Basic Principles of Biological Communication Flashcards
1
Q
What must all cells be able to do?
A
- be able to respond to their environment
2
Q
What types of things to cells detect and then do what?
A
- extracellular molecules /conditions
- integrate intracellular responses
3
Q
What are examples of cell responses?
A
- changes of gene transcription
- secrete stored substances
4
Q
What does a cell need in order convey information from signalling cell to target cell?
A
- signalling molecules
- ligands
- transmitters
5
Q
How do target cells detect molecules/signals?
A
- by the means of specific receptor proteins
6
Q
What are most target cell receptors?
A
- transmembrane proteins
- some receptors are intracellular
7
Q
What are the three types of local communication?
A
- contact dependant
- paracrine
- autocrine
8
Q
How is communication achieved via contact dependant?
A
- requires close contact
- e.g., membrane protein or communicating cell junction
= membrane bound signal
9
Q
How does paracrine communication work?
A
- diffuse over short distances to affect nearby cells
10
Q
How does autocrine communication work?
A
- signalling molecule binds to same cell
- signal cell is the target cell
11
Q
What are the two types of distant communication?
A
- endocrine
- synaptic
12
Q
What is endocrine communication?
A
- transport via bloodstream
- such as hormones
13
Q
What is synaptic communication?
A
- electrical message travels via neurone to release signalling molecule at synapse
14
Q
Where does local communication occur?
A
- in both unicellular and multicellular organism
- affects cell of the same or different types
15
Q
As animals increase in size and complexity what is required?
A
- distant communication (as well as local)
16
Q
The nervous system uses neural signalling for what?
A
- acquire information
- transmit and integrate the input
- bring about a response
17
Q
What information can be acquired?
A
- External (e.g. temperature, sound) or internal (e.g. blood pH, pressure)
18
Q
the NS is used to transmit and integrate the input - how does this work?
A
- Information is rapidly conducted as an electrical signal (action potentials) along the neurone
- Signal transmission between nerves/to organs (e.g. muscles) occurs at a synapse
- Synaptic transmission is usually mediated by neurotransmitters (e.g. acetylcholine)
19
Q
How do neurotransmitters bring about a response?
A
- Neurotransmitters exert actions through interaction with receptors
20
Q
What do dendrites do?
A
- receive inputs
21
Q
What does the cell body or soma of a neurone contain?
A
- organelles
22
Q
What does the axon do?
A
- connect to target
- only 1 axon per neurone
23
Q
The neurone has polarity - what does this mean?
A
- action potential travel from soma to synapse
24
Q
How do neurons synapse?
A
- they use electrochemical transmission to synpase to a specific target cell
25
How is endocrine communication conducted?
- what molecules are used?
- Where are they released from?
- How do they spread and act?
- uses signalling molecules (hormones)
- they are released from specialised cell populations forming endocrine glands
- enter the bloodstream and distribute systematically
- but target action through specific receptor expression
26
Duration of endocrine signal depends on what?
- half-life of signalling molecule
27
Endocrine receptor's can be where?
- intracellular
- on-cell surface (membrane)
28
Intracellular receptors are found where?
- inside the cytoplasm or nucleus
29
What must ligands be able to do and what molecules are they? (Intracellular receptors)
- be able to cross membrane of cell
- usually hydrophobic molecules
30
Steroid hormones are fat-soluble and so this means?
- they can pass through the plasma membrane and bind to intracellular receptors
31
What is an.intracellular receptor?
- a hormone-activated transcription factor
32
Membrane receptors have a general structure with 3 regions what are these?
- an extracellular domain
- a transmembrane domain
- an intracellular domain
33
What is in the extracellular domain?
- hormone binding site
- n-terminus
34
Whats in the transmembrane domain?
- one or more segments crossing the membrane
35
What the intracellular domain involved in?
- the next step of signal transduction
- c-terminus
36
How are ligand-gated ion channels formed?
- ligand binding changes channel shape
- certain ions such as sodium and calcium can pass through
37
Neurons have ion channels - how are these activated and what do these cause?
- activated by ligand binding (the neurotransmitter)
- causes an action potential
38
What are membrane receptors - enzyme-linked receptors?
- cell surface receptors with intracellular domains associated with an enzyme
39
What do enzymes do to a reaction?
- catalyses a reaction leading to cellular response
40
What is an example of an enzyme-linked receptor
- Receptor tyrosine kinases (RTKs)
41
What does kinase do?
- transfers phosphate groups
42
What is tyrosine?
= to the amino acid tyrosine
43
What are G-protein receptors?
- very diverse family of 7-pass transmembrane proteins
44
What do trimeric G-proteins relay?
- the signal
- alpha, beta, and gamma subunits
45
What does biding of the ligand receptor cause (g-protein coupled receptors)?
- activates alpha subunit and causes dissociation of beta-gamma units
46
G protein coupled receptors:
The subunits can interact with other proteins and trigger what?
- secondary messengers and a cellular response
- stimulating or inhibiting enzymes in cell membrane
- opening or closing ion channels
47
What do ligands include?
- light-sensitive compounds
- odours
- pheromones
- hormones
- neurotransmitters
48
G protein coupled receptors are involved in what diseases?
- thyroid adenoma and permanently active hormone receptors -> continual production of thyroid hormone
49
What is used to define the G-protein?
and how many different types are there?
- the alpha subunit
- at least 20 different types
50
How many different types of beta and gamma - G-proteins are there?
- b = 5+
- y = 10+
51
Different combinations of subunit define what?
and elicit what?
- function
- eliciting different responses
= same ligand = potential for different responses
52
Both neuronal and endocrine communication release signalling molecules which are?
- neurotransmitters/hormones
53
Signalling molecules activate receptors on target cells - what are these?
- Intracellular (e.g. transcription factors)
- Cell surface (e.g. ligand gated ion channel, GPCRs, RTKs)
54
Receptors mediate a cellular response - which can be?
- transcriptional and translational effects
- cell depolarisation
-secondary messengers
55
Endocrine communication is ...
speed -
target -
energetic cost -
- slow
- widespread
-cheap
56
Neural communication is ...
speed -
target -
energetic cost -
- fast
- targeted
- expensive
