transduce this

Question 1

Difference between intracellular and intercellular?

Answer 1

intercellular is communication between cells, intracellular is within a single cell

Question 2

4 functions of intercellular signaling

Answer 2

signaling can tell a cell to survive,
divide,
differentiate,
die or increase/decrease functioning (change kinetics).

A single signaling molecule can perform multiple tasks (ex: acetylcholine has multiple functions). A signaling molecule can exist as a gas

Question 3

Where are receptors located on cells? For intracellular? For intercellular?

Answer 3

intracellular vs. extracellular
Intracellular are within cell, usually for steroid hormones via endocrine function.
Extracellular receptors are on the outside of a cell

Question 4

What are the 3 types of extracellular receptors? Examples of each?

Answer 4

Extracellular receptors are on the outside of a cell and have three types:

1. Ionotropic receptor
   a. Nicotinic AChR main one mentioned in slides
2. Metabotrophic receptor
   a. Tyrosine kinase and all g-protein coupled receptors are metabotrophic
3. Enzyme-linked receptor
   a. Insulin, nerve growth factor, brain derived neurotrophic factor, epidermal growth factor, platelet derived growth factor

Question 5

What is an inotropic receptor?

Answer 5

also known as ligand gated ion channels, allow ions into the cell in response to the binding of a chemical messenger

Question 6

What is a metabotrophic receptor?

Answer 6

function through a secondary messenger, are indirectly linked with ion channels on plasma membrane. When a metabotrophic receptor is activated, a series of intracellular events are triggered, which may result in an ion pathway opening but you need a lot of secondary messengers to make that happen

Question 7

What is an enzyme receptor?

Answer 7

binding of extracellular ligand causes enzymatic activity within a cell

Question 8

Intercellular receptors can take 4 different forms, what are they?

Answer 8

1. Contact dependent: receptor on one cell must bind to signal molecule on another cell
2. Paracine: signaling cell sends out signaling molecules to neighboring cells
3. Synaptic: in neurons, neurotransmitters act on target cells thru axons
4. Endocrine: cells send hormones out to blood stream to affect other cells

Question 9

Can one signaling molecule perform multiple functions?

Answer 9

yes
Example: Acetylcholine can be used for 
-Decreasing rate of force of contrxn in heart muscle cells
-Contraction in skeletal muscle cells
-Secretion in salivary gland cells

Question 10

What is the pathway for how signaling occurs through cascade of intermediate signaling complexes? There are 6 steps

Answer 10

1. Signaling molecule
2. Cell surface receptor
3. G-Protein
4. Enzyme
5. Intracellular mediator
6. Target protein

Question 11

____ ___ and ___ are types of ligands interact with intracellular receptors, they usually bind to intracellular receptors.

Answer 11

steroid hormones and IP3

Question 12

you can inactivate a receptor by ___it, ___ ___ it, or producing an __ __

Answer 12

sequestering it; down-regulating, inhibitory protein

Question 13

G-protein coupled receptors: sense molecules outside the cell and then activate inside __ ___ pathways, only in ___, two major pathways: ___ and _____

Answer 13

signal transduction; eukaryotes; cAMP and phosphatidylinositol

Question 14

____ units dissociate when stimulated

Answer 14

G-protein

Question 15

The cAMP pathway is a __ __ coupled receptor triggered signaling cascade used in cell communication.

Answer 15

G protein

Question 16

The cyclic AMP cascade, 3 main steps

Answer 16

1. cAMP activates protein kinase A (PKA)
2. which causes the catalytic units of PKA to phosphorylate substrate proteins.
3. PKA does a ton of stuff: can turn enzymes on/off, bind to DNA to increase gene expression, act directly on ion channels

Question 17

What is PKA?

Answer 17

family of enzymes who’s activity is dependent on cAMP levels in cell

Question 18

What are the steps involved in PKA activation

Answer 18

1. Cytosolic cAMP increases
2. Two cAMP molecules bind to each PKA regulatory subunit
3. The regulatory subunits move out of the active sites of the catalytic subunits and the R2C2 complex dissociates
4. The free catalytic subunits interact with proteins to phosphorylate Ser or Thr residues.

Question 19

__ and ___ are secondary messengers used in signal transduction and lipid signaling. They work together to activate protein kinase C. ___ can travel to the endoplasmic reticulum where they stimulate release of Ca++ to cytoplasm.

Answer 19

IP3 and DAG; IP3;

Question 20

___ ___ ___ are the high-affinity cell surface receptors for many polypeptide growth factors, cytokines, and hormones. Two of these receptors may be linked to create a dimer. This process leads to rapid activation of the ___ ___ domains by triggering neighboring __ ___ ___.

Answer 20

Receptor tyrosine kinases (RTK); cytoplasmic kinase; RTKs

Question 21

2 examples of receptor tyrosine kinases

Answer 21

Example: PDGF and insulin receptor

Question 22

tyrosine kinase domains come together and ____.

Answer 22

autophosphorylate

Question 23

__ __ are small G-proteins, involved in cell signaling, when switched on it subsequentely switches on other proteins that turn on genes.

Answer 23

Ras proteins

Question 24

Ras proteins are involved in __ __, ____ and ____.

Answer 24

cell growth; differentiation; survival

Question 25

Overactive Ras proteins can cause ____. They are GTP dependent (when GTP is bound ras is active) and activate ____ kinases, which change protein activity or gene expression.

Answer 25

cancer; MAP

Question 26

A ___ ___ is a sequence of events where one enzyme phosphorylates another, causing a chain reaction leading to the phosphorylation of thousands of proteins.

Answer 26

phosphorylation cascade

Question 27

__-___ is a protein complex that controls transcription of DNA, cytokine production and cell survival.

Answer 27

NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells)

Question 28

What is the pathway of activation for NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells)? There re 4 steps

Answer 28

1. Cell surface TNF receptor activated 2. NFkB is inactive in cytoplasm with IkB 3. Kinase removes IkB 4. NFkB moves to nucleus and target genes are transcribed

Question 29

Start codon, the most common is ___, codes for ___in eukaryotes and ___ ___ in prokaryotes

Answer 29

AUG; methionine ; modified methionine

Question 30

DNA is read in triplets, changing __ __ will change the codons thus changing __ __

Answer 30

reading frame; protein stucture

Question 31

Structure of transfer RNA

Answer 31

clover leaf shaped with a D loop (closest to 5’ end), an anticodon loop and a T loop (closest to 3’ end)

Question 32

__-__ is an amino acid the tRNA codes for is attached on the 3’ O

Answer 32

Aminoacyl-tRNA

Question 33

What are the 3 ribosome domains?

Answer 33

Ribosome domains: A: aminoacyl-tRNA P: Peptidyle-tRNA E: Exit

Question 34

Stop codon: nucleotide triplet that signals the termination of translation: __, ___, and ___ are the most common

Answer 34

UAA, UAG, UGA

Question 35

Importance of protein folding

Answer 35

if they are fucked up then horrible things happen such as prion diseases (Creutzfeldt-Jakob and mad cow disease)

Question 36

Function of proteasome

Answer 36

The main function of the proteasome is to degrade unneeded or damaged proteins by proteolysis, a chemical reaction that breaks peptide bonds

Question 37

The addition of ____ to a substrate protein is called ___ or _____.

Answer 37

ubiquitin; ubiquitination or ubiquitylation

Question 38

Ubiquitination can affect proteins in many ways (3):

Answer 38

1. it can signal for their degradation via the proteasome alter their cellular location 2. affect their activity 3. promote or prevent protein interactions.