glycolysis and TCA Flashcards
true or false:
-glucose and related sugars are important components of our diet eg. breakdown product of carbs such as starch
- the Boyd has to maintain constant glucose levels in circulation
- some tissues can only use glucose as a metabolic fuel as: brain erythrocytes renal medulla cornea testes excersising muscle
all true
—- a common disorder caused by the disregualtion of glucose metabolism
diabetes
glycolysis is the pathway that converts —- to —- which is the metabolic precursor of —-
- glucose
- pyruvate
- acetyl coA
the map of metabolism :
- glucose ( 6 carbon ) —> 2x pyruvate ( 3 carbon ) this step is glycolysis by which only one glucose gives 2 pyruvate
- 2 pyruvate —> NADH , ATP generated , 2x acetyl coA carbon 2 ( done by pyruvate dehydrogenase )
- 2 x c leaves the TCA cycle as C02 NADH FADH2 and GTP generated , this is the TCA cycle
key enzyme reactions in energy generating pathways:
redox reactions catalysed by —– many are reversible reactions generate ——–
- dehydrogenase
- NADH , FADH2 , NADPH
substrate level phosphorylation reaction catalysed by —- some reversible , generate —
- kinases
- GTP , ATP
key mechanism regulating energy generating pathway:
- usually a rate limiting step in biochemical pathways
- feedback and allometric regulation of enzyme activity
such as:
- NADH can inhibit enzymes leading to its production
- NAD+ can stimulate - hormonal regulation as:
- insulin regulates glucose uptake to cells which increases GLUT4 - activation and inactivation of enzymes by phosphorylation/dephosphorlation
- avaliability of intermediate as:
- availability of oxaloacetate affects the rate of citrate sythesis via citrate synthesis in TCA cycle
- availability of oxygen by which oxygen is the finally acceptor of electrons entering the electron transpire chain from NADH/FADH2 generated during glycolysis and TCA cycle , hypoxia ( insuffiencet 02 ) or anoxia ( lack of 02 ) - failure of oxidative phosphorylation
glucose enters most cell types by —— mediated by —– also —–
- facilitated diffusion mediated by GLUT protein
- sodium dependent co transport SLGT protein
there are at least —- GLUT proteins transporters —– which differ in their tissue specific expression eg. ——adipose and skeletal tissue
- 14
-isoforms - GLUT4
once inside the cell the glucose is —- by phosplhaton and the are no cell membrane transport systems for phosphorylated sugars
trapped
- glucose is converted to glucose-6-phosphate by —– which is most cell types of —- found in liver parachemyl cells and pancreatic islet cells
- hexokinase
- glucokinase
-glucokinase helps — cells in the pancreas to sense —- of glucose concentration so it triggers —- release
- allows the —- to mop up the high concentration of glucose in the portal circulation after a meal
- high kn only kicks in at — concentration of glucose which —- the uptake of glucose by the liver during fasting so it prevents unnecessary synthesis of —- and the development of hypoglycaemia
- high kmax —> high —- allowing to handle the high glucose levels occurring post prandially
- b cells
- rise
- insulin
- liver
- high
- minimizes
- glycogen
- capacity
hexokinase has — km which leads to — affinity for glucose even at — concentration , it allows glucose to enter the cell , specially cells in brain and rbc during fasting
- low kmax —> —- capacity
- low
- high
- low
- limited
( check slide 9 )
lack of — promotes —- glycolysis resulting in —– synthesis from pyruvate , the end product of glycolysis instead of acetyl CoA ( which is formed under aerobic conditions ) , shuts down —– which results in reduction of —- sythesis
-02
-anarobic
-lactic acid
- oxidative phsophorlation
- atp sytehsis
1.lactic acid accumulates in —- during vigours , extended exercise as cramp
2. —– refers to the elevated plasma levels of lactic acid secondary to > circulatory collapse ( MI,PE, haemorrhage ) > shock , and is potentially fatal
- muscles
- lactic. acidosis
