Understanding Genes, DNA, and Chromosomes

Dec 23, 2024

Lecture Notes: Genes, DNA, and Chromosomes

Overview

  • Genes, DNA, and chromosomes are fundamental to determining individual identity.
  • These elements act as instructions inherited from parents.
  • Present in all cells, these components are essential to life.

Cells

  • All living organisms are composed of cells.
  • Different types of cells include:
    • Nerve cells
    • Hair cells
    • Skin cells
  • Basic cell structure:
    • Membrane: The outer border of the cell.
    • Cytoplasm: Liquid material within the cell.
    • Nucleus: Contains chromosomes.

Chromosomes

  • Humans typically have 23 pairs of chromosomes (46 total) in each cell.
    • 22 pairs are autosomes, appearing the same in both males and females.
    • 1 pair is the sex chromosomes:
      • Females: XX
      • Males: XY

DNA (Deoxyribonucleic Acid)

  • Long strings forming the chromosomes.
  • Structure:
    • Double helix: Ladder-like shape that is twisted.
    • Composed of four bases:
      • Adenine (A)
      • Thymine (T)
      • Guanine (G)
      • Cytosine (C)

Genes

  • A segment of DNA is known as a gene.
  • Genes function like a recipe for building proteins.
  • Protein Synthesis:
    • Order, length, and sequence of DNA bases determine the protein's size and shape.
    • Protein size and shape dictate its function in the body.

Biological Hierarchy

  • Proteins form cells.
  • Cells form tissues.
  • Tissues form organs (e.g., eyes, skin).

Determinants of Physical Traits

  • Genes influence:
    • Species identity (e.g., human, cow, apple).
    • Physical attributes:
      • Hair color
      • Skin color
      • Eye color

Conclusion

  • Genes, DNA, and chromosomes are crucial for defining not only our species but also individual physical characteristics.