Biochemistry Flashcards
Where in the cell contains circular DNA?
Mitochondria - contains its own genome
What is the difference between wet and dry beriberi?
What is the nutritional deficiency
Wet = heart failure present
Dry = just peripheral neuropathy
Thiamine deficiency
What is the diagnostic test for cystinuria?
Cyanide Nitroprusside
Where in the cell does
- metabolism
- protein synthesis occur?
Cytoplasm
Where in the cell does protein modification occur?
Endoplasmic Reticulum
Where in the cell does protein processing occur?
Golgi apparatus
Where in the cell does protein degradation occur?
Lysosome
What part of the cell cycle does the cell spend the most time in?
G1
When is DNA replicated?
Synthesis
Fates of absorbed glucose (3)
Glycolysis
Storage as glycogen
Converted to triglycerides/amino acids/lipids
Where does glycolysis occur?
What is the aim of glycolysis?
Cytoplasm
Make ATP and NADPH available
Produces pyruvate - intermediary
Hexokinase vs glucokinase
Glucokinase is when glucose is oxidised in the liver
Where in the cell does gluconeogenesis occur?
Cytoplasm
Explain pentose phosphate shunt and G6PD
Aim
Glucose to glucose-6 phosphate
Requires G6PD
G6PD allows RBC membrane to be intact
loss = haemolysis under certain conditions
Aim = give NADPH for reduction reactions
Glycogen Storage Disease
- inheritance
- example
A recessive
McArdle’s Disease
Where is cholesterol absorbed?
What is needed to absorb cholesterol?
Small intestine
Bile acids
How is cholesterol transported to the liver in the blood?
As chylomicrons/remnants
What does the liver export cholesterol as?
VLDL
What is VLDL transformed into?
IDL
What is IDL transformed into?
LDL
Where are the LDL receptors located?
Hepatic tissue
Adipose tissue
What is lipogenesis?
Where does it occur?
= synthesis of triglycerides
Occurs in liver and adipose tissue
How does fat into the duodenum trigger the release of bile acids?
Triggers release of cholecystokinin
= contraction of gallbladder and release of bile
2Y causes of hypercholesterolaemia (5)
Hypothyroidism
Jaundice 2y to biliary obstruction
Nephrotic syndrome
Pregnancy
Diabetes
Where does lipolysis occur?
- organ
- where in the cell
- inhibited by
Liver and muscle
Mitochondria
Insulin
Where does lipogenesis occur?
- organ
- where in the cell
Liver and adipose tissue
Cytoplasm
What is the main function/location of cholesterol?
Cell membrane
What is involved in the metabolism of cholesterol?
HMG-CoA reductase
What is the main dietary lipid?
Triglycerides
Dietary fat > liver - what is the process?
Digested in small intestine, converted into chylomicrons, processed in liver, churned out as VLDL
Where is glycogen stored (3)?
Liver
Muscle
Kidney
Pathophysiology of DKA
Insulin deficiency
= lack of available intracellular glucose
Excessive lipolysis to produce ketones > acidosis
Breakdown of fatty acids =
Acetyl coA
Ketone bodies
= can be used by all cells except brain in exceptional conditions
Types of membrane receptors (4)
Ligand gated ion channels
Voltage gated channels
G protein coupled
Tyrosine kinase receptors
Where does the urea cycle occur?
Liver and brain
e.g. cirrhosis - hepatic encephalopathy
Pathophysiology of cystinuria
- presentation
- investigation
= defective amino acid transport
Px: malabsorption, ataxia, pellagra
Ix:cyanide nitroprusside test +VE
Pathophysiology of homocystinuria
- presentation
- similar condition + difference
= collagen disorder
Px: mental retardation, marfanoid, DOWNward lens dislocation
Similar to Marfan’s, in Marfan’s the lens dislocation is UPward (because they are taller)
What is Fanconi’s Syndrome?
- where does it effect?
- presentation (4)
= renal tubular acidosis
- proximal renal tubules
- amino aciduria, hyperphosphataemia, hypokalaemia, osteomalacia
B1 =
Cause (2)
Presentation (3)
= thiamine
Chronic alcoholism, rice only diet
Px: dry and wet beri beri, Wernicke’s and Korsakoff syndrome
B2 =
Presentation (2)
= riboflavin
Px: angular stomatitis, peripheral neuropathy
B3 =
Causes (2)
Presentation
Similarity
= niacin
Chronic alcoholism, malabsorption
Px: pellagra
= diarrhoea, dementia, dermatitis
Can see neurological symptoms similar to subacute combined degeneration of cord
B6 =
Causes (3)
Presentation
= pyridoxine
Alcoholics, pregnancy, isoniazid
Px: peripheral neuropathy
Cholecalciferol > 25 hydroxycholecalciferol
- where does this occur?
Liver
Presentation of hypomagnesiaemia (2)
Tetany
Cardiac arrhythmia
Where is iron absorbed?
What happens there?
How is it carried in plasma?
Small intestine
Converted to ferritin
Carried in plasma as Fe3+ bound to transferrin
Methahaemoglobinaemia
- problem
- causes (4)
= iron is oxidised to Fe3+ so cannot carry O2 in Hb
Causes = haemoglobinopathies. quinine, sulphonamides (co-trimoxazole), nitrates
How is CO2 carried?
Most - bound as bicarbonate
Some is free in the plasma
