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Ch 13: Meiosis; Ch 14: Mendelian Genetics; Ch 15: Chromosomes

Mutations

mutation

genetic or chromosomal (deletion, inversion, translocation, polyploidy) abnormality

karyotype

diagram that shows size, #, & shape of chromosomes

nondisjunction

failed separation of homologous chromosomesaneuploidy(trisomy, polyploidy

Mendelian Laws

Law of Dominance

offspring of 2 organisms that are homozygous for 2 opposing traits will be hybrid but will only exhibit the dominant trait and not the recessive trait

Law of Segregation

during formation of gametes, the 2 traits carried by each parent will separate

Law of Independent Assortment

alleles of a gene for one trait segregate independently from alleles of a gene for another trait (applies w/dihybrid cross)

Genes

linked

genes on the same chromosome

sex-linked

traits carried on X chromosome

linkage mapping

distance between genes on chromosome=chance of separation by crossing over

recombination frequency

=total recombinants/total # offspring x100

pedigree

used to determine how traits are inherited

Barr body

inactivated X chromosome in each female mammal’s somatic cellgenetic mosaic

Types of Crosses

monohybrid cross

Tt x Tt; phenotype ratio=3:1; genotype ratio=1:2:1

testcross

B/__ x b/b to determine B/__’s genotype

dihybrid cross

TtYy x TtYy; can produce 4 types of gametes & phenotype ratio=9:3:3:1

Types of Inheritance

incomplete dominance

hybrids show blending of traits

codominance

hybrids show both traits

multiple alleles

more than 2 allelic forms

pleiotropy

1 gene affects an organism in several/many ways

epistasis

2 genes, 1 trait; 1 masks expression of the other

polygenic

blending of several genes that vary along a continuum

You are watching: AP Biology Unit 7: Genetics Cheat Sheet by hlewsey. Info created by GBee English Center selection and synthesis along with other related topics.