Cellular Communication

Question 1

single vs multi cell signaling?

Answer 1

single-outside world communicate

multi-respond to and other cells

Question 2

How does local signaling work?

Answer 2

Cell junctions allow signaling molecules to pass freely between adjacent cells.
Cell to cell recognition occurs via cell-surface molecules. (markers on cell) Cells releasing signal to cells in local vicinity for that ligand–able to respond to it

Question 3

What does long term signaling use?

Answer 3

Hormones
it travels through the bloodstream to reach targets
ability of a cell to respond depends on whether it has a receptor that can bind to that signaling molecule.
Response depends on cells in its membrane– determines response type

Question 4

What are the 3 stages of cell signaling?

Answer 4

1. Reception
2. Transduction
3. Response

Question 5

How does reception work?

Answer 5

A receptor protein on the surface of the cell (or inside the cell) binds the signaling molecule (ligand-change in protein shape) and transmits the signal

Question 6

Binding is very _______and usually causes the receptor to __________

Answer 6

specific

change its shape

Question 7

What are the 3 types of membrane receptors?

Answer 7

• G protein coupled receptors
• tyrosine kinase receptors
• ion channel receptors

Question 8

What are G-protein coupled receptors?

Answer 8

Plasma membrane receptors that are associated with G protein. G protein acts like on/off switch.

Question 9

What are Receptor Tyrosine Kinases?

Answer 9

• membrane receptors with enzymatic activity which attach phosphates to tyrosine residues.
• one RTK may activate 10 or more different pathways

Question 10

Abnormally activated RTKs associated with?

Answer 10

Many types of cancer

Question 11

How do Ion Channel Receptors work?

Answer 11

• Binding of ligand causes confrontational change

- when gate opens specific ions can pass through

Question 12

Why is cellular signaling important?

Answer 12

cells must talk to each other in order to respond to environmental stimuli

Question 13

Where are intracellular receptors found?

Answer 13

cytoplasm or nucleus

Question 14

Intracellular Receptors

Signaling molecules must be able to..?

Answer 14

• Pass through the membrane
• steroid hormones
• thyroid hormones
• nitric oxide

Question 15

What happens during transduction?

Answer 15

• The relay of signals from receptors to target molecules in the cell
• often involves multiple steps
• allows the signal to be amplified
• allows for more regulation

Question 16

A transduction message is often passed through what?

Answer 16

A change in phosphoralyation. =protein kinases

Question 17

Dephosphorylation =___________

Answer 17

phosphatese

Question 18

How does a phosphorylation cascade work?

Answer 18

-Reception- ligand to receptor –>activate protein kinases–>add phosphate—>keeps activating by adding phosphates–> leads to cellular response

Question 19

What are second messengers?

Answer 19

small, nonprotein, water soluble molecules

-they can easily spread a message throughout the cell

Question 20

What are the 2 most common second messengers?

Answer 20

• cyclic AMP (cCAMP)

- Calcium ions

Question 21

What is cAMP?

Answer 21

cyclic adenosine monophosphate

adenylyl cyclase + ATP—->cAMP

Question 22

What does vibrio cholerae do?

Answer 22

it produces a toxin that causes a G protein to to be unable to hydrolyze GTP to GDP so it remains in “on” position..continually activating cAMP

these increased levels of cAMP causes salt to be excreted into the intestines and water follows=diarrhea

Question 23

_________is used as a second messenger in both G-protein and tyrosine kinase receptor pathways

Answer 23

Ca2+

Question 24

What responses does increasing ca2+ have?

Answer 24

• muscle contraction
• secretion
• cell division

Question 25

Where are levels of ca2+ highest?

Answer 25

10000X higher outside the cell

Question 26

How is Ca2+ transported? Where is it transported

Answer 26

actively, out of cell or into ER

Question 27

What does the response step do?

Answer 27

regulates gene expression (protein synthesis)

regulates protein activity (open ion channel)

Question 28

All cells contain the same DNA-why is a heart cell different from a liver cell?

Answer 28

different genes turned on in different cells

therefore different cells have different proteins

Question 29

What needs to happen for cell to respond to new signals?

Answer 29

Old signals must be shut off

Question 30

Binding of signaling molecules to receptors is ______

Answer 30

reversible

Question 31

The messengers return to their inactive form?

GTP hydrolyzes to

Answer 31

GDP

Question 32

The messengers return to their inactive form?

Camp converted to

Answer 32

CMP

Question 33

________remove ________to deactivate proteins

Answer 33

phosphotases, phosphates

Question 34

__________is necessary for proper development?

Answer 34

apoptosis