Genes, DNA, and Chromosomes

Overview

• Genes, DNA, and chromosomes are fundamental components that determine the traits and characteristics of an organism.
• These elements are inherited from both the father and the mother.
• Present in all living organisms, which are composed of cells.

Cells

• Different types of cells: nerve cells, hair cells, skin cells, etc.
• Structure: despite different shapes and forms, all cells have basic parts.
  • Cell membrane: outer border.
  • Cytoplasm: liquid material inside the cell.
  • Nucleus: located within the cytoplasm; contains chromosomes.

Chromosomes

• Humans typically have 23 pairs of chromosomes, totaling 46.
• Autosomes: 22 pairs are the same in both males and females.
• Sex Chromosomes:
  • 23rd pair differs between males and females.
  • Females: two X chromosomes (XX).
  • Males: one X and one Y chromosome (XY).

DNA (Deoxyribonucleic Acid)

• Chromosomes are long strings of DNA.
• Structure: DNA is shaped like a twisted ladder (double helix).
  • The steps of the ladder are made of four bases:
    • Adenine (A)
    • Thymine (T)
    • Cytosine (C)
    • Guanine (G)
• A gene is a stretch of DNA.

Protein Synthesis

• The body reads genes like a recipe to build proteins.
• The sequence and length of the DNA bases determine the size and shape of the protein.
• Protein function: determined by size and shape.
  • Proteins make up cells.
  • Cells make up tissue.
  • Tissue makes up organs (like eyes and skin).

Genetic Determinants

• Genes influence the organism's type (e.g., cow, apple, human) and appearance (e.g., hair color, skin color, eye color).