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57 Cards in this Set
- Front
- Back
Microscopy |
The process of using microscopes to magnify the image of an object. |
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Object |
The material put under the microscope. |
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Image |
The appearance of the material when viewed under the microscope. |
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Resolution |
The minimum distance apart that two objects can be in order for them to appear as separate items. |
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Cell fractionation |
The process where cells are broken up and the different organelles they contain are separated out. |
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Isotonic |
Solutions that possess the same concentration of solutes and therefore have the same water potential. |
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Homogenation |
When cells are broken up by a homogeniser (blender) which results in a fluid called homogenate. |
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Ultracentrifugation |
The process by which the fragments in the filtered homogenate are separated in a machine called an ultracentrifuge. |
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Light microscope |
A microscope which has poor resolution due to the relatively long wavelength of light. |
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Transmission Electron Microscope (TEM) |
A microscope that focuses a beam of electrons onto the specimen. It must be in a vacuum, stained and extremely thin. |
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Scanning Electron Microscope (SEM) |
A microscope that focuses a beam of electrons onto the specimen, which does not have to be thin (as it does in TEM). |
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Photomicrograph |
A photograph of an image produced by a microscope. |
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Epithelial cell |
They are eukaryotic cells, which have a distinct nucleus and possess membrane-bounded organelles.
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Ultrastructure |
The further, internal structure of a cell. |
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Nuclear envelope |
A double membrane that surrounds the nucleus. The outer membrane is continuous with the ER of the cell and often has ribosomes of its surface. It controls the entry and exit of materials. |
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Nuclear pores |
They allow the passage of large molecules, such as messenger RNA, out of the nucleus. |
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Nucleoplasm |
The granular, jelly-like material that makes up the bulk of the nucleus. |
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Chromatin |
The DNA found within the nucleoplasm. This is the diffuse form that chromosomes take up when the cell is not dividing. |
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Nucleolus |
The small, spherical body within the nucleoplasm. It manufactures ribosomal RNA and assembles the ribosomes. |
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Mitochondrion |
Rod-shaped in length and made up of a double membrane, cristae and matrix. |
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Double membrane |
Surrounds the organelle. The outer one controlling the entry and exit of material. The inner one is folded to form extensions known as cristae. |
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Cristae |
Shelf-like extensions of the inner membrane. These provide a large surface area for the attachment of enzymes involved in respiration. |
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Matrix |
Makes up the remainder of the mitochondrion. It is a semi-rigid material containing proteins, lipids and traces of DNA for the production of its own proteins. |
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Rough Endoplasmic Reticulum (RER) |
3D system of sheet-like membranes which has ribosomes present on the outer surfaces of the membranes. |
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Smooth Endoplasmic Reticulum (SER) |
3D system of sheet-like membranes which lacks ribosomes on its surface and is often more tubular in appearance. |
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Golgi apparatus |
A stack of membranes that make up flattened sacs, or cisternae, with small, rounded hollow structures called vesicles. |
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Lysosomes |
When vesicles produced by the golgi apparatus contains enzymes, such as proteases and lipases. |
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Ribosomes |
Small, cytoplasmic granules found in all cells. They may be found in the cytoplasm or be associated with the RER. |
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Microvilli |
Tiny finger-like projections from cell-surface membrane of some animal cells to increase surface area for more efficient absorption. |
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Lipids |
A varied group of substances that contain C, H and O. They are insoluble in water, but are soluble in organic solvents, such as alcohols and acetones. |
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Saturated |
A fatty acid in which there are no double bonds between the carbon atoms. |
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Mono-unsaturated |
Fatty acid that possesses a carbon chain with a single double bond. |
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Polyunsaturated |
Fatty acid that possesses carbon chains with many double bonds. |
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Phospholipids |
Triglycerides in which one of the three fatty acid molecules is replaced by a phosphate molecule. Phospholipids are important in the structure and functioning of the membranes. |
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Hydrophilic head |
Interacts with water but not with fat. |
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Hydrophobic tail |
Orients itself away from water, but mixes readily with fat. |
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Polar |
Molecules that have two ends which behave differently (lipids). |
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Plasma membranes |
Surrounds the cell and forms a boundary between the cell cytoplasm and the environment. |
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Extrinsic proteins |
Occur either on the bilayer or partly embedded on it. They give mechanical support to the membrane or as cell receptors for molecules, such as hormones. |
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Intrinsic protiens |
Completely span the phospholipid bilayer from one side to the other. Some act as carriers to transport water-soluble material across the membrane while others are enzymes. |
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Fluid-Mosaic model |
Where individual phospholipid molecules can move relative to one another (fluid) and when proteins in the bilayer vary in shape, size and pattern (mosaic). |
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Diffusion |
The movement of molecules or ions from a region where they are in high concentration to one where their concentration is lower. |
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Facilitated diffusion |
Diffusion involving the presence of protein carrier molecules to allow the passive movement of substances across plasma mebranes. |
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Osmosis |
The passage of water from a region of high water potential to a region where its water potential is lower, through a partially permeable membrane. |
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Water potential |
The pressure created by water molecules. It is the measure of the extent to which a solution gives out water. The greater number of water molecules present, the higher (less negative) the water potential. Pure water has a water potential of zero. |
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Active transport |
Movement of a substance from a region where it is in low concentration, to a region where its concentration is high. The process requires the expenditure of metabolic energy. |
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Villi |
Finger-like projections of the intestinal wall, which increases the surface area for more efficient absorption. |
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Absorption |
Uptake of substances. |
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Lumen |
The hollow cavity inside a tubular structure, such as the gut or a xylem vessel. |
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Sodium-potassium pump |
The mechanism by which glucose is absorbed from the small intestine. |
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Carrier protein |
A protein on the surface of a cell that helps transport molecules and ions across plasma membranes. |
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Cholera |
An infectious disease characterised by dehydration, watery faeces (diarrhoea), vomiting, etc. |
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Cell wall |
Physical barrier that protects against mechanical damage and excludes certain substances. |
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Capsule |
Protects bacterium from other cells and helps groups of bacteria to stick together for further protection. |
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Flagella |
Aids movement of bacterium because of its rigid, corkscrew shape and rotating base that helps the cell spin through fluids. |
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Plasmids |
A small, circular piece of DNA found in bacterial cells. |
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Diarrhoea |
An intestinal disorder in which watery faeces are produced frequently. |