ANP2 Class: Genetics and Heredity Summary

Key Concepts

Genotypes vs. Phenotypes
- Genotype: Genetic makeup or combination of alleles.
- Phenotype: Physical expression of a trait (e.g., eye color).
Dominant vs. Recessive Alleles
- Dominant Allele: Represented by uppercase letters (e.g., B for Brown eyes) and masks the recessive allele.
- Recessive Allele: Represented by lowercase letters (e.g., b for Blue eyes); expressed when paired with another recessive allele.
Inheritance Patterns
- Homozygous: Two identical alleles (e.g., BB or bb).
- Heterozygous: Two different alleles (e.g., Bb).

Diploid Cells: Contain 46 chromosomes (23 pairs), including 22 autosomal pairs and 1 sex chromosome pair.
Haploid Cells: Sperm and ova with 23 chromosomes, not pairs.
Sex Chromosomes: XX for females, XY for males.

Tool used to predict the probability of offspring having specific genotypes and phenotypes.
Example: Brown eyes (B) vs. Blue eyes (b)
- Four possible genotype combinations: BB, Bb, bB, and bb.
- Corresponding phenotypes: Brown (BB, Bb, bB) and Blue (bb).

Involves genes located on the sex chromosomes, often focusing on X-linked traits.
Hemophilia: Caused by a recessive allele on the X chromosome.
- Females (XX) can be homozygous or heterozygous for normal, carriers, or affected.
- Males (XY) have a 50% chance of inheriting the disorder if the X chromosome carries the recessive allele.

Dominant alleles express traits even when paired with recessive alleles.
Only recessive alleles express the trait when paired together.
Punnett Squares help visualize genetic probabilities.
Sex-linked traits can significantly differ in probability between males and females.

Understanding the differences between genotypes and phenotypes, dominant and recessive alleles, and inheritance patterns is crucial.
The use of Punnett Squares and understanding sex-linked inheritance provides insight into genetic probabilities and trait expression.