Transcript PPT File
Mendelian Exceptions Mendel’s Principles Revisited 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. Mendel’s Principles Revisited Organisms typically have ____copies of two each gene, (one from each _______) parent An organism’s _____ pair of genes (2 alleles) are segregated from each other when gametes are formed. ________ genes usually Alleles for different ______ independently of one segregate _____________ another. (through meiosis) (Law of Independent Assortment) Independent Assortment in Peas 9 Round yellow __ __ 3 Round green 3 Wrinkled yellow __ __ 1 Wrinkled green Incomplete Dominance 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 = 3rd phenotype) red pink white Incomplete Dominance 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 RW RW Incomplete Dominance RR and blue In another flower, if red ____ BB flowers are crossed, they ____ RB flower produce a 3rd 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 ____ What are gamete possibilities? R genotype ratio RR 1RR : 2RB : 1BB R red phenotype ratio 1red : 2 purple : 1 blue RB B purple Can you have a heterozygous red or no hybrid blue flower? ___ B RB purple BB blue Codominance alleles contribute to the Both _______ phenotype of the organism by showing up simultaneously (at the same time) in heterozygous individuals. In cattle and horses, if you red (RR) cross a pure ____ with a pure ______ white (WW), you get (RW) which roan produces the color _____. Codominance 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… R W W RW roan WW white W RW roan WW white Codominance 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 In this pattern of inheritance, the genes two alleles controlling have more than _____ them and are therefore said to have multiple alleles. No individual has more two alleles, but there are more than _____ two possible alleles in a than _____ trait will be expressed population, so a ______ in more than two forms. Multiple Alleles Blood type in humans is an example of this inheritance pattern. Phenotype Genotype four The ______ different blood groups: A I I or I i A, B, O, and AB B I I or I i Are produced three different by ______ AB I I only alleles: O i i only A, B, and O AA AO B B B O AB O O Multiple Alleles Examples of Blood type crosses Multiple Alleles Blood Groups Phenotype (Blood Type Genotype Antigen on Red Blood Cell Safe Transfusions To From Multiple Alleles rabbit hair color, which The example of _______ has at least four different alleles, is seen in these different Rex rabbits. Polygenic Traits Traits controlled by two or more genes Show a wide range of phenotypes The phenotype is produced by the interaction of more than 1 pair ________ of genes. Polygenic Traits polygenic traits, These are called ___________ many genes”. which means “having _______ eye color, In humans, _____ skin color, _____ Polygenic Traits polygenic traits, These are called ___________ many genes”. which means “having _______ eye color, In humans, _____ skin color, _____ hair color and _____ Polygenic Traits polygenic traits, These are called ___________ many genes”. which means “having _______ eye color, In humans, _____ skin color, _____ hair color and _____ are just a few of the many traits controlled by __________ many genes. James Bond Height Chart Polygenic Traits Sometimes the combination of the different genes results in continuous __________ variation of these traits. The combined size of all the ______ body parts from head to foot, determines the _______ height of the person.