Mendelian Exceptions Chapter 11 Section 3 Mendels Principles

Mendelian Exceptions Chapter 11 Section 3

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.

Mendel’s Principles Revisited l l 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 another. segregate _______ (through meiosis) (Law of Independent Assortment)

Independent Assortment in Peas 9 Round yellow __ __ 3 Round green 3 Wrinkled yellow __ __ 1 Wrinkled green

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 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 population, so trait a ______ will be expressed in more than two forms.

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

Multiple Alleles l Examples of Blood type crosses

Multiple Alleles l Blood Groups Phenotype (Blood Type Genotype Antigen on Red Blood Cell Safe Transfusions To From

Multiple Alleles l rabbit hair color, which The example of _______ has at least four different alleles, (on text pg 273) is seen in these different Rex rabbits.

Polygenic Traits l l l 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 l l l polygenic traits, which These are called ______ means “having _______many genes”. eye color, In humans, _____ skin color, _____

Polygenic Traits l l polygenic traits, which These are called ______ means “having _______many genes”. eye color, In humans, _____ skin color, _____ hair color and _____

Polygenic Traits l l l polygenic traits, which These are called ______ means “having _______many genes”. 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 l l 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.