cell communication and signaling

Question 1

electrical signals

Answer 1

changes in the membrane potential of a cell

Question 2

chemical signals

Answer 2

molecules secreted by cells into ECF
bind to specific receptor on (usually) or in target cells

Question 3

what are the methods of communication between cells

Answer 3

local ( gap junctions, contact-dependent, autocrine, paracrine)

long distance (neuronal, endocrine)

Question 4

gap junction communication

Answer 4

local
form direct cytoplasmic connections between adjacent cells

Question 5

contact- dependent signals

Answer 5

require interaction between membrane molecules on two cells

Question 6

autocrine signals

Answer 6

act of the same cell that secreted them
do by itself

Question 7

paracrine signals

Answer 7

secreted by one cell and diffuse to adjacent cell
acts nearby locally

Question 8

hormones long distance communication

Answer 8

secreted by endocrine glads or cells into the blood. Only target cells with receptors for the hormone will respond to the signal

ie/ insulin is secreted from pancreatic beta cells and binds to insulin receptors on cells throughout the body, enabling glucose to enter these cells

Question 9

neurotransmitters long distance communication

Answer 9

chemicals secreted by neurons that diffuse across a small gap to the target cell

ie/ acetylcholine is a neurotransmitter that can be used to elicit skeletal muscle contraction

Question 10

neurohormones

Answer 10

chemicals released by neurons into the blood for action at distant targets

ie/ oxytocin is released by neurons in the posterior pituitary gland into the blood and stimulates uterine contractions during labor and delivery

Question 11

what are the major classes of chemical signaling molecules

Answer 11

amino acids (glutamate, glycine, GABA)
amines (epinephrine, norepinephrine)
peptides or proteins (insulin, glucagon)
steroids
others (calcium, acetylcholine)

Question 11

receptor channel

Answer 11

ligand binding opens or closes the channel

Question 12

g protein coupled receptor

Answer 12

ligand binding to a GPCR opens an ion channel or alters enzyme activity

ligand binds to a receptor that is physically coupled to a guanosine nucleotide-binding protein.

type of g-protein involved will determine which intracellular cascade is initiated

Question 13

kinases

Answer 13

phosphorylate proteins, phosphate groups on things

Question 14

phosphatases

Answer 14

dephosphorylate proteins, take off

Question 15

signal transduction in enzyme linked receptors

Answer 15

ligand binds to receptor, which activates associated enzyme

signal molecule binds to surface receptor
activates tyrosine kinase of cytoplasmic side
phosphorylated protein

Question 16

g-protein coupled receptors and phospolipase C

Answer 16

1. signal molecule activates receptor and associated G protein
2. G protein activates phospholipase C an amplifyer enzyme
3. PLC converts phospholipids into diacylglycerol (DAG), which remains in the membrane and IP3 which diffuses into cytoplasm
4. DAG activates Protein kinase c which phoshorylates proteins
5. IP3 causes release of calcium from organelles creating calcium signal

Question 16

g-protein coupled receptors and adenylyl cyclase

Answer 16

activation of AC will trigger the production of cAMP which activates PKA and then will go on to phosphorylate targetsh

Question 17

ligand-gated channels

Answer 17

generally selective
signal molecule (ligand) binds to its receptors. The receptor is an ion channel that is gated by ligand binding