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blood glucose concentration in the body
5 mM
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grams of glucose in blood
6 grams
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glucose oxidation equation:
Glucose + 6O2 --> 6CO2 + 6H2O + energy
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what is aerobic glycolysis
oxidative decarboxylation of pyruvate to acetyl CoA
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aerobic glycolysis equation:
Glucose + 2ADP + 2Pi + 2NAD+ --> 2Pyruvate + 2ATP + 2NADH + 2H+ + H2O
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net ATP gain of aerobic glycolysis
2 ATP
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molecules of NADH produced per glucose
2 molecules of NADH
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what is anaerobic glycolysis
pyruvate is reduced to lactate as NADH is oxidized to NAD+
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anaerobic glycolysis equation:
Glucose + 2ADP + 2P --> 2Lactate + 2ATP +2H2O
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molecules of ATP generated for each molecule of glucose in anaerobic glycolysis
2 ATP
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net gain/loss of NADH in anaerobic glycolysis
no net production or consumption
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what is reductive biosynthesis
using reduction to build up something
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what is glycolysis followed by
TCA cycle and electron transport chain
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where does the TCA cycle occur
mitochondrial matrix
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where does electron transport chain occur
inner mitochondrial membrane
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what tissues go through anaerobic glycolysis?
erythrocytes, leukocytes, lens, cornea, medulla of the kidney, testes, ischemic tissues
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which produces more ATP, aerobic or anaerobic glycolysis?
aerobic glycolysis
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why do we have inefficient anaerobic process?
faster, easier, less complicated. may not have the time/resources to go the aerobic route.
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what type of fibers do skeletal muscles consists of?
type I and II fibers
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Type I fibers are more aerobic/anaerobic and Type II fibers more aerobic/anaerobic.
- type I: more aerobic
- type II: more anaerobic
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Type I fibers are richer/fewer in mitochondria and Type II fibers are richer/fewer in mitochondria.
- type I: richer in mitochondria
- type II: fewer in mitochondria
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Type I fibers are dominant in muscles associated with _______
endurance (marathon runners)
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Type II fibers are dominant in muscles associated with _________
rapid movement (sprinters)
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Type I fibers are _____ to fatigue. Type II fibers are _____ to fatigue
- Type I: resistant
- Type II: easy
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Type I fibers are _____ twitch. Type II fibers are _____ twitch.
- type I: slow (dark meat)
- type II: fast (white meat)
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what are the 2 phases of glycolysis?
energy investment phase and energy generation phase
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what is the energy investment phase?
phosphorylated forms of intermediates are synthesized at the expense of ATP (breaking down ATP to invest in glycolysis)
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The energy investment phase is _____, and the energy generation phase is _____. (endergonic/exergonic)
- investment: endergonic
- generation: exergonic
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How much ATP is gained/used in energy investment phase?
2 ATP are broken down
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what is the energy generation phase?
net of 2 ATPs is formed by substrate-level phosphorylation per glucose molecule metabolized
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energy generation phase: _____ ATP are produced and _____ NADH are produced.
4 ATP, 2 NADH
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What are the 3 irreversible/regulatory glycolytic enzymes?
hexokinase, phosphofructokinase, pyruvate kinase
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what enzyme catalyzes the phosphorylation of glucose?
hexokinase
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what enzyme catalyzes the isomerization of glucose-6-phosphate to fructose-6-phosphate?
phosphoglucose isomerase
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what are hexokinase and glucokinase?
isozymes
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Hexokinase has product inhibition by _____
glucose-6-phosphate
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Hexokinase has a _____ affinity and a _____ capacity for glucose.
- high affinity (low Km)
- low capacity (low Vmax)
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What does high affinity of glucose allow?
efficient phosphorylation and subsequent metabolism of glucose even when concentration is low
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what does low capacity allow?
prevents cell from trapping more sugars than it can use
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Glucokinase functions to _____ _____ from the blood.
remove glucose
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Liver channels glucose in _____ _____. Beta cells of pancreas will respond by _____ _____.
- storage pathways
- secreting insulin
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Glucokinase has a _____ affinity and a _____ capacity for glucose.
- low affinity (high Km)
- high capacity (high Vmax)
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what does low affinity allow?
functions only when glucose level is high (right after you eat)
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What does high capacity allow?
allows liver to effectively remove flood of glucose; prevents large amounts of glucose from entering systemic circulation after eating
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Hexokinase is found in _____ cells and glucokinase is found in _____ cells.
