1.2 Energy Reactions In Cells Flashcards
(10 cards)
What is cell metabolism and what are its functions?
Set of processes which derive energy and raw materials from food stuffs and use them to support repair, growth and activity of the tissues of the body to sustain life.
… set of processes needed to maintain life.
Organised into metabollic pathways:
- all cells
- only certain types of cells
- compartments in cells (e.g. lysosomes)
Catabolism vs Anabolism
Catabolic: large molecules broken into smaller molecules. Oxidative, releasing H atoms.
Anabolic: larger molecules synthesised from intermediary metabolities, using energy catabolic reactions.
Why do cells need a continuous supply of energy?
To maintain function:
- biosynthetic work, creating cellular components
- moving ions/nutrients across membranes
- muscle contraction
- nervous conduction
- osmosis (e.g. in kidneys)
What is the role of redox reactions, including hydrogen carrier molecules?
Exergonic and endergonic reactions are coupled together in biological processes.
H-carrier molecules used when fuel is oxidised - transferring electrons/protons to the molecules. E.g. NAD, NADP, FAD.
- complex vitamin derived molecules.
- constant concentration.
Downhill oxidisation reactions provide energy to the uphill reduction reactions. (Think of the cliff railway analagy).
What are the roles of ATP?
Provide energy needed for reactions.
ATP consists of adenine, ribose sugar and 3 phosphates.
Exergonic reactions release energy, which powers ADP + Pi –> ATP. ATP/ADP cycle, with oxidised fuel providing this energy.
ATP is stable in the absence of specific catalysts, which allows energy flow to be controlled.
What are the roles of creatine phosphate?
creatine + ATP –> creatine phosphate + ADP
reversible reaction - if ATP concentration falls, the reverse reaction is favoured.
enzyme is creatine kinase.
Explain the roles of high and low energy signals in the regulation of metabolism?
Low energy signals (ADP, AMP, NAD, NADP, FAD) –> catabolic pathways activated.
High energy signals (ATP, NADH, NADPH, FADH2) –> anabolic pathways activated.
Cells detect ratios of the above molecules.
adenylate kinase: 2ADP –> ATP + AMP
AMP accumalates, so more ATP generation.
AMP dependent kinase activated by AMP –> regulates gene expression to switch from anabolic to catabolic pathways.
What does isothermal mean?
Cannot use heat energy for work, often having to remove heat. E.g. in humans.
Difference between exergonic and endergonic?
Exergonic = energy released
Endergonic = energy needed.
What is creatinine and what is it used for clinically?
Produced at a constant rate from the break down of creatine and phosphocreatine.
Only constant if muscles are not wasting.
Excreted via kidneys, so can be used to assess kidney function, urine dilution and an approximation of muscle mass.
