Cell Bio Lecture 30

Front 1

Signals are

Back 1

environmental cues are converted into the molecular/chemical language cells use to carry out biological functions

Front 2

definition of signals

Back 2

any electrical, chemical, mechanical cue that informs the cell of a change in extracellular and/or intracellular conditions
-cilia is a mechanical signal: a mechanical change is a change in air pressure for example

Front 3

types of signals

Back 3

proteins, lipids, nucleotides, ions, NO, light and sound waves

Front 4

the whole signal process is a ___ response

Back 4

cascade

Front 5

signals tend to be ___

Back 5

very low in concentration (less than 10^-8 molar)
-bind with very high affinity

Front 6

signal cascade transfer of info from ___ to ___

Back 6

from the outside to the inside of the cell

Front 7

the response to a signal is dependent on

Back 7

type of signal and ultimate intended signal

Front 8

gene regulatory protein doesn't necessarily ____

Back 8

turn it on or off but alters gene transfer info, it can turn it on or off

Front 9

the response to a signal is dependent on

Back 9

type of signal(s) reaching the cell
-the receptors the cell possesses
-intracellular machinery that the cell uses to interpret and integrate incoming signals

Front 10

what are the target proteins?

Back 10

metabolic enzyme
gene regulatory protein
cytoskeletal protein

Front 11

metabolic enzyme
gene regulatory protein
cytoskeletal protein

Back 11

altered metabolism
altered gene expression
altered cell shape or movement

Front 12

general pattern for how cells transduce signals

Back 12

1) ligand (or stimulus) interacts with the receptor
2) receptor-ligand interaction generates a cascade of intracellular signaling events that alter the behavior of the cell

Front 13

general pattern for how cells transduce signals
(3)

Back 13

cells respond to incoming stimulus in various ways:
-change (ionic), effects on channels & pumps
-effects on lipid metabolism and turnover
-transient rise in intracellular Ca2+ levels
-change in the PO4 state of proteins
-effects on gene expression, up-and/or down-regulate specific genes

Front 14

general pattern for how cells transduce signals (4)

Back 14

signals often generate a cascade of effects
multiple things can occur at a time

Front 15

the type of intracellular signaling has an affect on whether or not a ____

Back 15

signal will be activated
-not all signals are loosely diffusible, in fact some are bound

Front 16

contact dependent

Back 16

signal molecule remains bound to the surface of the signaling cell and influence only the cells in direct membrane-membrane contact
-speed of response is dictated by deliver

Front 17

paracrine provides local effects

Back 17

cells in contact or in the immediate area
-fast and short-lived

Front 18

synaptic is unique to ____

Back 18

neurons. chemical signals delivered to specific cells in a very controlled environment. Fast. High local concentration- due to close proximity of signal cell and target cell

Front 19

endocrine

Back 19

signals deliver information to cells which are distant. signals travel thru bloodstream. slow. dilute

Front 20

synaptic and endocrine are specialized cell signaling that controls ____

Back 20

the behavior of cell

Front 21

autocrine signaling

Back 21

also called reinforcement
i.e. reinforcement during development, cancer
-cells can influence same cell type as well as themselves
-cell can respond coordinately as group
-most effective when performed simultaneously (development)
-cancer cells use it to overcome normal controls on cell proliferation

Front 22

half-life of a molecule

Back 22

amount of time required for its concentration to fall by half if all synthesis of the molecule were stopped

Front 23

the turnover rate determines

Back 23

the promptness of response when the signal is turned on

Front 24

the first degradation occurs

Back 24

within a minute

Front 25

slow degradation occurs at ___ minutes

Back 25

40 minutes

Front 26

the concentration of a molecule can be adjusted quickly only if

Back 26

the lifetime of the molecule is short

Front 27

neurons and how they work? check youtube

Back 27

nothing

Front 28

can cells work in isolation?

