Link reaction and krebs cycle

Question 1

how does pyruvate and hydrogen ions enter the mitochondrial matrix for the link reaction

Answer 1

-outer and inner mitochondrial membranes have symport transport proteins embedded in phospholipid bilayer =transport pyruvate and hydrogen ions into matrix

Question 2

explain the steps of the link reaction

Answer 2

-pyruvate (3C) passes from cytoplasm into mitochondrial matrix (two pyruvates per one glucose)
-in the presence of oxygen:
-pyruvate is decarboxylated (releasing CO2)
-pyruvate is also dehydrogenated, hydrogen is transferred to hydrogen acceptor NAD forming reduced NAD
-this results in an acetyl group (2C) which combines with coenzyme A (CoA) to form the 2C molecule acetyl coenzyme A which enters the Krebs cycle

Question 3

what is the purpose of coenzyme

Answer 3

Accepts acetyl group and in the form of acetyl CoA carries it to the krebs cycle

Question 4

what is the major role of link reaction where does it occur

Answer 4

-in mitochondrial matrix
-to deliver acetyl to krebs cycle

Question 5

what are the products of the link reaction per glucose

Answer 5

-2 reduced NAD
-2 CO2
-0 ATP

Question 6

what is the site for the krebs cycle

Answer 6

mitochondrial matrix

Question 7

what is the purpose of FAD coenzyme

Answer 7

flavine adenine dinucleotide, carries hydrogen atoms to the electron transport chain on the cristae of the mitochondria

Question 8

explain the steps of the krebs cycle

Answer 8

-acetylcoenzyme A (2C) releases acetyl group which combines with a 4C molecule oxaloacetate to produce a 6C molecule= citrate
-decarboxylation and dehydrogenation (removal of 2 x CO2 and hydrogen) results in a 4C molecule, reduced NAD and FAD and a single molecule of ATP
-the 4C molecule can then combine with more acetyl (citrate reconverted to oxaloacetate)
-the hydrogens removed are carried by coenzymes NAD and FAD to electron transport chain to generate ATP

-total: 1ATP 2 CO2 per acetate (double if per glucose)