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Biochem3
Mary
94
Biochemistry
Graduate
03/12/2011

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Term
What are the two ways the body makes ATP?
Definition
Chemical energy-Substrate Level Phosphorylation
Redox energy-reducing equivalents
Term
What is the end product of glycolysis dependent upon?
Definition
How the tissues recycles NAD for the GAPDH reaction so that glyclysis can continue.
Term
In which state is ATP made/NAD/NADH turned over? (Fed or Fasting)
Definition
Both. It doesn't matter b/c we always have to be ready for muscle contraction
Term
How does cytoplasmic NADH get back to NAD?
Definition
Passing on reducing equivalents
Term
2 Main mechanisms for NAD recycling?
Definition
Cell has mitochondria and oxygen and ready
RBC with no mitochondria so no way you can do ox phos recycling
Term
Fate of pyruvate in aerobic tissues
Definition
Reducing equivalents from cytoplasmic NADH eventually end up in mitochondria where they pass down ETC to O2 to form H2O
Term
Role of the shuttle mechanisms?
Definition
Transport NADH across inner mitochondrial membrane, since it is impermable.
NAD/FAD is also recycled allowing shuttles to continue
Term
Malate Shuttle
Definition
Oxaloacetate->Malate (NADH goes to NAD)
Malate cross into mitochindria (w/ reducing equiv)
Malate goes back to oxaloacetate (NAD to NADH)
2.5 ATP per NADH
Term
Glycerol P Shuttle
Definition
Dihydroxyacetone Phosphate->G3P (NADH to NAD)
Glycerol 3 phosphatase dehydrogenase complex takes FAD->FADH2 (this goes to complex 3 at UB)
This makes 1.5 ATP/NADH
Term
End product of aerobic glycolysis?
Definition
Pyruvate
Term
What happens after pyruvate is formed?
Definition
Taken into mitochondria and converted to acetyl CoA
Term
Where are reducing equivalents recovered in the shuttle systems?
Definition
NADH and FADH2
Term
Purpose of Ox/Phos?
Definition
Make lots of ATP
Recycle NAD/FAD so ATP production can continue
Term
Examples of electron transport limited conditions?
Definition
Hypoxia Cyanide poisoning
Term
Fate of pyruvate in electron transport limited conditions, anaerobic conditions, or anaerobic oral bacteria?
Definition
Reduced coenzymes NADH and FADH2 build up b/c can't pass into ETC; Production of NADH and FADH2 are inhibited (PDH ICDH); NAD depletes
NADH passes it's reducing equivalents to pyruvate which forms lactate; lactate dehydrogenase catalyzed reaction
Term
End product of anaerobic glycolysis?
Definition
Lactate
Term
Net ATP made in anaerbic glycolysis?
By what process are these made?
Definition
2
Substrate level phosphorlation
Term
Result of anaerbic conditions?
Definition
2 vs. 32 ATP; so much lactate overwhelms the system (lactic acidosis)
Oral bacteria metabolize sugar via anaerbic glycolysis, acid effects teeth.
Sometimes we die. (not teeth thing)
Term
LDH
Definition
Lactate dehydrogenase
When conditions are anaerbic
Lactate is the end product
Term
PDH
Definition
Pyruvate Dehydrogenase
Aerbic conditions
Water is end product
Term
Overall goal of fuel metabolism after meal?
Definition
Lower blood glucose
Term
Ways blood glucose is lowered after a meal?
Definition
-Stimulate glucose uptake into ALL cells (especially muscle/adipose)
-Turn on all pathways that use glucose
-Convert the excess calories to storage forms->glycogen and fat, for use between meals
-Turn off pathways that generate glucose (prevents hyperglycemia)
Term
Regulation of Fed State pathways?
Definition
Insulin turns on
Glucagon turns off
Term
Pathways of the fed state
Definition
-Glycolysis
-Glycogen Synthesis
-Pentose Shunt (Provide NADPH for fatty acid biosynthesis)
-PDH turned on
-TAG/FA biosynthesis
Term
What cells use the pentose shunt pathway?
Definition
Most cells
Term
Where does the pentose shunt reaction occur?
