Metabolism & Bioenergetics Flashcards
Which ONE of the following systems synthesises all of its molecules from CO2?
A) Chemotrophs
B) Autotrophs
C) Heterotrophs
D) Mammalian
E) None of the above
A) Chemotrophs
(Could also be B)
If the ΔG0’ value of a biochemical reaction is 25 under standard conditions the reaction:
A) Is at equilibrium
B) Is endergonic
C) Proceeds in reverse
D) Is exergonic
E) Is inhibited
B) Is endergonic
∆G’0 is POSITIVE
Catabolic pathways are which of the following?
A) Reductive and divergent
B) Oxidative and convergent
C) Oxidative and divergent
D) Reductive and convergent
E) Reductive and oxidative
B) Oxidative and convergent
If the ΔG0’ of biochemical reaction 1 is +5 kJ/mol and a coupled reaction 2 has a ΔG0’ value of -8 kJ/mol, what is the overall ΔG0’ for this coupled reaction?
A) 13 kJ/mol
B) 3 kJ/mol
C) -3 kJ/mol
D) -13 kJ/mol
E) 10 kJ/mol
C) -3 kJ/mol
+5 kJ/mol + -8 kJ/mol = -3 kJ/mol
Which one of the following values is the nearest approximation of the ΔG0’ value for ATP hydrolysis & energy transfer?
A) -300 kJ/mol
B) -31 kJ/mol
C) -13 kJ/mol
D) -3000 kJ/mol
E) -30,000 kJ/mol
B) -31 kJ/mol
ATP consists of which of the following?
A) Guanine, 2 phosphates and a ribose
B) Adenine, 2 phosphates and a ribose
C) Adenine, 3 phosphates and a ribose
D) Cytosine, 3 phosphates and a ribose
E) None of the above
C) Adenine, 3 Phosphates and a Ribose
ATP is hydrolysed at which of the following bond types?
A) Phosphoanhydride
B) Thiol
C) Carboxylic acid anhydride
D) Phosphodiester
E) Hydroxide
A) Phosphoanhydride
Bonds between Phosphate groups
Which of the following components of NAD accepts a hydride ion?
A) The niacin ring
B) Adenine
C) The nicotinamide ring
D) Ribose
E) The dinucleotide
C) The nicotinamide ring
What happens in the following reaction AH2 + B –> A + BH2
A) A is reduced and B is oxidised
B) A is oxidised and B is reduced
C) Electrons are added to A
D) Electrons are removed from B
E) None of the above
B) A is oxidised and B is reduced
FAD is derived from which ONE of the following?
A) Vitamin E
B) Niacin
C) Nicotinamide
D) Acetyl-CoA
E) Riboflavin
E) Riboflavin
AKA. Vitamin B2
What is cellular metabolism?
All the chemical activities that support life in all cells and organsims
What is the source of energy for Chemotrophs?
Chemical
What is the source of energy for Heterotrophs?
Organic compounds
What is the source of energy for Phototrophs?
Sunlight
What is the source of energy for Autotrophs?
CO2
What is Catabolism?
Transforms fuel into energy from energy-containing nutrients
Is Catabolism Oxidative or Reductive?
Oxidative
Is Catabolism Convergent or Divergent?
Convergent
What is Anabolism?
Uses energy to synthesise macromolecules from precursor molecules
Is Anabolism Oxidative or Reductive?
Reductive
Is Anabolism Convergent or Divergent?
Divergent
What is the Metabolome?
All the metabolites in a cell or system
What is Metabolomics?
Systemic characteristics of the metabolome, including under specific conditions
What diseases have defective metabolism?
- Diabetes
- Cancer
- Neurodegeneration
- Heart Disease
- Infection
- Inflammation
- Immunological Dysfunction
What is Bioenergetics?
Quantitive study of energy transductions in living cells / organisms / systems
How are changes in energy measured in biological systems?
Gibb’s Free Energy (∆G’0)
What is an Exergonic reaction?
If ∆G’0 is negative the reaction CAN spontaneously occur
What is an Endergonic reaction?
If ∆G’0 is positive the reaction CAN’T occur spontaneously
What equation shows how the change in free energy (∆G’0) relates to the equilibrium constant (Keq) of a reaction?
∆G’0 = -RTlnK’eq
Which direction does a reaction go if K’eq is > 1.0 and ∆G’0 is negative?
Forward
Which direction does a reaction go if K’eq is 1.0 and ∆G’0 is zero?
At equilibrium
Which direction does a reaction go if K’eq is < 1.0 and ∆G’0 is positive?
Reverse
What are the units of ∆G’0?
kJ/mol
Approx. how much energy is released by complete oxidation of Glucose?
~ 2840 kJ/mol
Approx. how much energy is released by complete oxidation of Palmitate?
~ 9,770 kJ/mol
Where in the cell is ATP synthesised?
Inner membrane of Mitochondria
Why is ATP a high energy compound?
Strong negative charges between Phosphate groups that repel each other
What is the synthesis of ATP in the presence of oxygen called?
Oxidative Phosphorylation
What are some examples of life processes that ATP is essential for?
- Cell division
- Biomolecule synthesis
- Muscle contraction
- Transcription
- Translation
- Cell signalling
What is the major reaction type responsible for cell work?
Oxidation / Reduction
What is the difference between Oxidation and Reduction?
Oxidation - loss of electrons
Reduction - gain electrons
What is EMF?
Electron Motive Force
The transfer of electrons
Does EMF relate to ∆G’0?
∆G’0 directly relates to the number of electrons transferred in a metabolic reaction
∆G’0 = -nF∆E0
n = number of electrons transferred
How are electrons transferred in biological systems?
Through intermediate biomolecules called Electron Carriers to the final electron acceptor, O2
What are the FOUR main ways that electrons are transferred in biological systems?
- Directly
- As hydrogen atoms
- As hydride ions
- By direct combination of organic reductants with O2
Why are Dehydrogenase enzymes important?
They remove hydrogen atoms in oxidations in catabolism
What does Alcohol Dehydrogenase do?
Oxidises ethanol from an alcohol to an aldehyde
What are the names of the major electron carriers in the cell?
- NAD
- NADP
- FAD
- FMN
What are the components of NAD?
Nicotinamide Adenine Dinucleotide
Two nucleotides joined together through their phosphate groups
What is NAD derived from?
Niacin
AKA. Vitamin B3
Which metabolic pathway does NAD generally function in?
Catabolism
Which metabolic pathway does NADP generally function in?
Anabolism
What disease can lack of the NAD precursor cause?
Pellagra
Characterised by Dermatitis, Diarrhea, and Dementia
How does NAD work to accept and donate electrons?
Works with dehydrogenase enzymes to carry electrons
What is the difference between NAD and NADP?
NADP has an extra phosphate group
What is the difference between FAD and FMN?
FAD contains 2 nucleotides
FMN contains one nucleotide
FAD - Flavin Adenine Dinucleotide
FMN - Flavin Mononucleotide
How does FAD / FMN work?
Isoalloxazine ring accepts 1 or 2 electrons to form hydrogen atoms
