Genetics Quiz 2 Flashcards
Trait
are characteristics that are inherited from parents to offspring through reproduction
Alleles
Alternative form or version of the gene
(example blue vs green eyes)
Gregor Mendel
developed the fundamental principles of genetics & heredity
Monohybrid Cross
a cross between two individuals in which only one (1) trait is involved
parent/ P generation
the original pair of parents at the start of a genetic cross experiment. The first generation that is produced by the p generation is called the F1 generation.
dominant traits
are always expressed or appear in an individual if present
recessive traits
not usually expressed, they are either present but inactive or only active if they are the ONLY trait present
principle of dominance
when dominant and recessive traits are crossed only the dominant trait will be expressed
how are dominant traits represented
capital letters
how are recessive traits expressed
lowercase letters
law of segregation
inherited traits are determined by pairs of “factors”(genes), which separate in the gametes, each offspring receives only one (1) from each parent.
F2 second generation (ratios)
75% of the time dominant trait is expressed
25%of the time the recessive trait is expressed
3:1 ratio produced
purebred dominant
Homozygous dominant
purebred recessive
Homozygous recessive
mix of recessive and dominant genes
Heterozygous
genotype
the genetic makeup of an organism
(hetero/homozygous)
phenotype
the physical appearance of an organism
(blonde vs brown) (blue vs green) (tall vs short)
genotype ratio
1:2:1
25% homozygous dominant
50% heterozygous
25% homozygous recessive
phenotype ratio
3:1
75% dominant
25% recessive
(used when describing specific trait)(blue vs green eyes)
Test cross
if you only know one phenotype
always done using the unknown individual (genotype) and a homozygous recessive individual
Dihybrid Cross
a cross between two individuals focusing on two specific traits. (tracking 2 traits at the same time)
Dihybrid cross ratio
9:3:3:1 phenotypic ratio
Dihybrid Cross (therefore)
for ANY dihybrid cross between 2 individuals that are HETEROZYGOUS for 2 traits the result will ALWAYS be a phenotype ratio of 9:3:3:1!!!!!
law of independent assortment
the inheritance of alleles for one trait does not affect the inheritance of alleles for another trait.
Chromosome theory of Inheritance
traits determined by genes are inherited through the movement of chromosomes during meiosis (division of sex cells)
