L14 Cell Signalling

Question 1

What percentage of eukaryotic genomes code for signalling molecules?

Answer 1

10-15%

Question 2

Signalling over very short distances can occur between cells via…

Answer 2

Gap junction signalling

Question 3

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

Answer 3

• Diffusion

* Small

Question 4

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

Answer 4

Paracrine signalling

Question 5

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

Answer 5

Endocrine signalling

Question 6

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

Answer 6

Autocrine signalling

Question 7

Receptors can be located on either the (2)…

Answer 7

Cell surface OR are intracellular

Question 8

Intracellular receptors bind to (hydrophilic/hydrophobic) ligands

Answer 8

Hydrophobic (e.g. steroids or NO) ❌💧

Question 9

Cell surface receptors bind to (hydrophilic/hydrophobic) ligands

Answer 9

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

Question 10

No receptor… ⛔️

Answer 10

No response! ⛔️

Question 11

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

Answer 11

Androgen receptors

Question 12

Two intracellular receptors are…

Answer 12

• Nitric Oxide (NO) Receptors

* Nuclear Hormone Receptors

Question 13

NO Receptors and Nuclear Hormone Receptors work by creating a…

Answer 13

Conformational change in response to ligand binding

Question 14

NO Receptors produce ? as a secondary messenger

Answer 14

cGMP (cyclic Guanosine MonoPhosphate)

Question 15

Nuclear Hormone Receptor-ligand complex regulates the…

Answer 15

Transcription of related genes

Question 16

3 Types of Cell Surface Receptors are…

Answer 16

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

*covered in earlier lectures

Question 17

Ion channel coupled cell surface receptors alter membrane…

Answer 17

Permeability

Question 18

G-Protein coupled cell surface receptors are the…

Answer 18

Largest family of receptors

Question 19

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

Answer 19

• Vision
• Smell
• Neurotransmission
• Autonomic nervous system

(and many others)

Question 20

G-Proteins act as ? which convert the signal

Answer 20

Transducers

Question 21

G-Proteins come in two types…

Answer 21

Trimeric and monomeric

Question 22

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

Answer 22

• Adenylyl Cyclase (converts ATP to cAMP)

* Phospholipase C (cleaves phospholipids into DAG and IP3)

Question 23

Trimeric G-proteins are composed of 3 subunits…

Answer 23

Alpha, beta and gamma

Question 24

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

Answer 24

GDP

Question 25

GPCR stands for...

Answer 25

G-Protein Coupled Receptors

Question 26

When the GPCR binds a ligand it induces a...

Answer 26

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

Question 27

cAMP produced by adenylyl cyclase binds to the...

Answer 27

cAMP-dependent protein kinases (PKAs)

Question 28

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

Answer 28

Active catalytic subunits to break away from the complex

Question 29

The active catalytic subunits of PKA go on to...

Answer 29

Phosphorylate proteins (turning them on or off)

Question 30

GTP and ATP share 3 roles....

Answer 30

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

Question 31

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

Answer 31

ATP

Question 32

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

Answer 32

GTP

Question 33

Calcium is a common...

Answer 33

Secondary messenger

Question 34

Calmodulin...

Answer 34

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

Question 35

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

Answer 35

DAG and IP3

Question 36

Calcium ions with DAG activate...

Answer 36

Protein Kinase C (PKC)

Question 37

Activated PKC...

Answer 37

Phosphorylates the target protein

Question 38

IP3 causes the release of...

Answer 38

Calcium ions from the Endoplasmic Reticulum

Question 39

RTK stands for...

Answer 39

Receptor Tyrosine Kinase

Question 40

Kinases are...

Answer 40

Phosphorylating enzymes

Question 41

RTK is an...

Answer 41

Enzyme-coupled receptor

Question 42

Binding of a signal molecule to RTK results in...

Answer 42

Autophosphorylation (Crossphosphorylation)

Question 43

A small protein that associates with Enzyme-coupled receptors

Answer 43

RAS

Question 44

RAS is a (monomeric/trimeric) G-protein

Answer 44

Monomeric

Question 45

RAS binds directly to the receptor (TRUE/FALSE)

Answer 45

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

Question 46

In order to hydrolyse GTP, RAS needs help from...

Answer 46

GAP

Question 47

RAS activates a downstream phosphorylation cascade known as the...

Answer 47

MAP Kinase pathway

Question 48

MAP kinase pathway (3)

Answer 48

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

Question 49

Mutations in RAS are present in...

Answer 49

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

Question 50

RAS and cancer - RAS is a...

Answer 50

Proto-oncogene

Question 51

A mutation can cause RAS to be...

Answer 51

Always on, leading to overproduction of growth factors

Question 52

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

Answer 52

Enzyme Inhibitors