slides 8-13 - physiology Flashcards
what are enzymatic cofactors and coenzymes?
a non protein substance required for catalytic activity of some enzymes
examples of cofactors or coenzymes
Mg2+, Zn2+, Mn2+ . . . and
NAD+, FAD
study of metab. in vitro advantages and disadvantages:
isolated , defined and modifiable conditions, quantative results
loss of compartmentation
- doesn’t reflect the actual cell (eg running out of Pi
study of metab. in vivo advantages and disadvantages:
in cell - realistic
hard to quantify (many variables)
why do we need metabolic pathways?
multistep pathway that allows control
what is a metabolic crossroad?
most pathways lead to the same common intermediates eg (Glucose - 6 - P)
what are some key cofactor carriers?
ATP, NAD+, FAD, NADPH , CoA
outline the two stages of glycolysis:
invstment and pay out
uses: 2 ATP
then produces: 4 ATP & 2 NADH
NET=2ATP
What happens if cofactors run out?
glycolysis stops
outline how NAD+ is regenerated in aerobic vs anaerobic:
pyruvate is oxidised and NADH gives e- to O2 forming H2O and NAD+
anaerobic : Glucose oxides to pyruvate and Pyruvate is reduced to ethanol or lactic acid
what makes glycolysis central to carbohydrate breakdown?
it is the original way of making energy and leads to many other pathways essential for modern organisms
outline the main stages of control and why of glycolysis:
1 stage –> not main regulation step as glucose is needed in other pathways
3 stage : main regulatory point
10 step : not main but needed as metabolic branch point.
name the enzymes in the control stages:
Hexokinase - feedback inhibition
Phosphofructo Kinase - energy levels (AMP/ATP) + Metabolic intermediates
Pyruvate Kinase - feed forward activation
what happens when there is a high level vs low level of ATP in glycolysis?
high = PFK inactivated
Low = PFK activated
liver control in glycolysis?
yes - liver regulates blood glucose
Fructose - 2, 6-P increases when blood glucose is high
makes a feed forward and reduces inhibition by ATP
sources for metabolism:
Galactose, Fructose
Outline gluconeogenesis:
pyruvate –> glucose
liver and kidney
uses: ATP and GTP
shares steps with glycolysis but not all because it is Anabolic pathway
what is generated from the hydrolysis of fructose -1, 6 bisP and glucose - 6- Pi?
not ATP (not regenerated) –> futile cycle
therefore tight regulation occurs –> PFK and Fructose -1, 6- bisphosphatase = oppositely regulates