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Cell Biology > L14 Cell Signalling > Flashcards

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)

A

GDP

25
Q

GPCR stands for…

A

G-Protein Coupled Receptors

26
Q

When the GPCR binds a ligand it induces a…

A

Conformational change (allowing the trimeric G-Protein to bind)

27
Q

cAMP produced by adenylyl cyclase binds to the…

A

cAMP-dependent protein kinases (PKAs)

28
Q

When cAMP binds to a PKA it induces a conformational change, causing two…

A

Active catalytic subunits to break away from the complex

29
Q

The active catalytic subunits of PKA go on to…

A

Phosphorylate proteins (turning them on or off)

30
Q

GTP and ATP share 3 roles….

A

1) RNA synthesis
2) Signal transduction
3) Energy carrier

31
Q

In cAMP/phosphorylation pathways (ATP/GTP) is involved

A

ATP

32
Q

In cGMP / G-protein activation pathways (ATP/GTP) is involved

A

GTP

33
Q

Calcium is a common…

A

Secondary messenger

34
Q

Calmodulin…

A

Modulates many of the effects of calcium ions. It binds 4 calcium ions.

35
Q

Trimeric G-proteins may also activate the protein Phospholipase C, which cleaves phospholipids to form secondary messengers (2)…

A

DAG and IP3

36
Q

Calcium ions with DAG activate…

A

Protein Kinase C (PKC)

37
Q

Activated PKC…

A

Phosphorylates the target protein

38
Q

IP3 causes the release of…

A

Calcium ions from the Endoplasmic Reticulum

39
Q

RTK stands for…

A

Receptor Tyrosine Kinase

40
Q

Kinases are…

A

Phosphorylating enzymes

41
Q

RTK is an…

A

Enzyme-coupled receptor

42
Q

Binding of a signal molecule to RTK results in…

A

Autophosphorylation (Crossphosphorylation)

43
Q

A small protein that associates with Enzyme-coupled receptors

A

RAS

44
Q

RAS is a (monomeric/trimeric) G-protein

A

Monomeric

45
Q

RAS binds directly to the receptor (TRUE/FALSE)

A

FALSE - binding is mediated by Grb-2 (pronounced ‘Grab’)

46
Q

In order to hydrolyse GTP, RAS needs help from…

A

GAP

47
Q

RAS activates a downstream phosphorylation cascade known as the…

A

MAP Kinase pathway

48
Q

MAP kinase pathway (3)

A
  1. Raf (MAPKKK)
  2. Mek (MAPKK)
  3. Erk (MAPK or MAP Kinase)
49
Q

Mutations in RAS are present in…

A

20% of human cancers (and 80% of pancreatic cancers)

50
Q

RAS and cancer - RAS is a…

A

Proto-oncogene

51
Q

A mutation can cause RAS to be…

A

Always on, leading to overproduction of growth factors

52
Q

In cancers involving RAS mutations, the pathway may be targeted by…

A

Enzyme Inhibitors

Cell Biology (21 decks)

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