Biochemistry of Metabolism Flashcards
Define metabolism:
All chemical reactions involved in maintaining the living state of the cells and the organism
Criteria for a metabolism:
- Individual enzyme reactions rarely occur in isolation
- Organised into pathways
- Pathways interconnect onto networks
What is the currency of free in energy on biological systems?
ATP
What is ATP?
Primary cellular energy carrier through the triphosphate group
What does ATP donate free energy to?
Anabolism/biosynthesis
- Mechanical work/movement
- Active molecular transport
How do you get energy form ATP?
hydrolyis
ATP + H20 =
ADP + Pi + H+
or
AMP + PPi + H+
What dos hydrolyse of ATP result in?
High phosphoryl transfer potential
What does the standard free energy of hydrolysis vary among?
Phosphorylated compounds
What are the major electron acceptors in biological systems?
NAD+ and NADP+
What do oxidation of fuel molecules result in?
Transfer of electrons to the terminal electron acceptor via carries
What is the terminal electron acceptor?
O2
NADH to NAD+ + H+ +2E^-
Is it reduction or oxidation?
Oxidation
NAD+ + H+ +2E^- to NADH
Is it reduction or oxidation?
Reduction
NADP+ + H+ +2E^- to NADPH
Is it reduction or oxidation?
Reduction
NADPH to NADP+ + H+ +2E^-
Is it reduction or oxidation?
Oxidation
What is the catabolic pathway?
Degradation/oxidation of fuel molecules to generate free energy
What are the three stages of catabolic pathway?
- Digestion and hydrolysis
- Conversion
- Oxidation
What happens in stage 1 of catabolic pathway?
Breaking down of complex molecules
What happens in stage 2 of catabolic pathways?
Breaking down to 2-, 3-carbon compounds and acetyl CoA
What happens in stage 3 of catabolic pathways?
Oxidation of acetyl CoA via citric acid cycle and electron flow to O2 via NADH
What are the major groups of energy rich nutrients?
- Carbohydrates
- Lipids
- Protein
What are minor dietary components?
Vitamins, minerals, drugs and toxins
What are the the different fates of nutrients?
- Oxidation to generate energy
- Storage, then release
- Conversion
Overview of glucose metabolism:
- Storage as glycogen
- Conversion to nucleotides and fatty acids
- Generation of ATP energy
Why is the catabolism of glucose so important?
Glucose accounts for more than 80% of dietary carbohydrate catabolism.
Galactose + glucose =
Lactose
Fructose + glucose =
Sucrose
Overview of aerobic glucose metabolism + OXYGEN:
- Storage as glycogen
- Conversion to nucleotides and fatty acids
- Generation of ATP energy
Overview of anaerobic glucose metabolism – NO OXYGEN:
- Storage as glycogen
- Conversion to nucleotides and fatty acids
- Generation of lessATP energy
- Lactate
What is the difference between anaerobic and aerobic glucose metabolism?
There is no citric acid cycle in anaerobic only production of lactate
What does the production of lactate cause?
Musle fatigue and cramp
Overview of anaerobic glucose metabolism in yeast cells:
Production of CO2 and ethanol
Overview of glycolysis:
- Rapid energy source for short, intense bursts of exercise
- Both prokaryote and eukaryote
What is the Net outcome of glycolysis?
1 glucose —
2 ADP —-
3 NAD+ ——
2 Pyruvate
2 ATP
2 NADH
What are three stages of glycolysis?
- the investment stage
- the investment stage continuous
- the energy generation stage
What happens at stage 1 of glycolysis?
- Glucose receives a phosphate group from ATP - irreversible
- Glucose 6-phosphate is isomerised
- Fructose -6 phosphate is phosphorylated
A rate limiting step
What happens at stage 2 of glycolysis?
- Fructose 1,6-bisphosphate is cleaved into two 3-carbon molecules that are isomers
Glyceraldehyde 3-phosphate is on the direct pathway of glycolysis
Dihydroxyacetone phosphate is isomerised to glyceraldehyde 3-phosphate generating two molecules for subsequent steps.
What happens at stage 3 of glycolysis?
- Generation of phosphorylated
1,3-Bisphosphoglycerate via oxidation of the aldehyde group
Reduction of NADH - Phosphoryl group transfer from 1,3-Bisphosphoglycerate Generation of ATP
- Phosphoryl group is shifted from the 3 carbon to the 2 carbon position
- Dehydration of 2-Phosphoglycerate elevates the transfer potential9. Phosphoryl group transfer from Phosphoenolpyruvate
Generation of ATP
What does glucose + ATP produce in the first stage of glycolysis?
Glucose-6-phosphate + ADP
Catalysed by hexokinase
Irreversible reaction
What does Fructose-6-phosphate + ATP produce in the first stage of glycolysis?
Fructose 1,6-BP + ADP
Catalysed by phosphofructokinase
Irreversible reaction
Rate-limiting control point
What does G-3-P + NAD+ + Pi produce in the third stage of glycolysis?
1,3 bisphosphoglycerate
+ NADH + H+
Catalysed by G-3-P dehydrogenase.
Reversible reaction
Oxidation reaction
The overall picture of glycolysis:
Glucose + 2Pi + 2 ADP + 2 NAD+ produced…
2 pyruvate + 2 ATP + 2 NADH + 2 H+ + 2H20
What is the overall free energy released in glycolysis?
197 KJ/mol
How are ADP and NAD+ regenerated?
NAD+ is regenerated via either:-
- Lactate dehydrogenase. (Anaerobic)
- Oxidative phosphorylation. (Aerobic)
How is metabolism controlled?
By controlling selected key enzymes
Which enzymes are controlled in metabolism?
- Irreversible enzymes
- Enzymes at the start of a pathway or a branchpoint
- Rate limiting enzymes e.g. phosphofructokinase
How are the enzymes controlled in the metabolism?
- By altering levels of synthesis of key enzymes (slow)
- By altering the activity of key enzymes (fast) e.g. phosphofructokinase.
Does insulin increase or decrease the rate of metabolism when introduced?
Increase
Does glucagon increase or decrease the rate of metabolism when introduced?
Decrease
What is energy balance?
The energy put in (DIET) vs the energy put out (EXERCISE)
What is need for a healthy energy balance?
Diet + products of anabolic pathways
must be balanced by catabolic pathways
What is type 1 diabetes?
Deficiency of insulin
What are symptoms of a diabetes 1?
- high blood pressure (Hyperglycaemia)
- Fatigue
- Weight loss
- Excessive hunger
How can obesity lead to diabetes?
Excess metabolic products are stored as fat
Can lead to insulin resistance
What is diabetes 2?
Insulin resistance
What are the symptoms of diabetes 2?
- high blood pressure (Hyperglycaemia)
- compensated by increase insulin production
- Impaired pancreas function to generate sufficient insulin
Use this quiz:
http://www.purposegames.com/game/glycolysis-quiz#