Question

3-carbon-atom (3C) molecule produced in glycolysis is called ______________Inside a eukaryotic cell, this molecule moves from ________________ to _______________ and is oxidized into _______________ . If oxygen is not present, it gets reduced into ______________ (in yeast) or ______________________ (in our muscle cells). Production of ATP in the absence of O2 is called _______________________ .

Answer 1

Glycolysis is process seen both in cellular respiration where glucose, a six carbon compound is broken down to two molecules of three carbon pyruvate. Glycolysis is a 10 enzymatic step process that results in production of 2 ATP and 2 NADH molecules. It is broken down to glyceraldehyde 3 phosphate which then forms pyruvate. Glycolysis occurs in the cytosol. Pyruvate is transported from the cytosol to the mitochondrial for the link reaction and TCA cycle. The transport of pyruvate occurs via the pyruvate translocase, a proton symporter. Pyruvate enters the mitochondria (present only in eukaryotic cells) and is converted to acetyl CoA. Acetyl CoA is then broken down to carbon dioxide, NADPH, FADH2 and ATP, via the TCA cycle. Electrons from FADH2 and NADH2 pass through the electron transport chain and are accepted by oxygen and there is ATP synthesis via the ATP synthase enzyme.

If oxygen is absent, then pyruvate cannot be converted to acetyl CoA. Instead, it undergoes anaerobic respiration to form either ethanol or lactic acid. Ethanol is produced in yeast from pyruvate via formation of acetaldehyde. CO2 is released as byproduct. In muscle cells, pyruvate is broken down to lactic acid by lactate dehydrogenase. Anaerobic respiration is also called fermentation.

Right choice:

Blanks from right to left:

pyruvate; cytosol; mitochondria; carbon dioxide; ethanol; lactic acid; anaerobic respiration/fermentation.

1. 3-carbon-atom …. glycolysis is called pyruvate.

2. Inside…eukaryotic cell, this molecule … cytosol to mitochondria and is .. into carbon dioxide.

3. If oxygen … reduced into ethanol (in yeast) or lactic acid (.. muscle..

4. Production..ATP .. called Anaerobic respiration or fermentation.