2 from parents to offspring Gregor Mendel“FATHER OF GENETICS”Genetics-scientific study of heredity; how traits are inheritedHereditythe passing of traitsfrom parents to offspring
3 Mendel’s Pea Plant Experiments Why Peas? Pea plants have many traits(tall/short, purple flowers/white flowers)self-fertilized or cross-fertilized
4 Tall x Short = Hybrid True-Breeding Plants: Hybrid Plants: create plants that look like themselvesHybrid Plants:offspring of true-breeding plantsTall x Short = Hybrid
5 Drill: April 2, 2012 What is a gene? An allele? Define and differentiate between a true/pure-breed and a cross-breed/hybrid?Self-pollination vs cross-pollination: Explain each and how did Mendel prevent self-pollination.
6 Tall x Short = all tall offspring (hybrids) Dominance-One trait dominates & “hides” the otherTall x Short = all tall offspring (hybrids)*Tall is the dominant trait* Short is recessive
7 Genes and AllelesMendel discovered that each trait is controlled by two factorsGenes – factors that determine your traitsAlleles-different forms of a gene
12 Let's review what you know about genetics......
13 what the organism looks like (tall or short) GENOTYPE - what genes the organism has (TT, Tt, tt)PHENOTYPE -what the organism looks like (tall or short)
14 Are these offspring the F1 or F2 generation? Check for understanding1. A one-eyed purple people eater is crossed with a two eyed purple people eater. All of their offspring have two eyes. Which trait is dominant?2. If you use the letter E for this gene. What is the genotype of the offspring? Are these offspring the F1 or F2 generation?4. If you crossed the offspring with each other? How many of the new offspring would you expect to have two eyes?
15 6. Who was the father of genetics? _________ More checking5. The passing of traits from parents to offspring is known as _________________6. Who was the father of genetics? _________7. A single gene will code for a ______________, such as flower color.8. Every gene is made of two ______________
16 Drill: Thursday 5, 20111) How did Mendel find out whether the recessive alleles were still present in the F1 plants?2) About one fourth of the F2 plants from Mendel’s F1 crosses showed the trait controlled ______ by the allele.3) The dominant allele is represented by and a recessive allele is represented by .
17 Probability:the likelihood that a particular event will occur is called_______.The probability that a single coin flip will come up heads.a. 100 percentb. 75 percentc. 50 percentd. 25 percent
18 Probability TRUE or FALSE The past outcomes of coin flips greatly affect the outcomes of future coin flipsQ: Why can the principles of probability be used to predict the outcomes of genetic crosses?A: The way in which the alleles segregate is completely random, like a coin flip
19 Show possible genotypes for the F2 offspring. Punnett Square can be used to predict and compare the genetic variations that will result from a cross.Show possible genotypes for the F2 offspring.
20 Practice #1:In seals, the gene for the length of the whiskers has two alleles. The dominant allele (W) codes long whiskers & the recessive allele (w) codes for short whiskers.a) What percentage of offspring would be expected to have short whiskers from the cross of two long-whiskered seals, one that is homozygous dominant and one that is heterozygous?b) If one parent seal is pure long-whiskered and the other is short-whiskered, what percent of offspring would have short whiskers?
22 Practice #2:A green-leafed luboplant (I made this plant up) is crossed with a luboplant with yellow-striped leaves. The cross produces 185 green-leafed luboplants.Summarize the genotypes & phenotypes of the offspring that would be produced by crossing two of the green-leafed luboplants obtained from the initial parent plants.
24 Allele Types Definitions Organisms that have two identical alleles particular trait (TT or tt) HomozygousOrganisms that have two different allelessame trait (Tt) HeterozygousPhysical characteristic of an organism PhenotypeGenetic makeup of an organism (Tt) Genotype
25 Independent Assortment In a 2-factor cross, Mendel followed 2 genes passed from one generation to the nextPhenotype Genotype (true-bred)a. round yellow peas __RRYY_b. wrinkled green peas __rryy_
27 Independent Assortment Circle the letter of the phenotypes that Mendel would expect to see if genes segregated independently.a. round and yellowb. wrinkled and greenc. round and greend. wrinkled and yellow
28 Overall concept:Q: What did Mendel observe in the F2 offspring that showed him that the alleles for seed shape segregate independently of those for seed color?A: He observed F2 offspring that had combinations of phenotypes—and therefore combinations of alleles—not found in either parent.
30 Dihybrid Cross Problem #1: In the breeding season, male Anole lizards court females by bobbing their heads up and down while displaying a colorful throat patch. Assume for this question that both males and females bob their heads and have throat patches. Assume also, that both traits are controlled by single locus genes on separate chromosomes. Now, suppose that anoles prefer to mate with lizards who bob their heads fast (F) and have red throat patches (R) and that these two alleles are dominant to their counterparts, slow bobbing and yellow throats. A male lizard heterozygous for head bobbing and homozygous dominant for the red throat patch mates with a female that is also heterozygous for head bobbing but is homozygous recessive for yellow throat patches
32 What percentage of the offspring will have a) How many of the F1 offspring have the preferred fast bobbing / red throat phenotype (assume 16 young)?b) What percentage of the offspring will lack mates because they have both slow head bobbing and yellow throats?What percentage of the offspring will havetrouble finding mates because because they lackone of the dominant traits?a) 12 b) 0% c) 25%