Introduction to Metabolism Flashcards
Definition of metabolism
Series of enzyme reactions within cells for converting fuel molecules into useful energy.
The enzyme reactions of synthesis/breakdown/interconversion of essential biomolecules
Definition of catabolism
Breakdown of complex molecules in living organisms to form simpler ones with energy release
Definition of anabolism
Synthesis of complex molecules in living organisms from simpler ones with the storage of energy
Definition of endergonic
Accompanied by or required the absorption of energy
The products being of greater free energy than reactants
Definition of exergonic
Accompanied by or requiring the release of energy
The reactants being of greater free energy than products
Definition of induction
Up regulation of the rate of transcription of a gene
Definition of repression
Down regulation of the rate of transcription of a gene
What occurs in catabolism
Heat is lost
Forms the building blocks for biosynthesis
Properties of catabolism
Names end in lysis
Glycolysis, lipolysis, glycogenolysis
Generate ATP, NADH
Mitochondrial
Properties of anabolism
Names end in genesis
Gluconeogenesis, lipogenesis, glycogenesis
Use ATP, GTP, UTP
Mainly in cytosol
Integration of glucose
Pathway of glycolysis and TCA cycle act together, convert glucose => CO2
C6H12O6 + 6O2 => 6CO2 + 6H2O + 30ATP
Through mitochondrial respiration, energy for tissue becomes available
Catabolism of glucose, fatty acids, amino acids
Glucose =glycolysis=> pyruvate
Fatty acids =b oxidation=> acetate
Amino acids =transamination=> acetate
Acetate enters the TCA cycle
2H + O => H2O
ADP + Pi => ATP oxidative phosphorylation
How do fatty acids enter the cell
Fatty acids bind to albumin, detach and freely diffuse through plasma membrane
How does glucose enter the cell
Glucose moves by facilitated diffusion via protein channels
Describe the structure of mitochondria
2 bilayers,
Inner mitochondrial bilayer has 3 transmembrane proteins and I integrated protein, forms ETC
Pyruvate converted into acetyl CoA by pyruvate dehydrogenase, enter TCA
Describe the energy currency of the cell
Adenosine triphosphate
Adenine and ribose (nucleoside) allows cells and organelles to recognize ATP
Chemically stable at pH6-9
ATP + H2O => ADP + Pi + H+ + energy
What bonds are broken in ATP
Phosphoanhydride bonds, v high energy (30.5kjmol-1)
Functions of ATP
Used directly in cell motility and contraction (myosin, dynein)
Used in NaKATPase pumo, AT systems and metabolic control
Used in metabolism to add Pi to metabolic intermediates
General feature of a metabolic pathway
Each step in a sequence of reactions needs a different enzyme
Enzymes and how they affect reactions
Rate of biochemical reaction dependent on enzyme activity
Equilibrium dependent on properties of the chemical molecules themselves
Enzymes provide a pathway with a lower activation energy
Reversible and irreversible steps in a metabolic pathway
Quite often different enzymes will act in opposite directions
Otherwise, many middle products will accumulate
How is enzyme activity regulated
Alter availability of substrate (by increasing transport into the cell)
Increase amount of enzyme present in cell by increase rate of transcription from gene in DNA => mRNA (induction, repression)
Interconversion of active and inactive forms of key enzymes
What enzymes are used in interconversions of active and inactive forms of an enzyme by covalent modification
Inactive enzyme =protein kinase ATP)=> active enzyme P
Active enzyme =(protein phosphatase)=> Inactive enzyme and Pi
Allosteric control mechanisms
Enzymes have an activating site, inhibitory site and a substrate binding site
Sigmoid curve
What do metabolic reactions need
Fuel molecules (substrates/intermediates)
Enzymes
Cofactors
activating ions
coenzymes/prosthetic group (ATOP for kinase enzymes)
Role of ATP in enzymatic reactions
High energy cofactor in the cell for driving mechanical events
Role of other high energy nucleotides
GTP, protein synthesis
UTP, drives complex sugar synthesis
CTP, lipid synthesis
