Signalling 1 - Intro Flashcards
1
Q
state 5 different types of signalling molecules
A
- protein - insulin, fibroblast growth factor
- small hydrophobic molecules - animal steroid hormones
- small hydrophilic molecules - plant auxins
- gas - ethylene, nitric oxide
- electrical - nerve impulses
2
Q
What are the 3 different types of signalling based on their ranges?
A
- endocrine - long range
- paracrine - intermediate range
- contact-dependent - juxtacrine
3
Q
what is endocrine signalling?
A
uses the bloodstream
4
Q
what is paracrine signalling?
A
diffusion along intermediate distances
5
Q
What is juxtacrine signalling
A
- contact dependent
- the signal never leaves the cell
6
Q
give 3 examples of endocrine signals
A
- male and female hormones in sexual dimorphism
- flowering plants triggered by day length
- the nervous system
7
Q
what are competent cells?
A
cells able to respond to a signal
8
Q
What are incompetent cells?
A
cells unresponsive to a signal
9
Q
how is endocrine signalling used in plant flowering?
A
- allows plants to time their signalling in a accordance to day length
- allows plants of the same species to flower at the same time
- sensor for light (CO protein) found in the leaf
- CO is a TF
- CO accumulates when days are long
- high CO, promotes synthesis of FT protein
- FT high when days are long
- FT move through sap from leaf to shoot
- flower forms at shoot
10
Q
Hoe does the nervous system use paracrine and juxtacrine signalling?
A
- axon navigation is determined by where the growth cone grows
- growth cone has receptors for guidance molecules
- paracrine - growth cone reacts as it gets close to this signal
- juxtracrine - growth cone reacts when it comes into contact will the cell expressing these signals
11
Q
What are cells secreting axon guidance signals called?
A
guidepost cells
12
Q
Explain electrical transmission between nerve cells
A
- signal moces alonf pre-synaptic cell
- cells contact each other at synapse - axon of one touches body of other
- electrical signal moves along post synaptic cell
13
Q
explain signalling at the synapse
A
- nerve impulse causes pre-synaptic cell to release a neurotransmitter
- neural transmitter travels a short distance across the synapse and binds to receptors on post-synaptic cell
- triggers nerve impulse in post synaptic cell
- nerve cells also synapse with muscle cells
