Biology AS Unit 1 Revision Summary

Cells And Organelles Basic Revision Summary

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  • Created by: Jas
  • Created on: 23-11-12 17:59
Prokaryotic Cell Type Examples
Prokaryotic: bacteria and cyanobacteria (which used to be called blue-green algae).
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Eukaryotic Cell type examples
Eukaryotic: all other cells, such as protoctista, fungi, plant and animal cells
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Endoplasmic Reticulum
A system of flattened cavities lined by a thin membrane. It is the site of the synthesis and so provides a compartmentalised area in which this takes place.
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Rough ER
looks rough on the surface because it is studded with very small organelles called ribosomes. Ribosomes are made of RNA and protein and are the site of protein synthesis
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Smooth ER
It is where lipids and steroids are made so you would expect there to be a lot of SER in liver cells where lipid is metabolised.
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Golgi Apparatus
Modifies & Transports the Protein
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Mitochondria
sausage-shaped organelles whose walls consist of 2 membranes.inner membrane is folded inwards to form projections called cristae. Inside this is the matrix.Aerobic Respration takes place inside- produces ATP for energy
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Nucleus
separated from the surrounding cytoplasm by the double membrane around it, the nuclear envelope. This regulates the flow of substances into and out of the nucleus.
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Vacuole
fluid-filled space in the cytoplasm surrounded by a membrane called the tonoplast, containg a solution of sugars and salts called the cell sap.
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Microtubules
hollow rod-like structures with walls of tubulin protein. Provide the structural support of cells and can aid transport through the cell
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Microfilaments
rod-like structures made of contractile protein. Again, like microtubules, provide support and aid movement.
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Centrioles
a pair of short hollow cylinders, usually found near the nucleus of an animal cell. They are involved in the formation of spindle fibres used in mitosis.
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Cilia
hollow tubes extending outside some cells. They move fluid, which is outside the cell - e.g, ciliated cells lining the respiratory tract move mucus, away from the lungs
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Flagella
similar to cilia, though longer. Used in the movement of the whole cell. The only structure like this in humans is the tails of the sperm.
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Cell Membrane (1)
made up of a 'sea' of phospholipids with protein molecules 'floating' in between the phospholipids.
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Cell Membrane (2)
The phospholipids are arranged in two layers (a bilayer). The phosphate heads are polar molecules and so are water-soluble. The lipid tails are non-polar and therefore are not water-soluble.
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Fluid Mosaic Model
Because the membrane is fluid, and because of the mosaic arrangement of the protein molecules, the structure of the membrane is called the fluid mosaic model.
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Diffusion
This is the process that is used in oxygen entering a cell, and carbon dioxide leaving.
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Osmosis
Movement of water from high W.P to low W.P through partially permeable membrane
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Water Potential
This is a measure of the tendency of water molecules to move from one place to another.
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Solute & Pressure Potential
The water potential of a cell is dependent upon the combination of its solute and pressure potentials.
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Osmosis in plant cells (1)
Water potential = Solute potential + Pressure potential
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Osmosis in Animal & plant cells Explanation
If the W.P surrounding animal cell is higher than that of the cell it will gain water swell & burst. If surrounding solutions W.P is lower than the cells it loses h20 & shrivel up. So its important to maintain constant WP in bodies of animals
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Osmosis in Animal Cells
Water potential = Solute potential
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Facilitated Diffusion (1)
If charged particles or large molecules are to move across the membrane, another process needs to be found, as they are less soluble (or even insoluble) in lipid. They move through protein-lined pores.
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Facilitated Diffusion (2)- Channel Proteins
Line water-filled pore in membrane so h20-soluble molecules can easily pass through. Different channels allow different substances to pass through (are selective). Some channels gated (only open when appropriately stimulated)
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Facilitated Diffusion (3)- Carrier Proteins
The substance combines with a protein and carried from 1 side of membrane to other.These proteins are specific for a particular substance. Move down conc gradient- no energy required.
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Active Transport
Moved from where they are at a lower conc to where they are at a higher conc - against the conc gradient so allows cells to take up essential molecules even when they are at a low conc outside. Moved against conc gradient- Energy required
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Exocytosis
material to be transported out of the cell is surrounded by membrane. The vesicle will fuse with the cell surface membrane and the contents leave.
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Endocytosis
Materials entering the cell can do so when the plasma membrane invaginates to surround the material. The membrane seals off to form a vesicle, which can then move into the cell.
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Endocytosis (2)
If the material is fluid, minute vesicles are formed. This type of endocytosis is called pinocytosis.
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Phagocytisis
If the material is relatively large, and is digested by enzymes after fusion of the vesicle with a lysosome, it is called phagocytosis. This occurs in white blood cells that ingest bacteria and other foreign bodies.
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Tissues
a collection of cells, together with any extracellular secretion, that is specialised to perform one or more particular function. Tissues may contain only one type of cell, or several types. E.g Xylem, phloem, Epithelial Tissues.
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Epithelial tissues
Animal tissues and form sheets covering surfaces.
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squamous and ciliated epithelia similarities
Both are one cell thick and so are called simple epithelia. The cells rest on a basement membrane which, is a network of collagen and glycoproteins that is secreted by cells underneath the epithelial tissue.
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Squamous epithelia
Cells are of 1 type,smooth, flat & very thin.Packed closely & provide low friction surface over which fluids can move. E.g lining of cheeks & chambers of heart, forms alveoli inside lungs & found inside blood vessels.
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Ciliated Epithelia
made up of cells with cilia and so is often found in areas where it is needed to transport something - for example, lining the oviducts and bronchioles of the lungs.
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Xylem (X) And Phloem (P) Brief intro
made up of more than one cell type. X- supports plant & transport of H20 and dissolved minerals. P-is responsible for translocation which is the transport of soluble organic substances - for example, sugar.
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Palisade Mesophyl
Found in leaf & made up of one type of cell.are tall and thin and are tightly packed together. Their function is to harness the light energy required for photosynthesis and so each cell is packed with chloroplasts.
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Organs
A group of tissues with a speciallised function e.g Plant - plant organs are leaves, roots and stems. E.g Animals-liver, brain, heart and kidney
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Organ Systems
A group of organs working together to perform a specific life function. E.g Digestive, Respiratory
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Other cards in this set

Card 2

Front

Eukaryotic: all other cells, such as protoctista, fungi, plant and animal cells

Back

Eukaryotic Cell type examples

Card 3

Front

A system of flattened cavities lined by a thin membrane. It is the site of the synthesis and so provides a compartmentalised area in which this takes place.

Back

Preview of the back of card 3

Card 4

Front

looks rough on the surface because it is studded with very small organelles called ribosomes. Ribosomes are made of RNA and protein and are the site of protein synthesis

Back

Preview of the back of card 4

Card 5

Front

It is where lipids and steroids are made so you would expect there to be a lot of SER in liver cells where lipid is metabolised.

Back

Preview of the back of card 5
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