Unit 1: Anaerobic respiration (energy from food without oxygen) Flashcards
what is the NHS daily energy requirement for women and men?
Women= 2000 kCal/ 8400 kJ Men = 2500 kCal/ 10500 kJ
what are glucose transporters?
transmembrane proteins which facilitate diffusion of glucose into cells
where are the five types of glucose transporters found and what is their function?
GLUT1: all tissue - basal rate of uptake
GLUT2: liver/ pancreatic- glucose sensor - simulates insulin secretion
GLUT3: all tissue - basl rate of uptake in neurons
GLUT4: muscle/ fat - stimulates insulin secretion which facilitates uptake of glucose during meals
GLUT5: small intestine - fructose uptake
what happens in terms of GLUT 4 when you do more exercise?
- expression increases in muscle/fat
- faster response to insluin
what type of carrier proteins are glucose transporters and how do they work?
- symporters: transport Na+ and glucose simultaenously
- secondary active transport: use electrochemical gradient
what type of cells only use glycolysis as source of ATP and give examples
- cells with no/ few mitochondria
red blood cells/ cornea & lenses of eye/ renal medulla
what are the main 4 stages of glycolysis and how many steps in each?
- investment stage (3)
- splitting stage (2)
- yield stage (1)
- substrate level phosphorylation (4)
how many ATP are invested to prime glucose metabolism?
2
what is the first regulatory step in glycolysis?
- phosphoryl transfer - production of glucose-6-phosphate
= regulatory enzyme: hexokinase - allosterically inhibited by its product
how does liver contribute to production of glucose 6- phosphate?
liver possess glucokinase which directly converts glycogen into glucose -6 phosphate and is not allosterically inhibited
what is the most important regulatory (rate limiting) step also found in the investment stage?
phosphoryl transfer of fructose 6 phosphate to fructose 1,6 phosphate
IRREVERSIBLE REACTION
How does the rate limiting step regulate rate of glycolysis?
Adenylate control: PFK allosterically inhibited by ATP - causes conformational change reducing affinity for Fru-6-P so reduces rate of reaction and glycolysis
what activates/ inhibits PFK?
AMP = allosterically activates PFK - prevents ATP inhibition
citrate/ pH/ ATP inhibits
what molecule is an important allosteric activator of PFK
Fructose 2,6 - biphosphate formed from fru6P by PFK2
- fru 6P accelerates formation of it which activates PFK1 so feed-forward activation occurs (accelerates its own metabolism)
how is the first ATP produced in substrate level phosphorylation?
phosphoryl transfer of 1,3bisP-glycerate to 3P-glycerate by enzyme phosphoglycerate kinase
how is the second ATP produced in substrate level phosphorylation?
phosphoryl transfer of PEP (phosphoenolpyruvate) to pyruvate by the enzyme pyruvate kinase
how is the last regulatory step regulated?
- adenylate control
- down regulation of alanin
- up regulation by fru 1,6 BP
how does liver prevent glucose conversion into pyruvate?
isoenzyme regulated by AMP converts glucose into glycogen instead
what is the net energy yield of glycolysis?
2 ATP per mole of glucose
what is lactic acid fermentation?
reduction of pyruvate by lactate dehydrogenase
what is the important of lactate? and what are its physiological effects?
- gets rid of NADH so allows anaerobic respiration to continue
- muscle fatigue to prevent extreme exhaustion/ reduced oxygen-carrying ability
where does the substrate cycle occur?
in liver
what happens when glucose is abundant in terms of substrate cycle?
Fru 6P (insulin) activates phosphoprotein phosphatase) - dephosphorylates PFK2 catalyses conversion of fru 6P to Fru 2,6 BP upregulates PFK1 (downregulates gluconeogenesis)
what happens when glucose is scarce - no insulin present in terms of substrate cycle?
glucagon activates PKA activates FBPase 2 Fru 2.6 BP to Fru 6P (downregulation of glycolysis - upregulation of gluconeogenesis)
