
- Structure
- Paired cylindrical organelles near nucleus
- Composed of nine tubes, each with three tubules, two centrioles form one centrosome
- Function
- Involved in cellular division
- Lie at right angles to each other
- forms spindle fibres to separate chromosomes during cell division
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- Chloroplasts
- Structure
- A plastid usually found in plant cells
- Contain green chlorophyll where photosynthesis takes place
- composed of a double layer of modified membrane (protein, chlorophyll, lipid)
- inner membrane invaginates to form layers called "grana" (sing., granum) where chlorophyll is concentrated
- Function
- site of photosynthesis chlorophyll
Carbon Dioxide + Water ---------------> Glucose + Oxygen radiant energy (food)
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- Cytoskeleton
- Composed of microtubules
- Supports cell and provides shape
- Aids movement of materials in and out of cells
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- Endoplasmic reticulum
- Structure
- Smooth type: lacks ribosomes; sheets of unit membrane with ribosomes on the outside. Rough type: Ribosomes embedded in the surface
- forms a tubular network throughout the cell
- Function
- Goes through cytoplasm onto cell membrane
- Stores, separates, and serves as cell's transport system
- transports chemicals between cells and within cells
- provides a large surface area for the organization of chemical reactions and synthesis
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- Golgi apparatus
- Structure
- stacks of flattened sacs of unit membrane ( cisternae )
- Protein 'packaging plant'
- A membrane structure found near nucleus
- Composed of numerous layers forming a sac
- Function
- modifies chemicals to make them functional
- secretes chemicals in tiny vesicles
- stores chemicals
- may produce endoplasmic reticulum
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- Lysosome
- Structure
- Membrane bound bag containing hydrolytic enzymes
- Hydrolytic enzyme= ( water split biological catalyst ) i.e uses water to split chemical bonds
- Vary in shape depending on process being carried out
- Cell breaks down if lysosome explodes
- Function
- break large molecules into small molecules by inserting a molecule of water into the chemical bond
- Digestive 'plant' for proteins, lipids, and carbohydrates
- Transports undigested material to cell membrane for removal
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- Mitochondria
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- Ribosomes
- Structure
- non-membraneous, spherical bodies composed of RNA and protein enzymes
- Each cell contains thousands of miniature 'protein factories'
- Composes 25% of cell's mass
- Stationary type: embedded in rough endoplasmic reticulum
- Mobile type: injects proteins directly into cytoplasm
- Function site of protein synthesis
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- Vacuoles
- Structure a single layer of unit membrane enclosing fluid in a sack
- Function
- Membrane-bound sacs for storage, digestion, and waste removal
- produces turgor pressure against cell wall for support
- stores water and various chemicals
- may store insoluble wastes
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Last modified: Tuesday, 17 January 2012, 10:42 AM