AS biology- 1A, Biological Molecules

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Carbohydrates, Lipids, Proteins, Enzyme action, factors effecting enzyme activity, enzyme controlled reactions.

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Biological Molecules Definitions
Question Answer
Biology Topic 1A- Biological Molecules (Hannif) Carbohydrates Lipids Proteins Enzyme Action Factors effecting enzyme activity enzyme controlled reactions
Carbohydrates * Carbs =polymer = chains of monomers eg monosaccharides(glucose(hexose sugar) fructose galactose) *condensation reactions- 2 molecules join & form new chemical bond with the release of water to form glycosidic bonds (mono join together) 9a719dd5-778c-4d70-900e-38a7570aea31.gif (image/gif)
*Hydrolysis- bond broken by the addition of a water molecule (polymers broken down to monomers) eg carbs-mono *benedicts reagent reducing (all mono, some di) add the reagent (blue) boil +ve = coloured PPT. non reducing: add dilute HCL, neutralise with hydrogen sodium hydrogen carbonate *Polysaccharides =2+monosaccharides via condensation reaction. *starch- plants stores excesss glucose mix of amylose- unbranched coiled compact, amylopectin- brabched+side enzymes break glycosidic bonds quick release. insoluble doesnt effect water potential. test iodine in KI solution= black
*Glycogen- stores excess glucose as glycogen (animal cells) side branches for quick release, compact= good storage *cellulose- longe unbrached chains beta glucose, bond for straight chains linked by H bonds to form strong fibres 'microfibrils' structural support in cells *Carbohydrates*
Lipids *Tricglycerides-1x glycerol 3x fatty acid, hydrophobic hydrocarbon tail tail varies * tails make lipids insoluble in water *joined in a condensation reaction, ester bond formed water molecule released *saturated no x2/ unsaturated 1+ (kink) *phospholipids, 2 fatty acid + phosphate *Tricglycerides- energy store in molecules - tails contain lots of energy, energy is released when broken down - insoluble no effect on water potential= insoluble droplets *phospholipids- bilayer in cell membranes, form x2 layer water soluble substances cant pass
emulsion test for lipids - shake sample with ethanol for a minute to dissolve - pour into water +ve forms a milky emulsion *lipids*
Proteins *proteins made of 1 or more polypeptides *variable in c containing R group but same carboxl (-COOH)and amino group (-NH2) *join condensation reaction to form peptide bonds, reverse in digestion structural levels chain^ *primary- sequence of AA in polypeptide *2nd- H bonds form between AA to coil a/b *3rd- folded further, more bonds eg H bonds, Ionic and Disulfide bridges in 2 sulfur atoms in cysteine. 1x poly= final3D *4th- several poly assembled final 3D
*Enzymes- spherical due to tight poly *Antibodies- immune, 2x light 2x heavy vary * transport proteins, cell membranes hydro pho+phil, transport of molecules & ions *structural- pysically strong long poly parallel & cross links- keratin collagen *biuret test- alkalin + sodium hydroxide then add copper(II) sulfate+p *proteins*
*Enzyme Action* *lower activation energy- "substrate to be joined enzymes hold closer reducing repulsion, breaking puts strain on bonds. *lock and key model, new evidence shows enzyme substrate complex changes shape - induced fit model, explains why so specific properties- very specific, only one complementary substrate will fit. active site shape determined by tertiary structure which is determined by primary , different enzymes have different tertiary structure = different active site shape altered wont fit eg mutation pH temp
*enzyme action* *Factors affecting enzyme activity* temp:more EK more b=vibrations more collisions but could cause bonds to break pH: H+ OH- acids and alkali ruin ionic/ H bonds above or below optimum enzyme conc: more successful collisions increaseROR but substrate limited no further effect
substrate conc: higher conc faster ROR more collisions until saturation point substrate conc decreases time competitive inhibitor: similar shape competes active site , lower ROR non competitive: change shape no longer fit increasing substrate conc makes no diff. *factors effecting enzyme activity*
*enzyme controlled reactions* alter a different variable eg pH (add a buffer with diff. pH) everything else to be constant *interpret graphs: compare ROR and initial ROR, use knowledge to explain why make comparisons. pg 14 15 *enzyme controlled reactions