cell biology final

its chemistry

what about a ligand determines its solubility

hydrophilic ligands

neurotransmitters, acetylcholine, amino acids, neuropeptides are all examples of what kinds of ligands

true

true or false: acetylcholine receptors can be ligand gated ion channels

ligand binds receptor at outside surface of cell --> binding sets off chain of intracellular signaling events --> cellular/metabolic effect

cell signaling via cell surface receptors (basic pathway)

excitatory synapse

type of synapse that causes depolarization

inhibitory synapse

type of synapse that causes hyperpolarization

false, neurotransmitters can bind to several different receptors

true or false: a specific neurotransmitter can only bind to one specific receptor

indirect

G-protein-coupled receptors are an example of what kind of transmission

direct transmission

if a ligand binds to a receptor (that is also an ion channel) and this induces opening of the ion channel, this is an example of what kind of transmission

indirect transmission

if a ligand binds to a receptor which causes intracellular effects that eventually open an ion channel, this is an example of what kind of transmission

transmembrane protein associated with a G protein

indirect receptor could be described as

false

true or false: neurotransmitters are the only ligands that use G-protein-receptor signaling

hormones

chemical messengers released into the bloodstream by endocrine glands

slow

hormone's effects are quick or slow

steroid and thyroid hormones

what kind of hormones penetrate plasma membrane and bind to intracellular receptors

non-steroid hormones

what kind of hormones bind to membrane receptors

on plasma membrane

where does hormone receptor binding occur

G protein

what does hormone receptor binding activate (indirect transmission)

cAMP is produced

what happens after the G protein is activated (general pathway)

metabolic reaction

what is the target cell's function (indirect transmission)

activated enzymes

what catalyze metabolic reactions

7 times

how many times does G protein coupled receptor pass through membrane

ICF

GEF is located in the ECF or ICF

alpha subunit

which subunit of G protein activates adenylyl cyclase enzyme

GTP

alpha subunit of G protein is activated because it has what molecule attached

adenylyl cyclase

what enzyme synthesizes cAMP

ATP

hydrolysis of what molecule leads to cAMP synthesis

GTP

G protein is activated when it has what molecule attached

GAPase activating protein (GAP)

what protein catalyzes GTP hydrolysis and returns G protein to resting state

glycogen phosphorylase

what enzyme catalyzes breakdown of glycogen into glucose-1-phosphate

epinephrine

amino acid derivative produced by adrenal medulla

kinases

when these type of enzymes are used, the signal can be amplified

glucose can enter bloodstream and be taken up by cells that need energy

what is the net effect for cell of epinephrine using G protein

fast

speed of effect of G-protein coupled receptor

false

true or false: if ligand levels are low, cell signaling will be low using indirect transmission

very large

even just binding a couple ligands to a receptor, using indirect transmission, effect can be

cAMP

during 2nd messenger system, what is the main enzyme that brings the signal from outside to inside

ECF

where are 1st messengers located

ICF

where are 2nd messengers located

false

true or false: cAMP is the only 2nd messenger

contraction, secretion, metabolism

examples of cellular response to 2nd messengers include

changes its conformation

how does phosphorylating a protein activate a protein

Ser, Tyr, Thr

most common phosphorylation targets (amino acids)

monomer

what form of the receptor tyrosine kinase is inactive

dimer

what form of the receptor tyrosine kinase is active

ECF

location of ligand binding domain

ICF

location of tyrosine kinase domain

once

how many times does receptor tyrosine kinase pass through membrane

true

true or false: growth factors often bind to receptor tyrosine kinases

growth/differentiation and immune cell proliferation

growth factors have what function in adults

no

can animal cells grow without growth factor

kinases autophosphorylate each other

what occurs after receptor tyrosine kinases are dimerized

phosphorylated tyrosine residues

downstream factors recognize what part of tyrosine receptors

phospho-tyrosine binding sites (SH2 domains)

proteins that bind receptor Tyr kinases have what binding sites

false

true or false: once a ligand binds to a tyrosine kinase, each downstream effect is the same

receptor tyrosine kinases

what are MAPK, PI3, PLC all activated by

Ras-GEF

what protein exchanges GDP for GTP to activate Ras

Raf

when Ras is active, what protein does it activate

GTP

Ras is active when it has what molecule attached

GDP

Ras is inactive when it has what molecule attached

Grb2

in Ras pathway, what protein has the SH2 domain (binds directly to receptor tyrosine kinase)

MEK (map kinase kinase) --> ERK (MAP kinase) --> cellular response

once Raf is activated, it causes downstream activation of what molecules

phosphorylates transcriptional activators

how can ERK influence transcription

suppresses apoptosis and promotes cell survival

main function of PI3 kinase pathway

regulates cell cycle

main function of phospholipase C pathway

true

true or false: many signaling pathways usually work in parallel in the cell

non-receptor tyrosine kinases are not receptors themselves (attached to receptors)

how are non-receptor tyrosine kinases different than receptor tyrosine kinases

non-receptor tyrosine kinases

cytokines and growth hormone use what kind of cell receptors

extracellular matrix

during integrin signaling, what is the ligand

posttranslational

what type of modification is ubiquitination

groups (like phosphate) are added to it

how is a protein targeted for ubiquitination

proteasome

when a molecule is targeted for ubiquitination, what is the protein that actually degrades it

ligand and receptor both membrane bound

during contact-dependent signaling, what parts are membrane bound

false

true or false: contact-dependent signaling requires ATP hydrolysis

false

true or false: a ligand-receptor pathway can only be inhibited at one location

feedback loops

how is the activity of pathways regulated

positive feedback

what type of feedback

negative feedback loop

what type of feedback

differentiation or apoptosis

examples of why a cell would want to inhibit a pathway

cell signaling networks aren't regulated correctly

cancers, developmental disorders, endocrine issues can be linked to what issue

G1, S, G2, M

what 4 stages are in the cell cycle

no growth factor (and other factors)

what causes cell to go into quiescence

false

true or false: if the growth factor is removed during any point of interphase, the cell cycle will stop

restriction point

what is the stage in which cell cycle could stop depending on presence of certain proteins

false

true or false: once the cell cycle has begun, it cannot be stopped

DNA damage and spindle assembly checkpoints

what 2 check points regulate the cell cycle

checks chromosome alignment during metaphase

what does the spindle assembly checkpoint do

M phase (mitosis)

MPF increases Cdk activity which induces entry into what phase

steadily, rapidly

cyclin B is expressed _______ while Cdk1 is expressed _______

interphase

what phase does the cell enter into after mitosis

cohesin proteins

primary proteins that contribute to chromosome segregation

false, they are still bound at the centromere

true or false: when cohesins are phosphorylated they are completely unlinked to chromatids

condensins

what proteins drive chromosome condensation

cohesin, condensins

_______ link sister chromatids together and ________ pack chromatin into loops

CycB/Cdk1

what activates condensin

true

true or false: condensin requires ATP hydrolysis to function

center of chromosome

where are condensin stacks located

proteins of nuclear pore complex

Cdk1/cyclin B phosphorylates what

disassembly of pore complex and detachment of inner nuclear membrane

what does phosphorylating proteins of the nuclear pore complex cause

prometaphase

during what phase does breakdown of nuclear lamins occur