Bio 181: Cell Signalling

Front 1

What are included as signalling molecules?

Back 1

protein, peptide, nucleotide, steroid, fatty acids, dissolved gases NO and CO. Light and odor are also signals.

Front 2

Cells have __________ for signaling molecules.

Back 2

receptors

Front 3

Binding signal leads to a ___________ of intracellular ________________, and may include regulators of gene expression.

Back 3

-cascade
-2nd messengers

Front 4

Most cell signals involve ___________- add phosphate to a protein (518 protein kinase genes in human cells, 1/3 proteins have Pi).

Back 4

protein kinases

Front 5

Cells are low in ____ and high in ____. Cells are also low in _____. Opening ion channels allows rapid signaling.

Back 5

- Na+ (or Ca2+)
- K+
- Ca2+ (or Na+)

Front 6

SG:
Describe features of cell signalling.

Back 6

-Systems can have multiple functions including vision, memory, cell division, muscle contraction.
-Cells have receptors for signaling molecules.
-Binding signal leads to a cascade of intracellular "2nd messengers"
-Most involve protein kinases

Front 7

Epinephrine: where is it produced, when is it used, and what is the biological response?

Back 7

-Produced in Adenal Gland
-used during emergencies; fight or flight.
-cellular glucose and metabolism go up.
-glucogen storage and insulin response goes down.

Front 8

Glucagon: where is it produced, when is it used, and what is the biological response?

Back 8

-Produced by Liver
-Used for food storage between meals or skipped meals.
-Blood glucose goes up.

Front 9

Insulin: where is it produced, when is it used, and what is the biological response?

Back 9

-Produced by pancreas
-used after a meal
-Blood glucose goes down.

Front 10

Leptin: where is it produced, when is it used, and what is the biological response?

Back 10

-Produced by adipose (fat) tissue
-signals fat levels in adipose tissue
-increases fatty acid oxidation in tissues

Front 11

________ and ________ regulate metabolism in our tissues, and signal our brain to reduce _________ and increase ________________.

Back 11

-leptin
-insulin
-eating
-metabolic rates

Front 12

What do cytokines do? and what are two common cytokines?

Back 12

-They cause differentiation and cell division.
-prolactin
-Erythropoietin

Front 13

What's prolactin's function?

Back 13

Prolactin causes epithelial cells of the breast to turn into milk producing cells.

Front 14

What's erythropoietin's function?

Back 14

Erythropoietin causes bone marrow progenitor cells to produce red blood cells.

Front 15

__________ receptor can be expressed in bone marrow cells; add __________ and cells produce red blood cells.

Back 15

-prolactin

Front 16

What does hormone binding to a receptor cause?

Back 16

It causes pre-existing transcription factors and kinases to follow their developmental program.

Front 17

What are the four common signalling mehanisms, and what do they do(/are)?

Back 17

Autocrine: signals to itself or same cells.

Paracrine: secretes signals to nearby cells; may be of different types

Endocrine: it's a hormone secreted into the blood.

Synaptic: sends neurotransmitters through cell to cell chemical synapse

Front 18

SG:
Describe the E. coli Env Z receptor system as a model for cell signaling.

Back 18

-EnvZ in the inner membrane changes shape and phosphorylates itself in response to high solute.

-The phosphate is transferred to OmpR in the cytoplasm which initiates transcription of ompF.

-Translation produces the OmpF protein which inserts into the outer membrane and prevents solute entry.

Front 19

What is a receptor (R)?

Back 19

cellular protein

Front 20

What is a ligand (L)?

Back 20

a signal that binds to a receptor

Front 21

R + L = ?

Back 21

RL

Front 22

SG:
List different kinds of receptor systems.

Back 22

Ion Channels
enzyme-linked receptors
G protein-coupled receptors
cytoplasmic receptors

Front 23

Breifly describe ion channels as a receptor.

Back 23

Gated, allowing ions such as Na+, K+,Ca2+, or Cl- to enter or leave the cell.

Front 24

Breifly describe enzyme-linked receptors.

Back 24

-Binding ligand causes receptor to activate a protein kinase, or to bind a subcellular protein kinase.

-Transfer of phosphate changes activities of enzymes (key to most cell membrane receptor systems).

