DNA Replication, Protein Synthesis, and Gene Therapy

DNA Replication

The process of DNA duplication, which allows identical genetic information to be shared between cellular daughters, consists of the following:

• The two strands of the double helix are separated.
• Free nucleotides can join the DNA nucleotides through their complementary bases. Only the nucleotides A can be combined with T, and C with G.
• The new nucleotides bind and form new DNA chains.
• Each of the two DNA chains serves as a template to create new strands.

Protein Synthesis

Proteins are formed by the joining of smaller molecules called amino acids. There are over 20 types of amino acids in different proteins. The order in which amino acids bind determines the type of protein.

Each cell produces thousands of proteins in its ribosomes, using the amino acids found in the cytoplasm. For amino acid synthesis, a copy of the gene's base sequence corresponding to each protein is needed. The base sequence of a DNA gene is copied into a messenger RNA molecule; this process is called transcription. RNA reaches the cytoplasm, where ribosomes synthesize protein, a process called translation.

Glucose Regulation

The cell uses glucose to obtain energy through cellular respiration. Glucose comes from the blood. The quantity of blood glucose is controlled by two hormones: insulin and glucagon. Insulin is responsible for stimulating the reduction of glucose in the blood, and glucagon performs the inverse function. The control process is as follows:

• High blood glucose stimulates insulin secretion.
• Insulin, spread throughout the body, stimulates the storage of glucose.
• When the blood glucose level is low, the pancreas produces glucagon, which stimulates the release of glucose from the body's stores.

Gene Therapy

Gene therapy is a procedure for treating genetic diseases using DNA technology. It consists of introducing a normal gene into the patient to replace the defective cellular gene. The intention is for the new gene to be capable of producing the protein that the affected gene is not capable of producing.

Stem Cells

A stem cell is a cell capable of dividing infinitely, leading to differentiated adult tissues. There are two types:

• Embryonic Stem Cells: These cells are derived from the cell mass of the embryo and can generate any other cell type in the body.
• Adult Stem Cells: These cells are capable of generating their own cell type.