Metabolism Flashcards
How does ATP provide immediate energy?
ATP (adenosine triphosphate) is a high energy molecule that functions as an immediate source of power for cell processes
One molecule of ATP contains three covalently linked phosphate groups – which store potential energy in their bonds
When ATP is hydrolysed (to form ADP + Pi) the energy stored in the phophate bond is released to be used by the cell
Products of Glycolysis
Glycolysis breaks down glucose (6-C) into two molecules of pyruvate (3C), and also produces:
Hydrogen carriers (NADH) from an oxidised precursor (NAD+)
A small yield of ATP (net gain of 2 molecules)
How does Anaerobic respiration allow for ATP to be produced?
The purpose of anaerobic respiration is to restore stocks of NAD+ – as this molecule is needed for glycolysis
By restoring stocks of NAD+ via anaerobic pathways, the organism can continue to produce ATP via glycolysis
How does Anaerobic respiration occur?
Anaerobic respiration proceeds in the absence of oxygen and does not result in the production of any further ATP molecules
In animals, the pyruvate is converted into lactic acid (or lactate)
In plants and yeasts, the pyruvate is converted into ethanol and carbon dioxide
Why do we respire anaerobically and what are the consequences of the process?
When exercising at high intensity, the cells’ energy demands will exceed what the available levels of O2 can supply aerobically
Hence the body will begin breaking down glucose anaerobically to maximise ATP production
This will result in an increase in the production of lactic acid, which leads to muscle fatigue
When the individual stops exercising, oxygen levels will increase and lactate will be converted back to pyruvate
What are the general processes in aerobic respiration?
Aerobic respiration consists of the link reaction, citric acid cycle (or Krebs cycle) and the electron transport chain
Glycolysis is an anaerobic process that happens before hand
How many ATP molecules form in each process between Glycolysis and Chemiosmosis
Glycolysis produce 2 ATP
The Link reaction produces 0 ATP
The Krebs cycle produces 2 ATP
The Electron Transport Chain produces 34 ATP
Applications of Anaerobic respiration
In yeasts, fermentation results in the production of ethanol and carbon dioxide
Bread – Carbon dioxide causes dough to rise (leavening), the ethanol evaporates during baking
Alcohol – Ethanol is the intoxicating agent in alcoholic beverages (concentrations above ~14% damage the yeast)
Bacterial cultures can also undergo fermentation to produce a variety of food products
Yogurt / Cheese – Bacteria produce lactic acid anaerobically, which modifies milk proteins to generate yogurts and cheeses
What is the range of wave lengths of visible light?
Colours are different wavelengths of white light and range from red (~700 nm) to violet (~400 nm)
What wave length is best absorbed and best reflected by chlorophyll?
Chlorophyll absorbs light most strongly in the blue portion of the visible spectrum, followed by the red portion
Chlorophyll reflects light most strongly in the green portion of the visible spectrum (hence the green colour of leaves)
What is the structure of Chlorophyl?
Chlorophyll is composed of a Chlorin ring which has a magnesium center and thus ia the light reactiing component
Additionally chlorophyll has a hydrocarbon tail which anchors itself to the tykloid membrane
Explain what a metabolic pathway is
Metabolism describes the sum total of all reactions that occur within an organism in order to maintain life
Metabolic pathways are typically organised into chains or cycles of enzyme-catalysed reactions
Metabolic pathways allow for a greater level of regulation, as the chemical change is controlled by numerous intermediates
Explain how enzymes catalyse reactions
Enzymes speed up the rate of a biochemical reaction by lowering the activation energy
When an enzyme binds to a substrate it stresses and destabilises the bonds in the substrateThis reduces the overall energy level of the substrate’s transitionary state, meaning less energy is needed to convert it into a product and the reaction proceeds at a faster rate
Classify anabolic and catabolic reactions into endergonic and exergonic
Catabolic is exergonic
Anabolic is endergonic
Describe competitive inhibition (3)
Competitive inhibition involves a molecule, other than the substrate, binding to the enzyme’s active site
The molecule (inhibitor) is structurally and chemically similar to the substrate (hence able to bind to the active site)
The competitive inhibitor blocks the active site and thus prevents substrate binding