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Flashcards in Rafferty 1 Deck (30):
1

define and give the equation for pI (where there are 2pK values)

pI is the zwitterionic form of an amino acid. (pK1+pK2)/2=pKI

2

give the henderson-hasselbalch equation

pH=pKa+log([A-]/[HA])

3

enzymes enhance the rate to go to the e_______ point

equivalence

4

do enzymes increase or decrease the energy barrier for the forward and backward reactions?

decrease

5

what is an apoenzyme and a holoenzyme? what is the equation that relate these two forms of enzyme?

apoenzyme = enzyme without cofactor
holoenzyme = enzyme with cofactor that is catalytically active
apoenzyme+cofactor=holoenzyme

6

give the 2 types of cofactor

metals and coenzymes

7

define a coenzyme

subdivision of a cofactor - small organic molecule

8

give the 2 types of coenzyme and define them

cosubstrate - loosely bound coenzyme (binds and is released from enzyme like substrate/product)
prosthetic group - tightly bound coenzyme

9

define a cofactor

additional molecule that increases the number of available functional groups to aid catalysis

10

name and describe the 6 types of enzyme

1. oxidoreductases: redox reactions eg by nad+
2. transferases: functional group transfer (1 e-philic group from 1 nucleophile to another)
3.hydrolases: specific transfer reaction via H2O addition
4.lyases: addition/removal of groups to make double bonds
5. isomerases: conversion between isomeric forms
6. ligases: joining two molecules, requires chem energy source

11

what type of bond stabilizes IgG?

disulphide bridge

12

name the 6 domains in IgG

VL/VH/CL1/CH1/CH2/CH3

13

where to ab's bind on IgG?

hypervariable beta-sheet loops on the N-terminal variable region

14

name and quantify the number of regions in IgG, how can these regions be separated?

2xFab 1xFc, split by papain

15

what are the 3 main functions of a membrane?

1. separate cells from env
2. internal membranes for boundaries of organelles
3. env for critical biological processes

16

name the types of molecule that are membrane (im)permeable

permeable: gases/small uncharged polar (can be semi-permeable)
impermeable: large uncharged polar molecules/ions/polar molecules

17

name 3 main types of lipid

phospholipids, isoprenoids and glycolipids

18

which molecule can form a micelle?

fatty acids

19

what does increasing the alcohol content of a phospholipid membrane do?

increases its curvature

20

what is the effect of increasing double bond content in a fatty acid?

increases membrane fluidity

21

what is the effect of asymmetric lipid distribution in a membrane?

changes in membrane curvature

22

what is the effect of cholesterol in a membrane?

decreases fluidity - cholesterol has planar steroid ring which gives it mechanical stability
increased order - this is due to its planar, inflexible tail, which makes the phospholipids elongate - therefore increased membrane thickness

23

what is the effect of increasing order in a phospholipid membrane?

membrane increases in thickness - this is because the f/a chains straighten

24

what is the effect of increasing temperature in membrane containing cholesterol?

gel consistency becomes more fluid which decreases phospholipid order and therefore decreases in thickness

25

what is FRAP?

fluorescence recovery after photobleaching - experiment to quantify lateral protein and lipid movement within a plasma membrane

26

name and describe the 3 main membrane proteins

1. integral: all/partly embedded in membrane, h.phobic exterior, need v specific detergent to remove from membrane (called solubilization)
2. peripheral: at membrane boundary, interact with both other membrane proteins
3. lipid anchored: f/a anchored in membrane via ester/amide link to protein OR isoprenoid group in membrane attached by cys residue to protein OR GPI linked to protein via c-terminus

27

why are alpha helices used in transmembrane proteins?

contain h.phobic residues

28

what is a hydropathy plot and why is it used?

the calculation of a/a seq of a protein to determine h.philic/phobic nature

29

name and describe the 3 transport proteins

1. channels and pores- molecules diffuse through, channel mediated (which is unlike simple diffusion)
2. passive transporters - with conc grad, carrier mediated
3. active transporters - against conc grad uses chem energy

30

describe the linkages in the three lipid anchored proteins

lipid anchored:
- f/a anchored in membrane via ester/amide link to protein
- isoprenoid group in membrane attached by cys residue to protein
- GPI linked to protein via c-terminus