Energy storage: glucose and fats

Question 1

describe the major energy stores in a 70 kg man

Answer 1

15kg are triacylglycerols,
0.4kg is glycogen. there is 100g of glycogen in liver and 300g in the muscles.
6kg is muscle protein

Question 2

Describe in outline the reactions involved in glycogen synthesis and breakdown.

Answer 2

glycogenesis
1- phosphorylation by hexokinase to turn glucose + ATP to glucose 6-P and ADP( glucokinase in the liver).
2- isomerism by glucose6-P to glucose-1-P by phosphoglucomutase.
3- Glucose1-P + UTP to UDP-glucose + 2Pi
4 - Glycogen in residues + UDP glucose to glycogen

Question 3

different functions of the two main glycogen stores and why

Answer 3

there is 100g of glycogen in the liver, the presence of glucose-6-phosphotase means liver glycogen is a buffer for blood glucose levels. the GLUT2 transporter allows for the movement of glucose in and out of the blood to the liver.

the muscle lacks the enzyme glucose-6-phosphotase so glucose 6 phosphate (G6P) enters glycolysis for energy production. muscle glycogen is not impacted by glucagon as there are no receptors for it. AMP is a allosteric activator ion muscle glycogen phosphorylation.

glucagon is a mobiliser of glucose hence why its not necessary in the muscle.

Question 4

explain why and how glucose is produced from non carbohydrate sources

Question 5

Describe how lipids are transported in the blood

Answer 5

lipids are insoluble therefore they are transported whilst associated to proteins. 98% of the lipid are lipoprotein particles.

2% are non covalently bonded to albumin.

l

Question 6

describe the structure of lipoproteins and its constituent functions

Answer 6

they contain peripheral and integral apolipoproteins. the structural role is to transport insoluble lipids, the functional role is to be a co factor for enzymes and to be a ligand for cell surface receptors.

Question 7

Explain how tissues obtain the lipids they require

Question 8

Explain how disturbances to the transport of lipids can lead to clinical problems

Answer 8

raised serum LDL due to : is associated with atherosclererosis

Question 9

Explain how hyperlipoproteinaemias may be
treated

Answer 9

signs - Xanthelasma
Tendon Nodules

Question 10

how much plasma glucose and what is there normal range for cholesterol

Answer 10

Plasma glucose is 5mM
Cholesterol is less than 5mM

Question 11

what are the five classes of lipoproteins

Question 12

what are the five classes of lipoproteins?

Answer 12

classes are divided based off protein %
Main carriers of fat
chylomicrons (least dense- only present 4-6 hours after a meal )
VLDL(very low density lipoproteins)

Main carriers of cholesterol esters
IDL ( intermediate density lipoproteins)
LDL(low density Lipoproteins)
HDL( high density Lipoproteins)

all contain variable content of apolipoprotein, triglyceride, cholesterol and cholesterol ester.

Question 13

where and how is glycogen stored in the body

Answer 13

Muscle glycogen is stored as granules. intermyofibrillar glycogen is found with the mitochondria. intramyofibrillar glycogen is within the sarcomere in the muscle.

Liver glycogen is stored in granules in the hepatocyte.