:M Flashcards

Question

when is PDH blocked for TCA? [2]

Answer 1

- PDC / PDH is blocked when: * *a) levels of Acetyl CoA levels are high b) If reduced NAD levels are high**

Answer 2

Acetyl CoA combines with oxaloacetate to form Citrate. (Citrate is a tricarboxylic acid, hence the name TCA) This enters the cycle and is progressively oxidised, each time producing NADH/FADH2, until finally forms oxaloacetate again and the cycle can begin again.

Answer 3

:) - PDH Kinases inhibit PDH by adding PO4 - PDH Phosphatases activate PDH by removing PO4 // * *control of PDH kinases** - PDH kinases are _activated_: by _ATP, acetyl Co-A and NADH_ (last two are products of PDH) = switch off PDH. - Pyruvate & insulin _inhibits PDH Kinasese_ (as pyruvate wants PDH to be active to break pyruvate down) = switch on PDH. **control of PDH phosphatases** _- Ca2+ ions activate PDH phosphatises - increases PDH_. occurs in muscle -\> eventually get more ATP production = switch on PDH _- insulin activates PDH phosphatases - actives PDH_

Answer 4

insulin caueses the activation of PDH & eventual production of acetyl co-A insulin = -ve effect on kinases (which inhibit PDH) +ve effect on phosphatases (which activate PDH) adrenaline and glucagon: want pyruvate untouched, so it can be used to make glucose via gluconeogenesis = inhibit PDH

Answer 5

- protons flow back to matrix through ATP synthase. This drives phosphorylation of ADP: ATP produced by oxidative phosphorylation: **ADP + P --\> ATP at ATP Synthase**

Answer 6

**1.Glycolysis of glucose to pyruvate** •Converted to acetyl-CoA using pyruvate dehydrogenase complex (PDC) •Produces 2 reduced NAD molecules per glucose •1 reduced NAD per pyruvate **2.Transamination of glucogenic amino acids to pyruvate** • Converted to acetyl-CoA using pyruvate dehydrogenase complex (PDC) **3.Beta-oxidation of fatty acids directly to acetyl-CoA** •Produces 1 NADH and 1 FADH2 per acetyl-CoA

Answer 7

- TCA end products: a) 1 GTP / ATP b) 3 NADH c) 1 FADH BUT BECAUSE HAVE 2 ACETLY CO-As GOING INTO TCA: a) 2 GTP / ATP b) 6 NADH c) 2 FADH

Answer 8

- during hypoxia: **formation of reactive oxygen species (ROS)** -\> highly damagin to lipids / proteins / DNA - oxygen is not there to mop up the electrons at complex 4. electrons are abcked into the ETC

Answer 9

during ox. phosph H+ are pumped across the inner mitochondrial matrix at which complexes? - complexes 1, 2 & 3 - complexes 1, 2 & 4 * *- complexes 1, 3, & 4** - complexes 2, 3 & 4

Answer 10

pancreatic islets of Langerhans - alpha cells: produce glucagon - beta cells: produce insulin - delta cells: produce somatostatin

Answer 11

glucose --\> glucose-6-phosphate --\> glucose-1-phosphate --\> UDP-glucose --\> glycgoen. aka **glycogenesis** Akt: phosphorylates and i**nactivates glycogen synthase kianse** = **activates glyocgen synthase**

Answer 12

effect of insulin at: muscles: * *i) activates glycogenesis ii) inhibits glycogenolysis** adipose tissues: i) **activates lipogenesis ii) inhibits lipolysis** liver: * *i) glycogensis Activated ii) lipogenesis activated iii) GNG inhbiited** protein synthesis: * *i) activates protein synthesis ii) inhibits protein catabolism**

Answer 13

insulin inhibits gluconeogenesis !

Answer 14

1. - Ca2+ is an allosteric **keeps the pyruvate deyhyrogenase complex activated.** - therefore causes **quicker conversion of pyruvate -\> acetly co-A - increases TCA to occur more** (PDH controls the entry to the TCA, it’s activity is regulated. The enzyme is phosphorylated and dephosphorylated depending on whether it is active or inactive. The calcium is promoting essentially the active state of PDH, by influencing PDH phosphatase (this PDH phosphatase will remove phosphates from the PDC and activate it) 2: calcium and ADP drive **activity of two dehydrogenase enzymes** in the TCA to maintain high ATP production 3. **Low levels of ATP/NAD pushes PDH into its active state.**

Answer 15

- during exercise, ATP runs low & AMP levels start increasing AMP stimulates: - increases recruitment of GLUT4 tranpsorter to membrane of muscle cells - allosterically activates inactive glycogen phosphorylase - allosterically activates phosphofructokinase-1 (PFK-1) (drives glycolysis)

Answer 16

most common pathway: i) ethanol ⇌ acetaldehyde (via enzyme alcohol dehydrogenase (ADH)) ii) acetaldehyde --\> acetate (ketone body - so can be used to make energy !) via enzyme ALDH2 iii) acetate can then be converted into (acetyl co-a important product: **NADHs** produced !! remember

Answer 17

1. glucose starts falling; insulin goes down, glucagon up 2. glycogen can keep brain alive for 2/3 days / 30 hrs 3. swith to FA break down = energy for 2-3 days due to gluconeogenesis 4. FA then switches to ketone bodies. (ketone bodies can go into brain - important !) 5. final resource = break down proteins to release amino acids for gluconeogenesis

Answer 18

1. promotes the recruitment of **GLUT4 tranporters to the membrane of muscle cells.** important: insulin-independint effect !! **2. Activates phosphofructokinase 2, (PFK2).** PFK2 strong allosteric activator of PFK-1 (to make fructose 1,6 BP -\> glycolysis). only happens in cardiac muscle !!! 3. s**hifts from glucose to fatty acid break down as a source of ATP:** i) phosphorylase acetyl co-A carboxylase (which makes FAs) ii) stops the production of malonyl-CoA (normally inhibits carnitine shuffle. cartinine shuffle is needed in FA break down)

Answer 19

- excess alchohol consumption leads to excess acetyl co-A - excess acetyl co-A: i) produces lots of ketone bodies: acidic --\> metabolic acidosis ii) gets converted to fats -\> **fat & obese** 2. fatty liver: - XS acetly co-A converted to fat & stays in liver. - often have low food intake - poor protein intake = **low albumin. = fat not transported** - **get scar tissue forming - results in cirrhosis**

Answer 20

- immune cells have increased requirement for co factor: **NADPH** - glucose is taken from glycolysis to pentose phosphate pathway to make NADPH

Answer 21

hypochlorite

Answer 22

NADPH functions: - as a reducing agent (like NADH) - to generate ROS: immune cells use NADPH oxidase to reduce O2 to free radical and the H202. H202 then used to kill engulfed pathogens = respiratory burst

Answer 23

cancer cell metabolism: **high metabolic rate** * *Warburg Effect / Hypothesis** - cancer cells use glucose for **aerobic glycolysis** rather than **oxidative phosphorylation** even in the prescence of oxygen - leads to build up of **lactate & lactic acid**

Answer 24

a) before the stomach**: greater sac** b) behind the stomach: **lesser sac**

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