Definition
Cytoplasm
Term
Oxidative Branch of the Pentose shunt?
Reversible?
Reaction?
Rate limiting?
Definition
Irreversible
Glucose to ribulose 5p
C6 glucose oxidized to C5 ribulose5p (losing CO2)
Begins with rate limiting step glucose 6pdehydrogenase
Maintain high NADPH/NADP
Term
Non-oxidative branch of pentose shunt reaction?
What is it for?
Reversible?
Enzymes
Reaction?
Definition
Reversible (interconvert sugars containing 3-7 carbons)
Rubulose 5p to ribose 5P
Nucleotide biosynthesis
Transketoases-TPP as cofactor
Transaldolases
Term
What do transketoases require?
Definition
Thiamin Para Phosphate as a cofacor
Term
Why is the pentose shunt path called a "shunt"?
Definition
Becuse the Ribose 5 phosphate is NOT needed, can be "recovered" for energy by conversion back to glycolytic intermediates
Term
Where is Pentose shunt regulated? How?
Definition
Glucose 6 phosphate Dehydrogenase
through induction
Allosteric feedback
Happens at the beginning so carbons aren't wasted.
Term
Why is the reducing atmosphere for the RBC important? (2 reasons)
Definition
1.Protects cell membranes against oxidative species (superoxides), ROS which are easy to form in RBC b/c of their high [O2].
2. Keep Fe2+ in functional state; doesn't work if Fe3+ (NADPH associated enzymes do this)
Term
How many people have G6PHD deficiencies?
Definition
100 million people
11% of African Americans have it
Term
Drug induced hemolytic anemia?
Definition
Drugs such as anti-malarials induce oxidative stress. Deficiency manifests, cell membranes are dameged by ROS and cell is lysed.
Term
Glycogen definition.
Definition
Insoluble storage form of glucose
Term
What does glycogen resemble? How?
Definition
Amylopectin. Becuause of the linear alpha 1,4 linkages and the alpha 1,6 linkages
Term
Significance of non reducing ends of glycogen.
Definition
Plentiful.
Where action of building or breaking down of glycogen happens
Term
Where does glycogen synthesis occur?
Definition
Cytoplasm
Term
Where is glycogen stored?
Definition
Cytoplasmic granules as needed for fuel.
Term
What is the primary purpose of liver fatty acid and TAG biosynthesis and adpipose TAG re-synthsis?
Definition
Storage along with glycogen, of excess dietary fuel for use during fasting states
Term
Where in the body does endogenous FA synthesis occur?
Definition
Liver, with excess calories/
Mammary gland also
Term
Where in the cell does fatty acid biosynthesis occur? What is usually made? What are the precursors?
Definition
Cytoplasm
C-16 palmitate
NADPH; 2 Carbon Acetyl CoA (made in the mitochondria by PDH)
-Acetyl crosses in the form of citrate; Citrate in mito converted to Acetyl CoA and OAA using ATP and Citrate lyase
Term
Delta G of ATP citrate lyase?
Definition
Very positve. Requires ATP
Opposite of citrate synthase (with -DetlaG)
Term
How does FA biosynthesis occur?
Definition
Made by repatitive addition of two carbon units to growing end
Term
In FA biosynthesis how is the ACP attached to the chain?
Definition
Covalently
Term
In FA synthesis what is attached to the growing hydrocarbon chain?
Definition
Acyl Carrier Protein (ACP)
Term
First step of FA Synthesis. Enzyme?
What happens?
Definition
Formation of malonyl CoA by acetyl CoA carboxylase.
-ATP dependent rxn
-Add CO2- group from bicarb
Acetyl CoA carboxylase =key regulated enzyme
-Co2 release from Mal-CoA as 22 C's are added to growing FA energetically drives 2C addition Rxn
Term
Fatty Acid Synthase
Definition
Multi-enzyme complex does the chain elongating.
Term
Cofactor of acetyl CoA carboxylase?
Definition
Biotin (Vit H)
Term
In FA biosynthesis, what are acyl groups carried as? How does this relate to the cofactor?
