Ch 5 Cellular Signaling

Question 1

4 principal mechanisms of cell communication

Answer 1

gap junctions
neurotransmitters
paracrines
hormones

Question 2

3 steps of cell signaling

Answer 2

1. receptor
2. transduction
3. response

Question 3

chemical messengers bind to specific target-cell proteins known as

Answer 3

receptors

Question 4

Types of chemical messengers

Answer 4

water-soluble
Lipid-soluble

Question 5

water-soluble chemical messengers bind…

Answer 5

to receptors in plasma membrane

Question 6

lipid-soluble chemical messengers bind…

Answer 6

to intracellular receptors in cytosol or nucleus

Question 7

Do hydrophobic or philic go faster

Answer 7

hydrophilic faster
hydrophobic slower

Question 8

Signal transduction

Answer 8

initiation of a sequence of events leading to a response

Question 9

Types of receptors

Answer 9

plasma membrane receptors
intracellular receptors

Question 10

plasma membrane receptors

Answer 10

integral membrane proteins; send signals without direct contact to DNA

Question 11

intracellular receptors

Answer 11

cytosol or nucleus; signals through direct contact to DNA

Question 12

Ligand binding specificity

Answer 12

binds to other proteins

Question 13

Central drogma

Answer 13

DNA -> mRNA -> Protein

Question 14

N-terminus vs C-terminus

Answer 14

N: front end of polypeptide chain, amino terminus
C: end of polypeptide chain, carboxylic terminus

Question 15

Receptor characteristics

Answer 15

specificity
affinity
saturation
Competition

Question 16

Receptor specificity

Answer 16

• selective expression leads to specificity in the systems
• Response of individual cells with the same receptor also vary on cell type

Question 17

Receptor affinity

Answer 17

High affinity
Low affinity
Competitor

Question 18

High affinity receptor

Answer 18

high concentration of bound messenger

Question 19

low affinity receptor

Answer 19

less ability to bind messenger to receptor

Question 20

Competitior

Answer 20

compete with availability

Question 21

Receptor competiton

Answer 21

ability of a molecule to compete with a natural ligand to bind for its receptor

Question 22

Agonist example

Answer 22

decongestant acts on alpha adregenic receptors like epinephrine
BOOST. ENHANCED CELL ACTIVITY

Question 23

Antagonist example

Answer 23

beta adrenergic receptor blocker (high blood pressure; epinephrine)
BLOCK CELL ACTIVITY

Question 24

Receptor saturation

Answer 24

there is a max limit of responsiveness of a receptor
Directly dependent to the number of receptors available in a cell

Question 25

Regulation of receptors

Answer 25

down-regulation up-regulation

Question 26

down regulation

Answer 26

decrease of number of receptors on a target aided by internalization

Question 27

up regulation

Answer 27

increase number of receptors on a target aided by insertion of stored vesicle bound receptors

Question 28

Signal transdsuction pathways

Answer 28

water-soluble lipid-soluble

Question 29

Lipid-soluble messengers...

Answer 29

diffuse through the plasma membrane Have intracellular receptors bind directly to DNA slow but sustained response

Question 30

Water-soluble messengers...

Answer 30

activate intracellular signaling faster response but not long lasting Require second messengers to carry out effects

Question 31

Ligand-gated ion channel...

Answer 31

- first messenger (ligand) causes a conformational change of receptor on plasma membrane - Opening of ion channels results in an increase in the net diffusion of one or more types of ions - change in membrane potential of cell

Question 32

Enzymes

Answer 32

- most are protein kinases that phosphorylate tyrosine: receptor tyrosine kinases - activate and act as docking site for other proteins

Question 33

Janus Kinases interactions

Answer 33

- JAK - immune response - example cytokines

Question 34

G Protein-Coupled Receptors

Answer 34

- most numerous - G-Proteins - protein complexes bound to inactive receptors on plasma membrane

Question 35

3 sub-units of G proteins

Answer 35

alpha beta gamma

Question 36

G-protein sub units can bind...

Answer 36

GDP and GTP

Question 37

Hydrophobic second messengers

Answer 37

DAG, and PI

Question 38

Hydrophilic second messengers

Answer 38

cAMP cGMP IP Ca2+