8.1 Flashcards by Matt Wong

ribose

is glucose without the third finger

“the RIB is missing the third bone”

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hydrolysis of polysaccharides is/is not thermodynamically favorable?

YES, MONOSACCHARIDES are lower energy than polysaccharides. we GET ENERGY from breaking down polysaccharides

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Glycolysis

produces ATP and NADH (2 each, net)
occurs CYTOPLASM (how does NADH get into the mitochondria - glycerol phosphate shuttle / malate-acetate shuttle)
does NOT require oxygen

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Pyruvate dehydrogenase (PDH)

pyruvate is decarboxylated to form an acetyl group

which is attached to coenzyme A with a Sulfur

2 NADH is produced per glucose

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Mg2+

required for ALL reactions involving ATP

stabilizes the negatives

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NADH is produced during glycolysis when

an glyceraldehyde (GAD3P) is oxidized to COOH (-ate) in the 5th step of glycolysis

mediated by GAP-DH (glyceraldehyde dehydrogenase)

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glycolysis ATP is made

when a phosphate comes OFF a substrate

is consumed when a phosphate is ADDED to a substrate

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PFK

Phosphofructokinase (3rd step, phosphorylates F-6-P)

irreversible, a “COMMITTED STEP”

Note: it is allosterically down-regulated by ATP, even though a reactant is ATP

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coenzyme A (CoA)

attached to acetyl unit, used to pass acetyl around (useful in fatty acid and cholesterol synthesis)

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pyruvate is oxidized/reduced to form acetyl-CoA

decarboxylated = oxidized

PDH

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glycerol phosphate shuttle

transports NADH from cytoplasm to the mitochondria, delivers directly to Ubiquinone (like FADH2) which generates 1.5 ATP per NADH

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Flavoprotein

FAD - useful in redox

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PGK and PK

In the second half of glycolysis, these KINASES take phosphates FROM the substrate and create 1 molecule of ATP

PK - 10
PGK - 7 (reversible)

pk = pyruvate kinase (think point to the right)
pgk = phosphoglycerate kinase

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HK, PFK

“Hong Kong is first”

they are kinases that phosphorylate in steps 1 and 3 of glycolysis - they PLACE phosphate on the substrate = LOSS OF ATP

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Gluconeogenesis

We’re out of GLUCOSE AND GLYCOGEN

occurs in LIVER (and kidneys)

NONCARB precursors -> glucose

precursors include LACTATE, PYRUVATE, Krebs cycle intermediates (less Krebs = more energy), carbon skeleton of amino acids

REQUIRES NADH and ATP

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Regulatory control of glycolysis

Steps 1, 3, and 10 are most IRREVERSIBLE

HK, PFK, PK

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glycerol enters (in gluconeogensis)

at DHAP

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phosphorylated glucose

CANNOT CROSS THE CELL MEMBRANE

dephosphorylation must occur before glucose can leave the liver

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ATP and GTP are

HYDROLYZED = release energy

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pyruvate carboxylase

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CARBOXYLASE = ADD CARBOXYL GROUP (COOH)

1st step of gluconeogenesis

PHOSPHATASE

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two useful at the END of gluconeogenesis

Fructose-1,6-bisphosphatase
Gluce-6-phosphatase
- TASE = REMOVE PHOSPHATES

“TASER removes criminals”

Steps of glycolysis that gain and lose ATP

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Step 1: LOSE ATP
Step 3: LOSE ATP
Step 6: GAIN 2 NADH
Step 7: GAIN 2 ATP
Step 10: GAIN 2 ATP

gluconeogenesis (steps in reverse order)

Step 1: LOSE 2 ATP
Step 2: LOSE 2 GDP
Step 5 (same as step 7): LOSE 2 ATP
Step 6: LOSE 2 NADH

GNG: needs 4 ATP, 2 GTP, and 2 NADH

what intermediates can take part in GNG?

