General Principles and Carbs Flashcards
Oxidation vs Reduction
Ox: loss of hydrogen, gain oxygen
Red: gain of hydrogen, loss of oxygen
Carboxylation
carboxyl group added/displaces H+ (COOH)
Hydrolysis
Cleavage of compound by addition of water
Phosphorylation via what enzyme? What removes a phosphate group? What transfers it
Phosphorylase
Phosphatase
Kinase
Function of a ligase?
Catalyzes the joining of two molecules
Vmax?
max velocity of reaction, proportional to enzyme concentration
Michaelis-Menten constant/Kmax?
substrate concentration to reach 1/2 of Vmax
Competitive inhibition v non-competitive vs allosteric regulation
Competitive: inhibitor binds to same active site as normal enzyme substrate, reversible
Non: inhibitor binds to non-active site, irreversible
Allosteric: binding of effector molecule at allosteric site can inhibit or activate
How many calories do you get per gram of CHO? protein? Fat? alcohol
4, 4, 9, 7
Energy fuels results in heat generation and ATP synthesis
Catabolism
Peptide bonds are formed by?
Dehydration
Ester bonds are covalent bonds between?
Glycerol and fatty acids
Glycosidic bonds occur between?
2 sugar molecules
Phosphodiester bonds occur between?
2 nucleotides (covalent)
Metabolic pathways that occur in the:
Mitochondria
Cytoplasm
Both
Mito: fatty acid ox, TCA cycle, ox phosphorylation
Cyto: glycolysis, fatty acid synth, HMP shunt, protein synth
Both: heme synthesis, urea cycle, gluconeogenesis
Rate limiting steps: Glycolysis? Gluconeogenesis? TCA cycle? Glycogen synth? Gycogenolysis?
Glycolysis: PFK Gluconeogenesis: F-1,6BP TCA cycle: isocitrate dehydrogenase Glycogen synth: glycogen synthase Gycogenolysis: glycogen phosphorylase
Rate limiting steps: HMP Shunt? Urea cycle? Fatty acid synth? Fatty acid ox? Cholesterol synth?
HMP Shunt: G6P dehydrogenase Urea cycle: Carbamoyl phosphate synthetase Fatty acid synth: Acety-CoA carboxylase Fatty acid ox: Carnitine acyltransferase Cholesterol synth: HMG-CoA reductase
long, unbranched chain of glucose a(1-4) in plants
Amylose
Highly branched glucose polymer a(1-4) with (1-6) bonds every 24-30 units?
Amylopectin
Sucrose is made of?
Lactose?
Sucrose: glucose and fructose
Lactose: galactose and glucose
Linear chain of D-glucose b(1-4) of plants?
Celluloe
Salivary amylase breaks down?
maltose (2 glucose)
Pancreatic amylase breaks down?
1-4 links to release di/tri saccharides
Lactase is secreted where?
Intestinal villi
Where do you find: GLUT1 GLUT2 GLUT3 GLUT4
1: RBC, prain, placenta, testis
2: liver, kidney, beta cells (pancreas) - couple w/Na+
3: neurons
4: adipose, skeletal, cardiac muscle - sensitive to insulin
Glycolysis prep phase steps:
1: G-G6P w/glucokinase (liver) and hexokinase, uses 1 ATP, irreversible
2: G6P-F6P via phosphoglucose isomerase
3: F6P-F16BP: PFK, RLS, 1 ATP, allosterically regulated
4: F16BP-G3P/DHAP: aldolase
5: DHAP-G3P via triose phosphate isomerase
Glycolysis pay off phase steps:
6: G3P-13BPG: G3P dehydrogenase, NADH H+ made
7: 13BPG-3PG: 2 ATP made/G, phosphoglycerate kinase break even step
8: 3PG to 2PG: phosphoglycerate mutase
9: 2PH to PEP - enolase (removes water)
10: PEP-pyruvate: pyruvate kinase, 2 ATP in this step, net 2 ATP
Tell me about hexokinase
G-G6P, in most tissue, used MgATP2-, inhibited by G6P, prevents accumulation in cell (dec swelling)
Tell me about glucokinase
in liver, activated by insulin, inhibited by F6P, works at high blood glucose levels
Tell me about PFK
RLS in glycolysis, inhibited by ATP citrate (Krebs), NADH, glucagon and activated by AMP/ADP, insulin, F26BP
What’s cool about Pyruvate Kinase?
Activated by F16BP and AP
Inhibited by ATP, fatty acids, alanine, acetyl CoA
What can happen to pyruvate made by glycolysis?
Oxidation: to acetyl CoA to Krebs (pyruvate dehydrogenase - ATP, Acetyl CoA, NADH)
Reduction: to regenerate NAD+ (lactate dehydrogenase)
Carboxylation: pyruvate to oxaloacetate (Pyruvate carboxylase)
Transamination: pyruvate to alanine (Alanine transaminase)
Aldose reductase can convert glucose to?
Sorbitol
What does sorbitol dehydrogenase do?
Turn sorbitol to fructose so that it can go to glycolysis
What cells is sorbitol dehydrogenase not found in?
Lens, retina, Schwann cells
Where does gluconeognesis take place?
Liver, kidneys in starvation (use ketone)
Gluconeogenesis Step 10 reversal?
1: pyruvate-oxaloacetate (mitochondria pyruvate carboxylase, biotin key (B7) to cytoplasm
2: oxaloacetate to PEP via PEP carboxykinase (hydroyze GTP, facilitated by glucagon, cortisol)
Gluconeogenesis Step 3 reversal?
PFK F6P-F16BP use F16BPase to get there - RLS, stim by ATP/citrate, - by AMP, F26BP
Gluconeogenesis Step 1 reversal?
