Intro to Metabolism Flashcards
Definition of metabolism
The totality of the chemical reactions and physical changes that occur in living organisms, comprising anabolism and catabolism
The enzyme reactions of synthesis, breakdown and
interconversion of essential biomolecules
What is Catabolism?
The metabolic breakdown of complex substances into smaller products - including the breakdown of
carbon compounds with the liberation of energy for use by the cell or organism
What is Anabolism?
The energy requiring part of metabolism in which simpler
substances are transformed into more complex ones as in growth or other biosynthetic processes.
Difference between Anabolism and Catabolism?
With Examples?
Catabolism Vs Anabolism
1. names end in ‘lysis’ names Vs end in ‘genesis’
2. glycolysis Vs gluconeogenesis
3. lipolysis Vs lipogenesis
4. glycogenolysis Vs glycogenesis
5. generate ATP & NADH Vs Use ATP, GTP, UTP
6. (mitochondria) Vs mostly in cytosol
Describe how seperate regulation?
Activating enzyme 1 (and/or enzyme 2) would speed up forward and reverse
pathways – a ‘futile cycle’
However …
Activating enzyme 1 speeds up forward pathway
Activating enzyme 3 speeds up reverse pathway
Explain the concept of controlled release of energy in enzyme catalysed metabolic pathways?
- Stepwise breakdown releases energy in useable small ‘packages’
- Pathways can be regulated by regulation of specific enzymes
What are activated carrier molecules?
Activated carriers are molecules that can be split (C → A + B) to release free energy but only if there is an excess of C relative to its equilibrium concnetration.
How is the energy stored?
Energy released at each step is stored in activated carrier
molecules
What are the activated carrier molecules used in metabolism?
- ATP
- NADH, NADPH, FADH2
- Acetyl CoA
- Carboxylated biotin
- S-adenosylmethionine
- Uridine diphosphate glucose
Group carried in high-energy linkage in Uridine diphosphate glucose?
Glucose
Group carried in high energy linkage of S-adenosylmethionine?
Methyl group
Examples of other ‘high energy’ nucleotides
- UTP drives the synthesis of complex sugar
- GTP drives the synthesis of proteins
Group carried in high-energy linkage in carboxylated biotin?
Carboxyl group
Group carried in high-energy linkage in Acetyl CoA?
Acetyl group
Group carried in high-energy linkage in NADH,NADPH,FADH2?
electrons and hydrogens
Group carried in high-energy linkage in ATP?
Phosphate group
What is ATP?
Structure?
15
- Energy currency of the cell
- Adenosine triphosphate
- Chemically stable at pH 6-9
Products of Hydrolysis of ATP?
Hydrolysis gives
* ADP
* H+
* O=P–O-–OH O- top and bottom pf P and -OH of P
+ ‘energy’
What makes the hydrolysis of ATP energetically so
favourable?
- Relieves electrostatic repulsion between phosphate groups
- The released phosphate ion is resonance stabilised: increased entropy
(ΔS +ve) - Concept of a high energy bond’ or ‘high energy phosphate group’
Hydrolysis of ATP to AMP and PPi realeases almost twice as much free energy as ATP to ADP hydrolysis
Breakdown of ATP to ADP
ΔG is - 31 to -50 kJ mole-1
Functions of ATP
- Used directly in cell motility and muscle contraction (motor proteins)
ATP ———> ADP + Pi myosin/dynein - Used in active transport systems e.g. Na+ / K+ pumps
- Used in metabolic control – regulates enzyme activity
- Used in metabolism to add Pi to metabolic
intermediates
What can ATP act as?
High energy cofactor for kinase enzymes
ATP breakdown releases 32 kj of energy per mole
ATP ——» ADP. + Pi
What do metabolic reactions require?
- Fuel molecules (substrates/intermediates)
- Enzyme catalysts
- Cofactors
Overview of the 3 stages of catabolism of:
1. Glucose
2. Fatty acids
3. Amino acids
Glucose
- Glycolysis (cytosol) - pyruvate ——> CH3 - C
- Kerbs cycle (mitochondria) - produces 2CO2 and 2H
- Oxidative phosphorylation (mitochondrial membrane) - 2H + O —-> H20 + ATP
Fatty acids
1. B- oxidation
2. Kerbs cycle
3. Oxidative phosphorylation
Amino ac
