L14 Cell Signalling Flashcards

1
Q

What percentage of eukaryotic genomes code for signalling molecules?

A

10-15%

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2
Q

Signalling over very short distances can occur between cells via…

A

Gap junction signalling

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3
Q

Gap junction signalling works via ( diffusion / active transport ) and allows the fast transfer of ( small / large / uncharged ) molecules

A
  • Diffusion

* Small

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4
Q

When a cell produces a signal which alters the behaviours of nearby cells it is known as…

A

Paracrine signalling

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5
Q

Paracrine signalling over long distances (i.e. signal molecules travel through blood vessels) is known as….

A

Endocrine signalling

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6
Q

When a cell produces a signal which it can itself bind to, this is known as…

A

Autocrine signalling

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7
Q

Receptors can be located on either the (2)…

A

Cell surface OR are intracellular

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8
Q

Intracellular receptors bind to (hydrophilic/hydrophobic) ligands

A

Hydrophobic (e.g. steroids or NO) ❌💧

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9
Q

Cell surface receptors bind to (hydrophilic/hydrophobic) ligands

A

Hydrophilic (e.g. cytokines, neurotransmitters) ❤️💦

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10
Q

No receptor… ⛔️

A

No response! ⛔️

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11
Q

In Androgen Insensitivity Syndrome the embryo develops a female phenotype, despite possessing XY chromosomes due to a lack of…

A

Androgen receptors

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12
Q

Two intracellular receptors are…

A
  • Nitric Oxide (NO) Receptors

* Nuclear Hormone Receptors

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13
Q

NO Receptors and Nuclear Hormone Receptors work by creating a…

A

Conformational change in response to ligand binding

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14
Q

NO Receptors produce ? as a secondary messenger

A

cGMP (cyclic Guanosine MonoPhosphate)

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15
Q

Nuclear Hormone Receptor-ligand complex regulates the…

A

Transcription of related genes

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16
Q

3 Types of Cell Surface Receptors are…

A

1) Ion-gated (ion channel coupled)*
2) G-Protein coupled (GPCRs)
3) Enzyme coupled

*covered in earlier lectures

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17
Q

Ion channel coupled cell surface receptors alter membrane…

A

Permeability

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18
Q

G-Protein coupled cell surface receptors are the…

A

Largest family of receptors

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19
Q

G-Protein coupled cell surface receptors are involved in (4)…

A
  • Vision
  • Smell
  • Neurotransmission
  • Autonomic nervous system

(and many others)

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20
Q

G-Proteins act as ? which convert the signal

A

Transducers

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21
Q

G-Proteins come in two types…

A

Trimeric and monomeric

22
Q

The two key proteins activated by trimeric G-proteins are…

A
  • Adenylyl Cyclase (converts ATP to cAMP)

* Phospholipase C (cleaves phospholipids into DAG and IP3)

23
Q

Trimeric G-proteins are composed of 3 subunits…

A

Alpha, beta and gamma

24
Q

Inactive trimeric G-proteins are bound to (GDP/GTP)

25
GPCR stands for...
G-Protein Coupled Receptors
26
When the GPCR binds a ligand it induces a...
Conformational change (allowing the trimeric G-Protein to bind)
27
cAMP produced by adenylyl cyclase binds to the...
cAMP-dependent protein kinases (PKAs)
28
When cAMP binds to a PKA it induces a conformational change, causing two...
Active catalytic subunits to break away from the complex
29
The active catalytic subunits of PKA go on to...
Phosphorylate proteins (turning them on or off)
30
GTP and ATP share 3 roles....
1) RNA synthesis 2) Signal transduction 3) Energy carrier
31
In cAMP/phosphorylation pathways (ATP/GTP) is involved
ATP
32
In cGMP / G-protein activation pathways (ATP/GTP) is involved
GTP
33
Calcium is a common...
Secondary messenger
34
Calmodulin...
Modulates many of the effects of calcium ions. It binds 4 calcium ions.
35
Trimeric G-proteins may also activate the protein Phospholipase C, which cleaves phospholipids to form secondary messengers (2)...
DAG and IP3
36
Calcium ions with DAG activate...
Protein Kinase C (PKC)
37
Activated PKC...
Phosphorylates the target protein
38
IP3 causes the release of...
Calcium ions from the Endoplasmic Reticulum
39
RTK stands for...
Receptor Tyrosine Kinase
40
Kinases are...
Phosphorylating enzymes
41
RTK is an...
Enzyme-coupled receptor
42
Binding of a signal molecule to RTK results in...
Autophosphorylation (Crossphosphorylation)
43
A small protein that associates with Enzyme-coupled receptors
RAS
44
RAS is a (monomeric/trimeric) G-protein
Monomeric
45
RAS binds directly to the receptor (TRUE/FALSE)
FALSE - binding is mediated by Grb-2 (pronounced 'Grab')
46
In order to hydrolyse GTP, RAS needs help from...
GAP
47
RAS activates a downstream phosphorylation cascade known as the...
MAP Kinase pathway
48
MAP kinase pathway (3)
1. Raf (MAPKKK) 2. Mek (MAPKK) 3. Erk (MAPK or MAP Kinase)
49
Mutations in RAS are present in...
20% of human cancers (and 80% of pancreatic cancers)
50
RAS and cancer - RAS is a...
Proto-oncogene
51
A mutation can cause RAS to be...
Always on, leading to overproduction of growth factors
52
In cancers involving RAS mutations, the pathway may be targeted by...
Enzyme Inhibitors