Metabolism 2.2 Flashcards
State intermediates of glycolysis
- DHAP
- 1,3 - BPG (1,3 - bisphosphoglycerate)
State uses of 1,3 - bisphosphoglycerare
Regulation of haemoglobin affinity for O2
(reduces affinity for oxygen promoting O2 release)
State uses of DHAP
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)
State where 1,3 BPG is produced
RBCs (high conc here)
Describe regulation of glycolysis
Enzymes catalysing irrervsivbe steps (1,3,10) are sites of control
State which enzymes are involved in regulation of glycolysis and state their functions
- Hexokinase - alosterically inhibited bt G-6-P (product inhibition)
- Phosphofructokinase-1 - in muscle, allosterically inhibited by high ATP : AMP ratio (feedback inhibiton) - in liver, activated by high insulin:glucagon ratio through dephosphorylation
- Pyruvate kinase - activated by high insulin : glucagon ratio through dephoshorylation
Describe regenration of NAD+ in glycolysis
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.
State monosaccharides which make up sucrose
FRUCTOSE
GLUCOSE
State where fructose is metabolised
Liver
Describe fructose catabolism
State the cause of essential fructosuria
Fructokinase deficiency
(in fructose catabolism, converts fructose to Fructose-1-Phosphate)
GENETIC
State a symptom of Fructosuria
Fructose in urine
(no other symptoms)
State the cause of fructose intolerance
Aldolase deficiency
(in fructose catabolism, aldolase cleaves fructose-1-phosphate into glyceraldehyde + DHAP)
How does fructose intolerance lead to liver damage and hypoglycaemia?
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
State symptoms of fructose intolerance
- Vomiting
- Nausea
- Abdominal Pain
- Failure to thrive
State a treatment for a fructose intolerance patient
Elimenation of SUCROSE + FRUCTOSE from diet
State which 2 monosaccharides produce lactose
Galactose + Glucose
State where galactose is metabolised
Liver
Diagram showing galactose metabolism
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
State causes of Galactosaemia
- Galactokinase deficicency (non-classic galactosaemia)
Galactose in blood (galactosaemia), galactose in urine (galactosuria)
Galactose + GALACTTITOLaccumulates in lens (leads to CATARCT) - GALT Deficiency (classic galactosaemia)
galactoseamia, galctosuria, Galactose + GALACTITOL accumulates in lens (leads to CATARCT), BRAIN + LIVER DAMAGE
State how accumulation Galacitol leads to cataract and liver damage
Deplets tissues of NADPH+ + H+
Which enzyme is responsible for reducing galactose to galactitol
Aldolase reductase
State symptoms of galactasaemia
- Vomiting
- Nausea
- Abdominal Pain
- Failure to thrive
- Diarrhoea
State treatment options for a patient suffering with galactosaemia
Elimination of lactose and galactose from diet
State the location of pentose phoshate pathway
Cytosol
State where pentose phosphate pathway is most common
Liver
Adipose tissue
RBCs
Overview of Pentose Phosphate Pathway
State the oxidative reaction in the pentose phosphate pathway
State the non-oxidative reaction
Rearrangement to glycolytic intermediates
State functions of the pentose phosphate pathway
- 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 - Production of intermediates for glycolysis F-6-P, G-3-P)
- Production of 5 carbon carbs for nucleotides in nucleic acid synthesis
State causes of glucose-6-phosphate dehydrogenase deficiency (G6PDH)
Genetic deficiency in Glucose-6-Phosphate Dehydrogenase
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)
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)
State how we can diagnose G6PDH Deficienecy
Full Blood Cell Count
G6PDH activity
State symptoms of G6PDH Deficicency
- Haemolytic anaemia
(Pallor, fatigue, jaundice)
State treatment options for patients suffering with G6PDH Deficiency
- Blood transfusion
- Folic acid
- Splenoctomy (removal of spleen)