Front 25

Breifly describe G protein-coupled receptors.

Back 25

-Receptor is a single polypeptide that passes through the membrane seven times (also called Serpentine receptors).

-Ligand binding activates the receptor causing a G protein to bind GTP.

Front 26

Breifly describe cytoplasmic receptors.

Back 26

Ligands that are non-polar can diffuse through the plasma membrane and interact with cytoplasmic receptors.

Ex: Steroid hormones bind a cytoplasmic receptor which then can enter the cell nucleus and activate gene expression.

Front 27

What are two ways in which drugs interact with receptors?

Back 27

Agonist: binds receptor and stimulates a response; maybe even stronger than normal ligand

Antagonist: binds receptor and blocks stimulation by ligand

Front 28

SG:
What are second messengers? and what do they do?

Back 28

-Second messengers are indirectly generated when a ligand binds to a receptor, and they eventually are the ones to direct the response.

-second messengers amplify a signal, and frequently activate protein kinases.

Front 29

SG:
What types of molecules serve as second messengers?

Back 29

cAMP, inositol triphosphate (IP3) and diacyl glycerol (DAG) from phospholipids, NO, Ca++

Front 30

SG:
Describe a Kinase Cascade.

Back 30

A kinase cascade is a series of protein kinases that activated and inactivated as a phosphate group is passed through them. Such a cascade usually signals a biological response.

Front 31

G proteins can form __(#)__ second messengers from __________.

Back 31

-2
-phospholipids

Front 32

SG:
Briefly describe the cellular response to epinephrine in muscle tissue.

Back 32

This response blocks glycogen synthesis and stimulates glycogen breakdown releasing glucose for metabolism in our tissues. (Glucagon stimulates the same pathway).

Front 33

What’s the function of adenylyl cyclase?

Back 33

Dephosphoralate ATP to cAMP.

Front 34

How are cell responses reversed?

Back 34

• Phosphatases remove phosphate
• GTPases remove GTP from G proteins
• Phosphodiesterases breakdown cAMP and cGMP

Front 35

SG:
List the kinds of and functions of cell junctions.

Back 35

Gap Junctions:
-Channels between cell membranes formed by proteins called connexons.
-Passage of small signaling molecules and ions permit metabolic cooperation and coordination between adjacent cells.
-Coordinated responses to signals are possible, for example in the muscle cells that regulate the regular contractions of the uterus during childbirth.

Plasmodesmata:
-Connections between plant cells, an extension of the ER penetrating the cell wall and connecting adjacent cells.
-Plants lack capillaries, and so nutrients and signaling molecules can directly pass between adjacent cells.
-Mesophyll and bundle sheath cells are connected by plasmodesmata allowing fixed carbon to move between tissues of the plant.

Front 36

What roles to cilia play in cell signalling?

Back 36

odorant receptors, neural function, development, receptors for leptin, etc.

Front 37

What is hypothesised from Endothelial NO synthesis?

Back 37

calorie restriction extends lifespan

Front 38

Estrogen and testosterone are steroid hormones, and are most likely to bind to what kind of receptors, and why?

Back 38

cytoplasmic receptors, since hormones are hydrophobic.

Front 39

The endogenous GTPase activity of G-proteins serves to...

Back 39

...hydrolyzes GTP returning the G protein to a pre-stimulated level of activity.

Front 40

In a fight-or-flight response, epinephrine released by the adrenal glands binds to a membrane receptor on muscle cells. What are the steps that result?

Back 40

1. G-protein is activated by binding GTP and activates adenylyl cyclase which produces cAMP.

2. The second messenger, cAMP activates protein kinase A which inhibits glycogen synthetase blocking glycogen synthesis.

3. Protein kinase A activates phosphorylase kinase which transfers a phosphate activating glycogen phosphorylase leading to the breakdown of glycogen and the production of glucose-1-phosphate.

4. Glucose produced from glucose-1-P stimulates glycolysis, producing energy for muscle contraction.

Front 41

Direct cellular connections such as gap junctions in animal cells and plasmodesmata in plant cells permit:

Back 41

second messengers produced in one cell to rapidly diffuse into and stimulate events in surrouncing cells