GBIO 200 Shocket test 3

lipid bilayers contain?

contain: phospholipids, glycolipids, and sterols

What are the differences between endocrine, paracrine, neuronal, and contact-dependent cell signaling

endocrine- long-distance signaling

paracrine- nearby cells (no blood stream)

neuronal- electrical signals via neurons

contact-dependent- a cell surface bound signal molecules binds to a receptor protein on adjacent cell

phospholipids made of? \#?

made up of glycerol head, 2 fatty acid tails. most abundant in number

What is signal transduction?

the transmission of molecular signals from a cell's exterior to its interior

glycolipids

sugars attached to the phospholipids

What types of molecules serve as signaling molecules in the cell?

Hormones, Neurotransmitters, Local transmitters, and Pheromones

sterols

cholesterol attached to phospholipids

What are some common outcomes of cell signaling?

Cell migration, changes in cell identity, and induction of apoptosis

can proteins in the bilayer move?

yes they can move laterally across the bilayer

Ras

A small GTP-binding protein that is bound by a lipid tail to the cytoplasmic face of the plasma membrane. VIrtually all RTKs activate Ras. Ras protein is a member of a large family of monomeric GTPases, resembles a-subunit structure and functions as molecular switch.

amphipathic parts (2) and examples? (3)

hydrophobic + hydrophilic parts. phospholipids, sterols, and glycolipids are examples of this in cell membranes

cholesterol does what? and what are they examples of?

can reduce the fluidity in unsaturated fatty acids, are also amphipathic

glycocalyx and aids in?

sugary outer coating of cells that keep the cell moist and protected. aids in cell - cell interactions (glycolipids + glycoproteins)

fluidity important in? and determined by (tail length/temp/sat + unsat fatty acid tails)

extremely important in cell - cell interaction

long tails = better interaction (fewer holes = less fluidity)

short tails = poorer interaction (more holes = more fluidity)

increased temp = more fluidity

decreased temp = less fluidity

saturated fatty acid tails = less fluidity

unsaturated fatty acid tails = more fluidity

saturated fatty acid tails

have single bonds and are solid at room temperature

unsaturated fatty acid tails (bonds? explain bonds? (2))

have double bonds and are soft/liquid at room temperature. double bonds are rigid and create bends - they are more difficult to pack together into solid form

cell membrane (2) and what determines what diffuses across it? (2)

asymmetrical, selectively permeable (determines what moves into the cell and what does not). molecules diffuse across based on size + hydrophobicity

small hydrophobic molecules (O2, CO2) dissolve?

dissolve in bilayer and diffuse across rapidly

small uncharged polar molecules (H2O, ETOH) dissolve?

diffuse across rapidly

large uncharged polar molecules (glucose, AA, nucleotides) dissolve?

do not diffuse well, needs transfer proteins

ions + charged molecules (H+, Na+, Ca2+, etc.) dissolve? why?

do not diffuse well because they are all very hydrophilic and cannot enter hydrophobic interior of bilayer. need transfer proteins

hydrophobic a-helix ribbon? balls? what passes through? any needed to form an aqueous pore/channel?

has hydrophobic AA side chains to allow the a-helix to pass through the membrane. ribbon = backbone, balls = side chains. nothing passes through the middle of an a-helix need multiple a-helices to form an aqueous pore/channel

how often does twisting occur?

every 3.6 AA

Bacteriorhodopsin (location/retinal function in it?)

protein found in salt-marsh archaeans. retinal absorbs light giving the protein energy to pump the hydrogen protons through

domains

areas of the membrane that contains a certain type of protein

tight junctions

barriers to prevent proteins moving past them

carrier proteins

can only carry 1-2 molecules at a time

ion channels (require energy?)

can move many molecules at a time (trapdoor), work by passive transport and do not require energy

passive transport (require energy?)

moves molecules with their concentration gradients and requires NO energy

active transport (require energy?)

moves molecules against their concentration gradients and requires energy

concentration gradient (moves from what to what?)

a difference in concentration of a solute over an area. always moves from high - low

passive glucose carrier (location/conformation?/direction of movement depends on?)

