Question

Explain the processes of aerobic respiration in mitochondria of a cell and anaerobic
respiration in yeast and muscle with the help of word equations.

Answer 1

Answer:

aerobic respiration

it occurs in the presence of oxygen

it involves the exchange of gases between the organism and the outside environment

it occurs in cytoplasm and mitochondria

it always releases CO2 and H2O

it yield 36 ATPs

Anaerobic respiration

it occurs in absence of oxygen

exchange of gases is absent

it occurs only in cytoplasm

end products vary

it yields only 2 ATPs.....

........

Answer 2

Explanation:

Aerobic respiration is the burning or oxidation of glucose in the presence of oxygen to release energy (ATP). The whole process of aerobic respiration takes place in three steps: glycolysis, Krebs’ cycle, and electron transport system. Sites of respiration are cytoplasm and mitochondria.

Glycolysis: Glycolysis is the lysis or splitting of sugars. During glycolysis, one molecule of 6-carbon compound glucose is broken down into two molecules of 3-carbon pyruvic acid. This occurs in cytoplasm either in the presence or in the absence of oxygen. Totally, in the end, we get two pyruvic acid molecules, two ATP molecules and two NADH electron carrying molecules.

Krebs’ cycle: Also known as the tricarboxylic acid cycle (TCA cycle) and the citric acid cycle. The pyruvic acid formed is transferred to the matrix of mitochondria and converted into acetyl CoA. After a series of stages, two molecules of ATP are produced. Also, two compounds- nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FADH2) are produced. They help to carry electrons for the next step.

Electron Transport System and Oxidative Phosphorylation: ETS directly depends on oxygen. Here through a chain of electron carriers such as NADH high-energy electrons are passed on which develops an electron gradient. Eventually, by oxidative phosphorylation ATPase convert ADP to ATP.

At last, in eukaryotes, the total sum of ATP molecules harvested is 36 whereas in prokaryotes it is 38 in a single respiration.

Anaerobic means “without air”. Therefore, this type of cellular respiration does not use oxygen to produce energy.  Sometimes there is not enough oxygen around for some organisms to respire, but they still need the energy to survive.  Due to lack of oxygen, they carry out respiration in the absence of oxygen to produce the energy they require, which is referred to as anaerobic respiration. Anaerobic respiration usually occurs in lower plants and microorganisms. In the absence of oxygen, the glucose derived from food is broken down into alcohol and carbon dioxide along with the production of energy.

Glucose → Alcohol + Carbon dioxide + Energy

Anaerobic respiration is also used by multi-cellular organisms, like us, as a temporary response to oxygen-less conditions. During heavy or intensive exercise such as running, sprinting, cycling or weight lifting, our body demands high energy. As the supply of oxygen is limited, the muscle cells inside our body resort to anaerobic respiration to fulfill the energy demand. Cramps occur when muscle cells respire anaerobically. Partial breakdown of glucose, due to lack of oxygen, produces lactic acid and the accumulation of lactic acid causes muscle cramps.

Glucose → Lactic acid + Energy

Anaerobic respiration produces a relatively lesser amount of energy as compared to aerobic respiration, as glucose is not completely broken down in the absence of oxygen.

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