Biology AQA AS level Unit 1.3 and 1.6

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  • Created on: 19-05-14 19:18
What is a limitation of the light microscope?
Wavelength too long - poor resolution
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Give the equation for magnification
Magnification = image size/object size
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What is resolution?
Minimum distance apart two objects must be to be distinguished as two separate entities
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There are three conditions of cell fractionation. What are they and why must they be established?
Cold - reduce enzyme activity from breaking organelles down. Isotonic - stop osmotic lysis. Buffered - maintain pH.
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What happens in homogenisation?
Blending of cells to release organelles, fluid filtered to remove cell debris
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Name the sedimentation order.
Nuclei - mitochondria - lysosomes - endoplasmic reticulum - ribosomes
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What happens in ultracentrifugation?
Supernatant spun at low speed, pellet removed (heaviest organelles form first), supernatant spun again at a faster speed and pellet removed etc
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List 3 advantages of the TEM.
Small object seen, high resolution, shorter wavelength
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List 2 advantages of the SEM.
Objects seen in 3D, objects need not be extremely thin.
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List 4 limitations of the TEM.
Living specimens cannot be observed as process in vacuum, complex staining process required, specimens must be thin, images only in black and white, artefacts may corrupt image
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List 4 limitations of the SEM.
Lower resolving power than TEM, risk of artefacts, complex staining process and images are only in black and white, dead specimens as vacuum required
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What is the function of the nuclear envelope?
Double membrane surrounding nucleus, controls entry and exit of materials of nucleus
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What is the function of the nuclear pores?
Allows large molecules like RNA out of nucleus
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What is the function of the nucleoplasm?
Jelly-like material making up bulk of nucleus
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What is the function of the chromatin?
DNA in diffuse form in nucleoplasm
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What is the function of the nucleolus?
Small sphere which manufactures ribosomes
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What are the functions of the nucleus in general?
Manufacture ribsomes, hold genetic material, act as a control centre
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What is the function of the mitochondria?
Respiration, produce ATP
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What is the function of the cristae?
Extensions of the inner membrane to increase surface area for enzyme attachment
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What is the function of the matrix?
Semi-rigid material containing enzymes for respiration
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What is the function of the rough endoplasmic reticulum?
Provide large surface area for synthesis of proteins, provide a pathway for material transport, especially proteins
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What is the function of the smooth endoplasmic reticulum?
Synthesise, store and transport lipids and proteins
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How is the RER different from the SER?
RER has ribosomes present on exterior
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What are the functions of the golgi apparatus?
Produce glycoproteins, produce secretory enzymes, secrete carbs, transport/store lipids, form lysosomes
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What is the function of the lysosome?
Exocytosis, autolysis, digest worn out organelles, digest phagocyte-ingested material
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There are 2 types of ribosomes - 80S and 70S. Which is eukaryotic and which is prokaryotic?
80S - Eukaryotic. 70S - Prokaryotic.
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Card 2

Front

Give the equation for magnification

Back

Magnification = image size/object size

Card 3

Front

What is resolution?

Back

Preview of the front of card 3

Card 4

Front

There are three conditions of cell fractionation. What are they and why must they be established?

Back

Preview of the front of card 4

Card 5

Front

What happens in homogenisation?

Back

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