theme 2- CB10, Cell communication, range of cell signalling molecules, their receptors and functions

Question 1

Why do cells communicate? = is just extra info to make sense of point, recall brackets and e.g. tho

Answer 1

• To develop( so defining position, function, fate, growth) = cells in the embryo exchange chemical signals they receive from other cells to decide what a cell will specialise into, its position, and whether it survives, divides or dies
• To function (as a community of cells) E.g. the physiological function of a tissue is co-ordinated via signals from other cells, e.g. biofilms, tissues
• To sense and respond to the environment (nutrients, infections, light, blood glucose levels etc.)

Question 2

The means by which cells communicate is called__________(transmission and interpretation of complex signals)

Answer 2

signalling

Question 3

Define signalling

Answer 3

transmission and interpretation of complex signals by cells

Question 4

What happens after a signal molecule from signalling cell reaches target cell?

Answer 4

0) signal reception by target cell (intercation with receptor)
1) Signal transduction (convert extracellular signal into intracellular signal)
2) molecular change occurs (e.g. gene transcirptio, protein function)
3) Cell behaviour alters

Question 5

What are the types of cell signals?

Answer 5

1. hormones
2. local mediators (target near by cells)
3. neurotransmittors
4. contact-dependent signal molecules (communication at cell membranes requiring cells to be right beside each other)

Question 6

For the following chemicals give the name of a signal molecule:

Question 7

For the following chemicals give the name of a signal molecule:

• Nucleotides eg
• Steroids eg
• Dissolved Gases eg
• Fatty acids derivates eg

Answer 7

• Nucleotides eg cAMP
• Steroids eg estrogen, testosterone, cortisol (stress hormone)
• Dissolved Gases eg Nitric oxide (NO)
• Fatty acids derivates eg the omega-6 fatty acid, arachidonic acid, is the building block for the eicosenoids — prostaglandins, thromboxanes, and leukotrienes (signalling molecules)

Question 8

Describe the following for the endocrine system:

1) Range, +explanation
2) period of time it effect lasts for
3) speed of responce

Answer 8

1) whole body, as acts systematically for homones are tranported in the blood stream
2) long-lasting effects
3) slow

Question 9

A) Describe the pathways of the following chemical cell signals in the endocrine signals to receptors? & B)state their effects

1) Amino acid derviatives
2) peptide hormones
3) steroid hormones

Answer 9

1&2) bind to extracullular receptors on plasma membrane (as can’t diffuse across plasma membrane),

B) regulate metabolism, developement, reproduction

3) A) bind intracellular receptors

B) regulate metabolism

Question 10

What are the 4 (+1) different ways animal signal?

Answer 10

1) Endocrine signalling

2) Paracrine signalling
(+1)) autocrine signallingwhen cells respond to the local mediators they themselves produce)

3) Neuronal signaling
4) Contact dependent signalling

Question 11

Describe:

a) the range, b) speed, c) selectivity, d) length of effects
1) Endocrine signalling
2) Paracrine signalling
3) Neuronal signaling
4) Contact dependent signalling

Answer 11

a) the range, b) speed, c) selectivity, d) length of effects
1) Endocrine signalling= a) whole body systemic, hormones via blood. b) slow, c) none.d) longterm
2) Paracrine signalling= a)low ECF, b) slow, c) medum, d) longterm
3) Neuronal signaling= a) large- nervousystem, b) fast, c) very, d) short term,
4) Contact dependent signalling= a) small (adjacent cells), b) slow ( required transciption), c) very, d)long term

Question 12

What is the name of the signal molecule type in endocrine signalling?

Answer 12

hormones

Question 13

What is the name of the signal molecule type in paracrine signalling?

Answer 13

local mediators like cyotkines and growth factors produced by some immune system cells

Question 14

What is the name of the signal molecule type in neronal signalling?

Answer 14

neurotransmittors

Question 15

What is the name of the hroup signal molecule type in contact-dependent signalling?what are these either?

Answer 15

Contact-denpendent signal molecules, these are either membrane or matrix bound molecules

Question 16

What does endocrine signalling do in general?

2) What does it respond to?
3) why is it importnat to gender?

