Mendelian Exceptions Chapter 11 Section 3

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

Mendel’s Principles Revisited Organisms typically have ____copies of each gene, (one from each _______) An organism’s _____ of genes (2 alleles) are segregated from each other when ________ are formed. Alleles for different ______ usually segregate _____________ of one another. (through meiosis) (Law of Independent Assortment) independently parent two gametes genes pair

Independent Assortment in Peas __ Round yellow __ Round green __ Wrinkled yellow __ Wrinkled green

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

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

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

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

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

Codominance These cattle or horses actually have both red and white hairs intermixed, or are spotted. Roan is a third ___________. If you cross a roan with a white… W W RW WWRW RW WW phenotype roan 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 have more than _____ alleles controlling them and are therefore said to have multiple alleles. No individual has more than _____ alleles, but there are more than _____ possible alleles in a population, so a ______ will be expressed in more than two forms. two two two trait

Multiple Alleles Blood type in humans is an example of this inheritance pattern. The ______ different blood groups: A, B, O, and AB Are produced by ______ different alleles: A, B, and O four three PhenotypeGenotype AAA or AO BBB or BO ABAB only OOO only

Multiple Alleles Examples of Blood type crosses

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 ________ of genes. 1 pair

Polygenic Traits These are called ___________ traits, which means “having _______ genes”. In humans, _____ color, _____ color, polygenic many skin eye

Polygenic Traits These are called ___________ traits, which means “having _______ genes”. In humans, _____ color, _____ color, and _____ color polygenic many skin eye hair

Polygenic Traits These are called ___________ traits, which means “having _______ genes”. In humans, _____ color, _____ color, and _____ color are just a few of the many traits __________ by many genes. polygenic many skin controlled eye hair