2.1.1 A LEVEL OCR BIOLOGY

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  • Created by: g.zel11
  • Created on: 19-05-19 16:55
What is the use of microscopy?
To observe and investigate different types of cell and cell structures in a range of organisms.
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What are the properties of light microscopy?
Easily available, relatively cheap, can be used out in the field and allows to observe both living and dead organisms. max resolution = 200nm, max magnification = x1500
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What are the sample prep methods?
Wet mount, Dry mount, Squash slides, Smear slides and Staining.
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Why do we use staining?
To be able to distinguish between types of organisms/ organelles that would otherwise be hard to identify, e.g. use of methylene blue to identify nucleus of a cell.
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Define magnification.
How many times larger the image is than the actual size of the object being viewed.
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Define resolution.
The ability to see individual objects as separate entities.
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what is the formula to calculate magnification?
magnification = size of the image/ actual size of the object
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What are the properties of TEM?
A beam of electrons is transmitted through a specimen and focused to produce an image. Can be used on dead organisms only as it requires a vacuum. max resolution = 0.5nm max magnification = x500000
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What are the properstion of SEM?
A beam of electrons is sent across the surface of the specimen and the reflected electrons are collected. Produces a 3D image. max resolution 3 -10nm, max magnification = x100000
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What are the properties of laser scanning confocal microscopy?
A single spot of focused light is moved across a specimen, causing fluorescence in compounds labelled with a dye.
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What is the function of a nucleus?
Control the cell's activities. Contains the DNA molecules.
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What is the function of a nucleolus?
Production of ribosomes.
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What is the function of a nuclear envelope?
To allow molecules in and out of the nucleus.
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What is the function of the rough endoplasmic reticulum?
Synthesis and transport of proteins.
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What is the function of the smooth endoplasmic reticulum?
Synthesis and storage of lipids and carbohydrates.
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What is the function of golgi apparatus?
Modification and packaging of proteins and lipids.
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What is the function of ribosomes?
Protein synthesis.
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What is the function of mitochondria?
Site of aerobic respiration and production of ATP.
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What is the function of lysosomes?
Breaking down of waste materials and old organelles.
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What is the function of vesicles?
Transport of materials inside the cell.
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What is the function of chloroplasts?
Site of photosynthesis.
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What is the function of plasma membrane?
Regulation of movement of substances in and out of the cells. Separation of chemical processes within the cells.
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What is the function of centrioles?
Separation of chromosomes during cell division.
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What is the function of cell wall?
Support of plant cells.
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What is the function of cillia?
Movement of substances along the cell surface.
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What is the function of flagella?
Movement of cells (e.g. sperm cells)
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What are the steps of protein production?
Proteins are synthesised on the ribosomes bound to RER. They are packaged into transport vesicles and moved towards golgi body. The vesicles fuse with its cis face and proteins are modified and packaged. The vesicles leave Golgi body via trans face.
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What is the cytoskeleton and why is it important?
It is a network of fibres and proteins needed for the shape and stability of the cell as well as cell movements and organelle movements.
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What are the 3 components of the cytoskeleton?
Microfilaments, microtubules and intermediate fibres.
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Describe microfilaments.
Contractile fibres formed from the protein actin. Responsible for cell movement and contraction during cytokinesis.
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Describe microtubules.
Globular tubulin proteins which determine the shape of a cell and track movements of organelles around the cell.
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Describe intermediate fibres.
fibres which give mechanical strength to cells and help maintain their integrity.
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How do prokaryotic cells differ from eukaryotic cells?
Prokaryotes do not have a nucleus, their DNA is circular and can also occur as plasmids, have smaller ribosomes, and a peptidoglycan cell wall.
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Card 2

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What are the properties of light microscopy?

Back

Easily available, relatively cheap, can be used out in the field and allows to observe both living and dead organisms. max resolution = 200nm, max magnification = x1500

Card 3

Front

What are the sample prep methods?

Back

Preview of the front of card 3

Card 4

Front

Why do we use staining?

Back

Preview of the front of card 4

Card 5

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Define magnification.

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