Chapter 4 of 10All chapters
Chapter 4 of 10
Inheritance
Why children resemble parents, imperfectly.
Alleles
Genes come in versions called alleles, one from each parent. A dominant allele shows with one copy; a recessive one needs two, which is why traits can skip generations.
- Mendel worked this out with pea plants before DNA was known.
- Most real traits involve many genes plus environment, so simple ratios are the exception.
Sex cells
Meiosis halves the chromosome count and shuffles the pairs, so every egg and sperm is a fresh combination. That shuffling is why siblings differ despite the same parents.