DNA, Chromosomes, Genes, and Genomes

DNA (Deoxyribonucleic Acid)

Definition: DNA stands for Deoxyribonucleic Acid, the chemical comprising all our genetic material.
Structure: It's a polymer, meaning it's composed of many similar units joined together.
- Formed as a double helix, a two-stranded spiral.
- If unraveled, the DNA from a single cell would extend over two meters in length.

Description: To fit DNA within the nucleus compactly and avoid tangling, it is segmented into 46 different sections known as chromosomes.
- Each cell has 46 chromosomes, representing 23 different types, with one pair from each parent.
- The 23rd pair is unique, determining sex: XX for females and XY for males.
Common Misconception: Chromosomes are often illustrated as X-shaped, which only occurs prior to cell division (meiosis or mitosis). Normally, they don't have this appearance.

Definition: A gene is a small section of DNA coding for a specific protein.
- Described as small segments of a chromosome.
- Essential for coding sequences of amino acids which combine to form proteins.
Function: Determines the proteins a cell produces, influencing its function (e.g., hemoglobin in red blood cells).

Definition: The genome encompasses an organism's entire set of genetic material.
Importance:
- Offers insight into genetic similarities/differences among individuals, relatedness, and predisposition to diseases.
- Enables the identification of genes linked to diseases, aiding in treatment selection and the development of new therapies.
- Facilitates the tracing of human migration patterns.

Next Video: Will cover alleles, genotypes, phenotypes, and the distinctions between homozygous and heterozygous.