Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
99 Cards in this Set
- Front
- Back
|
endergonic |
energy consuming |
|
|
exergonic |
energy yielding |
|
|
an (endergonic/exergonic) reaction must occur for any change --- but often.. |
exergonic, but often reactions are coupled for a net exergonic result |
|
|
can ATP cross cellular membranes? |
no because it is very highly charged |
|
|
dehydrogenase enzymes |
transfer hydrogen (in a red-ox reaction) |
|
|
what energy source drives fatty acid synthesis (and others) |
NADPH |
|
|
redox potential is standardized against the potential of a |
hydrogen electrode (at pH of 7.0, potential is .42 volts) - this is how we apply and measure data |
|
|
free energy (delta G) is |
the portion of total energy change in a system that is available for doing work (measured in joules or calories) |
|
|
when delta G is negative, |
energy is transferred or liberated |
|
|
a very negative delta G means... |
the products are more stable (less likely to reverse reaction) |
|
|
why are enzymes catalyzing a large negative delta G good rate limiters? |
the reactions are unlikely to reverse |
|
|
factors affection reaction rates of enzymes (3) |
pH temperature concentration of substrate |
|
|
how does pH affect the charge of an enzyme |
decreasing pH below the isoelectric point will decrease the negative charge (and affect the reaction rate of the enzyme) |
|
|
how can temperature affect enzymatic activity |
increasing temp increases kinetic energy (and frequency of substrate/enzyme contact) too much temp will denature the protein so a high fever can affect enzymatic activity |
|
|
velocity of an enzymatic reaction is measured in |
moles hydrolyzed per time (standardized per amount of protein) |
|
|
zero order reaction |
flux (mol product produced/time) = k flux is constant regardless of the amount of substrate graph would be a straight line |
|
|
first order reaction |
flux = kS rate is constant but flux is NOT rate of enzymatic activity is proportional to [S] |
|
|
second order reaction |
Michaelis-Menten derivation Vi = (Vmax)[S] / Km + S no constant relationship between rate and [S] |
|
|
Km's relationship to Vmax |
Km is = to 1/2 Vmax |
|
|
3 ways of regulation when more than one enzyme responds to the same substrate: |
feedback inhibition ([s]) genes controlling synthesis or degradation of enzyme (long term situation) compartmentalization in cytosol and mitochondria (to prevent competition) |
|
|
lineweaver-burk plot for classic competitive inhibition vs reversible non-competitive inhibition |
competitive - crosses at y axis; inhibitor mimics the ligand so more substrate is needed to outcompete (increases Km) Vmax is the same reversible - crosses at x axis; Vmax is decreased (i.e. the orientation or the charge of the enzyme might be altered by the inhibitor) |
|
|
what do the Vi vs. S graphs look like for competitive vs. non competitive inhibition |
competitive has a decreased km but same max non competitive has the same km but decreased max |
|
|
purified vs not purified enzyme |
purified tells you enzyme activity (i.e. vmax is always the same) non purified tells specific activity (i.e. activity of enzyme in a muscle biopsy) |
|
|
enzyme regulation: induction |
increases the enzyme's synthesis to increase |
|
|
enzyme regulation: constitutive |
amount of enzyme cannot be induced (regardless of gene expression, enzyme amount will always stay the same) |
|
|
enzyme regulation: repression |
decreases the enzymes synthetic rate |
|
|
enzyme regulation: mRNA stability |
regulation of the concentration of mRNA (mRNA can travel to the ribosome a lot.. stable.. or a little. |
|
|
enzyme regulation: enzymatic turnover |
increases the enzymes degradation rate |
|
|
enzyme regulation: allosteric effectors |
change in structure or function of the enzyme caused by dissociable ligands (typically bind somewhere other than the catalytic site) effectors can be positive or negative to increase or decrease flux |
|
|
enzyme regulation: covalent |
formation or hydrolysis of chemical bonds to change the structure/function of an enzyme i.e. phosphorylation |
|
|
kinase |
enzyme that adds a phosphate |
|
|
enzyme regulation: feedback inhibition |
inhibition of enzymatic activity in a pathway by an end product of that pathway typically allosteric on the first committed step of the pathway |
|
|
push vs pull in an [A] --> [B] metabolism |
increasing [A] pushes decreasing [B] pulls |
|
|
how do you control metabolism in the short term vs long term? (via enzyme) |
short term: change specific activity (not concentration), change concentration of coupled reactants i.e. NAD:NADH, reversible covalent modification (phosphorylation), move proteins w/in cell (moving GLUT 4 from cytosol to cell surface) long term: change concentration of enzyme in cell w/ no change in Km or Vmax |
|
|
order of digestion |
pre stomach stomach pancreatic enzymes small intestine (brush border membrane enzymes) |
|
|