- hexokinase: most cells
- glucokinase: liver and pancreatic beta cells
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Hexokinase is _____ by glucose 6-phosphate. Glucokinase is _____ by glucose 6-phosphate.
- hexokinase: inhibited
- glucokinase: not inhibited
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Hexokinase is _____ by insulin.
Glucokinase is _____ by insulin.
- hexokinase: not inducible
- glucokinase: inducible
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What happens when you have high glucose levels after a meal (post-prandial)?
liver glucokinase stores glucose as glycogen
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glucokinase is indirectly inhibited by _____ and indirectly stimulated by _____.
- fructose 6-phosphate
- glucose
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phosphorylation of glucose prevents leakage of _____ from the cell because it is not recognizable by the _____.
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Why is glucose 6-phosphate not recognizable by the GLUT?
glucose can leave the cell through the GLUTs. once you add the phosphate, it's more polar and more difficult to leave.
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What is GKRP and what does it do?
- glucokinase regulatory protein
- regulates activity of glucokinase through reversible binding
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What happens to GKRP in presence of fructose 6-phosphate?
glucokinase is translocated into the nucleus and binds tightly to GKRP, inactivating glucokinase
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What happens to GKRP in presence of glucose?
it will release glucokinase from storage form and make GKRP available for phosphorylating glucose to glucose 6-phosphate
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What happens when you no longer need glucokinase?
it goes back in storage form in the nucleus (GKRP) and is protected there
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Mice deficient in GKRP do not respond rapidly to injected glucose. Why?
absence of a nuclear reserve of glucokinase
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What is the most important control point of the energy investment phase?
fructose 6-phosphate --> fructose 1,6-bisphosphate
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What is the enzyme for the reaction: fructose 6-phosphate --> fructose 1,6-bisphosphate?
- phosphofructokinase-1
- rate limiting, committed, regulated step
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Phosphofructokinase-1 is activated by...
- AMP
- fructose 2,6-bisphosphate
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Phosphofructokinase-1 is inhibited by...
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Inhibition of phosphofructokinase-1 leads to the accumulation of _____.
glucose 6-phosphate
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What can the accumulation of glucose 6-phosphate be routed towards?
- gluconeogenesis in liver or kidney
- glycogen synthesis
- hexose monophosphate shunt
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phosphofructokinase-2 is a _____ enzyme: both a _____ and a _____.
- bifunctional
- phosphatase
- kinase
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Kinase activity of phosphofructokinase-2 produces _____.
- fructose 2, 6-bisphosphate
- (adds phosphate to fructose 6-phosphate)
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phosphatase activity of phosphofructokinase-2 produces _____.
- fructose 6-phosphate
- (dephosphorylates fructose 2,6 bisphosphate)
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Glycolysis is ACTIVATED by:
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glycolysis is INHIBITED by:
- glucagon
- ATP
- NADH
- cyclic AMP
- Acetyl CoA
- Citrate
- product inhibition
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What is short term regulation?
- allosteric activation/inhibition
- de/phosphorylation of rate-limiting enzymes
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What is long term regulation?
insulin/glucagon induce/repress the transcription of glycolytic enzyme genes
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15-25% of glucose converted to lactate in erythrocytes is shuttled through _____ _____
BPG shunt
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What induces synthesis of 2,3-BPG?
hypoxia
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2,3-BPG is found only in _____?
red blood cells
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What enzyme catalyzes PEP --> pyruvate?
pyruvate kinase
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What is special about pyruvate kinase?
it REMOVES a phosphate instead of adding one
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Pyruvate kinase is activated by:
fructose 1,6-bisphosphate
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Deficiency of _____, _____, and _____ can lead to hemolytic anemia.
- aldolase
- triode phosphate isomerase
- pyruvate kinase
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Why are red blood cells more affected by pyruvate kinase deficiency?
- not a lot of redundancy
- no nucleus or mitochondria
- energy in RBC used to fuel pumps that give it biconcave, flexible shape
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_____ deficiency in mice appears to be protective against _____.
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What is the result of phosphofructokinase deficiency?
- excess glucose 6-phosphate
- (fructose 6-phosphate will isomerize)
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What is added to blood samples and why?
