NRO quit 3 part 2

START OF EXAM 2 SHIT

active transport: define

form of transport that requires energy to move things against their concentrationn gradient

• usually uses carrier proteins or vesicles (for endo and exo)

electrochemical gradient

combination of electrical + chemical gradient

what charge are the interior of cells naturally?

negative

cellular respiration yields?

ATP

define catabolic metabolism

breaks large molecules → small molecules

requires no energy

define anabolic metabolism

goes from small → large molecules (building)

requires energy

what are the 3 steps of cellular respiration

• glycolysis

• KREBS cycle

• Electron transport chain

where does glycolysis take place? what does it start and end with?

cytoplasm

glucose → pyruvic acid

yields 2 ATP

where does the KREBS cycle take place? what do we make from it?

mitochondrial matrix

starts with acetyl CoA (made from pyruvic acid) and makes NADH and FADH2 to move onto ETC

where does the electron transport chain take place? what does it yield?

• takes place in mitochondria membrane

• yields 26-28 ATPs

describe anatomy of a mitochondria

-has an outer membrane and an inner membrane

has a matrix (this is inside inner membrane)

has inter membrane space between two membranes

folds = cristae

ATP Synthase in ETC is powered by…

proton gradient or “proton motive force”

the three phosphates from left to right in an ATP are..whats unique about the bond between gamma and beta?

gamma - beta - alpha

the bond between gamma and beta is a highly unstable phosphoanhydride bond

when broken it releases a lot of energy and makes ADP

what does the ATP/ADP cycle entail?

process by which cells store, release, and regenerate energy

goes from adenosine triphosphate to adenosine diphosphate (phosphate gets cleaved via hydrolysis) (specifically gamma-beta bond)

energy is released upon cleavage

we have to put in energy to attach the phosphate back on to make ATP again: this process = phosphorylation

how a signal gets received:

signaling cell releases protein (ligand)

binds in receptor on target cell

this binding triggers a response in the cell

list 4 types of cell signaling

• autocrine: cell targets itself

• juxtacrine: coms with direct contact

• paracrine: not touching but nearby

• endocrinology: cell targets distant cell thru bloodstream

direct (juxtacrine) signaling

communicating via direct contact

can be done across gap junction or thru receptors

paracrine signaling

• acts locally between close cells

• diffusion happens thru the extracellular membrane

• quick response that is short lasting

• ligand easily degraded

• ex: neuron signaling

endocrine signaling

• signal is from distant cell

• slow response but is long lasting

• ligands called hormones

• travel via the bloodstream

• concentration of ligand often low when it finally arrives to target cell

receptors can be either..

internal or external

types of gated ion channels

-voltage gated

-ligand gated

-mechncially gated

enzyme linked receptors

• cell surface receptors with intracellular domains that are associated with an enzyme

• ligand binds to extracellular domain, a signal is transferred through the membrane → this signal activates the enzyme

• activation of enzyme sets off a chain of events that leads to a response

• ex: RTK

in ETC, complexes are embedded in… what do they do?

embedded in the inner membrane, they push protons from the matrix into the inter-membrane space to create a proton gradient

if a complex in the ETC has an issue what could happen?

proton gradient is less extensive and therefore less ATP will be formed by ATP-synthase

what is a g-protein linked receptor and how does it work

• start with: inactive G protein

• ligand bind on the outside of cell and protein goes under a conformational change → this change activates the protein

• g-protein inside of cell loses GDP and picks up GTP

• alpha subunit dissociates from B and y unit, these subunits may activate other proteins as a result

• GTP on alpha subunit gets hydrolyzed → GDP and the By subunit is also deadvicated

• subunits resassociate to form inactive G protein

Receptor Tyrosine Kinase is an example of what kind of receptor?

enzyme linked receptor

name general steps of the RTK (Receptor Tyrosine Kinase) pathway

• ligand bind to extracellular domain of two nearby RTK

• the two neighboring receptors bond together, or dimerize

• dimers cross-phosphorylate eachothers tyrosine residues

• intracellular relay proteins bind to the phosphates → this activates the relay proteins

• triggers downstream signaling cascade → results in cellular response

types of ligands

• small and hydrophobic → can go through plasma membrane

• water soluble → polar and cannot pass through PM

• gaseous: → can diffuse across PM

phosphorylation

adding a phosphate group to protein

catalyzed by a kinase enzyme

second messengers

small molecules that propagate a signal after initiation

they spread signal through cytoplasm

ex: calcium, cAMP

in GPCR signaling, explain the Gs and Gi signaling,

Gs: stimulates adenylyl cyclase → AC converts ATP to cAMP

Gi: inhibits adenylyl cyclase —> AC cannot convert ATP to cAMP

what is the end result of the Gq path using GPCR?

• this path ends with calcium ions released from the ER

a single type of ligand can bind to different receptors

what is an example of this

an example of this is the flight/fight response

• norepinephrine and epinephrine (neurotransmitters) can bond to 3 different types of receptors (alpha 1, alpha 2, and beta.

• binding to different receptors causes different cell responses

why do cells use the RTK pathway?

• used for cell growth, proliferation, survival

know proteins involved in RTK pathway

how does a signal cascade get terminated?

• phosphatase take off phosphates → proteins are inactive

• phosphodiesterase destroys cAMP

• reverse of Ca++ release ( pump Ca++ back into ER) (some proteins need Ca to be active)

• destruction by cell via endocytosis (cell eats receptors) → makes cell unable to detect certain ligands

good example of paracrine signaling

transfer of signals across synapses between nerve cells

what are the small signaling molecules that pass directly through gap junctions called?

intracellular mediators

what kind of ligand do internal receptors usually interact with?

small hydrophobic molecules that have made their way across the plasma membrane

how do internal receptors directly influence gene expression?

the hydrophobic ligand binds to the receptor and exposes a DNA-binding site on the protein

ligand-receptor complex move into nucleus and binds to the regulatory regions of DNA, promoting the initiation of transcription

ion channel linked receptors

bind a ligand and open a channel through membrane that allows specific ions to pass through

ligand

act as chemical signals that travel to the target cells to coordinate responses

signal transduction only occurs with…

cell-surface receptors (only internal receptors can interact directly with DNA

how does a signaling pathway work

-starts when ligand binds to receptor which activates intracellular components

-enzymes (like kinases) and second messengers (like cAMP) then trigger a protein activation chain reaction

-this reaction leads to a change in cell behavior, metabolism, or gene expressions

second messengers

small molecules that propagate a signal after it has been initiated by the binding of ligand to receptor

• help spread signal thru cytoplasm by altering the behavior of certain cellular proteins

• ex: Ca2+, cAMP

examples of responses to the signal

gene expression, increase in cellular metabolism, cell growth, cell death, termination of signal cascade

one way of terminating the signal cascade

remove/destroy ligand