pre stomach digestion: |
salivary amylase (no big deal) |
|
|
acid and pepsin _______ |
unfold proteins |
|
|
pancreas releases digestive enzymes into: |
duodenum |
|
|
alpha amylase |
from pancreas digests starches |
|
|
trypsin and chymotrypsin |
from pancreas digests proteins |
|
|
lipases and colipases |
from pancreas digests triglycerides |
|
|
most digestion happens in the |
ilium |
|
|
ascending colon does... |
fermentation, 10% of energy production and H2O absorption |
|
|
colon has... |
microbiome |
|
|
brush border enzymes: |
sucrase, alpha-dextrinase, glucoamylase, lactase |
|
|
primary vs secondary lactose intolerance |
primary - genetic secondary - acquired; damage to mucosa |
|
|
GLUT2 works both directions |
high CHO diet can bring GLUT2 to brush border ALSO since we don't want to waste any carbs |
|
|
RBC energy production: |
no mitochondria (so glycolysis only) |
|
|
why does the brain not produce lactate? |
O2 is always available - no glycogen storage either - very high energy demand |
|
|
gums and mucilages |
similar to cell wall constituents not a major part of diet but often added |
|
|
resistant starch |
not digestible (raw potato) |
|
|
why is fiber good? |
satiety absorption of glucose slowed by soluble fiber (acts like a speed bump) - attenuated blood glucose can interfere with reabsorption of cholesterol in bile energy for colonocytes (and benefit gut health via both cells and bacteria) |
|
|
how does fiber affect satiety |
increases distention of stretch receptors (increases feeling of fullness) |
|
|
fiber degradation and fermentation |
starts as cellulose, pectin, or any resistant starch --> oligosaccharides --> glucose --> pyruvate pyruvate can go 4 different ways: lactate, succinate, acetyl coa, co2 + h2 ADP/ATP and NAD/NADH huge regulators of which way this pathway goes end product of: methane 2 acetate 1 butyrate or 2 propionate methane and propionate pathways USE NADH acetate and butyrate PRODUCE NADH |
|
|
dietary high fat affect on gut microbiota (4) |
improves cell growth, proliferation, apoptosis and motility better gut barrier function improved insulin sensitivity improved detoxification |
|
|
normal blood glucose concentration |
80 to 120 mg/dl (about 4.4 to 6.7 mM) |
|
|
can double after a CHO rich meal bc |
rate of glucose absorption is greater than blood glucose uptake by tissues |
|
|
2 tier blood glucose response |
liver gets what it wants 1st (about 1/3 of glucose) muscles 2nd |
|
|
hexokinase: |
traps glucose inside cells for rapid conversation to G-6-P (to keep concentration gradient high and sugar continually coming into the cell) high affinity for glucose expressed in most tissues (muscle) |
|
|
glucokinase |
in liver low affinity (but very specific to glucose) |
|
|
substrate level control via GLUT 2 |
high CHO meal increases glucose levels, increases flux through GLUT 2 (not glut 1 or glut 3 since they're always at vmax so they can't increase transport rate) |
|
|
SGLT1 |
controlled via expression of SGLT1 (not act of substrate since it has such a high affinity) uni directional (in) brings in water with glucose |
|
|
GLUT 5 |
pull in fructose that gets past the liver rarely pulls in glucose (low affinity) not in the pancreas because we want liver and muscle to get fructose first |
|
|
GLUT 1 |
similar to GLUT 3 very universal basal glucose transporter (glucose metabolism at rest) activity depends on expression of transporter (again, high affinity so its not depending on amount of substrate) |
|
|
GLUT 2 |
in kidney so glucose gets pulled out of urine associated with GK (liver and pancreas) insulin increases transcription of GK in liver high kt and km so increased blood glucose increases transport (not always at vmax like others) |
|
|
GLUT 4 |
in skeletal and cardiac muscle glucose only insulin binding required to move GLUT 4 to plasma membrane - then GLUT 4 degraded when insulin decreases low kt for glucose (so again increased glucose will increase activity) |
|
|
compartmentalization of G6P |
helps control flux of enzyme pathways (lots compete for G 6 p) G6P --> pyruvate G6P increases affinity of GK to GKRP in post absorptive phase (not absorptive bc G6P is used right away) |
|
|
fructose metabolism is independent from glucose metabolism but can help the liver absorb more glucose by: |
F-1-P (increasing GK concentration in cytosol) |
|
|
fructose metabolism in liver: |
uptake via GLUT 5 and GLUT 2 bipasses bifunctional enzyme (so independent from glucose metabolism |
|
|
insulin regulation on GK and G6Pase |
regulated oppositely by insulin to prevent a cycle that would waste ATP |
|
|
glucose transport and B cell |
glucose in via GLUT 2 increases G 6 P and stimulates insulin secretion increases GK transcription insulin inhibits G 6 P ase gene in liver (so G 6 P stays high as long as glucose is brought in) |
|
|
pancreas response to insulin |
basically unresponsive in the short term regulated via blood glucose concentration (substrate level regulation) |