Answer 16

1) Induces a wide-range of physiological and metabolic changes, by regulating systemic processes like glucose uptake and lipid synthesis
2) Involved in response to nutritional changes, changes in physical states (e.g. changes heart rate- adrenaline)
3) Involved in fundamental changes during development like induces and maintains secondary female or male characteristics (thyroid and steroid hormones)

Question 17

What local processes are regulated by paracrine signalling

Answer 17

Regulate local processes:

• Involved in development (growth factors) (stimulate cells to proliferate (increase rapidly in number))
• Involved in wound healing (e.g. transforming growth factor, TGF)
• Involved in inflammation (e.g. Interleukin-1, IL-1)

Question 18

How is the message passed from the signalling cell to the target cell in paracrine signalling?

Answer 18

1) signalling molecules exocytosised into extracellular fluid
2) DIFFUSE and bind to receptors on plasma membrane of target cells

Question 19

Why is paracrine signalling very important?

Answer 19

involved in immune responce and local inflammation e.g. gingervitus

Question 20

How is the message passed from the signalling cell to the target cell in neuronal signalling?

Answer 20

1) electrical impulse travels along axon then reaches axon terminal
2) the electrical impulses stimaulate the nerve terminal to exocytose neurotransmittor
3) diffuses across synaptic cleft in otherwords relay (recieve and pass on) signal across synapse
4) binds to receptors on target cell membrane

Question 21

What is lidocaine?

Answer 21

a dental aneasthetic

Question 22

Lidocaine is often administered with adrenaline: why?

Answer 22

Adrenaline will constrict blood vessels, through its action on the adrenergic receptors found in the walls of blood vessels. It is used to slow the dispersal, and thereby prolong the effect, of lidocaine.

Question 23

How does lidocaine work?

Answer 23

Lidocaine stops the sodium entering the nerve ending at the site of the pain. Therefore despite pain receptors being stimulated, an electrical signal is not fired along the nerve fibres to the brain.

Question 24

why is contact dependent signalling importatn?

Answer 24

1) In developement e.g. allows adjacent cells that are initially similiar to specialise into different cell tyeps , nerve cell prevents surrounding epithelial cells from specialising into anything else
2) In the immune responce e.g. t-cells and b-cells

Question 25

How is the message passed from the signalling cell to the target cell in contact dependent signalling?

Answer 25

cells make **direct physical contact** through signal moelcules in plasma membrane of signalling cell **binding to receptor proteins in the plasma membrane** of the target cell

Question 26

What determines what receptors are on the surface of a cell?

Answer 26

the cells history and current state

Question 27

Why do cells respond differently to a signal molecule?

Answer 27

1) may not have a receptor for the signal molecule 2) different cell types respond to the same signal differently, 3) the response is determined also by the signalling pathways as much as the nature of the signal.e.g.

Question 28

What determines cell behaviour?

Answer 28

the way a cell responds to signals

Question 29

What determines how a cell responds to a signal?

Answer 29

1) If it even has a receptor for the signal- which is determined by its history and current state 2) The behaviour of the cell e.g. muscle vs secretory cell 3) the signalling pathway of the signal molecule 4) the nature of the signal (size?) e.g. lots of neurotransmittor at neuromuscular synapse 5) if there are multiple signals: the presence of one signal can modify responces to another e.g. cell divides instead of survives

Question 30

How does having multiple receptors and signals complex the prediction of cell responce?

Answer 30

- the same signal can bind to more than one receptor - the same signal/receptor combinations can still result in a different responce in different cells - due to multiple signals responce also depends upon the interactions of intra-cellular signalling pathways

Question 31

Why are some responces to signalling fast? +e.g.

Answer 31

affects the activity of protiens and other molecules already present in the cell e.g. secretion and contraction

Question 32

Why are some responces to signalling slow? +e.g.

Answer 32

requires changes in gene expression and the production of new proteins e.g. cell growth and division

Question 33

What are the 2 classes of extracellular signalling molecules? WHAT ARE THERE ACITIVITES?

Answer 33

1)Large and hydrophilic so can't cross plasma membrane they bind to recpetors on plasma membrane, receptors relay signal across membrane and activate intracellular signalling molecules 2) Small and hydrophilic so can cross plasma membrane activate intracellular enzeymes OR they bind to nuclear receptors (cytosolic and nuclear receptors)= receptors undergoes conformational change= activates protein= promote or inhibit transcription of a specific target gene