G6Pase converts G6P to G in ER of liver and kidney cells
How much ATP is used in gluconeogenesis?
6 to make one glucose
Each acetyl CoA from pryuvate produces what?
3 NADH, 1 FADH2, 1 GTP, 2 CO2
Kreb cycle GO!
1: citrate from oxaloacetate (4C) + Acetyl CoA (Citrate synthase, ATP inhibits)
2: Isocitrate from citrate (Aconitase)
3: aKG from IC via IC dehydrogenase (RLS) ADP activates, ATP/NADH inhibit, one NADH produced and CO2 released (5C)
4: succinyl CoA from Akg (aKG dehydrogenase req b1, 2, 3, 5) makes NADH and CO2 (4C)
5: Succinate via succinate thiokinase/succinyl CoA synthetase, 1 GTP made
6: Fumarate via succinate dehydrogenase (bound to mitochondrial membrane uses FAD) makes 1 FADH2
7: malate via fumarase
8: oxaloacetate via malate dehydrogenase, reversible, 1 NADH made
NADH makes how much ATP? FADH2?
3, 2
Total energy production from Kreb cycle?
38 ATP 2 ATP net from glycolysyis 6 ATP from 2 NADH 6 ATP from pyruvate to acetyl coA (2 NADH) 24 ATP acetyl coa to oxaloacetate
Four points protein can enter kreb cycle?
Succinyl CoA, oxaloacetate, fumarate, aKG
What is the purpose of the malate-aspartate shuttle?
To have malate enter mitochondria w/e- and oxidized to oxaloacetate regenerating NADH in matrix (free e-) then converted to aspartate so it can be reconverted to oxaloacetate in cytosol
What is the purpose of the G3P shuttle?
DHAP reduced to G3P by NADH G3P into mitochondria to react w/FAD where the e- enters the matix so DHAP is regenerated and re-enters the cytosol and FADH2 gives e- to complex 2
Hemoglobin in cytochromes carries what?
electrons
Iron-sulfur proteins participate in what reaction?
Redox
What is unique about FAD/FMN?
3 oxidation states, can carry 2 e-, pick one up at a time
Pyridine-linked dehydrogenases remove 2H from the substrate in what forms?
H+, NADP+ gets one
Ubiquinone/Coenzyme Q is a -_____ which participate in what type of rxns?
Quinone (small organic molecule, not protein)
redox rxns and carry 1 or 2 H
Complex 1 in the ETC?
NADH dehydrogenase complex (Coenzyme Q), 1st comp of ETC H+ pass from NADH to FMN then iron sulfur centers, FMN picks up another H+ from aqueous medium,main ELECTRON DONOR, CoQ takes freed e- to inner mtiochondrial membrane
Complex II in the ETC?
Succinte dehydrogenase complex (w/CoQ) FADH2 formed in krebs enters ETC, transfers H to iron sulfur groups to CoQ as ELECTRON DONOR and another H+ from surrounding, lipid soluble diffuses w/in inner mitochondrial membrane
Complex III in the ETC?
Cytochrome reductase or c complex (w/CoQ)
removes 2 e- from CoQH2 at Q0 site and sends them to cytochrome c in intermembrane space and the other 2 to Qi site where quinone reduce to quinol
Complex IV in the ETC?
Cytochrome c oxidase (oxidative phase-O2 added)
e- to inner mitochondrial membrane from cytochrome c to CuA –> Cu+ transition, and copper passes e- to cytochrome a to CuB and a second e- thru IV picked up by CuA then cytochrome a then ends up as cytochrome a3
O2 molecule takes 2H to make water so OXYGEN IS THE ELECTRON ACCEPTOR
Complex V in the ETC?
ATP synthase (phosphorylation phase adds phosphate) Final step H+ re-enters matrix through V to turn and this converts ADP and PO4- to ATP
What inhibits cytochrome c in the ETC?
Cyanide, CO
Purpose of the Cori cycle?
Prevent lactic acid buildup from anaerobic glycolysis
Maintain NAD+ to use in glycolysis
How much ATP is used in the Cori cycle?
4 ATP
Steps of the Cori cycle?
1) pyruvic acid + lactate dehydrogenase = lactic acid (removes protons from NADH back)
2) Lactic acid to liver converted back to pyruvic acid then glucose
Purpose of the pentose phosphate pathway?
Produce NADPH for fatty acid synthesis, detoxification, protection from free radicals
Rate limiting enzyme of the pentose phosphate pathway?
G6P dehydrogenase
What energy molecules are produced in the pentose phosphate pathway?
2 NADPH
Glycogenesis steps?
G + Glucokinase = G6P
G6P + phosphoglucomutase = G1P
G1P + UDP-Glucose pyrophosphorylase = UDP
UDP + glycogenin + glycogen synthase (RLS) = glycogenin a(1-4) glucose + glucosyl (4-6) transferase for branching
Glycogenesis is activated by? Inhibited?
Insulin (high blood glucose)
Epinephrine, glucagon
How is glycogen structured?
Backbone of glucose molecules a1-4 links, every 8-10 branches of a(1-6) links
Rate limiting enzymes for glycogenolysis?
Glycogen phosphorylase A/B
Steps of Glycogenolysis?
1: glycogen phosphorlyase cleaves a(1-4) linkages until 5 glucose chain left
2: amylo-a-1-6, glucosidase makes G1P
3: phosphoglucomutase converts G1P to G6P
Hormonal regulation of glycogenolysis:
cAMP, stim by glucagon and epinephrine, inhibited by insulin
What do you remember about cAMP?
2o messenger, synth from ATP by adenylyl cyclae, activates phosphorylase kinases, activates glycogen phosphorylase
Inhibits glycogen synthase
Regulates passage of Ca2+ thru ionic channels
