Energy (Metabolism) Flashcards
What is METABOLISM?
the CHEMICAL PROCESSES that occur within a living organism in order to MAINTAIN LIFE.
What are the two types of Metabolism?
Catabolism & Anabolism
What is Catabolism?
BREAKDOWN of complex molecules to release energy or carry out mechanical work
What is Anabolism?
SYNTHESIS of new molecules from less complex components
Why is it important to study metabolism?
- Many diseases are due to metabolic issues like diabetes and galls stones.
- By understanding how the normal body deals with nutrients we can better understand the disease as the body in the diseased state changes the way it uses the food. This aids in DIAGNOSING diseases and TREATMENT
Why should metabolism be viewed as an integrated whole?
Usually the PRODUCT of one pathway is the SUBSTRATE of another
What is ATP?
Adenosine Triphosphate
Short term energy reservoir
Can act as an acceptor and donor of energy
Adenine base + Ribose + 3 Phosphate Groups
About how much ATP does the body have? Is it enough?
It only has 100g.
When used, it must be resynthesized through oxidative phosphorylation in the mitochondria
Exercise uses 500g per minute
At rest, 40 Kg per DAY
What are the 4 major oxidative pathways?
- Glycolysis
- Citric Acid Cycle
- Electron Transport Chain
- Fatty Acid Oxidation
Illustrate and explain the process of Glycolysis
including production of Lactate and Acetlyl CoA
https://www.unm.edu/~lkravitz/MEDIA2/GLY1aa.gif
What occurs during phosphorylation in glycolysis?
A hexose sugar (glucose) is phosphorylated by two molecules of ATP to form hexose bisphosphate.
The molecules becomes less stable and more reaction preventing it from diffusing out of the cell.
What happens during lysis in glycolysis?
The hexose bisphosphate is split into 2 triose phosphates
What happens during oxidation in glycolysis?
Hydrogen atoms are removed from each of the triose phophates and it reduces NAD+ to NADH
Due to this, a total of 2 NADH are produced
What happens during ATP formation in glycolysis?
Substrate level phophorylation occurs to directly produce 4 molecules of ATP (2 are used in Glucose to Fructose 1,6 bisphosphate = net +2 ATP)
What happens during ATP formation in glycolysis?
Substrate level phophorylation occurs to directly produce 4 molecules of ATP (2 are used in Glucose to Fructose 1,6 bisphosphate = net +2 ATP)
How can Glycolysis be regulated?
It can be regulated by:
reversible binding of allosteric effectors,
covalent modification,
transcription
Enzymes that catalyze irreversible reactions are potential sites for regulation.
What are the 3 enzymes (kinases) that regulate glycolysis?
Hexokinase
Phosphofructokinase
Pyruvate Kinase
What is hexokinase regulated by?
The amount of Glucose 6 Phosphate (G6P).
Build up of G6P causes the step before that:
(Glucose –> G6P) to seize
What inhibits Phosphofructokinase?
- ATP (when cell has enough ATP, production of hexose bisphosphate stops)
- Citrate (product of the Citric Acid Cycle… Increase of citrate stop it)
- H + ions too (increased H+ decreases pH…. causes it to stop)
What stimulates Phosphofructokinase?
AMP (generated by metabolism of ADP) ADP generated by hydrolysis of ATP ADP + ADP --> ATP + AMP Uses Adenylate Kinase
How is regulation of glycolysis different in the Liver?
- PFK inhibited by HIGH conc. of ATP and citrate
- PFK stimulated indirectly by build up of F6P (fructose phosphate)
- Unlike hexokinase, Glucokinase is not inhibited by G6P
What 2 kinases in the liver are involved in regulating glycolysis?
Hexokinase and Glucokinase
What do tumours and exercising muscles have in common?
They generate large amounts of ATP through anaerobic respiration.
Why does the body produce lactate in glycolysis in anaerobic respiration?
NAD+ is required for second part of glycolysis to continue to make pyruvate from hexose bisphosphate. To produce lactate, NADH is metabolized to produce NAD+ and it can return to where it is required.
What are the consequences of producing lactate?
Lactate is acidic.
Accumulation of a lot of lactate inhibits Phosphofructokinase (PFK) in phosphorylation
(phosphorylation is required for starting glycolysis)
It can be overcome by the liver
Why do tumours use glycolysis?
Tumours usually get nutrients from blood supply but the often outgrow the blood supply.
This causes the oxygen levels to decrease and create an environment of hypoxia.
This causes the cell metabolism to revert to glycolysis.
The hypoxia activates the transcription factor HIF-1
TF HIF-1 regulates the expression of specific enzymes in glycolysis
(Increase hexokinase and PFK expression)
