Download Cell Signaling and Signal Transduction: Types, Receptors, and Mechanisms and more Quizzes Cell Biology in PDF only on Docsity!
Define signal transduction
- converting a signal from one form to another TERM 2
Define cell signaling
DEFINITION 2
- events of signal reception and transduction1. signaling cell: sends out signal molecule2. target cell: cell that responds to the signal molecule - contains receptors TERM 3
Define receptor
DEFINITION 3
- specific protein that detects a specific signal (like a button outside of the cell)- lock and key interaction- may be on inside or outside of cell- signal will only affect cells that have the correct receptor for it TERM 4
What kinds of molecules are used as cell
signals?
DEFINITION 4
- amino acids- nucleotides- steriods (cortisol)- fatty acids- gases TERM 5
Can the same signal induce different
responses?
DEFINITION 5 Yes- ex) adrenaline - constricts smooth muscle cells serving the viscera - dilates smooth muscle cells serving skeletal muscle- ex) acetylcholine - ^ <3 rate - ^ saliva production
If we activate receptors on a cells surface in
different combinations, will we elicit diff
cellular responses?
Yes(see figure 16.6) TERM 7
What happen if 2 diff. cell types (
DEFINITION 7
- they will respond differently TERM 8
What are the types of cell signaling?
DEFINITION 8 Endocrine Paracrine (autocrine) Neuronal Neuroendocrine Contact-dependent TERM 9
Endocrine cell signaling
DEFINITION 9 Chemical signal released: horomone (released into the blood or sap in plants) Pancreas is an endocrine organ
- secretes the horomones insulin and glucagon Signal has the longest range and is wide spread throughout the entire body TERM 10
Paracrine cell signaling
DEFINITION 10 Signal Molecule: local mediators dont enter the blood molecules involved in inflammation use paracrine cell signaling
Intracellular receptors
receptors are inside the cell small, hydrophobic, nonpolar molecules use these because they can cross the PM ex) cortisol, steriods, gases TERM 17
Cell-surface receptors
DEFINITION 17 receptors are on the cell surface large, hydrophilic, polar molecules must use these because they cannot cross the PM ex) glucose, proteins TERM 18
How do steroid hormones activate genes?
DEFINITION 18 Pass through the PM & bind to cytosolic receptors/to the nucleus ex) testosterone, estradiol, cortisol TERM 19
What are nuclear receptors?
DEFINITION 19 receptors that when bound, travel to the nucleus and act on DNA where it activates or suppresses the expression of specific genes TERM 20
What is AIS?
DEFINITION 20 Androgen Insensitivity Syndrome Genetically male make testosterone but do not have receptors for it testes are in the abdomen instead of ovaries look female discovered when female does not menstrate
How do dissolved gases diffuse across the
PM?
ex) nitric oxide (NO) <-- helps control our blood flow diffuse directly through the PM of smooth muscle cells once inside the cell, it binds to an intracellular receptor which begins a series of reactions to relax the smooth muscle cell result=dilation of BV this ^'s blood flow
- nitroglycerin: a <3 medicine is converted into NO = ^ blood flow & decrease in blood pressure TERM 22
How do cell-surface receptors relay
extracellular signals?
DEFINITION 22 2nd messengers relay signals from outside to inside ex cAMP, Ca, IP3, DAG TERM 23
Do hydrophilic signals activate genes directly
or indirectly?
DEFINITION 23 Indirectly because hydrophilic molecules cannot pass through the PM and need a cell-surface receptor to do so TERM 24
How are cell-surface receptors classified?
DEFINITION 24 by mode of transduction (how they relay a signal) TERM 25
What are the 3 classes of cell-surface
receptors?
DEFINITION 25 ion-channel coupled receptors (ligand- gated channels) G-protein coupled receptors Enzyme-coupled receptors
What enzymes are activated by G-proteins?
Adenylyl Cyclase: produces cAMP Phosphodiase: produces IP3 and DAG IP3 - promotes accumulation of Ca TERM 32
What is the function of cAMP
phosphodiesterase?
DEFINITION 32 to break down cAMP into AMP thie regulates cAMP TERM 33
What inhibits the function of cAMP
phosphodiesterase?
DEFINITION 33 caffeine inhibits the functions of cAMP phosphodiesterase allows cAMP to linger longer in the cell acts as a stimulant TERM 34
How does cAMP phosphodiesterase work?
DEFINITION 34 it rapidly converts cAMP to AMP by decreasing the concentration of cAMP and slows down cascades TERM 35
What does adenylyl cyclase
do?
DEFINITION 35 produces cAMP converts ATP to cAMP a ring forms when aenylyl cyclase removes 2 P from ATP forming AMP the remaining P of the AMP joins with the sugar on the same molecule forming cAMP
How does cAMP exert most of its effects?
activates PKA (a kinase) TERM 37
What does PKA
do?
DEFINITION 37 phosphorylates a protein -> turns it on dephosphorylation -> turns it off causes a cascade TERM 38
How does vibrio cholerae interefere with G-
proteins? What dz does it cause? sx?
DEFINITION 38 locks g-proteins in the on position causes cholera disease sx) watery diarrhea TERM 39
What are the 2 enzymes activated by G-
proteins?
DEFINITION 39 adenyl cyclase phospholiapse TERM 40
What are 2nd
messengers?
DEFINITION 40 intracellular signaling molecules generated by enzymes in response to an extracellular signal ex) cAMP, IP3, DAG once activated they produce large quantities of 2nd messangers to amplify the signal
What are RTK's?
enzyme-coupled receptor receptor = tyrosin kinase extracellular signal binds to an RTK then the 2 RTK's come together --> the tails phospharalate eachother (activate eachother) --> phosphorylation occurs on the tyrosine amino acid --> this trigger 20 more proteins to join and form a scaffold TERM 47
What is Ras?
DEFINITION 47 GTP binding protein binds to GTP turns on with GEF turns off with GAP active state = bound to GTP inactive state = bound to GDP RAS resembles a G-protein TERM 48
What happens if we mutate RAS?
DEFINITION 48 cancer Ras inactivates GTPase activity, makes it stay on constantly, cells % continously = cancer TERM 49
What does RAS resemble?
DEFINITION 49 G-protein TERM 50
What are promoters?
DEFINITION 50 have a specific sequence of DNA that lies next to a gene promotes gene expression
