Cellular Respiration and Photosynthesis Pathways

Metabolic Pathways in Biology

Glycolysis

Consists of a series of chemical reactions in the process of respiration that leads to the transformation of glucose into pyruvic acid.

Krebs Cycle

Includes a series of reactions starting from when acetyl groups are converted into citric acid, and then, by a sequence of reactions, water originates.

Electron Transport Chain

Includes a series of reactions between various substances, during which the electrons are gradually losing energy, so that upon reaching the last element of the chain, they are at a low energy level.

Calvin Cycle

It operates in the dark phase of photosynthesis, specifically in the stroma of chloroplasts. It is named after Dr. Melvin Calvin, who won a Nobel Prize in 1962 for determining the sequence of reactions that occur in the dark regarding the separation of carbon dioxide.

The cycle begins when carbon dioxide is fixed by a pre-existing molecule in the plant called ribulose bisphosphate, which is a 5-carbon sugar attached to two phosphate groups, forming a 6-carbon molecule. This gives rise to two 3-carbon molecules; one of them is converted into glucose, which is a product of photosynthesis, and again combines with carbon dioxide by ribulose diphosphate to form again and start the cycle anew.

Krebs Cycle Details

Pyruvic acid is a 3-carbon molecule that enters the mitochondrial matrix and releases a carbon dioxide molecule to form acetic acid. This 2-carbon molecule, together with the above mentioned "A" (acetyl-CoA), enters the Krebs cycle and combines with a 4-carbon molecule called oxaloacetic acid, forming a 6-carbon molecule called citric acid. This loses carbon dioxide, leaving a 5-carbon molecule called ketoglutaric acid.

It loses one carbon molecule and is converted back into a 4-carbon molecule. The purpose of the Krebs cycle is to produce carbon dioxide, and it owes its name to the biochemist Krebs.

Relationship Between Specialization and Cell Evolution

It can be said that cellular evolution is performed using the specialization of each cell. Each cell works with an additional function: specialization drives evolution.

Plant Tissues

Meristematic Tissue

Their function is related to the growth of plants. They are located at the ends of the stem, at the root, and inside the stem, forming the apical meristem, cambium, and radial meristem.

Permanent Tissue

These tissues cover, feed, hold, conduct, and protect the plant. They are located on the surface of the plant and throughout the plant, constituting the protective, fundamental, and conductive tissues (xylem and phloem).