bio 2.3

 Krebs cycle

 also known as the citric acid cycle or TCA cycle, is a series of chemical reactions that break down the energy stored in glucose, fatty acids, and amino acids to produce energy

mitochondrial matrix

the second stage of aerobic cellular respiration occurs in the __ of eukaryotic cells

Citrate Formation

 A two-carbon molecule called acetyl CoA, which is the product of the breakdown of pyruvate, combines with a four-carbon molecule called oxaloacetate. This reaction forms a six-carbon molecule called citrate.

Isomerization

Citrate is rearranged to its isomer, isocitrate

Oxidation and Decarboxylation 1

Isocitrate is oxidized, releasing a molecule of carbon dioxide and forming a five-carbon molecule called alpha-ketoglutarate. In this step, one molecule of NAD+ is reduced to NADH

Oxidation and Decarboxylation 2

Alpha-ketoglutarate is further oxidized, releasing another molecule of carbon dioxide and forming a four-carbon molecule called succinyl CoA. Another molecule of NAD+ is reduced to NADH in this step

ATP/GTP Production

Succinyl CoA is converted to succinate. This reaction is accompanied by the production of one molecule of ATP (or GTP).

Oxidation 1

Succinate is oxidized to form fumarate. In this step, one molecule of FAD is reduced to FADH₂.

Hydration

A water molecule is added to fumarate, converting it into malate.

Oxidation 2

Malate is oxidized back to oxaloacetate, the starting molecule. This final step reduces one more NAD+ to NADH, and the cycle is ready to begin again

Nicotinamide adenine dinucleotide

NAD+

is the oxidized form of NAD

NAD+

is the reduced form of NAD

NADH

 NAD+

is a key coenzyme in many metabolic reactions, including glycolysis and the Krebs cycle. It accepts electrons and a proton from a molecule, becoming reduced to NADH

NADH

then carries these electrons to the electron transport chain, where they are used to generate a large amount of ATP, the cell's energy currency

For every NADH molecule that enters the electron transport chain, approximately _ molecules of ATP are produced

2.5-3

Flavin adenine dinucleotide

FAD

 is the reduced form of FAD 

FADH₂

FADH₂

is produced specifically during the Krebs cycle, when FAD accepts electrons and protons from a molecule called succinate. Like NADH, it also delivers its electrons to the electron transport chain. However, it enters the chain at a different point than NADH, which results in a slightly lower ATP yield

For every FADH2 molecule that enters the electron transport chain, approximately _ molecules of ATP are produced.

1.5-2

Aconitase 1

citrate is dehydrated, turning to cis-acotinate

cis-acotinate

result of aconitase 1

Aconitase 2

cis-aconitate is rehydrated, turning to isocitrate

isocitrate

result of aconitase 2, an isomer of citrate

Isocitrate dehydrogenase

Isocitrate is oxidized, releasing CO₂ and forming a five-carbon molecule called alpha-ketoglutarate. One molecule of NAD+ is reduced to NADH

alpha-ketoglutarate

result of isocitrate dehydrogenase

Alpha-ketoglutarate dehydrogenase

Alpha-ketoglutarate is oxidized, releasing CO₂ and forming a four-carbon molecule called succinyl-CoA. Another molecule of NAD+ is reduced

succinyl-CoA

result of Alpha-ketoglutarate dehydrogenase

succinyl-CoA synthetase

Succinyl CoA turns to succinate. This produces one molecule of ATP (or GTP)

succinate

result of succinyl-CoA synthetase

guanosine triphosphate

GTP

succinate dehydrogenase

Succinate is oxidized to fumarate. reducing FAD to FADH₂.

fumerate

result of succinate dehydrogenase

Fumarase

water is added to fumarate turning to malate

Malate

result of fumarase

Malate dehydrogenase

malate is oxidized to oxaloacetate, reducing a NAD+

Oxaloacetate

result of Malate dehydrogenase

Citrate synthase

acetyl CoA combines with oxaloacetate, forming citrate.

citrate

result of Citrate synthase

acetyl CoA

A two-carbon molecule called _ which is the product of the breakdown of pyruvate