metabolism + cell motility Flashcards
give an overview of glycolysis
Glycolysis overview;
Preparation phase -
Converts glucose, a 6C molecule, into two 3C molecules of glyceraldehyde-3-phosphate (G3P)
Consumes 2 ATP
Payoff phase -
Converts the two G3Ps into pyruvate
Produces 4 ATP and 2 NADH
Net products -
2 NADH, 2ATP
how is glycolysis regulated?
Pyruvate kinase activity is promoted by fructose 1,6-bisphosphate (product of step 3)
Pyruvate kinase is inhibited by ATP and acetyl CoA, products of glycolysis
briefly outline the process of the TCA or krebs cycle
Combines the 2C acetyl CoA with the 4C oxaloacetate to form a 6C molecule
Then removes electrons from the 6C molecule (as well as the 2 carbons) in order to reduce NAD+ and FAD+ for large ATP payoff in ox.phosphorylation
in terms of the Krebs cycle, what does one molecule of glucose get you?
One molecule of glucose = two cycles:
4x CO2
2x ATP (or GTP)
2x FADH2
6x NADH
why is losing weight difficult?
The only way to metabolise fats is by putting them into the krebs cycle and oxidative phosphorylation, they cannot be converted into glucose (glycerol can via gluconeogenesis but fatty acids cannot)
Fats are energy rich, one regular fatty acid provides around 4 acetyl-CoA molecules, which gives 8x FADH2 and 24x NADH, or 64 electrons
so don’t need loads of it for lots of energy
what molecules can we use as an energy source/to produce ATP?
amino acids - different ones can feed in to the Krebs cycle at different positions
glucose (sugars)
fats (fatty acids)
give an outline of the process of oxidative phosphorylation
Essentially electrons from FADH2 and NADH are transferred to oxygen to produce water
The process is about using the free energy provided by redox reactions to pump H+ from the matrix into the intermembrane space, so the H+ can travel back into the matrix via ATP synthase
Transport complexes 1, 3 and 4 pump H+ across into intermembrane space
ATP synthase then allows H+ to move down gradient, pushing it like a turbine to generate ATP
O2 + 4H2 —> 2H2O
what are uncoupling agents and why are they so dangerous?
bind protons in intermembrane space and transport them across membrane, dismantling the proton gradient before ATP can be produced
Drive oxidative phosphorylation harder and harder, literally generates heat and cells die - very dangerous
have previously been used (not officially) for weight loss
example = 2,4-dinitrophenol
aside from uncoupling agents, what kind of metabolism inhibitors are there?
e- transport inhibitor - can target the different complexes in the transport chain
examples = cyanide, CO, sodium azide (all target complex IV)
ATP synthase inhibitors
example = oligomycin
metabolism is C__________?
compartmentalised - glycolysis in cytosol, krebs and ox.phos in mitochondria
metabolism in the brain?
Normally, only uses glucose
In starved/fasted states, ketone bodies can be used but only after several days
Consumes 120g/day - 60-70% of your glucose production
metabolism in kidney?
Kidneys produce urine – ie secrete waste products
reabsorbs water and glucose in the process
during starvation the cortex of the kidneys are a major site of gluconeogenesis (1/2 blood glucose???)
muscle - what does it use to generate ATP?
Needs ATP, uses different fuels to get it
Mostly uses glucose, fatty acids and ketone bodies
muscles - what occurs during ‘burst’ exercise, and resting?
anaerobic respiration, uses glucose from glycogen stores in the muscle (¾ of all glycogen stores are in the muscles) or creatine …
Resting - aerobic respiration, typically uses fatty acids
how is creatine used?
In burst exercise, to give a chance for glycogen to be converted to glucose, phosphocreatine transfers its P to ADP, to form ATP, via the enzyme creatine kinase
