Biochemistry Flashcards
What is the role of glucose in the body?
The principal source of energy
-storage
-production
Also used in other biosynthesis processes.
Protein modification
Redox Homeostasis
For which organs or cells are glucose important?
Brain
RBC
Muscle cell
-production of ATP in these cells.
Where is glucose stored and in which form?
Liver- glycogen
Adipose- triglycerides
Muscle- glycogen
Compare the roles of Glycogenesis in the liver to the muscle.
Liver: maintains blood glucose
Muscle: energy metabolism
Compare the B-oxidation in the muscle vs Liver.
The liver produces ketones during the fasting state.
Muscles- TCA and oxidative phosphorylation ATP
Describe the metabolism of glucose after a meal.
Glucose is absorbed and taken to the muscle, liver, and adipose
In liver:
it undergoes glycogenesis, glycolysis, and Fatty Acid Synthesis
In muscle:
Glycogensis and glycolysis, muscle energy specifically
In adipose:
Glucose enters and undergoes Fatty acid synthesis.
The Fatty acid synthesis (liver) produces VLDL and this transports triglycerides to adipose.
Insulin spikes, III
glucagon decreases
What happens to glucose after an overnight fasting state?
Adipose:
Decrease uptake of glucose
promotes B-oxidation and the formation of Acetyl CoA and Free Fatty Acids.
Increase Lipolysis
In the muscle:
B-oxidation and uptake of free fatty acids (produce from adipose) to produce acetyl coA.
inhibits glycolysis
promotes glycogenolysis
Release Lactate and alanine
Liver:
Increase in glycogenolysis
Upregulates Gluconeogenesis
-Glycerol, fatty acids (adipose)
-Lactate muscles
Glucagon increases
insulin decreases
What are the effects of alcohol on glucose?
Alcohol catabolism increases the NADH: NAD ratio, driving the LDH and MDH of gluconeogenesis in the wrong direction.
Hence a decrease in gluconeogenesis. Worsen when the patient is fasting.
Explain what happens in Diabetic people.
In patients that are insulin resistant:
There is already hyperglycemia
But the body detects it as starving, due to the failure of cells to take up glucose.
Hence increase in Gluconeogenesis, Glyconolysis that further increases glucose levels
simultaneously the lipolysis increases, which increases ketogenesis–> Ketonemia.
Both cases lead to Osmotic Diuresis: Glycouria and Ketonuria- Dehydration
Ketonemia leads to Acidosis, and respiratory compensation.
What is the Glycation process (Maillard reaction)?
Due to high sugar in the blood, it reacts with proteins and produces AGES
Sugars reduce amino acids and this produces Eary Glycation Products that eventually produce AGES.
Increases Vulnerability to oxidative stress
Describe the ways in which AGE causes problems.
RAGE:
Endothelial cells, Macrophages and smooth muscle cells
promotes cellular activation that leads CVS, Neuropathy, Nephropathy and retinopathy, CNS
AGE cross links to proteins
Malfunctions
What are the anti-glucagon effects of insulin?
Increase:
GTPase
Phosphodiesterase
Phosphoprotein phosphatase
Protein tyrosine kinase
What is the effects of insulin on gene expressions?
repression of gluconeogenic and catabolic enzymes
induction of biosynthetic and anabolic enzymes
How does insulin affect the different metabolism processes?
Increases
Glycolysis
Glycogenosis
Protein synthesis
Lipogenesis
Which enzymes of gluconeogenesis does insulin inhibit?
G-6-pho
Fru-1,6-bispho
Pep Carboxykinase
