Biology cell structure

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How do you calculate magnification?
Image size/actual size.
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What is the function of the cell membrane?
Controls the passage of substances into and out of the cell.
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What is the function of mitochondria?
Produces ATP during respiration.
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What is the function of lysosomes?
Digests unwanted material in the cell.
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What is the difference between the function of the rough endoplasmic reticulum and the smooth endoplasmic reticulum?
Rough ER synthesises and transports proteins around the cell, smooth ER synthesises lipids.
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What is the function of the golgi apparatus?
Packages and processes proteins for use in other parts of the cell or exporting outside the cell. It also forms lysosomes.
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What is cytology?
The study of cells.
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Define magnification.
The degree to which the size of an image is larger than the object itself.
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Define resolution.
The degree to which it is possible to distinguish between 2 objects that are close together. The greater the resolution the greater the detail.
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How do you calculate total magnification?
Objective magnification/eye piece magnification.
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Briefly describe the two preparation methods for light microscopes.
Staining-chemicals that bind the specimen. Sectioning-specimens are embedded in wax and sliced into thin layers without distorting the shape.
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What are the two types of electron microscopes?
Scanning electron microscope (SEM) and transmission electron microscope (TEM).
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Name one advantage and one disadvantage of of SEM's.
Advantages-surface structures can be seen, great depth of field obtained so lots of the specimen is in focus at once, allows you to see 3D structures. Disadvantages-cannot achieve the same resolution as TEM's, only the reflected bean is observed.
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Name one advantage and one disadvantages of TEM's.
Advantages-high resolution images, can see up close and in detail. Disadvantages-only electrons transmitted are seen, thin sample needed, expensive, water has to be removed so only dead specimen can be used.
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Name two roles of cell membranes.
Separate contents of cell to surroundings, control exchange, separate components formed in the cell, site of reactions, cell recognition and signalling.
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What is the difference between phospholipids and lipids?
Lipids have three fatty acids but phospholipids have two fatty acids.
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Briefly describe the phospholipid bilayer structure.
Plasma membranes, consists of two layers of phospholipid molecules (hydrophilic head and hydrophobic tail) with proteins and cholesterol embedded in it, 7-10nm thick.
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True or false: Bilayers can't be seen using light microscopes.
True-they can only be seen using an electron microscope.
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Explain why a phospholipid bilayer forms.
The hydrophilic head loves water, however the hydrophobic tail hates water, herefore the tail separates from the water whilst the head doesn't, so a layer forms.
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In the fluid mosaic membrane, which component gives it the fluidity and which gives it the mosaic look?
Lipids give it fluidity and proteins give it the mosaic look.
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What do the terms extrinsic and intrinsic mean?
Extrinsic-proteins are partially embedded n the bilayer. Intrinsic-proteins are completely covering (spanning) the bilayer.
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What is a fluid membrane needed for?
Diffusion of substances across the membrane, membranes to fuse, cells move and changes shape.
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What is the difference between exocytosis and enocytosis?
Exocytosis-substances leaving the cell, enocytosis-substances entering the cell.
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Define the term actively pumped.
Going against the concentration gradient requiring energy e.g.ATP
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What is the function of cholesterol?
Helps to control fluidity and reduces uncontrolled leakages by diffusion.
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What are glycoproteins and glycolipids and what function do they have in common?
Glycoprotein-branching carbohydrates attached to proteins. Glycolipid-branching carbohydrates attached to lipids. They both act as receptors.
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What is the need for transport through membranes (diffusion) ?
Constant supple of nutrients to grow and survive, remove toxins.
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Name three factors affecting the rate of diffusion.
Temperature, concentration, surface area, thickness of cell.
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Define the term equilibrium.
When molecules are equally distributed and there is no concentration gradient.
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What is facilitated diffusion?
Helping diffusion-larger/charged molecules need to be carried across and channel proteins help this as they have pores in the membrane shaped to allow certain substances through. Carrier protiens are shaped to fit certain molecules.
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What is active transport?
The movement of molecules/ions against the concentration gradient across membranes using ATP to power protein pumps within the membrane.
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Fill in the blanks: A substance that dissolves is called a __. The liquid it dissolves in is called a __. The two together is called a __.
Solute, solvent, solution.
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As water moves in via osmosis, what happens to a plant and animal cell?
Plant cell is turgid as the cell wall prevents bursting. Animal cell is haemolysed as it bursts.
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As water moves out via osmosis, what happens to a plant and animal cell?
Plant cell is plasmolysed as the membrane pulls away from the cell wall. Animal cell is crenated and shrinks.
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Define the term isotonic.
Equilibrium as it has the same concentration of solution, solute and solvent.
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What is the difference between hypertonic and hypotonic?
Hypertonic-higher solute concentration, hypotonic-lower solute concentration.
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True or false: water moves from a hypertonic solution to a hypotonic solution.
False it moves from a hypotonic solution to a hypertonic solution.
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Card 2

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What is the function of the cell membrane?

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Controls the passage of substances into and out of the cell.

Card 3

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What is the function of mitochondria?

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Card 4

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What is the function of lysosomes?

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Card 5

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What is the difference between the function of the rough endoplasmic reticulum and the smooth endoplasmic reticulum?

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