amino acids Flashcards

Question

types of keratin

Answer 1

fibroin (beta keratin) antiparallel beta sheets long regions of alternating glycine and alanine = closely packed creates strong, flexible molecule alpha keratin (nails and hair) forms alpha helix (non-helical regions at each end) helical regions have repeating 7 amino acid sequence

Answer 2

polypeptide chains with tertiary structures doesn't always have a quaternary structure has complex tertiary = specific shape gives them specific functions - transport, storage, protection most soluble shape allows recognition and binding of other molecules

Answer 3

myoglobin - stores and releases oxygen haemoglobin - transports oxygen to tissues quaternary of 2 alpha and 2 beta subunits = 4 oxygen molecules functions vary due to different structures

Answer 4

proteins held in suspension in watt by hydrogen bonds made between polar groups of protein and water Ionic strength of environment low concentrations heavy metals organic acids

Answer 5

high concentration of ions (salts) react more strongly with water than protein hydrogen bonds breaks = protein precipitates

Answer 6

salts (ions) beneficial to solubility salts interact with water and protein increase interactions between water and protein = more soluble (salting in) up to a certain point where protein precipitates (salting out)

Answer 7

alkaline pH = negative charge so react with positive charged heavy metal ion reduced reactions with water = precipitate

Answer 8

increased acidity = more positive charges on surface of protein react with negative charge on the anion reduced reactions with water = precipitate

Answer 9

the pH at which the net charge is 0 PI = pH number of negative and positive charges is equal hydrogen bonds not made = least soluble pH above PI = protein is negatively charged pH below PI = protein is positively charged further from equal = more soluble (more H bonds)

Answer 10

measure of substances ability to insulate charges from each other (taken as a measure of solvent polarity) high e = higher polarity so greater ability to stabilise charges ethanol decreases overall polarity so decreases interactions between water and proteins

Answer 11

disruption to protein structure resulting in unfolding of protein = shape change cant carry out function often exposure to hydrophobic groups = precipitation loss of secondary, tertiary or quaternary = shape change

Answer 12

detergents heat pH

Answer 13

have high affinity for non-polar structures disrupts hydrophobic interactions due to higher affinity results in exposure of hydrophobic residues to outside = loss of structure

Answer 14

gives extra energy to the system so atoms vibrate more causes bonds to break and protein unfolds = loss of structure vibrations = new bonds can be formed (cross linking) some bonds require more energy to break (covalent strongest, hydrophobic weakest)

Answer 15

inverse measure of its hydrogen ion concentration - measure of hydroxide ions in a solution - (alkaline = high) pH alters ionisation = alters electrostatic bonding results in unfolding of tertiary structure increased pH = lose positive side chain decreased pH = lose negative charge means electrostatic bonds can't be made

Answer 16

minimise change is pH in response to increase or decrease of hydrogen ions in a solution mops up hydrogen ions through dissociation of acid to its conjugate base

amino acids Flashcards

(40 cards)