Term
| 3 major lipid components of eukaryotic membranes |
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Definition
glycerophospholipids
sphingolipids
cholesterol |
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Term
hydropathy index:
positive delta G?
negative delta G? |
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Definition
positive delta G = hydroPHOBIC
negative delta G = hydroPHILIC |
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Term
| what AA residues are found at interface of water and lipid? |
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Definition
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Term
| Where are positively charged AA residues found? |
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Definition
| inside, cytoplasmic side of cell |
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Term
| what is the strength of attachment? |
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Definition
| GPI > palmitoylation or prenylation > myruistoylation (lenght and number of fatty acid chains) |
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Term
| what are phospholipids degraded by? |
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Definition
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Term
| How are sphingolipids degraded? What do they yield? |
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Definition
| Degraded by set of lysosomal enzymes that remove sugar yielding a ceramide |
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Term
| ______ (higher/lower) temperatures = more ______ (saturated/unsaturated) fatty acids in the structural lipids |
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Definition
High temp = more saturaed
low temp - more UNSATURATED |
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Term
| membrane rafts are enriched with what |
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Definition
cholesterol and sphingolipids in outer leaflet
rich in GPI-anchored proteins
Glycerophospholipids in cytoplasmic leaflet |
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Term
| what is the purpose of rafts? |
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Definition
| contain proteins that are in specific enzyme pathways; rafts are a way to super concentrate those enzymes |
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Term
| Net movement of an electrically charged solute is dictated by combo of: |
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Definition
| electrical potential Vm and the ratio of chemical concentrations (C2/C1) |
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Term
| transporters and channels are |
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Definition
| membrane proteins that speed up movement of solute across membrane by facilitating diffusion |
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Term
| hallmarks of passive transport |
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Definition
saturability
specificity
Kt is transport constant
D-glucose Kt is 1.5mM |
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Term
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Definition
allow transmembrane transport approaching the limit of free diffusion (10^7 ions/sec)
don't function as pump
not saturable with ion substrate |
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Term
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Definition
bind with high affinity for substrates
transport at rates below the limits of free diffusion
are saturable |
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Term
| graph of initial velocity vs extracellular solute concentration; what does channel look like vs what does transporter look like |
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Definition
channel- linear
transporter- bottoms out |
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Term
| active transport results in accumulation of a solute ______ (above/below) equilibrium point |
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Definition
| active transport results in accumulation of a solute ABOVE equilibrium point |
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Term
| what is the equation for simple transport against a gradient w//a charged solute |
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Definition
deltaGt = RT ln(C2/C1) + ZF(delta psi)
Z = charge of species
F = faraday's constant
delta psi = change is membrane potential
inside --> outside : negative |
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Term
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Definition
| reversibly phosphorylated by ATP |
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Term
| what is the primary function of ABC transporters (ATP-binding cassette)? |
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Definition
| to pump AAs, peptides, proteins, metal ions, bile salts, and drugs OUT OF THE CELL against the concentration gradient |
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Term
| what is secondary active transport |
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Definition
| a transporter protein couples the movement of an ion (typically Na+ or H+) down its electrochemical gradient to the uphill movement of another molecule or ion against a concentration/electrochemical gradient |
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Term
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Definition
found in all organisms
water secretion by exocrine glands
play role in kidney urine production + water retention; can be regulated by hormones
VERY FAST- 10^9 molecules/s vs enzyme turnover 10^7/sec |
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Term
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Definition
very fast transport 10^7-8 ions/secvs 100/s by pumps
along with ion pumps, determine membrane potential |
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Term
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Definition
| open in response to ligand binding |
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Term
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Definition
| open to a change in membrane potential |
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Term
| what is the difference between voltage-gated channels and ion channels? |
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Definition
voltage-gated: open in response to change in membrane potential
ion channel- opens at specific pH |
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Term
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Definition
| conversion of information (signals) into a cellular response |