Definition
Thioesters; Using SH of cysteine and of the cofactor phosphopantethiene in ACP
Term
Initiation Rxn of FA biosynthesis
Definition
Charge ACP with acetyl CoA and malonyl CoA, and start the chain with the 1st condensation Rxn (adding 2 carbons to Acetyl-ACP from 3 carbon malonyl CoA, driven by release of CO2)
Term
What happens after the initial 2 carbon addition in FA synthesis?
Definition
Remodeling of the growing chain occurs. This involves Reduction, Dehydration, Reduction. (Using NADPH,losing water, using NADPH)
Term
What are the reducing equivalnets in FA biosynthesis?
Definition
NADPH x2
Term
How are additional carbons added to the chain in FA synthesis?
Definition
Malonyl ACP site is re-charged and the next cycle beings with 2 C addition from malonyl-CoA as elongation continues, finally releasing a completed fattyacylCoA
Term
Cost to make 16 carbon palmitate
Definition
-8 Acetyl CoA
-7 Malonyl CoA
-7 ATP used
-17 NADPH
Term
In what form are fatty acids stored in adipose tissues?
Definition
TAGs
Term
Where does TAG synthesis occur? What are they made from?
Definition
In the liver from excess dietary fuel
Term
What is the first step of TAG synthesis?
Definition
Phosphatidate is made from glycolytic DHAP and fatty acyl CoA esters(activated from of fatty acids)
Term
How do you make a TAG from phosphatidate?
Definition
Replace PO3 with another fatty acyl group
Term
How are liver tags packaged?
Definition
Within the liver into a carrier called VLDL
These deliver TAG via blood to adipose and other tissues
Term
VLDL->TAG?
Definition
Free fatty acids are cleaved off the VLDL-TAG complex and taken up by adipose cells. This is used to re-make TAGS as above for storage until they are needed.
Term
Ways to drop your blood glucose
Definition
Increase glucose uptake into cells
turn on glucose use for energy
Store excess calories as glycogan and fat
Turn off glucose production and production of TAG based fuels (fatty acids, ketone bodies. )
Term
Major regulatory hormone governing the fed, anabolic state?
Definition
Insulin
Term
Insulin definition
Definition
Peptide hormone releaed by pancreas in response to rise in blood glucose
Term
Insulin regulatory mechanisms
Definition
-Controls substrate supply
-Induction/Repression of certain regulated enzymes
-Promoting dephosphorylation of phosphorylated proteins
Term
When does insulin increase glucose uptake into cells?
Definition
In muscle/adipose tissues by increasing glut 4
Term
What does insulin do to the liver?
(Glycolysis, Glycogen, Glucose??)
Definition
Increases muscle/adipose glycolysis
Increases glycogen synthesis, fatty acid/TAG biosynthesis and decrease glucose production
Term
What does insulin do to muscles/adipose?
(glucogen, TAG)
Definition
Decreases glycogen breakdown and TAG breakdown (lipolysis)
Term
Regulation of glycogen synthase
Kinase/Phosphatase activity.
Definition
Turn on when glucose is abundant (store glycogen)-dehphosphorylation activates
Turn off between meals(break down glycogen for fuel)-phosphorylated is inactive
Term
What effect goes glycogen have on the effect of insulin?
Definition
Antagonizes insulin effects
Term
What do glucagon/epinephrine do to glycogen synthase?
Definition
Phosphorylate it--inactivate it.
Term
Overall glucose to fat pathway:
Definition
1.Glycolysis
2.PDH
3.Citrate synthase(TCA cycle)
4.Citrate moves into cytoplasm
5.ATP citrate lyase
6.Acetyl CoA carboxylate/fatty acid sunthase
7.With glycerol 3-P, make TAG's for adipose storage
Term
Key regulated enzyme in FA biosynthesis?
Definition
Acetyl CoA Carboxylase
Term
Regulation of acetyl CoA carboxylase?
Definition
1. Citrate allosterically activates acetyl CoA carboxylase (feed forward)
2. Palmityl CoA inhibits allosterically (feedback)
3.Dephosphorylation promoted by insulin activates
-Phosphorylation..glucagon inactivates
Term
Insulin induction effects what enzymes in the overall glucose to TAG pathway?
