C2.1 Chemical Signalling

Question 1

Local signalling (4)

Answer 1

cell-cell recognition

local regulators

paracrine (growth factors)

synaptic (neurotransmitter)

Question 2

Long distance signalling

Answer 2

hormones

Question 3

Define a ligand

Answer 3

specially shaped molecule that will bind to a specifically shaped larger molecule

Question 4

Define receptors (2)

Answer 4

specifically shaped proteins that will bind to certain signal molecules

changes shape after binding ligand

Question 5

Creating action potentials

Answer 5

generator potential - few sodium channels opened to create small depolarisation

many generator potentials come together to reach the threshold of an action potential

Question 6

refractory period

Question 7

Applications of quorom sensing (3)

Answer 7

medicine - blockicng receptors of bacteria

biomediation - breakdown pollutants from environment

food spoilage - autoinducers block receptors of bacteria which cause food spoilage

Question 8

Categories of cell signalling (4)

Answer 8

paracrine signalling

autocrine signalling

endocrine signalling

signaling by direct contact

Question 9

Gap Junctions as direct contact cell-cell communication

Answer 9

cells are in direct contact

protein channels connect 2 adjoining

Question 10

Paracrine signalling

Answer 10

simultaneous response to more than one cell

Question 11

Synaptic signalling (2)

Answer 11

nervous system

neurotransmitters diffuse from one nerve cell to stimulate the next

Question 12

Intercellular signalling (2)

Answer 12

communication among cells

through signalling molecules

Question 13

Examples of signalling molecules (4)

Answer 13

proteins, small peptides, amino acids

nucleotides

steroids, retinoids, fatty axis derivatives

nitric oxide, carbon monoxide

Question 14

Hydrophilic signalling molecules (5)

Answer 14

proteins

amino acids

peptides

nucleotides

cannot pass through cell membrane

Question 15

Hydrophobic signalling molecules (3)

Answer 15

steroids - hormones

gases

can enter cell membrane

Question 16

Endocrine signalling (3)

Answer 16

signalling molecules (hormones) secreted by spceialised endocrine cells

carried through circulation to act on target cells at distant body sites

e.g lipid steroids (testosterone, estrogen)

Question 17

Paracrine signalling (2)

Answer 17

moleucle (neurotransmitter) released by one cell acts on neighboring target cells

diverse group of hydrophillic molecules (dopamine, serotonin)

Question 18

Signal transduction (3)

Answer 18

process where external signal becomes internal cellular response

cells receive signal + pass signal along using signal transduction

Question 19

3 Stages of cell signalling (3)

Answer 19

reception - detection of signal molecule coming from outside of cell

transduction - convert signal to form that can bring about cellular response

response - cellular response to signal molecule

Question 20

Features of reception in cell signalling (4)

Answer 20

complementary binding of signal molecule (ligand) to receptor

water soluble (hydrophillic) - binds to outside membrane

intracellular (hydrophobic) - bind to receptors inside the cell

ligand binds to receptor –> protein changes shape –> initiates transduction signal

Question 21

Types of receptors (2)

Answer 21

plasma membrane receptor

intracellular receptor

Question 22

3 most common types of membrane receptor proteins

Answer 22

G-protein coupled receptors

Receptor tyrosine

Question 23

Describe G-protein cell receptor

Answer 23

cell surface transmembrane receptor

ligand binds to outside

passes through thr cell membrane 7 times

G-protein (complex) is inside the protein

Question 24

Intracellular Receptors

Answer 24

signal molecule is hydrophobic

many are molecular switches

Question 25

Types of switching on mechanisms in intracellular receptors (2)

Answer 25

phosphorylation - GTP binding - GDP bound = inactive, GTP bound inactive

Question 26

Examples of intracellular receptors

Answer 26

Testosterone

Question 27

3 main classes of hormones (3)

Answer 27

Amino acid/amine hormones peptide hormones lipid based hormones

Question 28

Features of amino acid hormones (3)

Answer 28

small molecules derived from amino acids tyrosine + tryptophan water soluble - hydrophillic bind to surface receptors

Question 29

Features of peptide hormones (4)

Answer 29

polypeptide chains, small proteins, glycoproteins include insulin + oxytocin water soluble - hydrophillic bind to surface receptors

Question 30

Features of lipid-based hormones

Answer 30

derived from cholesterol insoluble in water - hydrophobic require carrier protein to attach to transport via blood remain in circulation longer

Question 31

Gonadotrophin releasing hormone (3)

Answer 31

causes pituitary gland to make + secrete hormones men - these hormones cause testicles to make testosterone women - cause ovaries to make estrogene + progesterone

Question 32

Effects of estrogen

Question 33

Features of estradiol (7)

Answer 33

mainly secreted by cells of ovarian follicles regulates mesntrual cycle + reproduction regulates bone density regulates brain function regulates cholesterol mobilisation develops breast tissue + sexual organ controls inflammation

Question 34

Genomic Estrogen-mediated signalling

Answer 34

migration of estrogen-receptor complexes to the cell nucleus direct interaction