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Term
| what are the two modes of signal transduction |
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Definition
contact-dependent
secreted molecules |
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Term
| what are some examples of secreted molecules? |
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Definition
paracrine
endocrine- acts at very low conc
autocrine- acts on itself
synaptic- high conc b/c operating at very short distance and short period of time |
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Term
| what are key features of signal transduction |
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Definition
specificity
amplification
desensitization/adaptation
integration |
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Term
| what is specificity signal transduction? |
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Definition
signal molecule fits binding site on its complementary receptor; other signals don't fit
high affinity between signal and receptor can be expressed by dissociation constant, Kd |
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Term
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Definition
| affinity for receptor and ligand |
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Term
| what is amplification signal transduction |
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Definition
when enzymes activate enzymes, the number of affected molecules increases geometrically in an enzyme cascade
enzyme 1 makes 3 enzyme 2's and those enzyme 2's make 9 enzyme 3's |
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Term
| what is desensitization/adaptation signal transduction? |
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Definition
| turn down response even though signal persists; feedback circuit can turn off receptor or remove receptor from cell |
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Term
| what is signal integration signal transduction? |
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Definition
| ability to receive multiple signal sand produce a unified response |
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Term
| what happens when 2 signals have opposite effect on metabolic characteristic? |
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Definition
| the regulatory outcome and membrane potential results from the integrated input from both receptors |
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Term
| what are the 2 major classes of receptors for secreted molecules |
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Definition
intracellular
cell surface |
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Term
| what is an intracellular response |
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Definition
| cytosolic proteins activate pathway; ligands are usually hydrophobic molecules that readily permeate plasma membrane |
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Term
| what are nuclear receptors |
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Definition
type of intracellular response
proteins that traffic to the nucleus and regulate gene expression |
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Term
| what is a cell surface receptor |
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Definition
membrane proteins that bind ligands that are either too big or too hydrophilic to cross plasma membrane
cell-surface receptors coupled to intracellular biochemical reactions
conformational change results in either (1) generation of itnracellular signaling molecule known as second messenger or change in membrane potential (2) activation of enzyme cascades involving protein kinases, phosphatases, or proteases |
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Term
| what are signal transduction pathways |
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Definition
| cell-surface receptors coupled to intracellular biochemical reactions |
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Term
| what are the 3 essential components of G protein-coupled receptors? |
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Definition
cell-surface receptor
a G protein that cycles between active (GTP-bound) and inactive (GDP-bound)
an effector enzyme or ion channel |
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Term
| what does adenylyl cyclase do |
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Definition
| when alpha subunit w/GTP is attached, it cyclizes AMP to cAMP |
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Term
| what are the types of ligands |
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Definition
biological ligand
agonist
antagonist |
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Term
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Definition
| a structural analog that stimulates the receptor |
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Term
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Definition
| an analog that binds the receptor without triggering the normal signal, therefore blocking the effects of agonists, including the biological ligand |
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Term
| receptor tyrosine kinases do what |
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Definition
| have a cytolplasmic domain that is a kinase that phosphorylates tyrosine residues on target proteins |
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Term
| what does the binding ligand do in receptor tyrosine kinases |
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Definition
| stimulates autophosphorylation of the beta subunits at key residues |
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Term
| what is the general enzyme cascade pathway for insulin |
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Definition
insulin attaches through receptor tyrosine kinases
receptor is phosphorylated and active
phosphorylates tyrosine residues on protein
stimulates phos cascade that results in activation/transcription of target genes
insulin acts as growth factor |
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Term
| what are multivalent adaptor proteins |
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Definition
they can interact with several different proteins simultaneously and form multiprotein signaling complexes
proteins that aren't enzymes but transmit signal thru binding interactions |
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Term
| what are membrane rafts in further lectures |
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Definition
| regions rich in sphingolipids, sterols, and proteins attached by GPI anchors |
