BIOL211 - L12

?
  • Created by: Katherine
  • Created on: 18-04-17 16:21
Where are odourant molecules percieved?
In the main olfactory epithelium at the top of the nasal cavity
1 of 27
What does the main olfactory epithelim contain?
A large amount of sensory neurons (up to a million in humans)
2 of 27
How many cilia does each sensory neuron have?
12
3 of 27
Where are the sensory neurons?
They project through the mucous lining into the naval cavity
4 of 27
What are odourant molecules percieved by?
GPCRs - odorant receptors are part of the 7TM receptor family.
5 of 27
What happens when a odorant molecule is in the receptor?
Interaction with receptor activates first downstream effector, a heterotrimeric G protein G(Olf)). The contact causes the exchange of GDP to GTP , which activates it by allowing the alpha subunit to dissociate from the beta gamma complex.
6 of 27
In the olfactory pathway, what is the target for the alpha subunit?
It is the enzyme adenylate cyclase - responsible for making cAMP
7 of 27
What does the increase in cAMP do?
It targets the cAMP gated ion channel , which allows Na+ and Ca2+ through
8 of 27
The acrivation of voltage gated Na+ channels in the cell body triggers...
An action potential
9 of 27
Which human cells detect low levels of light?
Human Rod cells
10 of 27
Which part of the rod cell is involved in photodetection?
The outer segment
11 of 27
What is the membrane potential of rod cell like?
Less negative than we'd expect
12 of 27
What is the visual pigment in rod cells
Rhodopsin
13 of 27
What is rhodopsin composed of?
A light absorbing component, 11 cis Retinal moiety, and opsin
14 of 27
What happens when you expose rhodopsin to light?
You get isomerisation of 11 cis retinal moiety to all trans retinal and that moves rhotopsin to metarhodopsin ii and activates opsin, allowing the signal to be transduced in a similar way to how a signal is transduced in a standard GCPR.
15 of 27
What is the g protein that goes to the GPCR once light hits Rhodopsin?
Transducin
16 of 27
What happens to transducin?
GDP in transducin is exchanged for GTP and the beta and gamma subunits dissociate. It binds to phosphodiesterase and breaks down cGMP to GMP
17 of 27
What does the breakdown of cGMP do?
It is no longer able to active at the cGMP gated ion channel - we no longer get an influx of Na or Ca2+. Closure of cGMP gated channels causes hyperpolarisation of the plasma membrane.
18 of 27
What does decreased turgor do to stomata cells?
The close,
19 of 27
Which ions are associated with increased turgor?
Gain of K+, gain of Cl-, increased malate 2-
20 of 27
Which ions are associated with decreased turgor?
Loss of K+, loss of Cl-, malate 2-
21 of 27
What does ABA do?
Causes an influx of ca2+ across the plamsma membrane through ca2+ permeable chnnels or amplification of the ca2+ signal from stores
22 of 27
What does the influx of calcium ions do?
It inhibits K+ influx and H+-ATPase, activates anion channels and channels in the vacuole membrane that allow K out of the major store in the vacuole, into the cytosol.
23 of 27
What are all the +++
Depolarisation of the membrane
24 of 27
Why is the depolarisation important?
Because it activates K+ out
25 of 27
How is the calcium signal amplified?
Influx of Ca2+ through plasma membrane Ca2+ permeable membranes. Increase in Ca2+ (cyt),. Activation of Slow vascuolar (SV) channels in vacuolar membrane and release of Ca2+ from the vacuole into the cytoplasm.
26 of 27
Activation of second messenger induced increases in...
Ca2+ (cyt)
27 of 27

Other cards in this set

Card 2

Front

What does the main olfactory epithelim contain?

Back

A large amount of sensory neurons (up to a million in humans)

Card 3

Front

How many cilia does each sensory neuron have?

Back

Preview of the front of card 3

Card 4

Front

Where are the sensory neurons?

Back

Preview of the front of card 4

Card 5

Front

What are odourant molecules percieved by?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Cell Biology resources »