Definition
1.Glucokinase and pyruvate kinase (glycolysis)
2.ATP citrate lyase
3.Glucose 6 phosphate dehydrogenase (pentose shunt for NADPH)
4.Acetyl CoA carboxylase
5.F.A. Synthase
Term
Can insulin/glucagon affect things in the mitochondria?
Definition
No. they can't get inside.
Term
Goals of fuel metabolism in the fasting state?
Definition
Maintain blood glucose levels, esp for tissues that depend on glucsoe for fuel (RBC's, brain)
Provide alternative TAG based fuels to spare available blood glucose
Term
Pathways for the fasting state: Where do they occur?
Definition
-Gluconeogenesis (liver)
-Glycogenolysis (liver)
-Adipose TAG lipolysis (provides FFA)
-Fatty Acid beta oxidation (aerobic tissues; esp muscles and liver)
-Ketone body production (liver)
-Ketone body use (aerobic tissues; except liver)
Term
What does glucagon work on?
Definition
Directly on liver and adipose only. Affects fuel supply of other tissues (FA, Ketone bodies, and glucose)
Term
What are a main storage form of energy? Why
Definition
TAG's, b/c of their highly reduced nature
Term
How are TAG's mobilized?
Definition
Hormone sensitive lipase; releases FFA
3 times to glycerol
Term
FFA transport after release from adipose tissue?
In blood? Once inside cell?
Definition
In blood, FFA are transported when bound to serum albumin. Readily taken up by cells
-Once inside cell, they are activated by conversion to CoA thio-esters. then they are transported into the mitochondrion using acylarnitine system (b/c CoA's can't cross mitochondrian)
Term
Why kind of cavities do alpha helicies have? What does this allow them to do?
Definition
Hydrophobic. Allows them to carry hydrophobic particles, such as drugs
Term
Beta Oxidation of fatty acids.
Location
Reactions
Other key products
Definition
Mitochondrial matrix in a spiral pathway
Oxidation/Hydration/Oxidation
NADH and FADH2
Term
Compare Beta oxidation and FA synthesis.
Definition
Basically opposite.
Reduction in synthesis
Oxidation (pulls off red. equivalents to make ATP)
Term
Products of Beta Oxidation of an 18 C stearate
Definition
9 Acetyl CoA
8 NADH
8FADH2
9GTP from TCA cycle.
Term
What regulates Beta Oxidation?
Definition
SOLELY by the supply of fatty acids that get into the mitochondrion. Substrate supply
Term
Odd chain fatty acid metabolism
Definition
3 C propionyl-CoA (final product)->Succinyl CoA via poppionyl-CoA carboxylase
Biotin cofactor
Term
How and where are ketone bodies produced?
Examples.
Definition
Made in the liver mitochondria from acetyl CoA that is produced there (buildup of it)
Beta hydroxy butyrate
Acetoacetate
Acetone
Term
Conditions that favor liver ketone body production during fasting states?
Definition
1. The rate of the TCA cycle is decreased
2. Acetyl CoA builds up with high fatty acid oxidatoin
3.Acety CoA->ketone bodies (converted) for the liver to export to other tissues. This conserves our blood glucose
Term
Why is the TCA cycle reduced when in the fasting state and making ketone bodies?
Definition
-OAA is shuttled out to make glucose, which decreases level of TCA cycle intermediates.
-Redcuing equivalents, NADH and FADH2 from the TCA cycle are not needed--plenty are produced in fatty acid oxidation to meet the liver's energy needs
Term
Use of ketone bodies as an alternate fuel for fasting state metabolism
Definition
-Liver can NOT break down ketone bodies-this is GOOD b/c we do not want the liver to use/breakdown the ketones before it gets exported out of the body
-Other aerobic tissues cleave ketone bodies back to acetyl-CoA for oxidation in the TCA cycle/os phos for energy.
Term
What does liver fatty acid oxidation provide?
Definition
Products needed for glucose production during fasting.
Term
How is blood glucose concentration maintained between meals?
Definition
-Dietary carbs can maintain blood glucose levels for a few hours (2-4)
-Beyond this time, blood glucose is supplied by the liver in 2 ways
-breakdown of glycogen
-gluconeogenesis
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