Metabolism 2.2 Flashcards

1
Q

State intermediates of glycolysis

A
  1. DHAP
  2. 1,3 - BPG (1,3 - bisphosphoglycerate)
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2
Q

State uses of 1,3 - bisphosphoglycerare

A

Regulation of haemoglobin affinity for O2
(reduces affinity for oxygen promoting O2 release)

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2
Q

State uses of DHAP

A

DHAP converted to Glycerol 3 phosphate
Glycerol 3 phosphate used to synthesise TGs in adipose tissue + liver
Glycerol 3 phosphate used to synthesises phospholipids (cell membrane components)

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3
Q

State where 1,3 BPG is produced

A

RBCs (high conc here)

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4
Q

Describe regulation of glycolysis

A

Enzymes catalysing irrervsivbe steps (1,3,10) are sites of control

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5
Q

State which enzymes are involved in regulation of glycolysis and state their functions

A
  1. Hexokinase - alosterically inhibited bt G-6-P (product inhibition)
  2. Phosphofructokinase-1 - in muscle, allosterically inhibited by high ATP : AMP ratio (feedback inhibiton) - in liver, activated by high insulin:glucagon ratio through dephosphorylation
  3. Pyruvate kinase - activated by high insulin : glucagon ratio through dephoshorylation
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6
Q

Describe regenration of NAD+ in glycolysis

A

IMPORTANT

NAD+ re-oxidised in stage 4 aerobic catabolism (AEROBIC GLYCOLSIS) / stage 2 anaerobic catabolism (ANAEROBIC GLYCOLYSIS)

Most cells:
occurs in Stage 4 Catabolism - Oxidative Phosphorylation
NADH⁺ + H⁺ is re‐oxidised to NAD⁺

However, in some cells, NAD+ is regenerated in anaerobic glycolsyis. For examples,

RED BLOOD CELLS (no mitochondria)
Kidney medulla, lens, cornea (few mitochondria), this means that stages 3 and 4 of catabolism are insuficcient in these cells

Another example where NAD+ is regenrated using anaerobic respiration is during vigorous exercise of muscles, stage 4 catabolism is not efficient.

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7
Q

State monosaccharides which make up sucrose

A

FRUCTOSE
GLUCOSE

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8
Q

State where fructose is metabolised

A

Liver

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9
Q

Describe fructose catabolism

A
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10
Q

State the cause of essential fructosuria

A

Fructokinase deficiency
(in fructose catabolism, converts fructose to Fructose-1-Phosphate)
GENETIC

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11
Q

State a symptom of Fructosuria

A

Fructose in urine
(no other symptoms)

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12
Q

State the cause of fructose intolerance

A

Aldolase deficiency
(in fructose catabolism, aldolase cleaves fructose-1-phosphate into glyceraldehyde + DHAP)

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13
Q

How does fructose intolerance lead to liver damage and hypoglycaemia?

A

Fructose intolerance due to aldolase deficiency. Aldolase cleaves fructose-1-phosphate into glyceraldehyde and DHAP.
This does not happen without aldolase, fructose-1-phosphate accumulates in liver, leads to liver damage + hypoglycaemia

GENETIC CONDITION

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14
Q

State symptoms of fructose intolerance

A
  1. Vomiting
  2. Nausea
  3. Abdominal Pain
  4. Failure to thrive
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15
Q

State a treatment for a fructose intolerance patient

A

Elimenation of SUCROSE + FRUCTOSE from diet

16
Q

State which 2 monosaccharides produce lactose

A

Galactose + Glucose

17
Q

State where galactose is metabolised

18
Q

Diagram showing galactose metabolism

A

Important enzyme:

GALACTOKINASE
(Gactose phosphorylated to galactose-1-phosphate)

GALT
This coverts galactose-1-Phosphate to Glucose-1-Phosphate

PHOSPHOGLUCOMUTASE
Glucose-1-Phosphate isomerised (phosphoglucomutase)
Glucose-6-Phosphate

19
Q

State causes of Galactosaemia

A
  1. Galactokinase deficicency (non-classic galactosaemia)
    Galactose in blood (galactosaemia), galactose in urine (galactosuria)
    Galactose + GALACTTITOLaccumulates in lens (leads to CATARCT)
  2. GALT Deficiency (classic galactosaemia)
    galactoseamia, galctosuria, Galactose + GALACTITOL accumulates in lens (leads to CATARCT), BRAIN + LIVER DAMAGE
20
Q

State how accumulation Galacitol leads to cataract and liver damage

A

Deplets tissues of NADPH+ + H+

21
Q

Which enzyme is responsible for reducing galactose to galactitol

A

Aldolase reductase

22
Q

State symptoms of galactasaemia

A
  1. Vomiting
  2. Nausea
  3. Abdominal Pain
  4. Failure to thrive
  5. Diarrhoea
23
Q

State treatment options for a patient suffering with galactosaemia

A

Elimination of lactose and galactose from diet

24
State the location of pentose phoshate pathway
Cytosol
25
State where pentose phosphate pathway is most common
Liver Adipose tissue RBCs
26
Overview of Pentose Phosphate Pathway
27
State the oxidative reaction in the pentose phosphate pathway
28
State the non-oxidative reaction
Rearrangement to glycolytic intermediates
29
State functions of the pentose phosphate pathway
1. Production of NADPH+ + H+ this is reducing power, used in: -used in fatty acid synthesis in liver, adipose tissue, lactating mamary glands -maintains reduced state of GSH - glutathione - antioxidant 2. Production of intermediates for glycolysis F-6-P, G-3-P) 3. Production of 5 carbon carbs for nucleotides in nucleic acid synthesis
30
State causes of glucose-6-phosphate dehydrogenase deficiency (G6PDH)
Genetic deficiency in Glucose-6-Phosphate Dehydrogenase
31
State effects of G6PDH deficiency
Low levels of NADPH+ + H+ (inability to keep gluathione in reduced state, so oxidative damage to cells Haemolysis of RBCs (Haemoglobin + other proteins become cross linked by disulfide bridges This forms insoluble aggregates (Heinz bodies) attaching to RBC membranes, leading to haemolysis (destruction of RBCs)
32
Which cells are worst affected by G6PDH deficiency
RBCs Pentose phosphate pathway is only way they generate NADPH+ + H+ also, undergo oxidative damage (glutathione in oxidused state)
33
State how we can diagnose G6PDH Deficienecy
Full Blood Cell Count G6PDH activity
34
State symptoms of G6PDH Deficicency
1. Haemolytic anaemia (Pallor, fatigue, jaundice)
35
State treatment options for patients suffering with G6PDH Deficiency
1. Blood transfusion 2. Folic acid 3. Splenoctomy (removal of spleen)