Signal Transduction 1: Introduction To Receptors And Cellular Signalling Flashcards Preview

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Flashcards in Signal Transduction 1: Introduction To Receptors And Cellular Signalling Deck (42):
1

Overall process of signal transduction?

Signal to reception via (amplification) to transduction to response

2

What does the arrival of a signal in a cell need?

To be relayed through the cell (ie transduced)

3

Two reasons for needing to understand signal transduction?

1. Cellular signalling helps maintain homeostasis (balance) e.g. Hormones
2. Many medicines control cell signalling events via receptors

4

Examples of medicines that control cellular signalling via G protein-coupled receptors?

Cardiovascular drugs
Allergy drugs
Diabetes drugs
Migraine drugs
Asthma drugs
Anti-ulcer drugs

5

What is a hormone an example of?

Extra cellular signal

6

What does an endocrine signal do?

It's released from a gland and travels through the blood to act upon a distant target organ

7

Example of an endocrine hormone?

Insulin

8

What does an autocrine signal do?

Acts upon the same cell type they are released from

9

Example of autocrine signalling?

Growth factor

10

Example of paracrine signals?

Release of acetylcholine at the neurotransmitter junction

11

What do paracrine signals do?

They're released from cells to act upon adjacent cells

12

Where can cell to cell signalling occur?

In the immune system

13

What's an example of plasma membrane-attached proteins?

T-cell activation by proteins on the surface of antigen presenting cells

14

How do hormones and other extra cellular signals initiate a chain of events in the cell?

By activating receptors

15

What is a receptor?

A molecule on the surface or within a cell that recognises and bind with specific molecules, producing a special effect in the cell

16

What does the lock and key analogy explain?

How each hormone has its own specific receptor

17

What can activate the receptor and trigger intracellular signalling (leading to a response)?

When a hormone or ligand engages with the correct receptor

18

What do drugs do?

They take advantage of the lock and key mechanism to give highly specific medicines with few side effects

19

Examples of drugs that take advantage of the lock and key mechanism?

Ventolin (salbutamol)
Mimics adrenaline/epinephrine at the b2-adrenoceptor to treat asthma

20

What does transmitting a message across the cell membrane involve?

A conformational change in the receptor

21

Can signalling occur without the hormone passing through the membrane?

Yes

22

How does the receptor control hormone activity at the cell surface?

By acting as a gate keeper of cellular activity

23

What relays signals from receptors to target molecules in the cell?

Cascades of molecular interactions

24

How many steps does signal transduction involve?

Multiple

25

What can greatly amplify a signal?

Multiple pathways as it provides more opportunities for co-ordination and regulation of the cellular response

26

Two common mechanisms of signal transduction?

Second messengers
Phosphorylation

27

What are second messengers?

Chemical signals that aren't embedded in the membrane and can diffuse in the cell to pass on the message
(Aka they are intracellular molecules that change in concentration in response to environmental signals)

28

What conveys a message regarding second messengers?

The change in concentration

29

What is the hormone/ligand that activates the receptor sometimes called?

A first messenger

30

Can multiple receptors use the same common second messengers?

Yes

31

What are second messengers?

Molecules (chemical signals) inside cells that act to transmit signals from a receptor to a target ie they are free to move in the cell- not attached to the membrane

32

Why can common second messengers create different responses?

Because of other elements of specificity of cell signalling and coordination of the response

33

What do different cells have?

A different collection of proteins which allow cells to detect and respond to different signals- pathway branching and "cross talk" can further help the cell co-ordinate incoming signals

34

What turns protein activity on/off or up/down as required, like a switch?

Phosphorylation and dephosphorylation

35

What does protein kinase do?

Transfers phosphate from ATP to protein (phosphorylation)

36

What are many relay proteins in signal transduction pathways?

Protein kinase, which create a phosphorylation cascade

37

What three amino acids are phosphorylated?

Tyrosine
Serine
Threonine

38

What removes the phosphates from proteins (dephosphorylation)?

Protein Phosphatase

39

What is amplification?

At each step, the number of activated products is much greater than in the preceding step, which means only a very small amount of the initial hormone is needed, and few receptors activated, to produce a response

40

What is a response function of surface receptors?

Changes in chemicals result in the activation or inhibition of proteins (eg pumps, enzymes, gene transcription factors that directly control processes such as nerve transmission and metabolic pathways)

41

What is the termination of the signal function of the cell surface receptors?

After the cell has completed its response to a signal, the process must be terminated so that the cell can respond again to new signals (signalling processes that fail to terminate can have highly undesirable consequences)

42

Examples of many functions of receptors?

Vision
Taste
Smell
Neurotransmission
Cell growth
Development
Control of heart rate