Module 5 Section 6 - Respiration Flashcards
What is the structure of the mitochondria?
1) outer membrane and inner membrane and the area between the two membrane is the inter-membrane space.
2) the internal folds are cristae and the fluid is matrix
3) they have their own dna
What are the coenzymes in respiration + function?
NAD - transfer hydrogen from one molecule to another
FAD - transfer hydrogen from one molecule to another
Coenzyme A - transfers acetate between molecules.
What are the four stages in aerobic respiration?
1) glycolysis
2) the link reaction
3) the Krebs cycle
4) oxidative phosphorylation
What are the two stages in glycolysis?
1) phosphorylation
2) oxidation
What happens in the phosphorylation stage of glycolysis?
1) glucose is phosphorylated by adding a phosphate from a molecule of ATP. This creates one molecule of hexose phosphate and a molecule of ADP.
2) hexose phosphate is phosphorylated by ATP to form hexose bisphosphate and another molecule of ADP.
3) hexose bisphosphate is split into two molecules of triose phosphate.
What happens in the oxidation stage of glycolysis?
1) triose phosphate is oxidised (loses hydrogen), forming 2 molecules of pyruvate.
2) NAD collects hydrogen ions forming 2 reduced NAD.
3) 4 ATP are produced but 2 were used up in stage 1 so there is a net gain of 2 ATP.
What happens in the link reaction?
1) pyruvate is actively transported into the matrix of the mitochondria.
2) pyruvate is decarboxylated (so one C atom is removed in the form of CO2).
3) NAD is reduced (collects hydrogen from pyruvate), changing pyruvate into acetate
4) acetate is combined with coenzyme A to form acetyl coenzyme A. No ATP produced.
What happens in the kreb’s cycle?
1) acetyl CoA from link reaction combined with oxyloacetate to form citrate. This is catalysed by citrate synthase. Coenzyme A returns to link reaction to be used again.
2) the 6C citrate molecule is converted to 5C molecule. Decarboxylation occurs, where CO2 is removed. Dehydrogenation also occurs. The hydrogen is used to produced reduced NAD from NAD.
3) the 5C molecule is then converted to a 4C molecule. Decarboxylation and dehydrogenation occur, producing one molecule of reduced FAD and two of reduced NAD. ATP is produced by the direct transfer of a phosphate group from an intermediate compound to ADP. This is called substrate-level phosphorylation.
4) citrate has now been converted into oxaloacetate.
What happens in the first stage of oxidative phosphorylation?
1) hydrogen atoms are released for reduced NAD and FAD as they’re oxidised to NAD and FAD. The hydrogen atoms split into protons (H+) and electrons.
2) the electrons move along the electron transport chain (made up of 3 electron carriers), losing energy at each carrier. The electron transport chain is found in the inner mitochondrial membrane. This membrane is folded into cristae, which increases the membrane’s surface area to maximise respiration.
3) this energy is used by electron carriers to pump protons from the matrix to the intermembrane space.
4) the concentration of protons is now higher in the intermembrane space than in the mitochondrial matrix. this forms an electrochemical gradient.
What happens in the second stage of oxidative phosphorylation?
1) protons move down the electrochemical gradient, back into the mitochondrial matrix, by ATP synthase
2) this movement drives the synthesis of ATP from ADP and inorganic phosphate. This process is called Chemiosmosis.
3) in the mitochondrial matrix, at the end of the transport chain, the protons, electrons and oxygen combine to form water. Oxygen is said to be the final electron acceptor.
How many molecules of ATP can be produced by one glucose molecule?
32
What is anaerobic respiration?
A type of respiration that doesn’t use oxygen. It starts with glycolysis, but doesn’t have the other steps in aerobic respiration.
What are the two types of anaerobic respiration?
1) lactate fermentation
2) alcohol fermentation
What happens in lactate fermentation?
1) it occurs in mammals and produces lactate. The first step is regular glycolysis to produce reduced NAD, pyruvate, and ATP.
2) Reduced NAD from glycolysis transfers hydrogen to pyruvate to form lactate and NAD. NAD can then be reused in glycolysis.
3) this means that a small amount of ATP can be produced as glycolysis can continue.
What happens in alcoholic fermentation?
1) it occurs in yeast cells and produces ethanol. The first step is regular glycolysis.
2) CO2 is removed from pyruvate to form ethanal.
3) Reduced NAD transfers hydrogen to ethanal to form ethanol and NAD.
4) NAD can then be reused in glycolysis so a small amount of ATP is produced.
