Intro to metabolism Flashcards
What is metabolism?
The sum total of all the reactions that take place in a living cell
What do metabolic pathways do?
- Reactions are arranged into pathways - product for one reaction is the reactant (substrate) for the next
- Each step is catalysed by an enzyme
- Non-spontaneous reactions are driven by coupling them to spontaneous reactions.
- Energy is needed drive metabolism
Who conducted the first metabolic experiment?
Santorio Santorio
How did Santorio Santorio conduct his metabolic experiment?
- weighed himself before and after eating and doing anything for 30 years
- 8lb in food, 3lb out (waste product)
How much energy do we need per day?
As a 70kg male doing medium physical activity = ~2600 kcal per day
~ 1600 kcal to ‘exist’
Where is the energy we consume used?
- 20% = muscle
- 19% = liver
- 17% = brain
- 16% = other
- 10% digestion
- 8% = heart
- 7% = kidney
- 3% = fat
Define metabolism as an umbrella term
metabolism = catabolism + anabolism
Define catabolism
Energy-yielding metabolism:
- breaking down into simpler forms
- usually to release energy
Define anabolism
Biosynthetic metabolism:
- building up more complex forms
- usually requiring energy input
What happens to the energy sources in catabolism?
- heat
- metabolic products
- utilisable energy
What happens to the utilisable energy in catabolism?
- stored as ATP and ADP
- used in each step of anabolism
(slide 5)
What are the steps in anabolism?
- Uptake of external nutrients
- Formation of intracellular precursors
- Formation of intermediates
- Assembled into biopolymers
What is metabolism all about?
It’s all about regulation
- not all happening at the same time
What is a futile cycle?
A cycle where opposing pathways run at the same time, for no gain except to dissipate energy as heat
What are the types of regulation?
- intrinsic - from within the cell
- extrinsic - from outside the cell
