Bio Ch 11 Flashcards
Monohybrid cross
cross of a single trait with organisms that are hybrid; expected phenotypic results are 3:1
Law of Segregation
(1) Each individual has 2 factors for each trait (2) The factors segregate/separate during the formation of the gametes (3) Each gamete contains only one factor from each pair of factors (4) Fertilization gives each new individual two factors for each trait
Locus
physical location of a trait (or gene) on a chromosome
Alleles
alternative versions of a gene
Dominant allele
DNA sequence that comprises the gene makes a fully functional protein
Recessive allele
contains a slightly different DNA sequence and produces a protein with little or no function
Homozygous
when an organism has 2 identical alleles (TT or tt)
Heterozygous
when an organism has 2 different alleles at a gene locus (Tt)
Genotype
refers to the alleles an individual receives at fertilization
Phenotype
refers to the physical appearance of the individual, which is made from the proteins produced by the corresponding alleles
Dihybrid cross
cross between parents that differ in 2 traits; expected phenotypic ratio is always 9:3:3:1
Law of Independent Assortment
Each pair of factors segregates/assorts independently of the other pairs; all possible combinations of factors can occur in the gametes
Punnett square
diagram that allows for calculation of the chances/probability of genotypes and phenotypes among the offspring
Testcross
cross between an individual with a dominant phenotype and an individual with a recessive phenotype to determine whether the dominant individual is homozygous or heterozygous
Autosome
any chromosome other than a sex (X or Y) chromosome
Carriers
when the parent does not express the trait but is capable of having a child with the genetic disorder
Family pedigrees
chart of genetic relationship of family individuals across generations
Family pedigrees
chart of genetic relationship of family individuals across generations
Multiple alleles
gene exists within several allelic forms within a population
Incomplete dominance
exhibited when the heterozygote has an intermediate phenotype between that of either homozygote
Incomplete penetrance
dominant allele does not always determine the phenotype of the individual
Pleiotropy
occurs when a single mutant gene affects 2 or more distinct and seemingly unrelated traits
Polygenic inheritance
occurs when a trait is governed by two or more sets of alleles (ex. human height and prevalence of diabetes)
Polygenic traits
controlled by many genes and may be influenced by environmental factors
X-linked
used for genes that have nothing to do with gender, and yet they are carried on the X chromosome
Hemizygous
possessing only one allele for a gene in a diploid organism; males are this for genes on the X chromosome
