cells Flashcards
how do SEM and TEM work
-scans surface of sample to study surface of specimen with 3d image
-electron beam goes through very thin slice of sample to study internal ultra structure of sample with 2d image
difference in prokaryotic and eukaryotic cells
-DNA ring form without protein free in cytoplasm
-DNA with proteins as chromosomes enclosed within nucleus
-mitochondria
-internal organelle compartmentalisation to form organelles
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function of different parts of nucleus
-control cell activities such as growth and repair of worn out cells
-nucleolus plays a part in making of proteins
-nuclear envelope for regulate passage of molecules
-separate chemical reactions taking place inside and outside of nucleus
properties of cell surface
-contains cholesterol, proteins and polysaccharides
-phosphate end of phospholipid molecule has hydrophilic polar end that has attraction to other polar molecules like water
-other end of molecule is made up of two fatty acid tails that are hydrophobic and non polar and will not mix with water
how is a fat made
-three fatty acid molecules each join to a glycerol by ester linkage, bond between hydroxyl group and carboxyl group,
what is saturated and unsaturated fats
-fatty acid in which all carbons in hydrocarbon tail is linked together by single bond
-molecules closely packed together in liquid, hence solid
-fatty acid possessing one or more double bonds between carbon and hydrocarbon tail
-molecules cannot pack together closely enough to solidify because of they kinks in fatty acid tails
why is cytoplasm watery
-polar phosphate ends of phospholipid molecule attracted by water
-phospholipids align to form double layer with polar ends on outside of each layer of membrane, non polar tails are inside the bilayer
what are cholesterol
-component of animal cell membrane that act as bidirectional regulator of membrane fluidity at both high and low temperature
-sterol, combination of alcohol and steroid
effects of cholesterol on membrane fluidity
-greater steroid content, less fluid it is
-fit between phospholipid molecules, increasing rigidity and stability of membrane
-warm temp, restrains movements of phospholipid
-cool temperature, maintains fluidity by preventing tight packing
properties of intrinsic proteins
-integral proteins that span the membrane are transmembrane proteins
-hydrophobic region of the protein consist of one or more stretches of non polar amino acids often coiled into alpha helices
-weak hydrogen bonds between polar region of the protein and phospholipid keeps membrane stable
what are glycoproteins
-proteins that stick out of membrane like antennae that is important for cells to recognise each other
-act as antigens
functions of membrane proteins
-hormone binding sites
-immobilise enzymes
-channels for passive transport
-pumps for active transport
-cell to cell comm
-cell adhesion
how do RER function
-have ribosomes attached to its outer surface that synthesise proteins which is then transported to the Golgi apparatus for secretion out of cell
-ribosomes that lie freely in cytoplasm form proteins that are used within the cytoplasm
function of SER
-synthesize substances like fats and steroids, sex hormones
-detox
how do Golgi apparatus function
-chemically modify substances made by ER
-packages substances into vesicles that are secreted out of the cell
-produce macromolecules
