Inheritance Flashcards
homologous chromosomes
humans have 23 pairs
One pair from the father one from the mother
Genotype
Actual genetic makeup relating to a trait
Dominant allele
Dominate charactic
Uppercase letter
Recessive allele
presence is completely maskes
lowercase letter
Phenotype
The physical expression of the genotype
inheritance abnormalities occur when ?
Meiosis errors
Nondisjunction
Error in cell division resulting in abnormal number of chromosomes
Aneuploid
Chromosomes added or missing
Polygenic inheritance
Most inherited traits not controlled by one gene
Complex inheritance
combined effects of many genes and environmental factors aka skin color, hair color, height, metabolism rate, body build
so even if someone inherits tall gene, full height can only be reached with nutrition ( environmental factor)
Skin color
Depends in environmental conditions aka sun exposure and nutrition
3 genes and environment produces actual skin color
Karyotype
shows 46 chromosomes arranged in pairs by size and position 22 pairs are autosomes 23rd pair are the sec chromosome XX=female XY=male
Sex determination
Males produce sperm carrying an X or Y
Females only produce eggs that carry an X
Sex is determines by which letter, X or Y, the sperm is carrying
At week 7, embryos initiate gender pattern of development