|
|
muscle response to insulin |
take up more glucose via 2nd tier responses HK phosphorylates G6P (which will build up and inhibit HK) - glucose only taken in as fast as G 6 P ase can use it for energy or glycogen storage |
|
|
alpha cells |
in pancreas secrete glucagon when blood glucose declines (promotes gluconeogenesis and glycogenolysis in liver |
|
|
muscle glucagon response |
no glucagon receptors low insulin allows basal glycogenolysis (for glycogen storage in muscle) |
|
|
B cells after a rise in blood glucose: |
mediated by GLUT2 glucose --> pyruvate is increased biproduct ATP goes to K+ channels to open Ca2+ channels Ca2+ causes insulin vesicle to move to membrane and release insulin into blood |
|
|
taste receptors and GLUT2 |
taste receptors activate T1R2/3 which send GLUT2 FROM the apical membrane TO the brush border (GLUT2 is bidirectional) to help digestion after a high carb meal |
|
|
your kidneys and SGLT2 function |
SGLT2 transfers glucose out of your kidneys (out of your pee) and then GLUT2 transfers it to blood |
|
|
Glycemic index vs glycemic load |
GI = AUC test food/ AUC reference x 100 GL standardizes for starch (only accounts amount of digestible carb) |
|
|
incretins |
insulin secretion factors GLP 1 and GIP prelim stimulation for large release of insulin by B cell have a short half life- sustained increase in concentration needs to have sustained trigger (sustained levels of glucose) |
|
|
cAMP and adenylyl cyclase |
AC is transporter of cAMP epi glucagon and ACTH will activate AC for more cAMP PGE and adenosine will inhibit AC for less cAMP cAMP is the perfect second messenger (so I:G ratio has huge affect on cAMP control) cAMP --> PKA --> CREB --> increased G6Pase and PEPCK --> decreased transcription of glycolytic enzymes in the liver |
|
|
after insulin binds |
PI3K activation --> Akt activation --> GLUT 4 translocation --> glucose uptake and glycogen synthesis |
|
|
protein kinase C |
increased epi --> phospholipase C --> protein kinase C --> more Ca at membrane for muscle |
|
|
antagonist vs agonist |
antagonist: binds to receptor without eliciting a biological response (blocker) agonist: binds and stimulates activity (often positive control |
|
|
what catalyzes the first committed step in glycolysis |
PFK1 |
|
|
glyceraldehyde 3 P dehydrogenase |
crates high energy P bonds which are used to generate ATP by phosphoglycerate kinase (PK) in the next step of glycolysis |
|
|
what happens to NADH from G3P dehydrogenase |
2 NADH byproducts made in that step need to regenerate back to NAD or the rate of glycolysis will slow down NADH used for OAA --> malate step in krebs (so note importance of mitochondria to cytosol shuttle) OR pyruvate --> lactate will also produce NAD in anaerobic conditions for G3P d step to continue *rate limiting step* |
|
|
phosphoenolpyruvate |
PEP last reversible reaction in glycolysis FIRST CYTOSOLIC step in gluconeogenesis |
|
|
pyruvate kinase |
PEP ADP --> pyruvate ATP irreversible, so rate limiting step much more regulated in liver than muscle (because muscle wants to make and use glucose.. liver needs to save and share w/ other tissues) |
|
|
net reaction for glycolysis: |
Glu + 2 ATP + 2 NAD + 4 ADP + 2 Pi --> 2 pyr + 4 ATP + 2 NADH _ 2 ADP + 2 H2O (+2ATP) basically....5-7 ATP produces/mol glucose 2.5 ATP produced in ox/phos |
|
|
steps of glycolysis |
glucose to glucose 6 phosphate (via HK) (rate limiting) to fructose 6 phosphate (via PFK 1) (rate limiting) to fructose 1 6 bisphosphate to ...... PEP to 2 pyruvate (via PK and 2 ATP produced) |
|
|
fructose and the liver |
most fructose taken up in liver because HK not expressed well HK can equally take in fructose and glucose but a low affinity for GKRP in liver makes GK more active to fructose |
|
|
galactose entry into glycolysis |
converted to ...... glucose 6 phosphate and enters there |
|
|
mannose entry into glycolysis |
converted to fructose 6 phosphate and enters there |
|
|
fructose entry into glycolysis |
converted to fructose 6 phosphate via HK only (vs glucose --> glu 6 p uses HK and GK) |
|
|
location for gluconeogenesis |
mostly liver, kidney too b/c these two have g 6 p ase to allow free glucose back into the blood (otherwise g 6 p stuck in cells) |
|
|
where does gluconeogenesis occur in the cell |
in the cytosol |
|
|
steps of gluconeogensis starting from glycerol |
basically glycolysis backwards except rate limiters glycerol (from FFA mobilization of adipose) to G 3 P via glycerol kinase to glyceraldehyde 3 phosphate via glycerol 3 phosphate dehydrogenase (and NADH to NAD) then jumps into reverse glycolysis F 1 6 diphosphate to F 6 P via F 1 6 biphosphatase to G 6 phosphate to glucose via G 6 phosphatase all these enzymes only go one way.. so they're rate limiters |
|
|
steps of gluconeogenesis starting from PEP |
PEP can enter in the bottom of reverse glycolysis to pyruvate malate --> OAA --> PEP (from citric acid) starts in mitochondria and needs to be moved to cytosol |
