Cancer, Genes & Stem cells

By the end of this lesson, you will be on the path towards being able to:
  - ✅ Explain how genes regulate cell function and inheritance
  - ✅ Describe how mutations can lead to cancer
  - ✅ Understand how cancer spreads and why it is harmful
  - ✅ Recognize real-world applications, case studies, and ethical considerations

Mitosis is similar to a photocopier, making identical copies of cells to maintain bodily functions.
Purpose of Mitosis:
- Growth: Cells multiply to support the increasing size of the organism.
- Repair: New cells replace old or damaged ones.

Cancer Risk: When mitosis goes wrong, uncontrolled cell division can lead to tumors.
- Mutations during mitosis disrupt normal cell cycle regulation, leading to cancer, analogous to a printer stuck in infinite print mode.

Cells adapt to changing demands for survival.
  - When Demand Increases:
    - Hypertrophy: Cells increase in size (e.g., muscle growth).
    - Hyperplasia: Increased cell number (e.g., during wound healing but also linked to tumor formation).
  - When Demand Decreases:
    - Atrophy: Cells shrink when not in use (e.g., muscle atrophy from lack of exercise).
  - Role Changes:
    - Metaplasia: Cells switch roles/functions (similar to changing production lines in a factory).
    - Dysplasia: Cells become disorganized (warning sign for potential cancer).
  - Survival Mode:
    - Autophagy: Recycling damaged cellular components (prevention of cancer by removing damaged cells).
    - Apoptosis: Programmed cell death (cancer cells often evade this signal).
When cellular adaptations become uncontrolled, cancer can arise, resulting in chaotic growth.

Cancer is defined as uncontrolled mitosis, driven by genetic mutations that prevent cells from undergoing apoptosis.
Stem Cells:
- They serve as the body's master builders, capable of controlled repair and regeneration of specialized cells.
- They hold therapeutic potential in addressing injuries and diseases.
Key Takeaway: Cellular adaptations can be beneficial (healing) or detrimental (cancer). Understanding these processes aids in developing cancer treatments and stem cell therapies.

Genes consist of segments of DNA nucleotides that encode for proteins, acting as recipes for protein synthesis.
The genome represents the complete set of genetic instructions in an organism.
Genes influence hereditary traits, such as eye color, height, and susceptibility to diseases (e.g., BRCA1 gene links to breast cancer risk).

DNA Organization: DNA is structured into chromosomes housed in the nucleus.
Chromosome Numbers:
- Humans possess 46 chromosomes (23 pairs).
- Chromosomes carry various genes, with the number of chromosomes varying among species (e.g., fruit flies have 8 chromosomes).
Interesting Fact: Pufferfish possess genes related to Alzheimer's disease in humans.

Gene Types:
- Dominant Genes: Require only one copy for their trait to manifest.
- Recessive Genes: Require two copies (one from each parent) to be expressed.
Example:
  - Brown eyes (B) are dominant over blue eyes (b).
    - Inheritance Outcomes:
      - BB or Bb results in brown eyes.
      - bb results in blue eyes.
Some genetic disorders are determined by dominant (e.g., Huntington's) or recessive (e.g., Cystic Fibrosis) inheritance patterns.
Analogy: Dominant genes are akin to a loud voice in a discussion, while recessive genes resemble whispers—both parents must contribute their whisper to relay the trait.

Gene splicing is a technique for modifying traits by cutting and pasting DNA segments.
Applications of gene splicing include:
  - GMO Crops: Such as pest-resistant corn.
  - Disease-Resistant Animals: Animals engineered to resist specific diseases.
  - Gene Therapy: Techniques to treat various genetic conditions (e.g., sickle cell disease).
CRISPR Technology: Functions as a DNA spellchecker, allowing for precise genetic alterations to prevent disorders.
Ethical Concerns:
- Discussion around the appropriate use of genetic modification (e.g., curing diseases vs. designing future generations).
Brave New World Connection:
- A novel illustrating genetically designed humans to avoid flaws.
- Raises questions about the potential for real-world customization of humans and the ethical boundaries in biotechnology.

Gregor Mendel (1856-1863):
- Known as the "Father of Genetics" for his work on trait inheritance in pea plants.
Rosalind Franklin (1952):
- Captured critical X-ray images that aided in the discovery of DNA's structure.
James Watson & Francis Crick (1953):
- Identified the double helix structure of DNA, awarded a Nobel Prize for their discovery.
Barbara McClintock (1948):
- Discovered transposons or