GENETICS

Gregor Mendel considered the father of genetics Studied Pea Plants to learn about the transmission of traits from parents to offspring Trait = Genetically determined characteristic Characteristic = a heritable feature ( fur/hair color, eye color, height ect..)

Mendelian Genetics Mendel started with plants that were True-Bred (when self pollinate)  True-bred =all offspring of same variety Hybridization – Cross-Pollinated  ( crossing of 2 different true-breds) P generation (parents) F1 generation (first filial generation)

Leading to the Law of Segregation Alleles: Alternative versions of genes that account for variations in inherited characteristics  For each character, an organism inherits 2 alleles, one from each parent  Dominant – the allele that is fully expressed when carried by only one of a pair of homologous chromosomes ( designated by a capital letter P)  Recessive- an allele that is expressed only when two recessive alleles for the same characteristic are inherited Designated by a lower case p The alleles for each character segregate (separate) during gamete production (meiosis).

Genetic vocabulary……. Punnett square: predicts the results of a genetic cross between individuals of known genotype Homozygous: pair of identical alleles for a character Heterozygous: two different alleles for a gene Phenotype: an organism’s traits, what is physically shown Genotype: an organism’s genetic makeup Testcross: breeding of a recessive homozygote X dominate phenotype (but unknown genotype)

Codominance-both alleles for a gene are expressed in a heterozygous offspring; neither allele is dominant or recessive and there is no blending;  Ex. Blood Types Monohybrid cross-a genetic cross in which only one characteristic is tracked  Ex; Fur Color in guinea pigs Di hybrid cross- a genetic cross in which two different characteristics are tracked  Ex. Fur color and length of fur in guinea pigs

Probability is the likelihood that a particular event will occur It can be written as a: Fraction 1/4 Percent 25% Ratio 1:3

If we flip a coin we have a two outcomes  Heads or tails We can express this as  50%  ½  1:1 Alleles segregate randomly just like a coin flip... So can use probability to predict outcomes of genetic crosses.

Used to predict the probability of offspring. Show how both parents’ alleles might combine in their offspring. Punnett Squares

Start by drawing your punnett square. Place the genotype of the parents alleles above and beside the box Fill in the box by carrying the letters down and across B b B B rabbit heterozygous for Black fur (dominant B) Bb Rabbit homozygous for Black fur - BB

Did you get it? B b B B BB Bb Now Practice with Bikini Bottom Genetics Page One!

Agenda Go over Genetic Cross Worksheet Introduce:Incomplete Dominance and Dihybrid Crosses Complete Genetic Cross Worksheet #2 and go over Notes: Dihybrid Cross Worksheet How is the phenotypic outcome in a incomplete dominance cross different than a dominant cross? What process must you complete to determine what gametes a parent will produce in a dihybrid genetic cross?

Dihybrid-Two Factor Crosses A dihybrid cross involves two alleles per trait for two traits, for a total of four alleles. Due to independent assortment an allele for a particular trait has an equal chance of being in the gamete.  For example, a guinea pig's alleles for a dihybrid cross are BbSs.  Using foiling the possible allele combinations in the guinea pig's gametes are: BS, Bs, bS, bs,

P- parent F 1 - first generation F 2 -second generation

Incomplete dominance-phenotype of a heterozygote is intermediate between the phenotypes determined by the dominant and recessive traits – Ex. Red flowers crossed with white flowers produce pink flowers Red – AA White – aa Pink - Aa

Review How is the phenotypic outcome in a incomplete dominance cross different than a dominant cross? What process must you complete to determine what gametes a parent will produce in a dihybrid genetic cross? Complete Dihybrid Cross Worksheet

Agenda Notes: Sex-linked crosses Guided Practice Worksheet Genetic Disorder Project Why are more sex linked traits expressed in males? What is a woman called if she carries a sex-linked trait on only one of her chromosomes?

Sex-linked Traits X and Y chromosomes not only carry the genes that determine male and female traits but also those for some other characteristics as well. Genes that are carried by either sex chromosome are said to be sex linked.

XBXXBXXBYXBY XXXY XBXXBX Baldness is a sex-linked trait carried on the x chromosome Expressed more often in males because they only have one x chromosome Females with the gene present on one chromosome called “carriers” for the trait.

Review Why are more sex linked traits expressed in males? What is a woman called if she carries a sex- linked trait on only one of her chromosomes? Complete Sex-linked Cross Worksheet and hand in Work on Genetic Disorder Research Project

Agenda Notes: Multiple Alleles or Codominance

Multiple Alleles or Codominance Two alleles in a gene pair are each as sociated with different substances. When both substances appear together in heterozygotes, codominance occurs. The two alleles of a pair at a specific locus are not identical but the expression of both is observed.

An example is blood types Cross a heterozygous B with an heterozygous A IAIBIAIB IAiIAi IBiIBiii I B i IAiIAi

Agenda Genetics Quiz Notes: Pedigrees Worksheet: Pedigree Problems & Family Tree Project Sheets What are two ways we may use the information provided on a pedigree?

A pedigree chart is a diagram of family relationships that include two or more generations.

Example of Pedigree Charts The Shaded means that person has that trait

Interpreting a Pedigree Chart 2. Determine whether the trait is dominant or recessive. (remember: the dominant traits shows if there is one or two, the recessive shows only if there are two)  If the trait is dominant, one of the parents must have the trait.  If the trait is recessive, neither parent has to have the trait because they can be heterozygous.

Circle= female Square=male  Solid or colored in= express the trait  Dot or line inside= carrier of trait

eeEE Ee ee Ee ee

Below is a pedigree for an inherited lung disease, which is recessive. Provide the genotypes of each of the individuals marked with lower case letters. aaAA Aa aaAa aa Aa Aa, AA aa Lung cancer is a recessive disease. what are the genotypes of a, b, c, d.

Pedigrees can be drawn up to trace any trait through a family tree. They are used to trace genetic traits through several generations and determine the probability that a trait will be passed from one set of parents to their parents. The applications of Mendel’s Laws provide opportunities for treatment and prevention of genetic disorders.

Review What are two ways we may use the information provided on a pedigree? Worksheet: Pedigree Problems & Family Tree Project Sheets