cell communication

Question 1

name some examples of extracellular signalling molecules

Answer 1

proteins
nucleotides
amino acids
nuclei acids
dissolved gases
fatty acid derivatives

Question 2

what are the four main signalling pathways

Answer 2

endocrine
paracrine
neuronal
contact dependent

Question 3

paracrine signalling pathway

Answer 3

a form of cell-to-cell communication in multicellular organisms where cells release signalling molecules, called paracrine factors, into the extracellular fluid to influence neighbouring target cells or tissues

Question 4

endocrine signalling pathway

Answer 4

a type of cell-to-cell communication in multicellular organisms that involves the release of signalling molecules called hormones into the bloodstream

Question 5

neuronal signalling pathway

Answer 5

a specialized form of cell-to-cell communication that occurs within the nervous system.

Question 6

contact dependent signalling pathway

Answer 6

a form of cell-to-cell communication that requires direct physical contact between the signalling cell and the target cell.

Question 7

difference between the endocrine and the paracrine system

Answer 7

the paracrine system acts locally(in target cells that are in close vicinity), while the endocrine system can act in wide ranges throughout the body(so could be long or short range)

Question 8

in what range can the neuronal system act

Answer 8

in long or short ranges

Question 9

in what range can the contact- dependent system act

Answer 9

over long or short ranges

Question 10

by how many types of signals is each receptor USUALLY activated by

Answer 10

1

Question 11

how do cell surface proteins relay extracellular signals

Answer 11

via the intracellular signalling pathway

Question 12

intracellular signalling pathway

Answer 12

this is when the signal from cell surface receptor is transmitted into target cell by intracellular signalling molecules

Question 13

what are some of the things that intracellular signalling proteins can do to the incoming signals

Answer 13

they can;
relay it
amplify it
integrate it
distribute it

Question 14

intracellular proteins can act as molecular switches, true or false

Answer 14

true

Question 15

molecular switches

Answer 15

proteins or other molecules that can exist in two or more conformations or states and can transition between these states in response to specific signals or conditions

Question 16

function of molecular switches

Answer 16

molecular switches play pivotal roles in determining the cellular response to external stimuli, allowing cells to adapt to changing conditions and maintain proper functionality. Examples include G proteins and protein kinases that switch between active and inactive states to transmit signals within the cell.

Question 17

the two classes of molecular switches

Answer 17

allosteric
covalent

Question 18

allosteric molecular switches

Answer 18

In allosteric molecular switches, a molecule binds to a specific site (allosteric site) on a protein, which induces a conformational change in the protein, affecting its activity. Allosteric regulators can be either positive or negative, meaning they can activate or inhibit the protein, respectively.

Question 19

covalent molecular switches

Answer 19

Covalent molecular switches involve the addition or removal of specific chemical groups, such as phosphate groups (phosphorylation), to the protein, resulting in a change in its activity. These modifications can be reversible or irreversible.

Question 20

example of allosteric molecular switches

Answer 20

Enzymes often exhibit allosteric regulation. An example is the allosteric activation of phosphofructokinase in glycolysis by fructose-2,6-bisphosphate. When fructose-2,6-bisphosphate binds to the allosteric site, it activates the enzyme, allowing glycolysis to proceed

Question 21

example of covalent molecular switches

Answer 21

Protein kinases add phosphate groups to target proteins, often activating them. Protein phosphatases remove these phosphate groups, deactivating the proteins. Protein phosphorylation is a common covalent modification that acts as a molecular switch in many signalling pathways. For instance, the activation of the MAP kinase pathway involves a series of phosphorylation events.

Question 22

what are the three main classes of cell surface receptors( extracellular receptors)

Answer 22

ion-channelled
G-protein-coupled-receptors
enzyme-linked receptors

Question 23

what is the most common neurotransmitter

Answer 23

acetylcholine

Question 24

ion-channelled receptors allow for the …………… transmission of signals across the synapses in the CNS

Answer 24

rapid

Question 25

how do ion-channelled receptors allow for the flow of ions across the membrane

Answer 25

the membrane potential changes and an electric current is produced

Question 26

which enzymes are the most frequent targets for G proteins

Answer 26

Adenylyl cyclase
Phospholipase C

Question 27

what is the function of secondary messengers in G- protein coupled receptor signalling

Answer 27

they diffuse into the cell to act on intracellular signalling proteins

Question 28

which enzymes make cAMP

Answer 28

adenylyl cyclase

Question 29

what happens to the level of cAMP in the cell as due to extracellular signalling

Answer 29

cAMP levels increase

Question 30

functions of cAMP

Answer 30

often activates the cAMP dependent protein kinases (PKA)

Question 31

the activation of PKAs lead to increase in which effects in cellular signalling?

Answer 31

downstream effects

Question 32

what are some examples of downstream effects initiated by the activation of PKAs

Answer 32

glycogen breakdown in the skeletal muscle

phosphorylation of target proteins

amplification of the signal

integration of signals

termination of signals

Question 33

function of phospholipase C

Answer 33

makes inositol trisphosphate (IP3) and diacylglycerol (DAG)

Question 34

what are the two signalling pathways activated by Phospholipase C

Answer 34

Inositol Trisphosphate (IP3) Pathway

Diacylglycerol (DAG) Pathway

Question 35

largest group of enzyme-coupled receptors

Answer 35

receptor tyrosine kinases(RTKs)

Question 36

describe dimerization in terms of RTKs

Answer 36

Binding of signalling molecule to extracellular domain of RTKs

Question 37

what does the activation of tyrosine kinases on RTKs lead to

Answer 37

phosphorylation of each other on tyrosine residues

Question 38

what does the phosphorylation of tyrosine residues result to?

Answer 38

a conformational change in the structure of tyrosine residues, which makes it easier for specific secondary signalling molecules to bind to

Question 39

which enzyme does most RTKs activate

Answer 39

Ras(GTPase)

Question 40

function of Ras (GTPase)

Answer 40

hydrolyse GTP to GDP