cell structure and membrane

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  • Created by: katherine
  • Created on: 04-01-13 14:34
prokaryotic cells
no nucleus or membrane bound organelles
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cell fractionation
a method that sperates the organelles in a cell.
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DNA
the molecule in cells that stored genetic information
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fluid mosaic model
model describing the arrangement of molecules in a cell membrane
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gas exchange surface
boundary between outside environment and internal environment of an organism over which gas exchange occurs
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isotonic solution
solution with the same water potential
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magnification
how much bigger a microscope image is compared to the specimen
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phospholipid
a lipid containing glycerol attached to 2 fatty acids and a phosphate
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ultracentrifugation
a method where cell components are seperated using a centrifuge
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water potential
likelihood of water molecules to diffuse into or out of solution
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resolution
how well a microscope distinguishes between 2 points close together
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DESCRIPTION: plasma membrane
made mainly of lipids and protein
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nucleus
nuclear envelope (double membrane) no clear internal structure
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lysosome
round organelle surrounded by membrane.
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ER
system of membranes enclosing a fluid filled space
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Mitochondrion
oval shaped, double membrane-inner folded into cristae, matrix inside
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FUNCTION: nucleus
chromatin made from proteins and DNA. pores allow substances RNA in and out. laso makes ribosomes.
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ER
smooth: synthesises and processes lipids. rough: folds and processes proteins.
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Golgi apparatus
processes and packages new lipids and proteins. makes lysosomes
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magnification=
length of image/ length os specimen
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hw many micrometres (backwards y m) in a mm
1000
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how many nanometres nm, in a mm
1000000
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how do transmission electron microscopes work
electromagnets focus a beam of electrons that are transmitted through the specimen. denser parts absorb more electrons and come out darker
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scanning electron microscopes
scan beam of electrons across specimen. knock off electrons from the specimen, which are gathered in a cathode ray to form an image
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advantage of TEMs
high resolution so shows smaller objects
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disadvantage
only used on thin non living specimens
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advantage of SEMs
can be used on thick specimens, can be 3D
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disadvantages
lower resolution, non living
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Cell fractionation: homogenisation (breaking up cells)
vibrate or grind cells. cold to reduce enzyme activity, must be isotonic.
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ultracentrifugation
spin in centrifuge over and over slow to fast.
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what are plasma membranes made up of
phospholipids proteins and carbohydrates.
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explain the fluid mosaic model
phospholipids constantly moving, proteins scattered like tiles in a mosaic
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why cant water soluble substances (ions) get through
centre of bilayer hydrophobic
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how do cholesterol molecules help
fit between phospholipids reducing fluidity and preventing membrane breaking up
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fatty acid structure
carbon, double bon to O, OH and R (hydrocarbon tail)
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how are triglycerides formed
condensation reactions
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hypertonic
net movement out of cell
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hypotonic
net movement into cell
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how do carrier proteins work?
a large molecule attacks to a carrier protein, the protein changes shape releasing the molecule on the opposite side of the membrane
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how is the conc gdt for Na+ out of the lumen created
Na+ actively transported out of cell be Na+ K+ pump
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how does glucose diffuse into blood
facilitated diffusion (protein channel)
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what is the name of the bacterium that causes cholera
vibrio cholorae
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what does the cholera toxin do?
opens up chloride channels
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Other cards in this set

Card 2

Front

cell fractionation

Back

a method that sperates the organelles in a cell.

Card 3

Front

DNA

Back

Preview of the front of card 3

Card 4

Front

fluid mosaic model

Back

Preview of the front of card 4

Card 5

Front

gas exchange surface

Back

Preview of the front of card 5
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