Bioenergetics Flashcards
(249 cards)
What are the standard conditions for ΔG
pH 7
One atmosphere
298K
ΔG is a state function. What does this mean?
ΔG will be the same regardless of the path taken
This also means reactions can be coupled
Why is the hydrolysis of ATP so exothermic
Phosphate and ADP have more resonance stabilisation than ATP
Electrostatic repulsion. At pH7, ATP has ~4 negative charges in close proximity, weakening the bridging P-O-P bonds in ATP
Stabilisation due to hydration. More water can bind to ADP and Pi than ATP
What is phosphorylation potential
The free energy of ATP hydrolysis
What is the ATP turnover in humans during exercise
0.5kg/min
What is ATP often buffered by in mammals
Phosphocreatine
Give 3 examples of ATP hydrolysis
- Phosphorylate glucose to provide enough energy to prime the molecule to be broken down to pyruvate
- Peptides are unstable thermodynamically so ATP can be used to build long chains
- To join 2 nucleic acids at the start of DNA synthesis
What are the 4 main carrier molecules and what does each carry
What do they all have in common structurally
ATP - phosphoryl-
NADH and NADPH: e-
FADH2 and FMNH2: e-
Coenzyme A: acyl
An adenine base is present
What do biotin and uridine diphosphate glucose carry respectively
B: CO2
UDG: glucose
What is the main redox system for energy producing pathways
What is it for biosynthesis
NAD+/NADH
NADP+/NADPH
What does the phosphate group act as in NADP+
A tag allowing recognition of this redox system by biosynthetic enzymes
What does Coenzyme A provide
The activated form of acetate
Why is blood important for fuel economy
It is a fuel pipe as far as metabolism is concerned, carrying glucose, fructose, lipoproteins, fatty acids, ketone bodies, and amino acids
Why is the small intestine important for fuel economy
Absorbs glucose, fructose and amino acids and transfers them to blood
Fats are packed and transferred to lymph and then blood
Why is the liver important for fuel economy
Central role in glucose control
‘Fat factory’ in terms of synthesis and export of triglycerides to adipose tissue
Also partially oxidises fats to produce ketone bodies and is central to amino acid metabolism
Why is the heart the ‘dustbin’ of the body
It will metabolise a wide variety of substrates left over from other metabolic processes
Why is adipose tissue important for fuel economy
Fat storage and energy store
Secretes hormones etc
Why is the brain important for fuel economy
Largely uses glucose to maintain neuronal cell function but can use ketone bodies during fasting
What are the beginning and end products of gluconeogenesis
Pyruvate to glucose-6-phosphate
What are the beginning and end products of glycolysis
Glucose 6 phosphate to pyruvate
What are the beginning and end products of glycogen synthesis
Glucose 1 phosphate to glycogen
What are the beginning and end products of fat synthesis
Acetyl CoA to fatty acid
What are the beginning and end products of glycogen breakdown
Glycogen to glucose 1 phosphate
What are the beginning and end products of fat breakdown
Glycogen to glucose-1-phosphate