- sodium fluoride
- in order to stop glycolysis
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_____ ions inhibit enolase (an enzyme associated with glycolysis).
fluoride ions
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What is the mechanism for arsenic toxicity?
substitution of phosphorous anion in phosphate, preventing ATP and NADH synthesis.
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What enzyme catalyzes pyruvate --> lactate?
lactate dehydrogenase
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What are the 3 pathways for lactate?
- 1. aerobic: don't make it in the first place
- 2. anaerobic: mostly pyruvate --> lactate
- 3. don't use lactate locally, diffuses into blood
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Pyruvate --> Lactate serves to oxidize _____ to _____.
NADH to NAD+, providing more NAD+ for continued anaerobic glycolysis
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What is the final product of anaerobic glycolysis in eukaryotic cells?
lactate
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Which tissues derive their energy from anaerobic glycolysis?
erythrocytes, skeletal muscles in state of exertion, lens and cornea of the eye, testes, leukocytes, and kidney medulla.
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Lactate can be used by the ______ to generate glucose.
liver
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Lactate can be used by the _____ or _____ to regenerate pyruvate.
heart or kidney
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heart exclusively oxidizes _____ to _____ and _____ via the citric acid cycle.
lactate to CO2 and H2O
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in liver and heart, the ratio of NADH/NAD+ is _____ than in exercising muscle.
lower
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What is responsible for most of the muscle soreness felt on days following physical exertion?
tears in the muscle NOT lactate
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What are the 3 processes of glucose oxidation?
- 1. glycolysis
- 2. TCA cycle
- 3. electron transport chain
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These conditions raise the NADH/NAD+ ratio and promote the formation of lactate:
- 1. CO poisoning
- 2. sickling crisis
- 3. ischemic tissue
- 4. myocardial infarction
- 5. mitochondrial disease
- 6. warburg effect
- 7. alcohol intoxication
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What is the Warburg effect?
most cancer cells are anaerobic
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Alcohol intoxication is the _____ leading risk factor for death/disability.
5th
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Alcohol intoxication can lead to _____ _____ .
liver cirrhosis
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The oxidation of alcohol results in significant amounts of _____ in the liver.
NADH
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What is another way of metabolizing ethanol?
it will be metabolized as a xenobiotic and associated with CYPs
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What does MEOS stand for?
microsomal ethanol oxidizing system
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Citric Acid Is Kreb's Starting Substrate For Mitochondrial Oxidation
Citrate Aconitrate Isocitrate alpha-Ketoglutarate Succinyl CoA Succinate Fumarate Malate Oxaloacetate
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What happens in the TCA cycle?
oxidation of carbs, proteins, and lipids
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What other processes can the TCA cycle participate in?
transamination, deamination, lipogenesis, gluconeogenesis
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TCA cycle produces reduced co-enzymes _____ and _____
NADH and FADH2
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_____ genetic defects are associated with the TCA cycle.
few
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What kind of metabolism is the TCA cycle?
Amphibolic, both anabolic and catabolic
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Where are the TCA enzymes located?
mitochondrial matrix
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What enzyme catalyzes pyruvate --> acetyl CoA?
pyruvate dehydrogenase complex
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What 5 specific nutrients does the pyruvate dehydrogenase complex require?
thiamine, pantothenic acid, niacin, riboflavin, and lipoid acid
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Pyruvate Dehydrogenase Complex is ACTIVATED by:
calcium
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Pyruvate Dehydrogenase Complex is INHIBITED by:
acetyl CoA, NADH, and ATP
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phosphorylating PDH _____ it.
dephosphorylating PDH _____ it.
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Energy production of TCA cycle:
- 3 NADH --> 3 NAD+ : 3 ATP per (9)
- FADH2 --> FAD : 2 ATP per (2)
- GDP --> GTP : 1 ATP per (1)
12 ATP total
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TCA cycle is INHIBITED by:
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What does the TCA cycle generate?
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What is oxidative phosphorylation the opposite of?
substrate level phosphorylation
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How is the inner mitochondrial membrane arranged?
arranged in cristae
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What is the purpose of the cristae in the inner mitochondrial membrane?
increases the surface area
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The enzymes associated with oxidative phosphorylation and electron transport are located in the _____.
inner mitochondrial membrane
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Inner membrane is highly _____ to small ions, small and large molecules.
impermeable
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Outer membrane is highly _____ to small ions, small and large molecules.
permeable
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The space between the inner and outer membrane is called the _____.
intermembrane space.