operates in the liver cells + other cells, switches between 2 confirmations, and its direction of movement depends on the concentration gradient

passive glucose carrier: input of glucose pathway (List 6 steps)

input of glucose \= lots of glucose in blood \> blood travels to the liver \> lots of glucose outside liver cells \> passive glucose carrier binds glucose outside of liver cell membrane \> changes conformation \> glucose is moved into the cell (ex: chocolate easter bunny)

passive glucose carrier: hypoglycemic pathway (list)

if hypoglycemic, the pancreas makes glucagon which stimulates the liver cells to break down glycogen into glucose. this makes a lot of glucose inside the cell \> passive glucose carrier binds glucose inside the cell \> changes conformation \> moves glucose out of cell

movement of charged molecules influenced by?

influenced by the concentration gradient and the membrane potential

electrochemical gradient is the influence of what 2 elements?

known as the influence of the concentration gradient and the membrane potential

membrane potential (amount of charge + location)

the difference in charge across a membrane (large amount of + outside cell, small amount of + inside cell)

types of membrane proteins that mediate active transport against the electrochemical gradient

coupled pump, ATP-driven pump, light-driven pump

glucose-sodium symport (aids in? energy comes from?)

aids in the active import of glucose. energy comes from the sodium gradient

sodium-hydrogen exchanger (aids in? energy comes from?)

aids in the active export of hydrogen ions and pH regulation. energy comes from the sodium gradient

sodium-potassium pump (aids in? energy comes from? result in pump?)

aids in the active export of sodium and import of potassium. energy comes from ATP hydrolysis. sodium gradients are a result of this pump (pumps 3 sodiums out per 2 potassiums in)

calcium pump (aids in? energy comes from?)

aids in the active import and export of calcium ions. energy comes from ATP hydrolysis

hydrogen pump (aids in? energy comes from?)

aids in the active export of hydrogen ions. energy comes from ATP hydrolysis

coupled transport (3)

uniport, symport, antiport

uniport

1 molecule moving in a single direction

symport

2 molecules moving in the same direction

antiport

2 molecules moving in the opposite direction

aquaporin channel proteins (def/ helps with?)

facilitate water movement from outside of cell - inside of cell. helps with osmotic regulation

cations

positive ions

anions

negative ions

potassium leak channel (location/aids in?)

located in the plasma membrane of most animal cells. aids in the maintenance of resting membrane potential

voltage-gated sodium channel (location/aids in?)

located in the plasma membrane of the nerve cell axon. aids in the generation of action potentials

voltage-gated potassium channel (location/aids in?)

located in the plasma membrane of the nerve cell axon. aids in the return of the membrane to resting potential after initiation of an action potential

voltage-gated calcium channel (location/aids in? levels kept?)

located in the plasma membrane of the nerve terminal. aids in the stimulation of neurotransmitter release. calcium levels in the cytosol are kept low

acetylcholine receptor (acetylcholine-gated cation channel) (location/aids in?)

located in the plasma membrane of muscle cells at the neuromuscular junction. aids in excitatory synaptic signaling

glutamate receptors (glutamate-gated cation channels) (location/aids in?)

located in the plasma membrane of many neurons at synapses. aids in excitatory synaptic signaling

GABA receptors (GABA-gated chloride channel) (location/aids in?)

located in the plasma membrane of many neurons at synapses. aids in inhibitory synaptic signaling

glycine receptor (glycine-gated chloride channel) (location/aids in?)

located in the plasma membrane of many neurons at synapses. aids in inhibitory synaptic signaling

mechanically-activated cation channel (location/aids in?)

located in auditory hair cells in the inner ear. aids in the detection of sound vibrations

selectivity filter (def/ charge determines? ions do what?)

filter at the neck of ion channels that is made up of AA side chains. the charge of these side chains determine which ions pass through and which do not. ions shed their water before moving through the filter and will join back to water when they exit

patch clamp technique (allows?/measures?)

allows measurement of ion flow across a membrane. measures ion flow as current flow

voltage-gated

voltage sensors in channel protein sense change in membrane potential

ligand-gated

molecule binding to channel causes opening; can be extra or intracellular; causes conformational change in channel; example: neurotransmitter gated channel

(stress) mechanically-gated

physical force on channel causes opening; example: channels on auditory hair cells in your ear

gated

means controlled

depolarization (what to what?)

