Autosomal Linkage (AQA A-Level Biology): Flashcards
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What is autosomal linkage?
What is autosomal linkage?
Two or more genes located on the same autosome (non-sex chromosome)
What are linked genes?
What are linked genes?
Genes located on the same chromosome
What is a linkage group?
What is a linkage group?
All genes on a single chromosome
How many autosomes do humans have?
How many autosomes do humans have?
22 autosomes (44 total, 22 pairs)
How do linked genes pass into gametes?
How do linked genes pass into gametes?
They remain together as a unit during meiosis, not separated
Which law do linked genes violate?
Which law do linked genes violate?
Mendel's Law of Independent Assortment
How many gamete types from AaBb (non-linked genes)?
How many gamete types from AaBb (non-linked genes)?
Four types: AB, Ab, aB, ab
How many gamete types from linked genes (no crossing over)?
How many gamete types from linked genes (no crossing over)?
Two types only: AB and ab
Phenotypic ratio for linked heterozygous cross (e.g., GgNn × GgNn)?
Phenotypic ratio for linked heterozygous cross (e.g., GgNn × GgNn)?
3:1 (3 dominant phenotype : 1 recessive phenotype)
What factor affects linkage strength?
What factor affects linkage strength?
Distance between genes - closer genes are more tightly linked