session 4-storage,glycogen,TAGS,chylomicrons,NH3 toxicity,PKU,homocystinuria,amino acids Flashcards
what is the second step of glycogen synthesis?
glucose 6 phosphate glucose 1 phosphate (note: is reversible) (note 2: catalysed by phosphoglucomuctase)
what is the 3rd step of glycogen synthesis?
glucose 1 phosphate + UTP + H2O —> UDP-glucose + 2Pi
UTP is similar to ATP. UDP-glucose is highly active form of glucose
what is the 4th step of glycogen synthesis?
glycogen (n residues) + UDP-glucose —> glycogen (n+1 residues) + UDP (glycogen synthase=1,4 glycosidic bonds)(branching enzyme=1,6 glycosidic bonds)
what 2 enzymes are involved in glycogen degradation?
glycogen phosphorylase/debranching enzyme
what enzyme do muscles lack?
glucose 6 phosphatase
how do muscle glycogen stores differ from the liver?
glucagon has no effect on muscle stores as muscle does not have enzyme (glucose 6 phosphatase) to produce glucose
what disease is characterised by glucose 6 phosphatase deficiency?
von Gierke’s disease
what is the first step of glycogen synthesis?
glucose+ATP —>glucose-6-phosphate + ADP catalysed by……..(hexokinase and glucokinase in liver)
what disease is characterised by (MUSCLE) glycogen phosphorylase deficiency?
McArdle disease
name 3 ways in which gluconeogenesis can occur?
- lactate (anaerobically)
- amino acids
- breakdown of TAG from adipose tissue to produce glycerol
Some steps of glycolysis are used in gluconeogenesis…and even though some steps are irreversible,these can be bypassed by reactions catalysed by enzymes. What 2 enzymes are used to reverse step 10 in glycolysis from pyruvate—>oxaloacetate—>phosphoenolpyruvate
pyruvate—>oxaloacetate =(pyruvate carboxylase)
oxaloacetate—>phosphoenolpyruvate = PEPCK (phosphoenolpyruvate carboxykinase)
after phosphoenolpyruvate, the reverse steps of 9,8,7,6,5,4 occur until step 3. what enzymes are used to convert fructose 1,6-bisphosphate–>fructose 6 phosphate , step 2 and then step 1 of glucose 6 phosphate–>glucose
- fructose 1,6-bisphosphate–>fructose 6 phosphate =fructose 1,6-bisphosphatase
- glucose 6 phosphate—>glucose =glucose 6 phosphatase
what are TAGS (triacylglycerol) carried/transported in?
chylomicrons
what is produced from acetyl CoA using a key regulator (acetyl CoA carboxylase) in the formation of fatty acids (lipogenesis)?
malonyl CoA
fatty acid synthase complex builds fatty acids by sequential addition of 2 carbon units provided by malonyl CoA. What 2 molecules does lipogenesis require?
ATP and NADPH
what does it mean if amino acids are ketogenic or glucogenic?
- keto-produce acetyl CoA that can be used to synthesise ketone bodies
- gluco-gluconeogenesis
what enzyme converts alanine to glutamate?
ALT-alanine aminotransferase
what enzyme converts glutamate to aspartate?
AST-aspartate aminotransferase
how do you manage NH3 toxicity?
low protein diet and replace them with keto acids
what test is used to detect SCD, CF and hypothyroidism?
heel prick test
what enzyme deficiency causes PKU (phenylketonuria) and what type of inheritance is it?
phenylalanine hydroxylase
Autosomal recessive
what builds up in the urine and has a musty smell when it comes to PKU?
-phenylketones build up in urine
what happens to phenylalanine when it accumulates in the blood?
-transamination to phenylpyruvate and thus phenylketones
name 3 symptoms of PKU
- severe intellectual disability
- hypo-pigmentation
- seizures and microcephaly (small head)