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most intermediate of cellular respiration

EXCEPT ACETYL-COA

Free fatty acids CANNOT be converted to glucose

Glycerol backbone CAN

GNG is highly

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ENDERGONIC

starvation mode induces...

glycogenolysis, gluconeogenesis, lipolysis, and ketogenesis REDUCE insulin, INCREASE glucagon and epi and norepi ELEVATED cellular AMP which ACTIVATE PFK and inhibit F-1,6-BPase

glucagon

associated with Gluconeogenesis

insulin stimulates

F-2,6-BP, which stimulates PFK, which stimulates glycolysis, inhibits F1,6-bPase and therefore reduces gluconeogenesis

what regulates?

1. Enzymes that are irreversible 2. Intermediates inhibit (citrate decrease PFK) 3. Energy supplies Respiration is stimulated by high ADP:ATP NAD+/NADH inhibited by the opposite

memorize the glycolysis/gluconeogenesis table (p. 157)

Glycolysis is downregulated by ATP ("Think, the purpose of glycolysis is to MAKE ATP")

Glycogenesis and glycogenolysis occur in

LIVER and SKELETAL MUSCLES skeletal muscle LACKS glucose-6-phosphatase; the glucose stays phosphorylated and cannot leave the muscle cell

insulin stimulates

GLYCOLYSIS AND GLYCOGENESIS ("we have lots of sugar, let's create more glycogen") decreases GNG ("we have enough glucose"

glucagon stimulates

GLYCOGENOLYSIS, when blood sugar is low, release glucose from the liver into the blood "Break down glycogen, we need more glucose" and GNG.

NADPH

reducing agent in ANABOLIC processes = Fatty Acid synthesis NEUTRALIZES ROS!!

PPP primary enzyme

the first step is Glucose-6-phosphate dehydrogenase (G6PDH) = PRIMARY POINT OF REGULATION = inhibited by NADPH G-6-P -> 6-phosphogluconate

pyruvate decarboxylase

First step in alcohol fermentation; REMOVE a CO2 from pyruvate create Acetylaldehyde (2 carbon)

ETC is... versus substrate level phosphorylation

OXIDATIVE PHOSPHORYLATION!! NADH, FADH2 Substrate-level phosphorylation occurs with production of ATP or GTP from ADP and GDP (2 per krebs cycle)

fatty acid catabolism

an ALTERNATIVE to glycolysis/cellular respiration

fermentation products

Lactate, ethanol DRAW the steps (ethanol is two carbon, meaning pyruvate had to be decarboxylated via PDC) Lactate keeps the carboxylic acid, reduces the carbonyl group

Hexose monophosphate shunt

PPP produces NADPH and Ribose-5-phosphate, and intermediates of glycolysis

Ribose-5-phosphate

5 carbon: produces nucleotides

glycogen metabolism (glycogenolysis): phosphoglucomutase (reversible), glycogen phosphorylase (adds P to glucose)

glycogen phosphoryLASE = 1 glucose is REMOVED from glycogen and phosphorylated to form Glucose-1-P Glucose-1-P and Glucose-6-P is reversible, enzyme is phosphoglucomutase G-6-phosphaTASE = REMOVES phosphate (phosphotase = REMOVE!)

Phosphorylase versus kinase

Phosphorylase and kinase are very similar Phosphorylase takes from INORGANIC phosphate sources

glutamATE versus glutamic acid

ATE is the ANIONIC FORM "acid has the H"

3PG

phosphoglyceric acid (anionic form) - this is a carboxylic acid PGK = kinase that takes phosphate from ATP and adds it to 3PG

ENOlase

cleaves C-O bonds Step 9 of glycolysis removes H2O

PEP carboxykinase (PEPCK)

the 2nd step of GNG 2 GTP -> GDP two CO2 leave form PEP

hormonal control of Glycolysis and GNG

F-2,6-bP up-regulates PFK, inhibits fructose-1,6-bisphosphatase reciprocal control insulin + (lots of glucose, low ADP), glycolysis glucagon - (little glucose, high ATP), GNG

ATP downregulates

Glycolysis

CAC is regulated by...

ATP and NADH step 3) isocitrate dehydrogenase (D->S) step 4) α-ketoglutarate dehydrogenase

8.1 Flashcards

(49 cards)