Bob's 2 Flashcards
What are the four stages of catabolism?
Stage 1- GI breakdown to molecules for absorption
Stage 2- some oxidation and breakdown to metabolic intermediates like pyruvate.
Stage 3- Tricarboxylic acid or Krebs cycle where through oxidation reducin power and energy is released
Stage 4- oxidative phosphorylation in the mitochondrion. Reducing power converted to ATP.
Where does stage 2 catabolism occur?
Both in the cytoplasm and mitochondria.
Where does stage 3 (krebs orTCA cycle) of catabolism occur?
Matrix of the mitochondria
Where des stage 4 f catabolism occur?
Inner matrix of the mitochondria. Oxygen is required for electron transport chain.
What is the general structure of carbohydrate?
(CH2O)n
What should glucose concentration in the blood be?
5mM
What tissues have an absolute requirement for glucose metabolism meaning that it is essential for them?
Red blood cells
Neutrophils
Lens of eye
Innermost cells of kidney medulla
Brain much rather glucose but can use ketone bodies during starvation however it takes time to adapt to their use.
What are the three types of lactose intolerance?
Primary lactase deficiency where there’s an absence of lactase persistence allele. Only occurs in adults.
Secondary where small intestine lining is damaged. Gastroenteritis, coeliac disease, crowns disease and ulcerative colitis. Occurs in infants and adults and is generally reversible.
Congenital caused by an autosomal recessive defect in the lactase gene and this is extremely rare.
What shoudlblood glucose level be?
3.3-5 mmol/litre
How are monosaccharides absorbed?
Glucose and galactose into intestinal epithelium cell through SGLT 1 (sodium glucose transporter 1) through active transport.
From cell into capillary through GLUT 2 which is passive due to higher glucose concentration in epithelial cell.
Glucose transporters?
Facilitated diffusion.
Glut 2 is glucose sensing in pancreatic beta cells.
Glut 4 is recruited to the surface of cells in response to insulin.
Is glycolysis reversible?
No its irreversible
Where does glycolysis occur?
In the cytoplasm of every tissue.
What are the three key enzymes in glycolysis?
Hexokinase
Phsphofructkinase
Pyruvate kinase
To convert pyruvate to glucose in gluconeogenesis these steps must be bypassed
What des hexokinase do?
Adds a phosphate to glucose and this prevents it from crossing back through the cell membrane.
What does phosphofructokinase do?
Reaction is very exothermic and so is irreversible and a committing step.
Why do we invest ATP at the beginning of glycolysis?
To prevent glucose from passing back through the cell membrane and to make it more unstable so that it commits to glycolysis.
How many ATP are given and how many are made?
Two are given and four are made.
Why are there on many steps in glycolysis?
Efficient energy conservation as small energy releases easier to capture.
Chemistry is easier in small steps
Allows for fine control- can divert at various stages if necessary
Gives versatility- can make intermediates and some reactions can be used in reverse.
Clinical use of glycolysis?
measure uptake of radioactive deoxyglucose and use to see and measure cancers.