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What does the mitochondrial matrix contain?
TCA cycle enzymes, fatty acid oxidation enzymes, mtDNA, mtRNA, and mitochondrial ribosomes
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Electron transport chain uses electrons in such a way that you can generate _____.
ATP
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ETC shuttles electrons around to reduce _____ and eventually end up making _____.
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mitochondrial metabolic water
makes less than 10% of the amount we need
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As you move forward in the ETC, there is a _____ affinity for the electron until you reach O2.
higher affinity
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What is the free energy change in the ETC utilized for?
to pump H+s from the matrix into the intermembrane space
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How can the electrons in oxidative phosphorylation be transferred?
as lone electrons, hydrogen atoms, or hydride ions.
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What does the free energy change in ETC result in?
electrochemical gradient
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Energy released from electrochemical gradient will be harnessed to make _____.
ATP
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Why doesn't the ETC make as much ATP as it could?
- losses from inefficiency
- complexes use energy
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How is the electrochemical differential is resolved and where does it occur?
- by the H+s entering into the mitochondrial matrix
- point of entry is complex V
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What is the chemiosmotic theory?
proton motive force; free energy generated by ETC is used to produce ATP
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Where is ATP synthase located?
Complex V
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What is the ultimate acceptor of electrons in ETC?
oxygen
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How many molecules of H2O are produced for each molecule of both FADH2 and NADH?
1 molecule of water
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What enzyme catalyzes the synthesis of water and where is it located?
cytochrome oxidase on complex IV
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What is the electron transport chain composed of?
3-5 protein complexes and two mobile carriers
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What type of proteins are the complexes in ETC?
integral inner mitochondrial membrane proteins
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What are the two mobile carriers in ETC?
coenzyme Q (ubiquinone) and cytochrome c
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What kind of molecule is coenzyme Q (ubiquinone)?
derivative of quinone, NOT a protein
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Coenzyme Q (ubiquinone) possesses _____.
significant anti-oxidative capabilities
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ETC proteins may contain _____ or _____.
iron-sulfur or copper
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What is special about ETC cytochromes?
can switch back between ferrous and ferric states (unlike hemoglobin)
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ETC proteins may be _____ or _____.
flavoproteins or cytochromes
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ETC proteins may possess _____.
enzymatic ability
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Oxidative phosphorylation of the ETC complements _____.
substrate level phosphorylation
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What is a P:O ratio?
number of moles of ATP synthesized relative to the number of moles of O2 consumed
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What is the P:O ratio of NADH?
3
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What is the P:O ratio of FADH2?
2
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What is the approximate energy yield from aerobic respiration?
- 38 ATP
- (8 from glycolysis, 6 from pyruvate dehydrogenase, and 24 from TCA cycle)
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What is the free energy of hydrolysis of an ATP?
7.3 kcal/mole
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What is the efficiency of ATP synthesis?
39.4% efficiency of ATP synthesis
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What is the function of site-specific inhibitors?
prevent the passage of electrons in the ETC
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What are examples of site-specific inhibitors?
rotenone, amytal, antimycin, sodium azide, cyanide, carbon monoxide
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Rotenone is a _____ and _____.
insecticide and piscicide
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Amytal is a _____.
barbiturate (sedative)
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Antimycin is a _____.
piscicide
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Sodium azide (N3) is used as a _____.
chemical preservative
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Cyanide and carbon monoxide bind to _____ to prevent the last step.
cytochrome oxidase
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Oligomycin binds to a specific domain of _____ and blocks the H+ channel.
ATP synthase
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What is the function of oligomycin?
transport of electrons into the mitochondrial matrix.
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What do uncoupling proteins create and what does that allow?
proton leak, allows protons to reenter the mitochondrial matrix without capturing energy as ATP
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What is the energy from the proton leak used for?
heat production, NOT ATP production
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What molecules possess uncoupling capacity?
- bilirubin
- thyroxine
- ionophores
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Uncoupling occurs naturally in ______.
brown adipose tissue
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Why is brown adipose tissue brown?
rich in mitochondria
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What is thermogenin?
an uncoupling protein found in brown adipose tissue good for generating heat.
