Charles Darwin and Natural Selection Quiz

Chromosomal Inheritance

• Thomas Morgan established a link between specific genes and specific chromosomes through his research.
• Utilized the fruit fly (Drosophila melanogaster) due to its advantageous breeding characteristics.

Advantages of Using Fruit Flies

• Rapid breeding cycle: They reproduce quickly and can produce offspring in just two weeks.
• Simple genetic makeup: Only possess four pairs of chromosomes (three pairs of autosomes and one pair of sex chromosomes).

Findings on Eye Color

• During a year-long study, Morgan identified a male fruit fly with a white-eyed mutation, diverging from the typical red-eyed wild type.
• Initial cross between a white-eyed male and red-eyed female produced all F1 generation offspring with red eyes.

F1 Generation Analysis

• F1 red-eyed offspring were interbred to produce a second generation (F2).
• The resulting genetic ratio in offspring exhibited a 3:1 ratio of red-eyed to white-eyed flies, aligned with Mendelian expectations.
• All females from the F2 generation were red-eyed, while male offspring showed a 50% red-eyed and 50% white-eyed distribution.

Sex-Linked Genes

• Genes located on sex chromosomes (X and Y) are termed sex-linked genes, occurring in humans, plants, and certain insects.

Linked Genes

• Each chromosome comprises hundreds or thousands of genes.
• Genes positioned closely on the same chromosome are often inherited together during genetic crosses as they are considered a single unit.