Chapter 12 (Genetics) Flashcards
dominant
when an allele overrules the other allele
genotype
the genetic constitution of an individual organism
phenotype
a set of observable characteristics/traits of an organism
homozygous
having 2 identical alleles of a particular gene
heterozygous
having 2 different versions of the same gene
recessive
a trait expressed only when homozygous, tt
gene
basic unit of heredity passed from parent to child
allele
variants of genes, providing diversity. determines things like eye color, risk to certain diseases.
hybrid
When alleles combined, heterozygous. Ex: SsYy, Pp
true breeding
A true breeding is a kind of breeding wherein the parents would produce offspring that would carry the same phenotype. Homozygous. Ex: SSYY, PP, pp
Punnett square
used to predict phenotypes/genotypes of 2 organisms’s offspring
sex chromosome
A sex chromosome is a type of chromosome involved in sex determination. E.g. X & Y
autosomes
A chromosome that isn’t a sex chromosome. We have 22 autosomes.
locus
location of specific gene on a chromosome
monohybrid cross
cross between 2 homozygous organisms (XX + xx = Xx)
dihybrid cross
4x4 Punnett, used for two traits e.g. XxYy x XXyy. remember 9:3:3:1
Incomplete dominance
Both alleles of a gene are partially expressed, resulting middle. Ex. RR(Red) x rr(White) = Rr(Pink)
Co-dominance
When two alleles of the same gene are dominant & expressed separately. Ex. BB(Black) x WW(White) = BW (Black & White)
Law of segregation
During formation of gamete, gene separates from each other: each gamete has one allele for each gene
Sex linkage
characteristics/traits influenced by genes carried on sex chromosomes.
Law of Independent Assortment
alleles of two/more different genes sorted to gametes independently of another: one gene doesn’t influence other
