Relate the structure of a mitochondriion to it’s funtion[6] #
Describe how the structure of a mitochondrion is related to its function. [8]
- double membrane ;
- inner membrane
- folded or cristae ;
- increased or large, surface area ;
- has, ATP synthase or stalked particles ;
- has carrier (proteins) or cytochromes ;
- (site of) ETC or oxidative phosphorylation/chemiosmosis ;
- intermembrane space
- has low pH or high concentration of protons ;
- accepts protons from ETC ;
- proton gradient between intermembrane space and matrix or protons move from intermembrane space to matrix;
- ref. to ATP synthesis;
- matrix
- contains enzymes;
- site of, link reaction or the Krebs cycle;
- outer membrane
- presence of carriers for, pyruvate or reduced NAD ;
- e.g. ribosomes or DNA.
Outline the process of anaerobic respiration in both mammal and yeast cells. [8] #
- general
- reduced NAD produced in glycolysis ; A glycolysis described
- small amount of ATP produced in glycolysis ;
- in yeast cells
- pyruvate converted to ethanal ;
- carbon dioxide released / decarboxylation ;
- ethanal, reduced / accepts H ;
- by reduced NAD ;
- ethanol formed ;
- in mammalian cells
- pyruvate converted to lactate ;
- by reduced NAD ;
- in, liver / muscle, cells ;
- reversible in mammal / irreversible in yeast / single step in mammal / more than 1 in yeast / reoxidised NAD allows glycolysis to continue / named enzyme
Explain how the reduced NAD is oxidised under anaerobic conditions in mammalian muscle tissue and in yeast.[6] #
- Muscle
- pyruvate converted to lactate; A lactic acid
- hydrogen combines with pyruvate;
- lactate dehydrogenase;
- Yeast
- pyruvate converted to ethanal;
- release of carbon dioxide / decarboxylated;
- hydrogen combines with ethanal;
- ethanal converted to ethanol;
- alcohol dehydrogenase;
Explain the role of NAD in aerobic respiration. [6] #
- coenzyme;
- for dehyrogenase;
- reduced;
- carries electrons;
- and protons/H+/H/hydrogen;
- from Krebs cycle;
- and from glycolysis;
- to cytochromes/electron transfer chain;
- reoxidised/regenerated;
- ATP produced;
- 3/2.5 (molecules of ATP) per reduced NAD;
Explain the different energy values of carbohydrates, lipid and proteins as respiratory substrates [6] #
- lipid > protein > carbohydrate ;
- A lipid has more energy than either protein or carbohydrate
- comparative figures ;
- kJ g-1 / per unit mass ;
- more hydrogen atoms in molecule, more energy ;
- lipid have more, hydrogen atoms / C-H bonds ;
- (most) energy comes from oxidation of hydrogen to water ;
- using reduced, NAD / FAD ;
- in ETC ;
Describe the process of glycolysis[8] #
- (glucose) phosphorylated by ATP ;
- raises energy level / overcomes activation energy ;
- hexose bisphosphate ;
- lysis / splitting, of, glucose / hexose ;
- breaks down to two TP ;
- 6C(2) x 3C ;
- dehydrogenation / description ;
- 2 NAD reduced formed (from each TP to pyruvate formed) ;
- 4 ATP produced / net gain of 2 ATP ;
- pyruvate produced ;
- reduced NAD to oxidative phosphorylation / redox ;
Describe the main features of the Krebs Cycle. [8] #
- matrix;
- of mitochondrion;
- acetyl CoA combines with oxaloacetate;
- to form citrate;
- 4C to 6C;
- decarboxylation/produce CO2;
- dehydrogenation/oxidation;
- 2CO2 released;
- reduced NAD produced;
- reduced FAD produced;
- ATP produced;
- series of steps/intermediates;
- enzyme catalysed reactions;
- oxaloacetate regenerated;
Describe how ATP is synthesised by oxidative phosphorylation [8] #
Describe the process of oxidative phosphorylation in the mitochondria[8]
- reduced, NAD / FAD ;
- passed to ETC ;
- inner membrane / cristae ;
- hydrogen released (from reduced, NAD / FAD) ;
- split into electrons and protons ;
- electrons pass along, carriers / cytochromes ;
- ref. energy gradient ;
- energy released pumps protons into intermembrane space ;
- proton gradient ;
- protons pass through (protein) channels ;
- ATP synthase / stalked particles ;
- (ATP produced from) ADP and inorganic phosphate ;
- electron transferred to oxygen ;
- addition of proton (to oxygen) to form water / (oxygen) reduced to water ;