Biochemistry Flashcards
Where does fatty acid synthesis and activation occur?
Cytoplasm
What is the only substrate that can be synthesised to fatty acyl-CoA?
Malonyl Co-A
Where does B-oxidation occur?
Mitochondrion
What is the only form that fatty acids can cross the mitochondrial membrane for metabolism as?
Fatty acyl-carnitine
What is the breakdown pathway of fatty acids called?
B-oxidation
What is the first step of fat catabolism?
Lipolysis
What is the main storage form of lipids?
Triglycerides
What are the products of each B-ocidation cycle?
1 fatty acyl-CoA (shortened by 2C), 1 acetyl Co-A, 1 FADH2, 1 NADH + H
What is the calculation for the number of oxidation cycles for a fatty acyl-CoA chain?
For Cn, (n/2-1)
What would be the product of the breakdown of a 14C fatty acid?
7 acetyl-CoA, 6NADH + H, 6 FADH2
as one less oxidation cycle than no of acetyl-CoA produced
Is gluconeogenesis the reverse of glycolysis?
No
Where are ketone bodies formed?
Liver mitochondria
Under what conditions are ketone bodies formed?
Fasting
What smell do ketone bodies cause?
Pear drop breath
How do ketone bodies travel around the body?
In the bloodstream
Where does fatty acid synthesis mainly occur?
The liver (cytoplasm)
What enzyme converts acetyl-CoA to malonyl CoA?
Acetyl CoA carboxylase
Does insulin increase or decrease the activity of acetyl CoA carboxylase?
Increase
Signals fed state so increases fatty acid synthesis
Does glucagon increase or decrease the activity of acetyl CoA carboxylase?
Decrease
Signals fasting state so fatty acid degradation is required
What is the purpose of urea?
To deal with excess nitrogen in either the urine or sweat
Where does the urea cycle occur?
In the liver mitochondria
Where does the nitrogen for the urea cycle come from?
1 from aspartic acid (amino acid)
1 from free ammonium
What is the catalyst for the start of glycogen polymer and how many glucose molecules does it require?
Glycogenin protein
4
How does glycogen synthase work?
Adds on single glucose molecules to an existing glycogen polymer
Do fatty acids act directly as precursors to the TCA cycle?
No
Can amino acids provide carbons to the TCA cycle?
Yes
Where can muscle cell glycogen supply energy to?
Only the muscle cell
What is glyconeogenesis?
A pathway for the synthesis of new glucose from non-carbohydrate precursors
What is the type of protein contained within plasma?
Globulins
What form of globulin is utilised in the immune system?
Gamma globulin (forms the backbone of immunoglobulins)
Where are plasma proteins secreted from and what is their importance in maintaining BP?
Secreted from and produced in the liver
Maintain balance of fluid across the walls of vessels
What is the most abundant plasma protein?
Albumin
What is the importance of iron in the body and what is its transporter + storage protein?
Used to form haemoglobin
Transporter: transferrin
Storage: ferritin
What disease is due to copper deficiency?
Wilsons disease
What is used for fat transport between organs and tissues?
Lipoproteins
What is contained within the core of lipoproteins?
Cholesterol esters
Triglycerides
What is the only organ that can esterify and excrete cholesterol?
Liver
What is the importance of cholesterol in the body?
Rigidity of cell membranes
Precursor to bile acids, steroid hormones and vit D
How is cholesterol transported in the body?
Mostly esterified to insoluble long chain fatty acids
Where is cholesterol synthesised?
Cytoplasm of liver cells (very energy heavy process)
What compound is unique to cholesterol synthesis?
Mevalonic acid
What is the key rate limiting enzyme in cholesterol synthesis?
HMG-CoA reductase (generates mevalonic acid)
Which hormones are produced from cholesterol?
Steroid hormones: corticosteroids + sex hormones (androgens + estrogen’s)
