Cell Communication

Question 1

What does vasopressin do to the kidney

Answer 1

Vasopressin (ADH) is received by the cells of the kidney that form the collecting duct which takes the urine and moves it to the ureter

Question 2

when cells of the collecting duct receive a signal what do they do

Answer 2

do exocytosis of secretory vesicles that have aquaporins so that the aquaporins can put water into the bloodstream from the collecting duct

Question 3

what two things can be wrong with a diabetes insipidus person who can’t respond to ADH

Answer 3

1) they can have defects in the ADH receptor

2) defects in aquaporins so that they never get into the secretory vesicles

Question 4

Nuclear response

Answer 4

changes in gene expression and is slow and long-lasting

Question 5

cytoplasmic response

Answer 5

no change in gene expression, fast but temporary

Question 6

what is an intracellular steroid receptor

Answer 6

a steroid receptor inside the cell cytoplasm

Question 7

how does intracellular steroid receptor work

Answer 7

receptor binds to steroid and is activated, enters nucleus and gene expression is changed (nuclear response)
steroids are hydrophobic so can diffuse through membrane

Question 8

Ligand gated ion channels

Answer 8

ligand binds to and opens up an ion channel (the neurotransmitters are the ligands)

Question 9

which mechanisms use molecular switches

Answer 9

G proteins and kinase receptors

Question 10

What are G proteins

Answer 10

G proteins are GTPases that hydrolysze GTP to GDP +P

Question 11

when is a g protein on or off

Answer 11

when it is bound to GTP it is on, when it is bound to GDP it is off

Question 12

What is a GEF

Answer 12

protein that turns on G protein - they make the drop GDP and pick up GTP

Question 13

what turns off g proteins

Answer 13

GAP - g protein hydrolyzes GTP to GDP

Question 14

what do tyrosine kinase receptors do

Answer 14

use phosphorylation of tyrosine amino acids to turn on signaling pathway

Question 15

kinase

Answer 15

enzyme that adds a phosphate group to another protein (phosphorylation) to turn it on

Question 16

phosphatases

Answer 16

enzyme that removes phosphate groups, turns a protein off

Question 17

structure of tyrosine kinase receptor

Answer 17

transmembrane protein with tyrosine amino acids, binds to ligand making two receptors bind to each other and they phosphorylate each other, relay proteins bind to these and become activated and initiate the signal transduction pathway

Question 18

function of signal transduction

Answer 18

connects function to response

Question 19

purpose of using a signaling cascade

Answer 19

to amplify the signal and is regulatory (can remove a part of cascade)

Question 20

how does a phosphorylation cascade work

Answer 20

kinase 1 is phosphorylated and activated, Kinase1 phosphorylates kinase 2…etc

Question 21

what is a second messenger

Answer 21

a small non protein hydrophilic signaling molecule (ions, etc)

Question 22

how is IP3 made

Answer 22

by cutting PIP2 ( a phospholipid in plasma membrane inside cell) using phospholipase C,

Question 23

what does IP3 do

Answer 23

it can diffuse into cytoplasm and send signals

Question 24

function of released IP3

Answer 24

IP3 binds to ligand gated sodium channels in the SER and makes them opened, Ca2+ released binds to proteins

Question 25

fertilization and IP3

Answer 25

1. during fertilization phosopholipase C from the sperm goes into the newly fertilized egg
2. sperm phospholipase C cuts PIP2 that was in the membrane of the egg and releases IP3
3. IP3 then causes calcium release from the smooth ER of the egg. calcium activates the egg and it starts dividing

Question 26

adenylyl cyclase

Answer 26

enzyme that turns ATP into cAMP by stealing 2 phosphates from ATP and sticking it onto itself

Question 27

cAMP pathway

Answer 27

1. G-protein coupled receptor activates a G protein
2. activated G-protein (bound to GTP) will bind to the adenylyl cylase enzyme and activate it
3. Activated adenylyl cyclase will convert ATP to cAMP
4. cAMP will bind to protein kinase A and activate
   it.
5. Activated Protein kinase A will then
   phosphorylate other proteins to change their
   biological activity.

Question 28

EGF signaling

Answer 28

paracrine signal that regulates cell division, Stem cells in our body receive EGF signals from surrounding cells that helps them keep dividing.

Question 29

blood stem cells and EGF signaling

Answer 29

our blood stem cells get EGF signalling that tells them to keep dividing