Back 28

cells have to be able to talk to each other, can not work in isolation

Front 29

intracellular signal

Back 29

you have to bind a signal that is hydrophobic (needs to be able to move thru membrane, need a carrier protein)
-cells that target the outside are hydrophilic

Front 30

extracellular signal molecules bind to

Back 30

specific receptors
intracellular receptor
cell surface receptor

Front 31

intracellular receptor

Back 31

bind hydrophobic signaling molecules that diffuse thru the PM into the cytosol (steroid hormones, other hydrophobic molecules)

Front 32

cell surface receptor

Back 32

bind hydrophilic signals at the extracellular side of the PM (growth factors, protein hormones, neurotransmitters)

Front 33

cells that target the outside are

Back 33

hydrophilic

Front 34

hydrophobic signals are long lived which is important because

Back 34

we know they have low-turnover rate and thus slower responses

Front 35

steroids can persist in the blood for hours and thyroid hormones can be in there for days

Back 35

water insoluble, such as steroids can stay in longer

Front 36

example of steroid and thyroid hormones

Back 36

cortisol
metabolism
estradiol
2nd degree sex characteristics
testosterone, thyroxine (sterol-ring/aromatic)
retinoic acid (vertebrate development)
vitamin D3 (long chain, unsaturated aliphatic hydrocarbons

Front 37

intracellular receptor signals are:

Back 37

hydrophobic and relatively insoluble
-delivered to target cell by carrier protein

Front 38

nuclear receptor superfamily
-direct activation of a small number of genes that ___

Back 38

can occur within 30 minutes
-primary response

Front 39

protein products that arise as a result of turning on these genes can produce

Back 39

a delayed secondary response

Front 40

has affects first on gene then on ____ level

Back 40

protein

Front 41

intracellular receptor
steroid is delivered by

Back 41

carrier protein (serum)

Front 42

steroid is released and ____

Back 42

diffuses thru the PM to the cytosol

Front 43

receptor binds to either ______ which causes

Back 43

cytoplasmic or nuclear receptors causing inhibitory subunits (Hsp90) to dissociate; which in turn expose a DNA-binding domain, and sites for assembly of transcription factors

Front 44

____ complexes then

Back 44

cytoplasmic complexes then localize to the nucleus where they stimulate activation (or repression) of transcriptional of specific genes

Front 45

the cytoplasm is a _____ (active/inactive)

Back 45

inactive

Front 46

the nuclear is ____

Back 46

active

Front 47

intracellular receptors bind

Back 47

hydrophobic signals that diffuse thru the PM into the cytosol
(steroid hormones, other hydrophobic molecules)

Front 48

cell surface receptors

Back 48

bind hydrophilic signals on the extracellular side of the PM
(neurotransmitters, Growth factors, Protein hormones)

Front 49

what are the 3 types of cell surface receptor family

Back 49

G-protein linked receptors
ion-channel linked receptors
enzyme linked receptors

Front 50

cell surface receptor family

Back 50

all act as signal transducers*- converting/changing extracellular binding of ligand into intracellular signals
-grouped according to transduction method/mechanism they use
-dictated by accessory molecules that interact with them

Front 51

cell-surface receptors all share 1 characteristic

Back 51

they are transmembrane and possess multiple passes
-regardless of function, upon binding to signal they undergo conformational change that allows them to transmit the signal
-aid in rapid synaptic signaling that happens between 2 electrically excited cells
-their target is electrically-excitable cell
-effect: open/close ion channel

Front 52

all binding and conformational changes are

Back 52

very quick in real time

Front 53

g-protein-linked receptors function

Back 53

indirectly regulate activity of separate PM-bound target protein

Front 54

what is the downstream target upon binding signal for g-protein linked receptors

Back 54

a protein linked to the PM, tail is a fatty acid tail and is a G-protein that is kept in OFF state

Front 55

g-protein linked receptor target

Back 55

enzyme or ion channel (as simply present in the membrane, in indirect activation)

Front 56

the effect of g-protein linked receptor

Back 56

act indirectly to regulate the activity of a PM-bound protein

Front 57

what does a g-protein-linked receptors

Back 57

a third protein to mediate the activity, a G-protein

Front 58

how many transmembrane domains do g-protein-linked receptors have?

Back 58

7, one of the key features of g-protein-linked receptors

Front 59

enzyme-linked receptors function

Back 59

directly as enzymes or associated with enzymes

Front 60

what is the critical difference for enzyme-linked receptors v. g-protein

Back 60

enzyme-linked doesn't mediate via a subsidiary protein, it mediates DIRECTLY through physical contact