Energy Reactions In Cells Flashcards
Define metabolism
Metabolism is the set of processes which derive energy and raw materials from food stuffs and use them to repair, growth and activity of the tissues of the body to sustain life.
(all about the extraction and utilisation of energy)
Where does metabolism start
It begins in the Gi tract as food is broken down into nutrients which is taken up into the blood.
What is cell metabolism?
Small chemical changes
Many reactions but few reaction types
Reactions are organised into metabolic pathways, which are distinct but integrated. Some in all cells, some in some cells and some only in compartments within cells.
What is the purpose of metabolic pathways?
Help us to picture what is going on, pathways are organised into maps showing: Start Intermediate (metabolites) End points Interconnections
What are the roles of catabolic pathways?
- Break down larger molecules into smaller ones (intermediary metabolites)
- Release large amounts of free energy
- Oxidative - Release H atoms and have ‘reducing power’
What are the roles of anabolic pathways?
- Synthesise larger important cellular components from intermediary metabolites
- Use energy released from catabolism (ATP)
- They are reductive (i.e. they use the H released in catabolism)
What are the products of catabolism?
- Building block materials (sugars, amino acids, fatty acids). These are for the dynamic state of cell components (turnover), cell growth and division, repair.
- Organic precursors (Acetyl CoA). This allows for the interconversion of building block material.
- Biosynthetic reducing power (NADH, NADPH)
- Energy for cell function (ATP)
What is energy?
The capacity to do work
What are different types of work?
Biosynthetic work (anabolism)- synthesis of cellular components
Transport work - membranes (for the maintenance of ion gradients and for nutrients uptake)
Specialised functions inc- Mechanical work (muscle contraction), Electrical work (nervous impulse conduction) and Osmotic work (in the kidney).
What is the difference between calorie and Calorie?
calorie = 1 calorie Calorie = 1000calories (1kcal) =4.2 kJ.
What energy required for whole body?
Basal Metabolic Rate- energy required by an awake individual during physical, digestive and emotional rest at 18*C
Activity (Muscular work)
Specific Dynamic of food (approx 150kcal) This is the cost of ingestion, digestion and absorption of food.
What happens if we consume more energy than need?
Growth -syntheis of new tissue (repair, children, pregnancy)
Production of adipose tissue
How long survive with just water?
Can survive approx 20-70 days if given water. This means there must be important regulatory mechanisms to govern supply an utilisation of energy.
Why is chemical bond energy good?
It can be used directly without prior conversion to heat.
Man is ISOTHERMAL. This means that they cannot use heat energy for work.
What is an Exergonic energy change?
Release energy (negative gibbs).
Spontaneous
In catabolic pathways
What is an Endergonic energy change?
Require energy (positive gibbs) In anabolic pathways.
What are Standard conditions?
25 degrees celsius,
1 atm
1 M
pH 7
But, cell has NON STANDARD conditions.
What is a redox reaction?
This is when both oxidation and reduction at once
What is oxidation?
Removal of electrons
Removal of H-atoms (H+ + e-)
What does OIL RIG stand for?
Oxidation Is Loss Reduction Is Gain (of electrons)
Give some examples of H carrier molecules?
How can they be used as evidence to show a cycle is taking place?
NAD+ / NADH + H+
NADP+ / NADPH + H+
FAD / FADH2
Total conc of oxidised and reduced carriers is constant Therefore, must be a cycle between oxidative and reductive processes.
How do H-carrier molecules act as carriers of reducing power?
ATP production -(NADH + H+)
Biosyntheiss (NADPH)
What are the properties of H carriers?
Complex molecules (contain components from vitamins (B Vitamins)) Converted to reduced form by adding two H atoms (H+ +e-) H+ dissociated into solution
How can the energy released during oxidative metabolism be used?
The energy released from food by oxidation is exergonic.it can be used:
- Directly eg the use of NADPH to drive biosynthesis
- Indirectly eg In mitochondrial systems to drive ATP production (oxidative phosphorylation)
What is the structure of ATP?
Adenine, Ribose and three phosphates
How much energy lost gained when +/- a phosphate?
31kJ mol-1.
When you remove a phosphate, it creates it (negative)
Is ATP a store or a currency?
ATP is NOT a store! It is a currency. This is because there is limited conc of ADP.
ATP is stable! This allows energy flow to be controlled.
How much ATP is in our bodies?
Our body contains 250g of ATP but, turn over body weight in ATP every day.
When are anabolic pathways activated?
Anabolic pathways are activated when ATP levels are high
When are catabolic pathways activated?
Catabolic pathways are activated when ATP conc. is low but ADP and AMP conc are high.
What is adenylate kinase?
It is a phosphotransferase enzyme that catalyzes the interconversion of adenine nucleotides (ATP, ADP, and AMP). It combines two ADP to produce an AMP and ATP.
What are high energy signals?
High energy signals activate anabolic pathways. They inc.: ATP NADH NADPH FAD2H
What are low energy signals?
Low energy signals activate catabolic pathways. They inc.: ADP, AMP NAD+ NADP+ FAD
How is energy stored in cells?
In form of polymer macromolecules of fuel molecules eg glycogen, trigyceride.
How is some energy stored in muscles?
Creatine phosphate. This is used as a reserve of high energy stores that can be used immediately.
How does creatine phosphate work?
Creatine +ATP (using creatine kinase as enzyme) = Phosphocreatine (PCr) + ADP.
When ATP high, creatine phosphate is formed, `If ATP conc falls, reaction reverses and produces a short term burst of ATP.
What is creatine kinase a marker of?
Creatine Kinase is a marker of myocardial infarction.
CK is released from cardiomyocytes. when they are damaged by cardiomyocytes. This appears in the blood after a few hours and it is how we diagnose an MI.
Look at isoform distribution (70:30), so know its form the heart.
How is creatine a clinical marker?
Related to muscle mass as constant degradation. Can be used to measure muscle mass in the body because the amount of creatinine is proportional to muscle mass.
Can also look at creatinine conc in the Urine as a marker of urine dilution. This is because the release of creatine is constant and level all day. It can be used to estimate true urinary loss of many substances.
