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54 Cards in this Set
- Front
- Back
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What is the equation for magnification? |
Magnification= size of object/size of image (real size) |
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Resolution |
The minimum distance 2 objects can be from each other before they appear as one |
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What is the purpose of cell fractionation? |
To break cells up into seperate organelles for scientific study |
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What is cholera? |
Infectious disease caused by prokaryotic bacterium Vibrio cholerae |
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How does cholera cause diarrhoea? |
Bacterium adheres to epithelium and secretes toxin CT which enters epithelial cells. Activates chloride ion channels in cell membrane. Cause chloride ions to diffuse out of cells into lumen. Lowers water potential in lumen. Water moves due to osmosis into lumen. Produces diarrhoea and dehydration |
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What is the treatment for diarrhoea? |
Oral Rehydration Therapy Drink solution of glucose and salt. Bind to sodium-glucose transport protein and are carried down concentration gradient into cell. Lowers epithelial water potential. Body is rehydrated as water moves by osmosis out of lumen |
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In cell fractionation, what kind of liquid do you place the broken up cell into and why? |
cold (reduce enzyme activity) isotonic (same water potential to prevent bursting or shrinking) buffer (to maintain constant pH) |
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what is a homogenizer and a homogenate? |
the blender to break up cells and the homogenate the leftover fluid which is later filtered to remove complete cells and debris |
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supernatant |
the top fluid left after using an ultracentrifuge |
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what is the order in which cells are seperated/forced to bottom of ultracentrifuge? |
nuclei, mitochondia, chloroplats, other membrane fragments, lysosomes, ribosomes |
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What are the advantages of a TEM? |
very high resolving power good for organelles and prokaryotes |
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What are the disadvantages of a TEM? |
must be in a vacuum only dead species complex staining process -> artifacts? only in black + white specimen must be very thin |
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What are the advantages of a SEM? |
3D image you can see surfaces! don't need thin sections don't need to stain |
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What are the disadvantages of a SEM? |
resolution not as good as TEM can't see internal structures
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ultrastructure |
internal structure suiting cell job |
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eukaryotic |
distinct nucleus and membrane bound organelles |
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prokaryotic |
no distinct nucleus |
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endocytosis |
import of molecules and particles into cell
vesicle internally folds around substrate and this is digested and transported into cytoplasm |
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exocytosis |
materials exported out through secretory vessles
golgi packages materials into vesicle, vesicle fuses with plasma membrane
important for excretory products |
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nucleus (eukaryotic) |
makes mRNA (for protein synthesis) and ribsomes and ribsomal RNA
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nuclear envelope (eukaryotic) |
in nucleus double membrane contains reaction, outher membrane has ribosomes |
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nuclear pores (eukaryotic) |
in nucleus around 300 allow passage of large molecules |
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nucleoplasm (eukaryotic) |
in nucleus granular, jelly-like contains chromatin (diffuse form of chromosomes) |
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nucleolus (eukaryotic) |
in nucleus manufactures ribsomal RNA and ribosomes |
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mitochondria (eukaryotic) |
facilitates certain stages of diffusion makes ATP |
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double membrane of mitochondria |
controls entry/exit
inner folds form cristae |
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cristae of mitochondria |
extensions which provide large s.a. for attachment of enzymes during respiration |
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matrix of mitochondria |
semi-ridgid material made of proteins, lipids, traces of DNA and enzymes |
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why would a cell have more mitochondria? |
if cell has high metabolic activity e.g. muscle cells |
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endoplasmic reticulum |
elaborate 3D system of membranes and flattened sacs (cisternae) throughout cytoplasm |
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RER |
has ribosomes synthesises proteins and glycoproteins provides pathway for material transport |
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SER |
no ribosomes synethise, store and transport lipids + transport |
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Golgi |
makes lysosomes, secretes, modifies, stores other stuuff |
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what cells would have a well developed ER? |
cells that need to make and store lots of carbohydrates, protein, lipis e.g. liver |
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what cells would have a well developed golgi appartus? |
secretory cells e.g. epithelial cells of intestine |
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ribsomes |
found in RER or cytoplasm SITES OF PROTEIN SYNTHESIS have 2 subunits which fit into each other
contain ribosomal RNA and protein super numerous!
80s type (eukaryotic) 70s type (prokaryotic) |
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lysosomes |
formed from RER and Golgi (just vesicles containing cocktail of digestive enzymes)
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when are lysosomes abundant? |
in secretory cells e.g. phagocytic cells |
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what are lipids? |
mixed ground of hyrdrophobic compounds containing carbon, hydrogen and oxygen
common lipis are triglycerides (fats and oils), phospholipids and waxes
insoluble in water, soluble in organic solvents e.g. alchohol |
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what are some functions of lipids? |
plasma membrane energy source waterproofing insulation fats protection fats around delicate organs (adipose tissue) |
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what are triglycerides? |
have 3 fatty acids with 1 glycerol made in condensation reactions |
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what are fatty acids? |
over 70 fatty acids super long molecules
all have carboxyl acid group (-COOH) and a hydrocarbon chain (R group, variably lengthed chain) |
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what is glycerol? |
small, 3 carbon molecule with 3 alcohol (OH) groups |
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How is a triglyceride formed? |
a condensation polymerisation reaction!
1 glycerole joins with 3 fatty acids by ester bonds
'kicks out' 3 H20 molcules |
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saturated fats |
no carbon-carbom double bonds
all carbons are joined to max. number of hydrogens |
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mono-unsaturated fats (oils) |
a single carbon-carbon double bond |
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polyunsaturated fats (oils) |
more than one double carbon-carbon bond
(double bonds cause molecules to bend, cannot pack themselves so closesly so are liquid at room temp.) |
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what are phospholipids? |
same as triglycerides but with a phosphate group instead of fatty acid chain
hydrophobic tails (fatty acids) hydrophilic head (glycerol and phosphate) |
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Describe the emulsion test |
test for lipids! test tube filled with sample and ethanol shake to dissolve lipi add equal amount of water shake again cloudy-white = LIPID
lipid is finely dispersed in water = emulsion. Light passing through is refracted as it passes from water to oil droplets = cloudy |
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whats the purpose of plasma membrane? |
controls entry/exit allows conditions to be different |
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what are purpose of phosholipids in plasma membrane? |
keeps membrane flexible allows lipid-soluble molecules to enter not water-soluble molecules |
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extrinisic proteins |
on surface or partially embedded |
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intrinsic proteins |
spans entire bilayer |
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what is the purpose of proteins on the bilayer? |
provide structural support allow active transport with ion channels e.g. sodium or potassium helps cells adhere together form recognition sites (often glycoproteins) act as receptors enzymes |
