Mendelian Exceptions Mendels Principles Revisited l l l

Mendelian Exceptions

Mendel’s Principles Revisited l l l Inheritance of biological _______ is determined by characteristics individual units known as genes ______. During sexual reproduction, genes are offspring passed from parents to _____. Two or more forms of the gene for a trait exist, some forms of the single _____ gene may be _____ dominant and others may be recessive.

Incomplete Dominance l l l In incomplete dominance, neither allele is dominant so there is a blending of _____ traits when two different alleles for the ______ same trait occur together. Colors blend together heterozygous (_______ individuals = 3 rd phenotype) red pink white

Incomplete Dominance l RR In Four O’ Clocks, if you cross a red _____ WW (which is always pure) with a white _____ (that is also always pure) , you get a RW (which pink _____ is always hybrid / heterozygous RW RW

Incomplete Dominance l l RR and blue In another flower, if red ____ BB flowers are crossed, they ____ RB flower produce a 3 rd purple ____ What would be the genotype ratio and phenotype ratio if you crossed two purple flowers?

Incomplete Dominance Cross of two purple flowers RB X ____ RB ____ l What are gamete possibilities? R l genotype ratio RR 1 RR : 2 RB : 1 BB R red l phenotype ratio 1 red : 2 purple : 1 blue RB B purple l Can you have a heterozygous red or no hybrid blue flower? ___ l B RB purple BB blue

Codominance l alleles contribute to the Both _______ phenotype of the organism by showing up simultaneously (at the same time) in heterozygous individuals. l In cattle and horses, if you red (RR) cross a pure ____ white (WW), with a pure ______ you get (RW) which roan produces the color _____.

Codominance l l These cattle or horses actually have both red and white hairs intermixed, or are phenotype spotted. Roan is a third ______. If you cross a roan with a white… W W R RW roan W WW white RW roan WW white

Codominance l l Andalusian chickens also show this pattern of inheritance. If you cross a black (BB) chicken With a white (WW) chicken You get black+white speckled (BW) chicken

Multiple Alleles l l l Blood type in humans is an example of this inheritance pattern. Phenotype Genotype four The ______ different blood groups: A AA or AO A, B, O, and AB B BB or BO Are produced three different by ______ AB AB only alleles: O OO only A, B, and O