Overview
This lecture explores fascinating genetic traits, mutations, and unique features of the human body, highlighting unusual conditions and rare body characteristics determined by our DNA.
Genes and DNA Basics
- Genes are segments of DNA on chromosomes that determine human traits like height and hair color.
- Humans have about 25,000 genes, resulting in numerous possible genetic combinations.
- Gene mutations are permanent DNA sequence changes that can cause unique features or disorders.
- Evolution relies on DNA variability and mutations for new traits in living things.
Rare and Remarkable Body Features
- Distichiasis: Double eyelashes caused by a dominant genetic mutation, resulting in fuller lashes.
- Anisocoria: Unequal pupil sizes, usually present at birth and often less than a millimeter difference.
- Werewolf Syndrome (Hypertrichosis): Excessive hair growth anywhere on the body, caused by rare genetic mutations.
- Webbed Toes/Fingers (Syndactyly): Fused digits forming a webbed appearance, may be inherited or a new mutation.
- Short Sleepers: Genetic mutation allowing people to regularly function with less than 6 hours of sleep.
- Cleft Chin: A Y-shaped dimple in the chin from incomplete fusion of jaw bones during development.
- Adermatoglyphia: A rare genetic disorder resulting in absence of fingerprints.
- Unbreakable Bones: Mutation in the LRP5 gene causing abnormally high bone density.
- Mallen Streak (Poliosis): White streak of hair from lack of pigment, often hereditary.
- Heterochromia: Eyes with different colors or patterns, can be congenital or acquired, with three distinct forms.
Surprising Vision Facts
- About 12% of women have tetrachromatic "supervision," allowing them to perceive more colors due to a fourth type of cone in the eye.
- Color blindness occurs when a cone in the eye does not function properly.
- A unique mutation on one X chromosome in women may expand visible color range beyond normal human perception.
Key Terms & Definitions
- Gene — A segment of DNA controlling specific traits.
- Mutation — A permanent change in DNA sequence.
- Distichiasis — Double row of eyelashes due to a gene mutation.
- Anisocoria — Condition of unequal pupil sizes.
- Hypertrichosis — Excessive hair growth, known as werewolf syndrome.
- Syndactyly — Webbing or fusion of fingers or toes.
- Adermatoglyphia — Absence of fingerprints.
- Heterochromia — Eyes with different colors.
- Tetrachromacy — Condition of having four types of color-detecting cones in the eye.
Action Items / Next Steps
- Review key definitions and examples of genetic traits discussed.
- Reflect on any unique genetic features in yourself or others for further exploration.