Energy Reactions In Cells Flashcards
Where do metabolic pathways occur?
In the cell cytoplasm. This is also where they are regulated.
What happens if a metabolic reaction needs to segregated from other reactions?
It will be restricted to a particular part of the cell.
Why do catabolic processes result in the release of large amounts of energy?
They involve the breaking of chemical bonds, breaking down
Larger molecules into smaller ones.
Are catabolic processes oxidative or reductive?
Oxidative. They release reducing power in the form of H atoms.
What drives anabolic pathways?
ATP energy from catabolic pathways. They are reductive pathways and use the reducing power released in catabolism.
Approximately how many calories does BMR use for a person at rest at 18 degrees?
1400 - 1700 kcal
How much energy do we use in one day for ingestion, digestion and absorption of food?
150kcal
If man is isotherm if and cannot use heat to drive reactions, where does energy for reactions come from?
Chemical bond energy
What is the difference between an Exogenic and an endogenic reaction?
Exogenic reactions release energy whilst endogenic reactions require energy.
What are the three H carrier molecules?
NAD+ –> NADH
NADP+ –> NADPH
FAD –> FADH2
Why do energy cycles occur with H carriers?
There are only a limited number of carriers and so a cycle must occur because they take up H atoms and then release them so that they can take up more H atoms from catabolic processes.
What does NADPH carry reducing power for?
Biosynthesis
Give an example of an indirect coupling system.
In the mitochondria, the systems are coupled to produce ATP from NADH but this is indirect because it involves two separate processes. An example of a direct coupling system is the use of NADPH is biosynthesis.
Why is the stability of ATP important?
It controls energy flow and holds onto energy when it is not requires which means energy from catabolic processes has nowhere to go and they slow.
How is ATP an energy carrier?
The energy is held in the high energy bond of hydrolysis of the terminal phosphate.
Define Metabolism.
A set of process which derive energy and raw materials from food and use it to support growth, repair and activity of tissues to sustain life.
What is a high energy signal in a cell and what does this cause?
High concentration of ATP.
This stimulates anabolism as there is sufficient energy for synthesis
Name two low energy signals and state the reaction by which one is formed.
ADP
AMP
When energy is really low, 2ADP –> ATP + AMP to provide a little more energy.
When there are low energy signals in a cell, what form will H carriers be in?
Their reduced form: NAD+, FAD, NADP+
What is the high energy store in skeletal muscle and why is this needed?
creatinine phosphate. It is needed because there can be a very sudden increase in metabolic activity.
Creatine + ATP –> Creatine Phosphate + ADP
State the enzyme in this reaction and when this reaction occurs.
Creatine Kinase.
This occurs when ATP levels are high and means that more catabolic processes can occur because ATP is recycled back to ADP.
When ATP falls this reaction reverses.
What is a useful marker in the blood of MI?
Creatine Kinase. When there is damage to the heart tissue this enters the blood stream.
Creatinine is found in the urine. What is it and why is it useful?
It is the breakdown product of Creatine and a useful indicator of muscle wastage. (Under normal conditions it is proportional to muscles mass). It is a good indicator for comparing loss of other substances too (e.g. Pregnancy hormones).
