Presentation on theme: "Question??? If two blue eyed people have kids, what color eyes will their kids have? If two brown eyed people have kids, what color eyes will their kids."— Presentation transcript:
1Question???If two blue eyed people have kids, what color eyes will their kids have?If two brown eyed people have kids, what color eyes will their kids have?Have color sticks!
2Genetics: Episode I A Monk, His Peas, and Genes Ag BiologySutherlin AST
3Genetics What is genetics? What is heredity? What are traits? Branch of biology studying heredityWhat is heredity?Passing of traits from parent to offspringWhat are traits?Physical characteristics
4Genetics Gregor Mendel A monk, 1800’s Austria First to study and determine factors of heredityUsed carefully controlled experiments: only changed one factor at a time
5Genetics Why peas? Produce sexually Male and female parts on same flowerMale parts are called?Female parts are called?
6GeneticsPollination – male sex cells (pollen) lands on female parts (pistil)Fertilization – DNA from pollen combines with DNA from ovum (egg)Becomes seed
7GeneticsSelf-pollination: male and female sex cells come from same plantCross-pollination: sex cells come from two different plantsCreate hybrid
8Genetics What did Mendel do? Studied TALL traits and SHORT traits in plants (parents = P1)Cross-pollinated these plants to get hybridsALL of the offspring (F1) were TALL
12Genetics What did Mendel do next? ¾ of plants were tall ¼ were short plantsThis is called a 3:1 ratio
13Genetics So what does this mean? Unit Factors Mendel concluded two factors control each traitWe know these are genesOne factor from the motherOne from the father
14Genetics Unit Factors For each gene, there are alleles Different forms of each geneExample: there is a gene for height (T)It could be the Tall allele – TIt could be the Short allele - t
15GeneticsUnit FactorsSince we have two copies of each gene, three combinationsTwo Tall (TT) allelesTwo Short (tt) allelesOne Tall allele and oneshort allele (Tt)But how is this possible?
16What else does this mean? GeneticsWhat else does this mean?Rule of DominanceOnly one allele is observableDominant alleles: observable traitRecessive alleles: unobservable traitSo which is dominant for height in pea plants?
18Genetics What about cows? If you cross purebred black angus cattle with red angus cattle, you get black cattleWhat does this mean?
19Question:You are growing peas. Use the chart of dominant and recessive genes.You are crossing axial (AA) and terminal (aa) bud plants. What would the F1 generation be?Would terminal or axial be more beneficial for the plant?
21Genetics Two organisms can look the same, but carrying different genes Phenotype: how an organism looks (think physical)Tall? Short?Genotype: the genes an organism hasTall: could be TtTall: could be TT
22Genetics Homozygous – both alleles are the same TT, ttHeterozygous – alleles are differentTtAll of this, by a monk, in the 1800s!
23Genetics Dihybrid cross Looking at just one trait (height) is monohybrid (one)But what if we track more than one trait?
24Round Yellow X Wrinkled Green GeneticsMendel’s Dihybrid CrossRound peas (R=round, r=wrinkled)Seed color (Y=yellow, y=green)Parents (P1)Round Yellow X Wrinkled Green
25Genetics Mendel’s Dihybrid Cross Parents (P1) Round Yellow X Wrinkled GreenRRYY rryyResult? Offspring (F1) ALL Round YellowsRrYy
26GeneticsMendel’s Dihybrid CrossF1 CrossXSo now what do you get?