Advanced A&P: Unit 1b

genetics

study of inheritance of characteristics

genes

the unit of inheritance; sequence of DNA that encode particular proteins

chromatin

relaxed form of DNA

chromosomes

DNA & protein in a condensed form; 46 in all, 23 pairs. They are paired because one comes from each parent. In meiosis, sperm and oocytes form and when they are fertilized, a full set is restored

alleles

different forms of a gene/trait

environmental factors influence gene expression

includes the chemical, physical, social, and biological factors surrounding and individual and the conditions to which a cell is exposed in the body

lifestyle factors

also influence gene expression

genotype

combination of alleles; reflects genetic information

homozygous genotype

identical alleles in a pair (ex: RR or rr)

heterozygous genotype

different alleles in a gene pair (ex: Rr)

phenotype

physical expression of the genotype

dominant allele

masks expression of recessive allele

recessive allele

form of a gene not expressed if dominant form is also present

trait/condition

carried on one of the autosomes

autosomal recessive conditions

albinism, cystic fibrosis

autosomal dominant conditions

huntington disease

female chromosomes

XX; the X chromosome houses many more genes than Y

male chromosomes

XY

Why are males are more likely to be affected by recessive X-linked trait?

Because males only have one X chromosome h

How are daughter affected by a X-linked recessive trait?

a daughter’s father must be affected, and her mother must be a carrier or affected

X-linked recessive disorders

colorblindness, hemophilia A, duchenne muscular dystrophy

mendelian inheritance

when traits are controlled in a purely dominant/recessive fashion