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What does thermogenin do?
increases the permeability of the inner membrane to H+ ions
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Why do newborn babies have brown adipose tissue?
- they can't shiver
- can't feed themselves
- higher ratio of surface to volume
- larger heads so heat escapes
- little body hair
- no effective blood vessel constriction
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What is the cause of mitochondrial disorders?
genetics
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What kind of tissues are mitochondrial disorders associated with? What are examples?
tissues that require critical levels of operant energy, examples: muscular or nervous system
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Do you have mitochondria in every cell of your body, and can they vary?
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Who do you get mitochondria from?
- mother
- sperm does not deliver mitochondria
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The mitochondrial genome consists of _____ base pairs?
16.5 thousand base pairs
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What shape is the mitochondrial genome?
circular
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The mitochondrial genome codes for _____ genes.
37 genes
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Is the mitochondrial genetic code identical to other organisms?
No, genetic code isn't universal
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90% of proteins associated with oxidative phosphorylation are encoded in the cell _____ and imported into the _____.
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_____ and _____ are variable for the mitochondria.
number and shape
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Rate of mutation in _____ genome is approximately 10x greater than _____ genome.
mitochondrial genome > nuclear genome
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How are mitochondrial disorders inherited?
maternal, autosomal dominant/recessive, and sec-linked dominant/recessive
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Mitochondrial _____ is released in response to cell death stimulus.
cytochrome c
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Release of mitochondrial cytochrome c leads to formation of the _____.
apoptosome
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What is an apoptosome?
large protein complex
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The apoptosome is involved in the initiation of the _____ _____.
caspar cascade
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Fasting or vigorous exercise ______ the amount of blood glucose.
reduces
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What is gluconeogenesis?
synthesis of new glucose
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What is glycogenolysis?
breakdown of glycogen to individual glucose molecules
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What 5 tissues are glucose essential for?
- brain
- erythrocytes
- adipose tissue
- skeletal muscle
- mammary gland
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What happens in the Cori Cycle?
- Muscle anaerobically makes lactate
- lactate goes through blood to liver
- lactate makes glucose in liver
- glucose is released into blood
- glucose taken up by muscle
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_____ is oxidized to _____ in the mitochondria in glycolysis.
NADH oxidized to NAD+
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In the absence of oxygen, _____ is regenerated by the formation of _____.
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Pyruvate -----> Lactate is catalyzed by _____.
pyruvate dehydrogenase
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What are 3 carbon sources for gluconeogenesis?
- 1. glycerol released from adipose lipolysis
- 2. muscle lactate
- 3. glycogenic amino acids
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Why does muscle not engage in gluconeogenesis?
- missing the essential enzyme glucose 6-phosphatase
- muscle lactate is transported to the liver
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What amino acid can be used as a source of carbon for gluconeogenesis?
alanine (glucose--alanine cycle)
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Where does gluconeogenesis occur?
primarily in the liver
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Where are gluconeogenesis enzyme located?
primarily in the cytosol
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What is glucose 6-phosphatase bound to?
smooth ER
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Where is pyruvate carboxylase located?
mitochondrial matrix
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How many reactions are bypassed by gluconeogenesis and why?
- 3 irreversible reactions
- large negative change in free energy
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Gluconeogenesis: CO2 is activated and transferred by _____ to its biotin prosthetic group.
pyruvate carboxylase
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Pyruvate carboxylase transfers CO2 to pyruvate, generating _____.
oxaloacetate
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_____ cannot cross the mitochondrial membrane, so it is reduced to _____.
-
In the _____, malate is re-oxidized to oxaaloacetate.
cytosol
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In the cytosol, oxaloacetate is converted to _____ by _____.
- phosphoenolpyruvate (PEP
- PEP carboxykinase
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In humans, PEP carboxykinase is located in both the _____ and the _____, but only the _____ enzyme participates in gluconeogenesis.
- cytosol
- mitochondria
- cytosolic
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What enzyme catalyzes fructose 1,6-bisphosphate --> fructose 6-phosphate?
fructose 1,6-bisphosphatase
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_____ inhibits fructose 1,6-bisphosphatase, therefore inhibiting gluconeogenesis.
fructose 2,6-bisphosphate
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High glucagon/insulin ratio causes elevated _____ and increased _____.
