Genetics: From DNA Structure to the Human Genome Project

The Fundamental Units of Life: Cells and DNA

The Cell: The cell is the basic unit of life. It can be divided into two distinct areas: the cytoplasm and the nucleus. The cytoplasm contains various cellular organelles, while the nucleus contains the genetic information that determines the characteristics of every individual: DNA.

Chromosomes and Genes

Chromosomes:

• Tiny threadlike structures found in the nucleus of eukaryotic cells.
• Contain nucleic acids, specifically DNA (deoxyribonucleic acid), and proteins.
• Divided into smaller units called genes.
• The number of chromosomes is characteristic of each species. For example, human cells have 46 chromosomes grouped in pairs, while reproductive cells (gametes) have 23.

Genes:

• The basic unit of heredity in living beings.
• A DNA fragment responsible for carrying out a particular function.
• Determines the inheritance of a particular characteristic or group of traits.

Genotype, Phenotype, and the Genome

Genotype: The set of genetic characteristics received from one's parents.

Phenotype: The observable physical or biochemical characters that appear in an individual.

Genome: The complete set of genes belonging to a specific species.

The Human Genome Project (HGP)

The Human Genome Project was an international initiative launched in 1990 to locate and sequence all the genes that constitute the human genome. It represents the first internationally coordinated effort in the history of biology.

Main Objectives of the HGP

• Determine the complete sequence of human DNA.
• Identify the genes that constitute the human genome.
• Store all obtained information in a centralized database.
• Create and implement new tools necessary to analyze the data.
• Study the ethical, legal, and social aspects of the human genome.

Genetic Engineering and DNA Structure

Genetic Engineering

Genetic engineering is defined as the set of techniques and strategies used to create new combinations of genetic material—that is, to modify genes.

DNA Structure

• Consists of small parts called nucleotides.
• Nucleotides contain the nitrogenous bases: adenine (A), guanine (G), cytosine (C), and thymine (T).
• The two strands of DNA are held together by bonds between bases that form base pairs.