new stuff

Question 1

importance of compartments

Answer 1

provide specific local environments

Question 2

3 types of protein sorting

Answer 2

gated
transmembrane
vesicular

Question 3

gated transport

Answer 3

protein sorting
between cytosol and nucleus
small molecules can diffuse through

Active transport of macromolecules
loading of cargo using Ran.GDP to cross the NPC
karyopherin.Ran.GTP complex

Question 4

transmembrane transport

Answer 4

between cytosol, mitochondria, plastids (chloroplasts) peroxisomes and ER
requires translocator proteins

Question 5

post-translational transport

Answer 5

between cytosol and mitochondria, plastids and perxosiomes

Question 6

co-translational transport

Answer 6

between cytosol and ER

Question 7

transmembrane transport from cytosol to mitochondria

Answer 7

proteins held as polypeptides by chaperone proteins (Hsp70 family)
TOM complex- used to cross outer membrane, dissociation of chaperones

TIM complex - used to enter matrix, Hsp70 bidnds, ATP hydrolysis, Hsp60 folds proteins correctly

mitochondrial membrane potential is driving force

Question 8

vesicular transport

Answer 8

between ER and golgi

between golgi and early/late endosomes
from golgi to cell exterior

Question 9

G-actin

Answer 9

globular actin
can be present as a free monomer

transitions into F-actin under nucleotide hydrolysis and actin binding proteins (ABPs)

Question 10

actin

Answer 10

2 stranded helical polymer
most abundant protein in most eukaryotic cells
most protein-protein interactions

Question 11

actin cortex

Answer 11

lies underneath plasma membrane

provides strength and shape to lipid bilayer

Question 12

actin based cell surface projections

Answer 12

filopodia

used for cell movement and actin-based motility of pathogens

Question 13

actin cytoskeleton

Answer 13

provides asymmetry to cells

e.g. seen in budding yeast cells

Question 14

Microtubules are used for

Answer 14

long range transport

Question 15

cell migration

Answer 15

actin polymerisation at plus end causes protrusion of leading edge
contraction of back edge caused by interaction with myosin

Question 16

actin in cytokinesis

Answer 16

actin and myosin make up contractile ring - belt that constricts to separate two daughter cells

Question 17

intermediate filaments

Answer 17

desmosomes - cell junctions
nuclear lamina (mechanical support/cell division)

Question 18

basis of muscle contraction

Answer 18

actin interaction with myosin

Question 19

G proteins

Answer 19

guanine nucleotide binding proteins
family of proteins
more than 700 in humans
transmit signals to cell interior

Question 20

G protein strucuture

Answer 20

7 transmembrane domain receptor

serpentine - polypeptide chain threads in and out bilayer

Question 21

ligand binds to g protein

Answer 21

causes 3D conformational change

Question 22

GEF

GAP

Answer 22

guanine nucleotide exchange factor
gtpase activating protein

induce GTP/GDP exchange

regulators of g proteins

multidomain proteins regulated by extracellular signals and localised cues

may be potential therapeutic targets for drug development

Question 23

Gi and Gs

Answer 23

effect adenyl cyclase activity

targets for medical toxins eg cholera

Question 24

transmembrane proteins are usually linked to

Answer 24

enzymes on their cytosolic side

e.g. kinases

Question 25

roles of phospholipase C (PLC)

Answer 25

liver - vasopressin - glycogen breakdown | smooth muscle - Ach - muscle contraction

Question 26

Rhodopsin

Answer 26

light activated GPCR in eye (in rods of retina)

Question 27

advantages of GPCR

Answer 27

most common method of cellular signalling allows amplification of signals works synergistically to produce correct response

Question 28

G proteins have pivotal function

Answer 28

molecular transducing elements that couple membran receptors to their molecular effectors

Question 29

Gq pathway

Answer 29

PLC activated PLC cleaves phospholipid PIP2 cleaves into DAG and IP3 IP3 released into cytosol and binds to receptors (e.g. Ca channels in ER) - cytosolic Ca conc increases DAG remains membrane bound and activates PKC with Ca causing phosphorylation cascade

Question 30

monomeric G proteins

Answer 30

used in cytoskeleton and vesicle trafficking first discovered in virus causing rat sarcoma tumours called Ras

Question 31

ras

Answer 31

small GTPase regulates cell differentiation and proliferation relayes signals from kinase receptors to the nucleus

Question 32

G proteins can directly bind and activate ion channels

Answer 32

seen in neurons and some heart muscle cells e.g. GPCRs bind Ach can influence membrane potential called muscarinic receptors

Question 33

GAPs

Answer 33

determine rate of GTP hydrolysys terminate signalling

Question 34

types of polarity

Answer 34

dorsal/ventral anterior/posterior left/right

Question 35

EPP

Answer 35

epithelial polarity programme

Question 36

apical surface

Answer 36

faces externally permeable to water soluble molecules SA can increase

Question 37

basolateral surface

Answer 37

impermeable | faces internally to blood supply

Question 38

why is cytoplasmic polarity required

Answer 38

to generate different cell progenes for tissue morphogenesis

Question 39

why is membrane polarity required

Answer 39

for crucial vectorial transport function s

Question 40

apical and basolateral surfaces of epthelium

Answer 40

separated by tight junctions | different lipid/protein compositions