3. CELLULAR RESPIRATION
All living things in the world including plants require
energy in order to function. This energy is obtained
from the food we eat. The cells break down the
energy stored in the food through a unique system
known as cellular respiration. In plain
language, cellular respiration means the procedure
through which the food is broken down by the cells
of living beings in order to produce the energy which
is in the form of ATP molecules (also known as the
Adenosine Tri Phosphate molecules). Plants use a
part of this ATP energy during photosynthesis for
producing sugar. The sugars are then broken down
during cellular respiration. This cycle is continued
again and again as long as the plant lives.
4. GLYCOLISIS
Glycolysis (it literally means glucose degradation)
is a metabolic pathway which changes glucose
C6H12O6 into pyruvate CH3COCOO + H. The free
energy which is generated in this process is utilized
to make high energy compounds namely ATP
(adenosine triphophate) and NADH (reduced
nicotinamide adenine dinucleotide).
This occurs in the cytoplasm.
Was found out by Gustav Embden and Otto
Meyerhof.
5. ANAEROBIC RESPIRATION
AN Anaerobic organism is called an
ANAEROBE
One way of doing this is to just get the
pyruvate to do oxidation; in this procedure
the pyruvate gets converted in to lactate (this
is the conjugate base of lactic acid) in a
process which is called lactic acid
fermentation. This process can be
represented in a word equation as:
pyruvate + NADH + H -> lactate + NAD
6. ANAEROBIC RESPIRATION
Some organisms like yeast turn NADH to NAD in a
reaction called as ethanol fermentation. In the
reaction the pyruvate is turned first into
acetaldehyde and CO2, after this into ethanol.
The lactic acid fermentation and ethanol
fermentation can happen in the lack of oxygen
presence. The anaerobic fermentation lets a lot of
single celled organisms to use glycolysis as their
only source of energy. From the two examples
above regarding the fermentation, NADH is
oxidized by sending 2 electrons to pyruvate. But
anaerobic bacteria use a big range of
compounds as the terminal electron acceptors in
the process of cellular respiration
7. Anaerobic respiration for
humans
In general in humans it is the muscle tissue
that respires anaerobically normally during
exercise, at which time the body cannot
intake the required oxygen for the cells to
respire. This clearly indicates that enough
energy is not made and the muscles require
more energy. So they achieve it in the
absence of oxygen. But when they have
stopped exercising, commonly an oxygen
debt has been created, because of the large
amount of lactic acid inside the muscles. It is
because of this fact the humans breath
heavily after exercising to negate the oxygen
debt.