Bio ch 10 Patterns of inheritance

gene

segment of DNA that carries the instructions for synthesizing a protein

chromosome

piece of DNA containing many different genes

locus

a genes location on a chromosome

chromosomes are paired in

diploid cells

each chromosome is a member of a

homologous pair

genotype

refers to the 2 alleles an individual has for a specific trait, if identical genotype is homozygous, if different genotype is heterozygous 

phenotype

refers to physical appearance

genotype can be

homozygous dominant, homozygous recessive, or heterozygous 

P generation 

parental

F₁ generation

first filial

F₂ generation

offspring of F₁

Gregor Mendel

used pea plants to study heredity, uncovered basic laws of inheritance

true breeding 

self-fertilization yields offspring with same seed color as parent plant; produce identical offspring 

Hybrid 

self-fertilization yields mix of seed colors; outwardly resemble true breeders but offspring is mixed  

dominant alleles 

exert their effects whenever they are present 

recessive alleles 

effect is masked if dominant allele is present

homozygous dominant

have 2 dominant alleles for a gene

heterozygous

1 dominant, 1 recessive allele

homozygous recessive

2 recessive alleles

punnet squares represent

gamete formation and fertilization; shows how the alleles divide during meiosis 

monohybrid cross

single phenotype trait

test cross

determines the genotype of an individual having the dominant phenotype by crossing it with a known homozygous recessive individual 

dihybrid cross

tracks the inheritance of 2 genes at once

the product rule

multiplies multiple individual probabilities together

genes close together on the same chromosome are 

linked 

when genes are linked they are physically near each other so 

they do not sort independently 

alternative patterns of inheritance 

incomplete dominance, codominance, pleiotropy

incomplete dominance

heterozygote has an intermediate phenotype; alleles don’t mask each other creating a blended phenotype

codominance 

both alleles are dominant and will be expressed; more than one allele encodes a functional protein ex.AB blood

pleiotropy 

one gene has multiple effects on the phenotype 

polygenic inheritance

traits depend on more than one gene ex. skin color

Egg always carries an

X

sex chromosome in what determines the offspring sex

sperm

males only have 1 allele for genes on the

x chromosome

females have 2 alleles for genes

interaction between the 2 determines phenotype

pedigree

depicts family relationships and phenotypes; shows modes of inheritance 

autosomal disorders can be

dominant or recessive