Energy Reactions in Cells Flashcards
Define metabolism.
Set of processes which derive energy and raw materials from food, and use them to support repair, growth and activity of tissues to sustain life
What are the two types of metabolic pathways?
Catabolic and Anabolic
Describe Catabolic metabolism.
Breaking down large molecules into small ones (intermediary metabolites)
Release energy, hence spontaneous
Pathways are oxidative (release H)
Describe Anabolic metabolism.
Make large molecules from intermediary metabolites (small molecules)
Use energy from catabolism (ATP)
Reductive (use/reattach H from catabolism)
Why are fuel molecules metabolised?
To form building block materials for:
Cell growth/division
Repair
Formation of cell components
Energy for cell function
Organic pre-cursors (eg. AcetylCoA) for rebuilding
Give examples of where energy is used in the body
Anabolic metabolism
Transport of ions, nutrients etc. across gradients
Mechanical work (muscle contraction)
What are exergonic reactions?
Spontaneous reactions
Energy of reactants is greater than products (energy is released)
Negative DeltaG value for reactions (exothermic)
What are endergonic reactions?
Reactions are not spontaneous
Take up and require energy (endothermic)
Positive DeltaG value for reactions
What does Delta G indicate?
Whether reactions spontaneous or not (NOT RATE)
Define OILRIG
Oxidation is loss (of electrons/H), Reduction is gain
What can be said about the conc. of oxidised and reduced carriers? Why is this so?
They are always constant
Bc. there is a constant cycle between oxidative and reductive processes
How is energy released from exergonic reactions used with ADP?
Allow ADP to bond to Pi to form ATP
Why is ATP a good source of energy?
Chemical bond between terminal phosphate group is high energy
ATP is also a stable molecule and releases energy in small quantities
Can ADP be stored?
No, fixed conc. of ADP in body so must be cycled constantly
How much ATP is in human body at any moment?
250g approx
What is Adenylate Kinase?
Enzyme used to convert 2 ATP molecules into ATP when energy is low
2ADP -> ATP + AMP
(AMP is low energy)
What do some cells use as a rapid energy source and why?
Creatine Phosphate
Used for rapid metabolic activity as it is has a high amount of stored energy from its phosphate bond
When is creatine phosphate formed and how?
When ATP levels are high
ATP phosphorylates creatine molecule using Creatine Kinase enzyme
How is creatine kinase used as a marker for myocardial infarction?
Creatine Kinase made of 2 subunits
Different isoform combos in different tissue
In heart muscle, CK-MM is 70%, CK-MB is 30%
CK released from cardiac myocytes when damaged in myocardial infarction
Appears in blood few hours later so can be measured for diagnostic
