chap 21 genetic inheritance Flashcards
genotype
genetic makeup of an organism (BB, Bb, bb)
phenotype
physical traits (ex: wings, hair/no hair etc.)
allele
different versions of a gene
simple dominance
dominant allele is expressed
what alleles go with homozygous Dominant, homozygous recessive, and heterozygous
BB
bb
Bb
cross: bb (blue) x BB (brown) =
cross: Bb x Bb = 25% blue eyed offspring
100% brown eyed offspring
what is the expected phenotypic ratio for dihybrid cross (AaBb x AaBb)
9:3:3:1
how many defective alleles do autosomal recessive disorders (Tay-Sachs, Cystic Fibrosis, Sickle Cell) need?
2 defective alleles
what is Tay-Sachs?
fat build up in the brain that causes nerve damage
what is Cystic Fibrosis?
thick mucus in the lungs and digestive tract
what is Sickle Cell disease?
misshaped red blood cells that cause poor oxygen transport
polygenic traits
controlled by multiple genes, show continuous variation
multifactorial traits
polygenic traits that are influenced by the environment
Pleiotropy
one gene affects multiple traits (ex: Marfan syndrome - affects connective tissue, long limbs, heart problems etc)
incomplete dominance
blended traits (ex: red + white = pink)
codominance
both alleles equally expressed (ex: blood type AB)
males (XY) inherit what from their mother?
X
colorblind carrier (XBXb) x colorblind male (XbY) =
50% of children will be color blind
Duchenne Muscular Dystrophy
muscle weakening, genetic defect in dystrophin
Fragile X syndrome
learning disabilities, behavioral issues
Hemophilia
blood doesn’t clot properly
