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PoM > MBC - Cell Signalling > Flashcards

MBC - Cell Signalling Flashcards

1
Q

What are the 4 needs for cell signalling?

A
  1. Process information
  2. Self preservation
  3. Voluntary movement
  4. Homeostasis
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2
Q

Why do cells need to process information?

A

We send and receive millions of inputs with crucial information, with with or without output. Output means that the brain must coordinate a response with different organ subsets.

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3
Q

What is an example of processing information?

A

Our eyes receive information that must be processed, giving us vision

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4
Q

Why do cells need to self preserve?

A

Most innate/voluntary responses are generated from an input received by the brain.

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5
Q

What is an example of self-preservation?

A

The spinal reflex arc with our fingers touching a hot flame or any other dangerous stimuli.

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6
Q

Why do cells need to move voluntarily?

A

interdependency between a variety of different sensory and motor organs all coordinated by different parts of the brain.

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7
Q

What is an example of voluntary movement?

A

Getting from A to B

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8
Q

Why do cells need homeostasis?

A

Allow our body to function normally through involuntary actions

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9
Q

What is an example of homeostasis in cells?

A

Blood sugar levels being regulated by the pancreas

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10
Q

What are the 2 main modes of intercellular signalling?

A

Neurotransmission

Blood vessels of the cardiovascular system.

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11
Q

What is neurotransmission?

A

Fast and almost instantaneous communication involving the PNS and CNS.

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12
Q

What is the first step of neurotransmission?

A

Propagation of the axon potential due to the sodium potassium pump.

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13
Q

What is the second step of neurotransmission?

A

NT release from vesicle, diffusion across the synaptic gap.

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14
Q

What is the third step of neurotransmission?

A

Activation of post synaptic receptors

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15
Q

How do blood vessels signal?

A

Blood vessels facilitate blood transport all over the body as well as the movement of chemical messengers known as hormones.

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16
Q

What are the 4 main methods of blood vessel (hormone) communication?

A

Endocrine
Paracrine
Communication between membrane receptors (proteins)
Autocrine

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17
Q

What is endocrine communication?

A

When hormones travel within blood vessels to act on a distant target cell/tissue

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18
Q

What is an example of endocrine communication?

A

Glucagon from alpha cells in the pancreas, causing glycogenolysis and gluconeogenesis in the liver

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19
Q

What is paracrine communication?

A

When a hormone acts on an adjacent cell

20
Q

What is an example of paracrine communication?

A

Insulin is secreted by B-cells in the islet of Langerhans to then act on adjacent A-cells and thus inhibit the secretion of glucagon.

21
Q

What is communication between membrane attached proteins?

A

Extracellular proteins act/induce effects in other cells through interaction with their different proteins or receptors.

22
Q

What is an example of communication between membrane attached proteins?

A

Blood borne virus being detected by antigen presenting cell.

This cell then expresses MHC II on surface to subsequently activate T lymphocytes via T cell receptors.

23
Q

What is autocrine communication?

A

Signalling when a molecule acts on the same cell

24
Q

What is an example of aubocrine communication?

A

Activated T cell receptor activates a cascade whereby interleukin-2 receptor is expressed on cell surface and IL-2 is secreted, thus allowing the cell to act upon itself

25
Q

What is the general overview of how receptors function?

A

Ligands bind to receptors, eliciting a reaction in the cell. This intracellular effect is usually due to a new chemical called the secondary messenger.

26
Q

What are the 4 categories of receptor?

A

G-protein coupled receptor
Intracellular receptor
Ligand gated ion channel receptor
Enzyme-linked receptor

27
Q

What is another name for G-protein coupled receptors?

A

7-transmembrane receptors as their protein channel crosses the membrane 7 times.

28
Q

Describe the structure of G-protein coupled receptors

A

Receptor is linked to G protein complex (heterorimer):

  • Ga subunit divided into 3 physiologically variable categories
  • Gby subunit which is physiologically active.
  • GDP molecules
29
Q

What are the steps of ligand binding to G-protein coupled receptors?

A

Ligand binding causes the protein complex to become associated with the receptor due to a change in receptor conformation. This causes GDP to be phosphorylated to GTP.
Ga attached to GTP uses energy to dissociate from Gby and move into target cell.
Ligand dissociated - GTPase on Ga hydrolysis GTP to GDP, restoring previous state

30
Q

What are intracellular receptors?

A

Essentially transcription factors to control mRNA and protein synthesis

31
Q

How do steroid hormones bind to intracellular receptors?

A

Hydrophobic so pass through lipid bilayer membrane and bind directly to receptor in the cell.

32
Q

What are the sub categories of intracellular receptors?

A

Type 1

Type 2

33
Q

Where are type 1 intracellular receptors located?

A

Cytosol

34
Q

Where are type 2 intracellular receptors located?

A

Nucleus

35
Q

What associates with type 1 intracellular receptors?

A

Chaperon molecules - normally heat shock protein (hsp)

36
Q

What associates with type 2 intracellular receptors?

A

Bound to DNA

37
Q

How do type 1 intracellular receptors work?

A

ligand binding leads to hsp (chaperone) dissociation allowing for hormone receptor complex formation. Then binds with identical complex, forming homodimer which translocates into nucleus to regulate transcription

38
Q

How do type 2 intracellular receptors work?

A

Binding of the hormone ligand which can translocate into the nucleus and bind to DNA to regulate transcription

39
Q

What is another name for ligand gated ion channel receptors?

A

Ionotropic receptors

40
Q

Describe the structure of ligand gated ion channel receptors?

A

Quaternary structure with ligand binding domain on external surface and a central pore located on the inside of the structure

41
Q

How do ligand gated ion channel receptors work?

A

Ligand binds to domain to cause conformational change and lead to opening of central pore. This allows facilitate diffusion of ions such as sodium, potassium and calcium.

42
Q

How do ligand gated ion channel receptors differ?

A

Different receptors have different ligands which will lead to different effects upon activation.

43
Q

What is an example of ligand gated ion channel receptors?

A

Nicotinic Ach receptor binds to Ach, facilitating skeletal muscle contraction and cognitive neuronal enhancement.

44
Q

What are enzyme linked receptors?

A

Transmembrane receptors consisting of only one domain to which a ligand binds.

45
Q

How do enzyme-linked receptors work?

A
  1. Binding of the ligand to each receptor leads to receptor clustering and thus activating intracellular enzymes (kinases)
  2. Enzymes phosphorylate receptor to activate it
  3. Activation causes signalling proteins to bind to cytoplasmic domain
  4. Signalling proteins recruit other signalling proteins and generate a signal within the cell

PoM (27 decks)

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