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Increased protein kinase A favors _____ form of PFK-2/FBP-2 complex.
phosphorylated
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phosphorylated PFK-2 is _____ which impedes formation of _____.
- inactive
- fructose 2,6-bisphosphate
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decreased levels of fructose 2,6-bisphosphate decreases the inhibition of _____, which increases _____.
- fructose bisphosphate phosphatase-1
- gluconeogenesis
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High insulin/glucagon ratio causes _____ cAMP and ______ protein kinase A.
-
Decreased protein kinase A favors _____ form of PFK-2/FBP-2 complex.
dephosphorylated
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dephosphorylated PFK-2 is _____ which favors formation of _____.
- active
- fructose 2,6-bisphosphate
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increased levels of fructose 2,6-bisphosphate activates _____, which increases _____.
- phosphofructokinase-1
- glycolysis
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What enzyme catalyzes glucose 6-phosphate --> D-glucose?
glucose 6-phosphatase
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glucose 6-phoshate is translocated to the ER membrane by _____.
glucose 6-phosphate translocase
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Gluconeogenesis is ACTIVATED by:
- glucagon
- elevated levels of gluconeogenesis precursors
- acetyl CoA
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Gluconeogenesis is INHIBITED by:
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What is glycogen?
highly branched polymer (dendrimer) of glucose
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What does the presence of branches on glycogen provide?
more opportunities for rapid degradation and synthesis
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Liver glycogen tends to _____ while muscle glycogen tends to _____.
- liver: fluctuate more
- muscle: be more stable
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Glycogenolysis is more _____ while gluconeogenesis is more _____.
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What is the function of glycogenesis and glycogenolysis in the liver?
maintenance of blood glucose levels during early portions of fast and during exercise
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What is the function of glycogenesis and glycogenolysis in the muscle?
provision of fuel to be used by the muscle during exercise
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What are 2 major hormones that regulate glycolysis and gluconeogenesis?
insulin and glucagon
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Insulin is more _____ and glucagon is more _____. (anabolic v catabolic)
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Every _____ glucosyl residues there is a branch.
8-10
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What kind of branch point is found in glycogen?
alpha (1->6) linkage
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Glycogen is stored in both muscle and liver in ______.
granules
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Where are the enzymes associated with synthesis and degradation localized?
in the muscle and liver granules.
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Glucose 6-phosphate is isomerization with _____.
glucose 1-phosphate
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_____ serves as the primer for glycogen synthesis. what is it attached to?
-
What enzyme extends the alpha 1,4 linkages on the nonreducing ends?
glycogen synthase
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_____ adds alpha 1,6 bonds to glycogen.
branching enzyme
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What is the rate limiting factor in glycogen synthesis?
glycogen synthase
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What enzyme catalyzes glucose --> glucose 1-phosphate?
glycogen phosphorylase
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What kind of enzyme is glycogen phosphorylase?
hydrolytic enzyme
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Glycogen phosphorylase requires coenzyme _____.
pyridoxal phosphate (vitamin B6)
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Glycogen phosphorylase is a _____ enzyme, meaning it moves one a at a time.
processive
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What is the rate limiting factor in glycogenolysis?
glycogen phosphorylase
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epinephrine and norepinephrine stimulate _____ and _____ by binding to alpha and beta adrenergic receptors.
- synthesis of cAMP
- elevation of intracellular calcium
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cAMP functions in a synergistic manner w/ _____ to regulate glycogen metabolism.
calcium
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Does glucagon have more of an effect on muscle or liver?
liver
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_____ and _____activates G proteins, _____ does not.
- glucagon and epinephrine
- insulin
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_____ activate protein phosphatase-1 to remove P from glycogen phosphorylase kinase a
insulin
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what is the role of calcium in muscle?
binds to calmodulin subunit to activate phosphorylase kinase
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what is the role of AMP in muscle?
activates glycogen phosphorylase b
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What ACTIVATES glycogen breakdown in liver?
- glucose
- ATP
- glucose 6-phosphate
-
What INHIBITS glycogen breakdown in liver?
glucose 6-phosphate
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What ACTIVATES glycogen breakdown in muscle?
- calcium
- AMP
- glucose 6-phosphate
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What INHIBITS glycogen breakdown in muscle?
