Cellular Respiration and Enzymes

 Compound which acts as a reservoir of phosphate-bond energy in the cell is phosphagen.

As the name suggests, these enzymes catalyze hydrolysis reactions (and their reverse reactions). The hydrolysis of an ester would be an example of such a reaction.

A nuclease is an enzyme capable of cleaving the phosphodiester bonds between the nucleotide subunits of nucleic acids. Older publications may use terms such as polynucleotidase or nucleodepolymerase. Nucleases are usually further divided into endonucleases and exonucleases, although some of the enzymes may fall in both categories.

Enzyme catalysis is the catalysis of chemical reactions by specialized proteins known as enzymes. Catalysis of biochemical reactions in the cell is vital due to the very low reaction rates of the uncatalysed reactions.

Biocatalysis is the use of natural catalysts, such as protein enzymes, to perform chemical transformations on organic compounds. Both the enzymes that have been more or less isolated and enzymes still residing inside living cells are employed for this task.

Covalent catalysis involves the substrate forming a transient covalent bond with residues in the active site or with a cofactor. This adds an additional covalent intermediate to the reaction, and helps to reduce the energy of later transition states of the reaction. This mechanism is found in enzymes such as proteases like chymotrypsin and trypsin, where an acyl-enzyme intermediate is formed.

Propionyl-CoA carboxylase catalyses the carboxylation reaction of propionyl CoA in the mitochondrial matrix. The enzyme is biotin dependent. The product of the reaction is (S)-methylmalonyl CoA. Propionyl CoA is the end product of metabolism of odd-chain fatty acids and is also a metabolite of most methyl-branched fatty acids.

Myo-inositol hexakisphosphate phosphohydrolase is any type of phosphatase enzyme that catalyzes the hydrolysis of phytic acid (myo-inositol hexakisphosphate) --an undigestible, organic form of phosphorus that is found in grains and oil seeds-- and releases a usable form of inorganic phosphorus.

3-Phosphoglyceric acid (3PG), or glycerate 3-phosphate (GP), is a biochemically significant 3-carbon molecule that is a metabolic intermediate in both glycolysis and the Calvin cycle. This chemical is often termed PGA when referring to the Calvin cycle.

Respiration is a catabolic process where organic compounds (like glucose) are oxidized (broken down) with oxygen to release energy (ATP), carbon dioxide, and water. Option B correctly states this. Option A is incorrect because respiration produces CO2, not reduces it. Option C is incomplete and reverses the process. Option D describes photosynthesis (the reverse of respiration).

The correct answer is option 3.

Thearubigins are polymeric polyphenols that are formed during the enzymatic oxidation (called fermentation by the tea trade) of tea leaves. Thearubigins are red in colour. Therefore, a black (fully oxidized) tea gives a reddish liquor while a green or white tea gives a much clearer one.

The bloat stage provides the first clear visual sign that microbial proliferation is underway. In this stage, anaerobic metabolism takes place, leading to the accumulation of gases, such as hydrogen sulphide, carbon dioxide, and methane.