Cell Communication And Signal Transduction Pathway

Question 1

What are the 3 stages of cell signaling?

Answer 1

Reception, transduction, response

Question 2

What are the 3 types of cellular messaging?

Answer 2

Local signaling, local regulators, long distance signaling (hormones)

Question 3

Local signaling

Answer 3

Animal and plant cell have cell junctions that directly connect to the cytoplasm of adjacent cells and signaling mediators in cytoplasm are passed directly

Question 4

What is a type/ example of local signaling?

Answer 4

Cell to cell recognition
2 animal cells communicate by interactions of membrane receptors

Question 5

Local regulators and 2 examples of it

Answer 5

A type of local signaling where messenger molecules travel short distances to bind to receptors of local regulators
Paracrine
Synaptic

Question 6

Paracrine signaling

Answer 6

Growth factors are secreted which locally influence the growth and division of local cells

Question 7

Synaptic signaling

Answer 7

Animal nervous system
Occur in narrow space between 2 nerve cells known as synapse
Neurotransmitters recreate chemical signal and it binds to receptors of adjacent cell to translate nerve impulse

Question 8

Tf: both local and long distance signaling can recognize signaling moleutes given by specific target cells

Answer 8

Tru

Question 9

What is the path of synaptic signaling?

Answer 9

Electrical signal → chemical signal → electrical signal

Question 10

Long distance signaling

Answer 10

Hormones are an example of endocrine signaling in animals
Carried in the bloodstream

Plants also secrete hormones into the air to promote ripening

Question 11

1. Reception

Answer 11

Chemical signal detected when molecule binds to receptor
Inside or outside cell
Receptors are specific for certain ligand lock and key )
Ligand binding: change 3d shape of receptor → actives receptors → receptors interact with relay molecules
Ligand binding CAN: several receptors on cell membrane → further signal transduction

Question 12

2. Transduction

Answer 12

Bounded receptor changes to affect relay molecules in signal transduction pathway

Question 13

3. Response

Answer 13

Cellular response is triggered
Cellar response can be cytoplasmic cell processes) or nuclear(gene transcription)

Question 14

Where are hormones made?

Answer 14

Brain and pancrease

Question 15

Explain yeast

Question 16

3 main categories of transmembrane receptors

Answer 16

G-protein coupled receptors
Receptor tyrosine kinases
Ion channel receptors

Question 17

G-protein coupled receptors

Answer 17

① ligand binds to gpcr which turns on g-protein with conformation change
② The active g-protein binds to g-protein linked receptor where GDP → gtp phosphorylation and alpha subunit
Active g-protein is alpha subunits with gtp instead of GDP
③ activated g-protein binds to aderylyl cyclase by giving phosphate
④ g-protem is now inactive and retains to og

Question 18

Receptor tyrosine kinases

Answer 18

① ligand binds to binding site found in extracellular domain and receptor tyrosine kinase gets phosphorylated
② 2 halves come together = dimer
③ tyrosine is activated by dimerization and each tyrosine kinase adds phosphate from ATP
④ this phosphate can binds with relay proteins

Question 19

Ion channel receptors

Answer 19

Has gate and changes shape found in nervous system
① ligand bind
② channel gate opens and ions flow in
③ when concentration is reached the ligand unbinds
④ gate closes

Question 20

Intracellelar receptors

Answer 20

Found in cytoplasm or nucleoplasm
Eg. Hormones testosterone
Are nonpolar/hydrophobic

Question 21

Purpose of signal transduction pathway

Answer 21

Amplify signal
Better regulation and fire-tuning of signal

Question 22

What are some ways pathways may active next protein

Answer 22

Phosphorlyation or de phosphorylation
-3d shape change
Releasing small molecules/ions like secondary messengers

Question 23

Protein kinase

Answer 23

Enzyme transferring phosphate group from ATP to other molecules
Many relay molecules are protein kinase

Question 24

Phosphorylation targets

Answer 24

Serine or threonine

Question 25

Protein phosphates

Answer 25

Enzymes removing phosphate groups fromproteins which turn off signal transduction pathway -Recycle protein kinase

Question 26

What regulates activities on and off switch

Answer 26

Phosphorylation and dephosphorylation Dependent on the balance of active kinase and active phosphates enzymes

Question 27

Second messengers

Answer 27

Small water-soluble which pass through cell membrane by diffusion Found in both g-protei coupled receptor and receptor tyrosine kinase -Cyclic amp -Calcium ions

Question 28

C amp

Answer 28

Second messenger Converts ATP → camp is what adenylyl cycles does Camp is deactivated with phosphatase (dephosphorylation) - eg. when it phosphorylates protemkinase A Discovered by Sutherland when epinephrine caused glycogen to breakdown but nothing was passing though plasma membrane

Question 29

Calcium ions

Answer 29

Second messenger Stimulate growth factors, hormone andneurotransmittes Using calcium flux

Question 30

Which second messenger is more prominent camp or Ca

Answer 30

Calcium

Question 31

What does Ca influence?

Answer 31

Muscle cell contraction Secretion of certain molecules Cell division Nerve impulse

Question 32

What is inositol triphophate IP3

Answer 32

Second messenger Stimulate release of calcium ions from Er

Question 33

Diacylglycerol DAG

Answer 33

Second messenger Other signaling pathway not related to Ca release

Question 34

What does pip 2 breakdown into

Answer 34

DAG IP3

Question 35

How is pip 2 produced?

Answer 35

The cleavage of plasma membrane lipid cleaved in half to produce pip 2→ DAG and IP3

Question 36

Nuclear cellular responses

Answer 36

Regulate protein synthesis in nucleus - transcription factors work to turn off and on genes encoding for protein → mRNA → protein encoded by specific gene

Question 37

Cytoplasmic cellular responses

Answer 37

Regulates protein function in cytoplasm - opening and closing ion channels - regulating enzyme functions - fine-tuning metabolism

Question 38

Scaffold protein

Answer 38

Large relay proteins to which several other relay proteas can attach to

Question 39

Apoptosis

Answer 39

Programmed cell death

Question 40

Which cells undergo apoptusts?

Answer 40

Infected cells, damaged, reached end of functional life span

Question 41

Process of apoptosis

Answer 41

DNA and organelles are fragmented (packaged in vesicles) Cell shrinks in size and bless are formed Scavenger cells recognize apuptotic cells and engulf for safe disposal

Question 42

How does apoptosis work?

Answer 42

Proteases called caspases are activated to degrade cellular protein - 15 caspases involved in apoptotic pathurys - signaling depends on which caspase

Question 43

What is aprominent apoptotic pathway starter in cell

Answer 43

Leakage of proteins from mitochondria

Question 44

Process of apoptosis signal

Answer 44

Cell death trigger(extrucellular) → pores of mitochondrial membrane → leakage of cytochrome c→ activates cell death protease ced-3, ced-4 (which is normally inhibit by ced-9