-
What are the functions of calmodulin?
- nerve growth
- muscle contraction
- inflammation
- apoptosis
- intracellular movement
- immune processes
-
Where does calmodulin function?
inside different organelles
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calmodulin: calcium is released from ______ in response to hormones or neurotransmitters.
endoplasmic reticulum
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Increase of intracellular Ca2+ favors formation of _____.
calmodulin-Ca2+ complex
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_____% of the calories ingested are fat, while the maximal percentage of fat in the optimal diet is _____%.
-
What are the functions of fat/lipids?
- energy storage
- transport/utilization of fat-soluble vitamins
- essential fatty acids
- insulation against heat loss
- insulation against trauma
- insulation against water loss
- brain structure and nervous function
- hormones
- cell membranes
- mother's milk
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What are the fat-soluble vitamins?
A, D, E, K
-
What are the representative lipids?
fatty acids, triacylglycerol, phospholipid, steroid, glycolipid
-
What is the predominant lipid in our diet?
triacylglycerol
-
_____ and _____ lipase hydrolyze short/medium chain TAGs
lingual and salivary
-
What is a short/medium chain TAG?
4-12 carbons
-
Where are bile salts made and where are they stored?
- MADE in liver
- STORED in gall bladder
-
What is the function of bile salts?
emulsify fats
-
Emulsify fat:
- help fat interact with water soluble environment
- make globular fat smaller
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_____ and _____ are recreated from the pancreas.
pancreatic lipase and colipase
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What does pancreatic lipase do?
hydrolyzes TAGs to 2-monoacylglycerols
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Why do you need a supporting enzyme (collapse)?
bile interferes with lipase so you need collapse to help get the job done
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What is the structure of a bile salt micelle?
hydrophobic inside, hydrophilic outside (easier to interact with water)
-
What do micelles contain?
TAGs, undigested monoacylglycerides, fatty acids, fat soluble vitamins
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Micelle contents are absorbed into _____.
intestinal mucosal cells (enterocytes).
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_____ are reformed in intestinal mucosal cells and _____ are assembled.
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What do chylomicrons consist of?
TAGs, cholesteryl esterified to free fatty acid, apoprotein, and phospholipids
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Where are chylomicrons found?
endoplasmic reticulum
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_____ are not incorporated into chylomicrons.
short/medium chain fatty acids
-
Where are short/medium chain fatty acids released?
portal circulation
-
What transports short/medium chain fatty acids into portal circulation?
serum albumin
-
How are chylomicrons released?
exocytosis into lymphatic vessels (lacteals)
-
What is chyle?
milky-colored fluid in lacteals
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TAGs in chylomicrons are hydrolyzed by _____/
lipoprotein lipase
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TAGs are hydrolyzed by lipoprotein lipase in _____ and _____?
in skeletal muscle and adipose tissue capillaries
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What can free fatty acids do?
- oxidized for energy
- transported with serum albumin to other cells
- re-esterified in adipose cells and in liver to TAGS
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chylomicron remnants enter liver through _____ and are hydrolyzed.
endocytosis
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What are 2 regulatory intestinal hormones?
secretin and cholecystokinin
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What is secretin stimulated by?
acidification
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Secretin stimulates the release of _____ from liver and pancreas.
water bicarbonate solution
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What is the purpose of the bicarbonate solution?
neutralize stomach acid
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Cholecystokinin stimulates pancreas to secrete _____.
digestive enzymes
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Cholecystokinin stimulates the gallbladder to _____ and the stomach to reduce its _____.
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lingual and gastric/salivary lipase are most active during _____.
early childhood
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where do pancreatic lipase hydrolyze fatty acids?
from positions 1 and 3
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_____ enhances pancreatic lipase.
colipase
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what enzyme catalyzes cholesterol ester --> cholesterol?
cholesterol esterase
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_____ liberates a fatty acid from a phospholipid.
phospholipase A2
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Cholic acid can be covalently attached to either a molecule of _____ or _____.
glycine or taurine
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which is more hydrophilic, taurine-conjugated chalice acid or glycine-conjugated chalice acid?
taurine-conjugated chalice acid
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what is taurine?
an amino acid-like structure
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What does bile consist of?
- water
- cholesterol
- bilins
- bile acids/bile salts
- phospholipids
- bicarbonate and other ions
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