Glycolitic Metabolites, Lactate And The Metabolism Of Sugars and pentose phosphate pathway

Question 1

What is 2,3 bisphosphoglycerate

Answer 1

Produced in RBC

Regulator of haemoglobin o2 affinity promotors release of o2

Question 2

Glycerol phosphate

Answer 2

Important to triglycerides and phospholipid biosynthesis

Produced from DHAP

Lipid synthesis required glycolysis

Liver can phosphorylate glycerol directly

Question 3

Why do RBC need to regenerate NAD+ in a another way

Answer 3

They have no stage 3 pr 4 of metabolism

Stage 4 needs 02 and the supply of 02 to muscles and gut is often reduced

Question 4

Lactate dehydrogenase reaction

Answer 4

NADH + H + PYRUVATE = NAD and lactate

Using lactat dehydrogenase

Question 5

What is hyperlactaemia?

Answer 5

2-5mM - plasma lactate
Below renal threshold
No change in blood pH

Question 6

What is lactic acidosis?

Answer 6

Above 5mM plasma lactate

Above renal threshold
Blood pH lowered

Question 7

How can fructose be used in glycolysis

Answer 7

Fructose can be converted to G3P which can under glycolysis to form pyruvate

Question 8

What is essential fructosuria?

Answer 8

Fructokinase missing

-fructose in urine

Question 9

Fructose intolerance

Answer 9

Adolase B missing

-fructose 1-P accumulates in liver leads to liver damage

Question 10

How is galactose metabolised

Answer 10

Galactokinase converted it to galactose 1-P

Uridyl transferase converts galactose 1-P to gluose 1-P then gluose 6P which can enter glycolysis

Question 11

What causes galactosaemia?

Answer 11

Deficiency in
UDP-Galactose epimerase
Uridyl transferase
Galactokinase

Question 12

What does UDP-galactose epimerase do

Answer 12

Converts galactose 1-p to UDP- galactose which tunes into UDP-glucose which can form glycogen

Question 13

What is galactosaemia ?

Answer 13

Milk rich diet in infancy

Unable to utilise galactose 
Galactokinase deficiency (rare)- galactose accumulates 

Trasnferase deficicy (common) - galactose and galactose 1-P accumulate

Galactose enters other pathways to form galacticol
Which depletes levels of NADH as it i used to form galacticol

NADH is important is preventing the formation of inappropriate disulphide bonds therefore when NADH levels are reduced they form which causes cross linking- cataracts

Question 14

What is the pentose phosphate pathway

Answer 14

Two stage pathway - cytoplasmic

Glucose -6-P to c5 sugar and CO2 using NADP
NADP is reduced to NADPH

Using glucose 6P dehydrogenase

Question 15

What is the function of the pentose phosphate pathway?

Answer 15

Produce NADH in cytoplasm

Bio synthetic reducing power- lipid synthesis

Maintain free SH cysteine groups on certain proteins
Prevent oxidation to disulphide bonds

Produce C5 sugar for nucleotides needed for nucleic acid synthesis

High activity in dividing tissues

Question 16

What occurs when there is a Deficiency of glucose 6-phosphate dehydrogenase deficiency

Answer 16

Leads to an inability to produce NADPH from NADP so NADPH will drop

In RBC this needs to disulphide bonds forming which cause appreciated proteins- Heinz bodies whic leads to haemlysis

Question 17

What is the important source of NADH required for

Answer 17

Reducing power for biosynthesis
Maintenance of reduced glutathionine (GSH) levels
Detoxification reaction

Question 18

What are C5 sugar-ribose required for

Answer 18

Synthesis of
-nucleotide
DNA
RNA

Question 19

what converts galactose to galacticol

Answer 19

aldose reductase using NADPH- galactosaemia

decreased NADPH levels leads to galactosaemia

Question 20

What is the rate limiting enzyme in the pentose phosphate pathway?

Answer 20

Glucose 6-phosphate dehydrogenase