positive outside, negative inside -\> negative outside, positive inside

ligand

any molecule that bonds specifically to a receptor site of another molecule.

acetylcholine (found where? def?)

found in the central nervous system nerve terminals. a neurotransmitter that binds to ligand-gated channels, causing them to open

resting membrane potential (mV? charge inside/outside? potassium? what changes occur?)

typical animal cells have a resting membrane potential of -60mV.

more positive charge outside, more negative charge inside = negative membrane potential.

very close to the equilibrium potential for potassium. potassium is very important in balancing the resting membrane potential

changes in membrane potential influences the opening of voltage-gated ion channels (and ion flow) which changes the membrane potential

nerve cell

neuron

stimulus

causes a change in membrane potential which triggers an action potential

what causes channels to open?

reaching the threshold for depolarization

stimulus pathway in neurons (list)

stimulus \> neurotransmitter binds to ligand-gated channel \> opens \> change in membrane potential \> voltage sodium channel opens \> depolarization \> action potential moved down axon

depolarization pathway(list)

depolarization \> peak action potential \> voltage-gated sodium inactivated \> voltage-gated potassium open \> potassium pours through \> membrane depolarizes (+ out, - in) \> voltage-gated sodium closes

positive feedback

output of one influences the input of another

neuron signaling (what occurs where?)

action potential moves down axon to nerve terminus and then across the synapse to a post-synaptic cell.

the conversion of an electrical signal (action potential) to a chemical signal (release of neurotransmitter) occurs at a nerve terminus

signaling cell

sends signals

target cell

receives signals

preceptor (location)

on a target cell, initially receives the signals

signal transduction (examples of cellular change? (3) )

a chemical change brought about by a ligand binding to a receptor site causing cellular change such as metabolism, shape, and gene expression

adrenaline (found/increases what?(3) )

found in the adrenal gland, helps to increase blood pressure, heart rate, and metabolism

cortisol (found/affects what? (3) )

found in the adrenal gland, affects metabolism of proteins, carbohydrates, and lipids in most tissues

estradiol (found/induces and maintains)

found in the ovary, induces and maintains secondary female sexual characteristics

insulin (found/ stimulates? (3) )

found in Beta cells of pancreas, stimulates glucose uptake, protein synthesis, and lipid enzymes in various cells

testerone (found/induces and maintains?)

found in the testes, induces and maintains secondary male sexual character

thyroid hormone (found/stimulates?)

found in the thyroid gland, stimulates metabolism in many cell types

epidermal growth factor (EGF) (found/ stimulates)

found in various cells, it stimulates epidermal and many other cell types to proliferate

platelet-derived growth (PDGF) (found/stimulates)

found in various cells, it stimulates many cells to proliferate

nerve growth factor (NGF) (promotes? (2) ) (found/promotes (2))

found in various innervated tissues, promotes survival of certain classes of neurons and promote their survival and growth of their axons

histamine (found/ causes? (2) )

found in mast cells, causes blood vessels to dilate and become leaky, helping to cause inflammation

nitric oxide (found/ causes? (2) )

found in nerve cells and endothelial cells lining blood vessels. causes smooth muscle to relax and regulates nerve-cell activity

lambda-aminobutyric (GABA) acid (found/inhibits)

found in nerve terminals, an inhibitory neurotransmitter in the central nervous system

delta (found/inhibits)

found in prospective neurons and various other developing cell types. inhibits neighboring cells from becoming specialized in the same way as the signaling cell

endocrine hormone (released/influences/distance of signaling?)

released by glands or specialized cells into the blood stream, influencing cell function at another location in the body (long distance signal traveling)

paracrine hormone (act on/ released)

are hormones that act on neighboring cells, just released in localized spots in the body

synaptic (between/location of?)

synaptic gap or synaptic space; tiny gap between the terminal of one neuron and the dendrites of another neuron (almost never touch); location of the transfer of an impulse from one neuron to the next

contact-dependent

cells must make direct physical contact for signal to be sent and received

barbiturates/benzodiazepines?

anxiety relief + sedation

nicotine

constriction of blood vessels, elevation of blood pressure

morphine/heroine

analgesia (relief of pain) and euphoria