Energy Reactions in Cells Flashcards
Define metabolism.
The 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.
Give a very brief overview of how nutrients reach desired cells.
Through the GI-tract the nutrients are absorbed into the blood and then transported into desired tissues.
What are catabolic pathways?
Breakdown of larger molecules into smaller ones called intermediary metabolites
Release of large amount of free energy
Oxidative -> release H-atoms which are reducing power.
What are anabolic pathways?
Synthesis of larger important cellular components from intermediary metabolites
Use energy released from catabolism (ATP)
Reductive (means it uses H atoms released from catabolism)
What are the products of catabolic metabolism?
Building block materials like sugars, amino acids and fatty acids.
Organic precursors such as acetyl CoA
Biosynthetic reducing power (NADH, FADH2 and NADPH)
Energy for cell function (ATP)
What is energy needed for?
Transport work Anabolism Mechanical work Electrical work Osmotic work
What is an exergonic reaction?
A reaction that releases energy.
What is an endergonic reaction?
A reaction that uses energy.
What are some characteristics of an exergonic reaction?
They occur spontaneously
There is a change in free energy (deltaG)
deltaG < 0
Reactants -> products means a lower energy
What are some characteristics of an endergonic reaction?
They do not occur spontaneously.
Energy is needed.
deltaG > 0
Reactants -> products means a higher energy.
What are redox reactions?
Chemical bond energy of fuel molecules is released by oxidation reactions. All oxidations reactions are accompanied by a reduction reaction. This is called redox reaction.
What is oxidation?
Removal of electrons or removal of h-atoms. (OIL RIG)
What is reduction?
Gain of electrons. (OIL RIG = Oxidation is loss, reduction is gain)
What are H-carrier molecules (reducing power)?
NAD+/NADH+H+
NADP+/NADPH+H+
FAD/FADH2
What are reducing powers used for?
ATP production (NADH + H+) Biosynthesis (NADPH + H+)
What is the H-carrier redox cycle?
NADP+ and NAD+ going to NADPH + H+ and NADH + H+ by reduction. Then NADPH + H+ oxidises due to biosynthetic reduction.
NADH + H+ oxidises due to ATP synthesis.
What happens when there is a high concentration of ATP in the body?
Anabolic pathways are opened to get rid of ATP.
What happens when there is a low concentration of ATP and a high concentration of ADP and AMP?
Catabolic pathways are activated to form ATP.
What is adenylate kinase used for?
To further help ATP production by:
2ADP -> ATP + AMP
What are high energy signals in the body?
ATP
NADH
NADPH
FADH2
What are low energy signal in the body?
ADP, AMP
NAD+
NADP+
FAD+
What is energy stored as in the body?
Usually as glycogen and triglycerides.
What is creatine phosphate?
Creatine phosphate derives from Creatine.
When ATP levels are high creatine is stored as creatine phosphate.
Creatine with the help of ATP is phosphorylated by an enzyme called creatine kinase to form creatine phosphate and ADP.
Why is creatine phosphate important?
Because the reverse reaction is possible to form ATP. This means that ATP can be formed anaerobically if needed. A phosphate bond energy is stored in creatine phosphate to be used later on. So in case of rest or intense energy usage creatine and creatine phosphate can be utilised.
How does creatinine production work?
There is a spontaneous breakdown of creatine and creatine phosphate into creatinine which occurs at a constant rate.
How can levels of creatinine be monitored or measured?
By urine sample.
Why is creatinine a useful clinical marker?
Because the rate is usually constant unless anything abnormal has happened the creatinine concentration can be used as a marker for urine dilution.
It also provides a measure of muscle mass in an individual.
Since it is excreted by the kidneys, it can detect kidney failure.
Can be used to estimate true urinary loss of many substances.
A lot of substances and hormones are standardised to creatinine levels.