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
| guanylyl cyclase receptor signaling |
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Definition
receptor enzymes that convert GTP to cGMP
cGMP-dependent protein kinase (protein kinase G- PKG) phosphorylates target proteins on Ser and Thr residues |
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Term
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Definition
plasma membrane proteins that mediate adhesion of cells to each other and the extracellular matrix; carry signals in both directions across membrane
COLLAGEN; FIBRONECTIN |
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Term
| what is the importance of phosphoryl transfer reactions |
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Definition
| they are kinetically stable to hydrolysis and yet have the capacity to transfer large amounts of free energy |
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Term
| what are three of the roles of ATP in living systems |
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Definition
early state nutrient breakdown- glycolysis, fatty acid beta oxidation
interconversion of nucleotide triphosphates by nucleotide diphosphate kinase
physiological processes: hydrolysis of ATP to ADP and Pi to energize endergonic physiological processes |
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Term
| what are two ways ATP is formed |
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Definition
| substrate-level phosphorylation- ATP from ADP and phosphoryl group transfer |
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Term
| what is the cleavage step of glycolysis |
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Definition
step 4
cleavage of fructose 1,6-bisphosphate to dihydroxyacetone phosphate and glyceraldehyde 3-phosphate (GAP) VIA aldolase |
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Term
| what is the interconversion step of glycolysis |
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Definition
5
dihydroxyacetone phosphate to glyceraldehyde 3-phosphate via triose phosphate isomerase (TPI) |
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Term
| what step is the first real harvest of energy in the presence of oxygen (glycolysis) |
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Definition
6
oxidation of glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate via glyceraldehyde 3-phosphate dehydrogenase (GAPDH) |
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Term
| what is first step of energy harvest if you're oxygen deprived in glycolysis? |
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Definition
step 7
phosphoryl transfer from 1,3-bisphosphoglycerate to ADP (+4-phosphoglycerate) via phosphoglycerate kinase |
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Term
| at what point in glycolysis does the ATP yield equal the ATP input? |
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Definition
7
phosphoryl transfer from 1,3-bisphosphoglycerate to ADP (+4-phosphoglycerate) via phosphoglycerate kinase |
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Term
| where does glycerol come from |
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Definition
adipose tissue
triacylglycerol --> glycerol |
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Term
| where does alanine come from |
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Definition
muscle
alanine is predom AA released from muscle during fasting
ALANINE CYCLE exchanges alanine and glucose between SM and liver |
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Term
| what upregulates phosphofructokinase-I (step 3 of glycolysis)? |
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Definition
| AMP, ADP and fructose 2,6-bisphosphate |
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Term
| what downregulates phosphofructokinase-I (step 3 of glycolysis)? |
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Definition
ATP, citrate
(if you have high ATP in cell, don't need to make more) |
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Term
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Definition
LOW glucose levels
acts at glucagon receptors (GPCR) |
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Term
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Definition
| glycogen breakdown and inhibits glycogenesis; also stimulates gluconeogenesis |
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Term
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Definition
LOW glucose levels or energy required
acts on beta-adrenergic receptors |
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Term
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Definition
glycogen breakdown + inhibits gluconeo
glucagon and epinephrine both stimulate intracellular pathway via inc levels of cAMP |
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Term
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Definition
| increases of glycogenesis and decreases of glycogen breakdown |
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Term
| how is storing glucose as a polymer helpful |
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Definition
| it avoids large increases in osmotic pressure in a cell |
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Term
| can fats be converted to glucose or catabolized anaerobically |
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Definition
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Term
| what enzyme is responsible for breaking down glycogen in LINEAR |
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Definition
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Term
| what enzyme is responsible for breaking down glycogen in BRANCHING |
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Definition
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Term
| what enzyme converts glucose 1-phosphate to glucose 6-phosphate |
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Definition
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Term
| what amino acid residues would most likely be found in the transmembrane helices? |
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Definition
tryptophan
phenylalanine
tyrosine |
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Term
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Definition
| hydrolyzes ATP to use for for transfer of molecule UP its concentration gradient |
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Term
| secondary active transport |
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Definition
moves from high to low concentration
symporter |
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