Cell Signalling

Question 1

Negative feedback

Answer 1

Move back towards comfortable homeostatic zone

Question 2

Positive feedback

Answer 2

Move outside comfortable homeostatic zone (ex. HR in crisis)

Question 3

Direct cell signalling

Answer 3

Signal passed directly from one cell to another through gap juntion

Question 4

Indirect cell signalling

Answer 4

Signalling cell releases chemical messenger, which is carried in extracellular fluid and binds to receptor of target cell. This activates signal transduction pathway or ion channel.

Question 5

Connexin

Answer 5

Specialized pore complex, which creates aqueous pore between adjacent cells

Question 6

Structure of connexins

Answer 6

Two hemichannels, each with six proteins

Question 7

Autocrine and paracrine signalling

Answer 7

Signalling cell releases chemical messenger which can act on target cell nearby (paracrine), or back on signalling cell (autocrine)

Question 8

Endocrine signalling

Answer 8

Signalling cell releases chemical messenger/hormone into circulatory system to act on target cell that is very far away

Question 9

Neural signalling

Answer 9

Chemical messenger/NT is releases from neuron, and NT acts of target cell

Question 10

Seven classes of chemical messengers

Answer 10

Peptides, steroids, amines, lipids, purines, gasses, amino acids

Question 11

Site of peptide/protein hormone synthesis

Answer 11

RER as preprohormones, and stored in vesicles as prohormones, then releases as active hormone via exocytosis

Question 12

Preprohormone

Answer 12

Produced in RER

Question 13

Prohormone

Answer 13

Preprohormones are processed in golgi, and stored in vesicles as prohormones

Question 14

Site of steriod hormone synthesis

Answer 14

SER or mitochondria

Question 15

Three classes of steroid hormones

Answer 15

Mineralocorticoids, glucocorticoids, and reproductive hormones
(also, molting hormone for insects that shed hard exoskeleton)

Question 16

All hormones are synthesized from…

Answer 16

Cholesterol

Question 17

Steroid hormones are produced and…

Answer 17

Used immediately, they are produced on demand as they diffuse quickly

Question 18

Steroid hormones show slow effects on cell through

Answer 18

Genetranscription; binding to intracellular receptors/transcription factors

Question 19

Amine hormones chemical classification

Answer 19

Possess an amine group; these are usually derived from amino acids

Question 20

Four components of signal transduction pathways

Answer 20

Receiver, transducer, amplifier, and responder

Question 21

Intracellular receptors

Answer 21

Chemical messengers bind to hydrophobic ligands

Question 22

Ligand-gated ion channels

Answer 22

Binding leads to changes in membrane potential (ion efflux or influx)

Question 23

Receptor-enzyme receptors

Answer 23

Binding leads to changes in intracellular enzyme activity

Question 24

G-protein coupled receptors

Answer 24

Binding leads to activation of membrane bound G-proteins

Question 25

Types of ligand-gated ion channels

Answer 25

Glutamate receptors, GABA receptors, nicotinic acetylcholine receptors, and 5-HG3, P2X receptors

Question 26

Examples of glutamate receptors

Answer 26

AMPA, NMDA, kainate

Question 27

What activates nicotinic acetylcholine receptors?

Answer 27

Acetylcholine

Question 28

Binding of ligand to single transmembrane receptor in receptor-enzymes causes...

Answer 28

Phosphorylation cascade of specific intracellular proteins

Question 29

Receptor tyrosine kinases activation causes...

Answer 29

Conformational change resulting on dimerization, and autophosphorylation of tyrosines (also known as transautophosphorylation)

Question 30

Activity of receptor-gyanylyl cyclase

Answer 30

GTP-->cGMP cGMP activates protein kinase G (PKG) PKG phosphorylates target proteins and relaxes smooth muscles/lowers blood pressure by vasodialtion

Question 31

G-protein couples receptors

Answer 31

Ligand binds to 7 transmembrane receptor; subunits of G-protein dissociate and either activate ion channels or amplify signal via formation of secondary messenger

Question 32

Insositol-phospholipid pathway net rxn

Answer 32

G-protein coupled receptor | PIP2 --> DAG + IP3