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Extra ESA 1 flashcards > MCBG (mostly topic 6 carbohydrates) > Flashcards

MCBG (mostly topic 6 carbohydrates) Flashcards

1
Q

which pathways are activated when ATP conc high

A

anabolic

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2
Q

which pathways are activated when ATP conc LOW

A

catabolic

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3
Q

List HIGH energy signals, activate which pathways?

A 
ATP
NADH
NADPH
FAD2H
activate anabolic
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4
Q

List LOW energy signals, activate which pathways?

A 
NAD+
FAD
NADP+
ADP/AMP
activate catabolic
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5
Q

clinical relevance of Creatine Kinase

A

marker for MI

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6
Q

Role of Creatine Kinase

A

converts creatine into phosphocreatine.
Requires ATP, produces ADP
Reversible reaction, can provide ATP when low in cell.

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7
Q

What can be used as marker for urine dilation?

A

Creatine excretion

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8
Q

Describe the 4 stages of catabolism

A

stage 1- complex molecules to building blocks e.g. carbohydrates to monosaccharides.
stage 2- building blocks to simpler (fewer) molecules e.g. monosaccharides to pyruvate.
oxidative (require coenzymes NAD+) some ATP produced.
stage 3- mitochondrial. TCA cycle. oxidative.
stage 4- mitochondrial. Electron transport and ATP synthesis (large yield). Oxygen required. NADH and FAD2H reoxidised.

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9
Q

Describe the absorption of monosaccharides into epithelial cell and uptake into target cells

A 
uses SGLT1 (sodium glucose transporter) into epithelial cell. 
Glucose uptake into cells via facilitated diffusion using transport proteins (GLUT1-5)
GLUT 1-5 all have different affinities and tissue distribution.
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10
Q

Describe glycolysis

A

Glucose C6 oxidation. Requires 2x ATP.
Reduction of 2x NAD+ –> NADH
4x ADP –> ATP
pyruvate C3 (Two produced)

yield = 2x ATP per glucose

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11
Q

which enzymes are important in glycolysis.

A

hexokinase (glucokinase in liver): glucose –> glucose 6P

Phosphofructokinase 1: Fructose 6P –> fructose bisphosphate.

Pyruvate kinase: phospoenolpyruvate –> pyruvate.

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12
Q

why so many steps in glycolysis?

A
  • chemistry easier in smaller steps
  • efficient energy conversion
  • allows interconnections with other pathways
  • can be controlled
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13
Q

List some important intermediates in glycolysis

A

1,3 bisphosphoglycerate feeds out pathway to 2,3 BPG which is produced in RBC, regulator of Hb O2 affinity (promotes release of O2)

glycerol phosphate -important to triglyceride and phospholipid biosynthesis. produced from DHAP in adipose tissue and liver

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14
Q

Which glucose transporter is regulated by insulin

A

GLUT4

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15
Q

describe what each glucose transporters main role is

A

GLUT1- in erythrocytes and also in endothelial cells of the blood–brain barrier. Required to sustain respiration

GLUT2- liver allowing the hepatocytes to export glucose made by gluconeogenesis into the blood. primary glucose transporter in pancreatic beta cells.

GLUT3-main transporter in brain. high affinity isoform for times of low glucose plasma conc.

GLUT4-insulin-regulated glucose transporter expressed by skeletal muscle and adipose tissue

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16
Q

Which enzyme is crucial for the regeneration of NAD+ from NADH in red blood cells?

A

Lactate dehydrogenase.
No mitochondria so no normal regeneration in stage 4 (electron transport chain). regenerate NAD+ by converting pyruvate to lactate.
Lactate is transported to the liver and converted back to pyruvate and used in gluconeogenesis to produce glucose.

17
Q

monomers of maltose

A

2x glucose

18
Q

monomers of lactose

A

glucose and galactose

19
Q

monomers of sucrose

A

fructose and glucose

20
Q

how does glycogen differ from cellulose

A

Glycogen- alpha glucose 1,4 and 1,6
Branched chains
made/used in humans
fuel reserve

cellulose- beta glucose 1,4
linear chains
made by plants
structural role

21
Q

what are the possible fates of lactate?

A
  • converted back into pyruvate via LDH in liver
  • converted into acetyl-coA in heart muscle to feed into TCA cyle
  • converted into glucose via glucneogenesis in liver
  • converted to acetyl-coA for lipid biosynthesis in liver.
22
Q

why may lactic acidosis occur

A

heavy eating
vigorous exercise
shock
congestive heart disease

23
Q

role of pyruvate dehydrogenase. when is this enzyme activated?

A

converts pyruvate into acetyl-coA. feed into TCA cycle.

activated when there’s high conc of glucose to be catabolised. (insulin activates)
ADP activates

24
Q

symptoms of lactase deficiency, why do these happen?

A

stomach cramping
diarrhoea

unhydrolyzed lactose is fermented by gut bacteria.irritates GI tract.

25
Q

how does liver disease/alcohol affect the conversion of lactate?

A

lactate –> pyruvate via LDH inhibited/impaired as no NAD to use. As alcohol converts NAD+ into NADH

26
Q

how does Glucose-6-phosphate dehydrogenase deficiency effect RBCs?

A 
dec NADPH
disulphide bonds form
aggregated proteins
Heinz bodies (RBCs with denatured Hb)
haemolysis (breakdown RBC as unable to transport O2)
27
Q

How does dinitrophenol (DNP) affect oxidative phosphorylation?

A

uncoupler of oxidative phosphorylation.
protonophore- allows protons to leak across the inner mitochondrial membrane. Bypass ATP synthase.

Temp inc as energy is released as heat.

28
Q

cyanide effect on electron transport chain?

A

Inhibits enzyme (cytochrome oxidase) complex so no longer able to facilitate acceptance of e- by O2.

prevents flow of e- through the e- transport chain. no p.m.f generated.
ATP production stops.

29
Q

how are dietary carbohydrates are digested? which enzymes

A

Starch, glycogen, cellulose, lactose, sucrose.

  • salivary amylase. Pancreatic amylase. polysaccharide into disaccharide. Release glucose and maltose, leave smaller polysaccharides.
  • Glycosidases (membrane bound) break disaccharides into monosaccharides.
  • enzymes: sucrase, glycoamylase, lactase
30
Q

enzyme that converts galactose to galacticol

A

aldose reductase

31
Q

why is the pentose phosphate pathway an important metabolic pathway in some tissues.

A

produces NADPH. Biosynthetic reducing power, lipid biosynthesis > high activity in liver/adipose tissue.

produce C5 nucleotides for nucleic acid synthesis > high activity in bone marrow

32
Q

compare oxidative phosphorylation with substrate level phosphorylation

A

Oxidative:

  • requires membrane associated complexes
  • energy uncoupling occurs indirectly through use of proton gradient (pmf)
  • REQUIRES O2
  • major ATP synthesis process

Substrate level:

  • requires soluble enzymes
  • energy uncoupling occurs directly through formation of high energy of hydrolysis bond
  • can occur to some extent w/o O2
  • minor ATP synthesis process
33
Q

Describe how uncoupling occurs in brown adipose tissue

A

thermogenic (UCP)- uncoupling protein.
response to cold:
- noradrenalin activates lipase, releases fatty acids to be oxidised and activate UCP
- produces NADH/FADH2 for electron transport
- UCP transports H+ into mitochondria bypassing ATP synthase.
> energy released as heat

Extra ESA 1 flashcards (17 decks)

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