Anaerobic respiration ( Fermentation ) And its Types | Biology Lecture |

Link of Glycolysis video https://www.youtube.com/watch?v=MsXQuRq2B8A&t=307s Fermentation and anaerobic respiration
enable cells to produce ATP without the
use of oxygen
Because most of the ATP generated by cellular respiration
is due to the work of oxidative phosphorylation, our estimate
of ATP yield from aerobic respiration is contingent
on an adequate supply of oxygen to the cell.
Fermentation is a way of harvesting chemical energy
without using either oxygen or any electron transport
chain—in other words, without cellular respiration.
Glycolysis oxidizes glucose to two molecules of pyruvate.
The oxidizing agent of glycolysis is NAD+, and neither oxygen
nor any electron transfer chain is involved. Overall, glycolysis
is exergonic, and some of the energy made available
is used to produce 2 ATP (net) by substrate-level phosphorylation.
If oxygen is present, then additional ATP is made
by oxidative phosphorylation when NADH passes electrons
removed from glucose to the electron transport chain. But
glycolysis generates 2 ATP whether oxygen is present or
not—that is, whether conditions are aerobic or anaerobic.
As an alternative to respiratory oxidation of organic
nutrients, fermentation is an extension of glycolysis that allows
continuous generation of ATP by the substrate-level
phosphorylation of glycolysis. For this to occur, there must
be a sufficient supply of NAD+ to accept electrons during
the oxidation step of glycolysis. Without some mechanism
to recycle NAD+ from NADH, glycolysis would soon deplete
the cell’s pool of NAD+ by reducing it all to NADH
and would shut itself down for lack of an oxidizing agent.
Under aerobic conditions, NAD+ is recycled from NADH by
the transfer of electrons to the electron transport chain. An
anaerobic alternative is to transfer electrons from NADH to
pyruvate, the end product of glycolysis.
Types of Fermentation.
In alcohol fermentation, pyruvate is
converted to ethanol (ethyl alcohol) in two steps. The first
step releases carbon dioxide from the pyruvate, which is converted to the two-carbon compound acetaldehyde. In
the second step, acetaldehyde is reduced by NADH to ethanol.
This regenerates the supply of NAD+ needed for the
continuation of glycolysis.
During lactic acid fermentation, pyruvate
is reduced directly by NADH to form lactate as an end product,
with no release of CO2. (Lactate is the ionized form of
lactic acid.) Lactic acid fermentation by certain fungi and bacteria
is used in the dairy industry to make cheese and yogurt.
#WhatIsAnaerobicRespiration
#LacticAcidVsAlcoholicFermentation

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