Social Cells

Question 1

What are the extracellular molecules that bind to receptors?

Answer 1

Ligands

Question 2

what is paracrine signalling?

Answer 2

cells signalling a neighbouring cell

Question 3

what is autocrine signalling?

Answer 3

Cell signals itslef

Question 4

describe endocrine signalling

Answer 4

hormone ligand, slow release, long effect, long distance

Question 5

describe synaptic signalling

Answer 5

neurotransmitter ligand, long distance, rapid release

Question 6

what is juxtacrine signalling?

Answer 6

contact dependent signalling, proteins in the membrane and cell interact

Question 7

what is a local mediator?
and give an example

Answer 7

paracrine ligands, medium release time
ex) histamines, thromboxane, leukotrienes.

Question 8

what are the 4 types of receptors?

Answer 8

ion channel coupled
G protein Coupled
Enzyme Coupled
Nuclear receptors

Question 9

describe the different types of passive transport

Answer 9

simple diffusion: small non polar molecules can move throughout the bilayer or through protein channels
facilitated diffusion: molecule specific, uses carrier proteins, limited capacity sos movement is regulated

Question 10

describe primary and secondary active transport

Answer 10

primary: uses ATP to move substances against their concentration gradient
secondary: transports a solute in the direction of the increasing electrochemical potential using facilitated diffusion.

Question 11

what is a uniporter

Answer 11

pump that pumps one ion and out

Question 12

name the ion pump that pumps 2 molecules across the membrane in the SAME direction

Answer 12

Symporter

Question 13

name the ion pump that pumps 2 molecules across the membrane in opposite directions at the same time

Answer 13

Antiporter

Question 14

describe the NA/K pump

Answer 14

uses ATP to pump 3 Na out and 2 K in

Question 15

what is an example of secondary active transport

Answer 15

Glucose movement: Low Na in cell causes Na to move in via FD so charge inside the cell increases, due to this glucose is cotransported into the cell

Question 16

name the different type of ion channels

Answer 16

ligand gated
voltage gated
leak channels
stretch activated

Question 17

how may Voltage gated ion channels open

Answer 17

depends on the electrochemical gradient. If the membrane around the channel has been depolarised, there will be a conformational change in the channels protein structure

Question 18

how are stretch activated ion channels opened

Answer 18

a disruption in the membrane leads to changing tension, compression causes a conformational change

Question 19

what is a compliant cell

Answer 19

when a cell expresses the correct receptor

Question 20

how is there variation in receptor responses

Answer 20

receptors have different isoforms, which may all be activated at once

some have different affinities for different ligands

Question 21

what is the speed of a ligand gated ion channel receptor and why?

Answer 21

channels open in a millisecond - synaptic

Question 22

how to ligand gated ion channel receptors get activated

Answer 22

ligand binds to the receptor and causes a conformational change, allowing the secondary messenger to interact, triggering a cascade reaction within the cell.

Question 23

Name for converting external signals to a cellular response

Answer 23

signal transduction

Question 24

what is the speed of G protein coupled receptors?

Answer 24

slower than ion channeled receptors,
medium speed as are used by multiple types of messengers

Question 25

what are functions of G protein coupled receptors?

Answer 25

immune response inflammation autonomic NS

Question 26

how are G protein coupled receptors activated?

Answer 26

ligand binds which causes a conformational change. the alpha subunit of the G protein binds to the receptor, causing the Alpha GDP component of the G protein to separate from the Beta Gamma component. Both components move along the membrane and interact with the signalling system. GDP on the alpha subunit is replaced with GTP when it dissocated. GTP gets hydrolysed back to GDP by GTPase this causes the Alpha and beta gamma subunit to rejoin.

Question 27

what are the components within a G coupled receptor

Answer 27

binding domains and 7 alpha helices

Question 28

what are the 4 types of G proteins? and what makes them different?

Answer 28

Gas, Gai, Gao, Gaq have different alpha subunits and have many different complementary G protein coupled receptors and secondary messengers.

Question 29

what is the function of Gao protein

Answer 29

interacts with K/Ca ion channels.

Question 30

what is the function of Gas and Gai proteins

Answer 30

stimulate adenyl cyclase which converts ATP to cyclic AMP

Question 31

what is the function of Gaq protein

Answer 31

catalyses the production of IP3 and DAG from phospholipase C

Question 32

what is the speed of enzyme linked receptors?

Answer 32

transduction takes minutes/hours. are slower than GPCRs

Question 33

what functions do enzyme linked receptors aid?

Answer 33

cell growth/ devision inflammation immune response

Question 34

describe the structure of enzyme linked receptors

Answer 34

they have an extracellular binding domain and a catalytic site within the cell.

Question 35

what is the most common enzyme linked receptor? and describe how it is activated

Answer 35

Kinase linked receptor the alpha helix proteins come in pairs, so the signal binds to the 2 proteins, bridging them together forming a dimer. this becomes active kinase

Question 36

descrive what happens after the kinase linked receptor is activated

Answer 36

tryosine (the alpha helix) gets phosphorylated and becomes a docking site for intracellular relay proteins. when these proteins get activated it leads to a cascade reaction in the cell

Question 37

what terminated downstream signalling (of kinase linked receptors) ?

Answer 37

tryosine phosphatases

Question 38

what processes to RAS and P13 Kinase play a part in?

Answer 38

cell division/growth/ differentiation used as anticancer drugs

Question 39

what is the JAK STAT pathway?

Answer 39

inflammation, activated by cytokines

Question 40

what drug inhibits JAK kinase? and why is it used?

Answer 40

Octacitnib targets cytokines to treat inflammation, usually for allergies or dermatitis

Question 41

what is the speed of nuclear receptors? and why?

Answer 41

very slow with long lasting effects as they are hormone receptors

Question 42

where are nucear receptors found?

Answer 42

within the cells, so lipid soluble ligands must enter the cell

Question 43

what are type 1 nuclear receptors?

Answer 43

bind to ligands in the cytoplasm bind to DNA as homodimers

Question 44

what are type 2 nuclear receptors?

Answer 44

are in the nucleus. Hormone binds to the RXR retinoid receptor. are heterodimers

Question 45

describe the type 1 nuclear receptor pathway

Answer 45

hormone (oestrogen or progesterone) bind to the receptor, leading to the dissociation of HSP the receptor and HP (HSP dissociate) enter the nucleus. here they interact with coreceptors and coactivators these act as transcription factors

Question 46

describe the type 2 nuclear receptor pathway

Answer 46

hormone (thyroxine, retanoic acid) dind to RXR receptor which is bound to a corepressor (ensures the receptor is inactive untill hormone binds). Coactivator induced to act as a transcription factor.

Question 47

describe autologous receptor homeostasis

Answer 47

the conc of receptor can change due to their activation - positive feedback

Question 48

describe heterologous receptor homeostasis

Answer 48

conc of receptor changes depending on a different nuclear receptors activation.

Question 49

when are nuclear receptor drugs used?

Answer 49

hormone deficiencies hormone antagonists treat non endocrine diseases that prevent endocrine sectretion