2 Mendel and Heredity Terms Gregor Mendel- “Father of Genetics”Traits- characteristics that areinheritedEx. Eye color, hair colorGenetics- study of biological inheritance patternsPurebred- offspring inherit allof parents characteristics,genetically uniform
3 Mendel and Heredity Terms Cross- mating of two organismsGene- piece of DNA that provides a set of instruction to a cellAllele- any alternative formof a gene that may occur
4 Mendel and Heredity Terms Homozygous- two of the same allelesHeterozygous- two different alleles
5 Mendel and Heredity Terms Genotype- genetic makeup of a specific set of genesPhenotype- physical characteristics or appearance of an organismDominant- allele is expressed when two different alleles are presentRecessive- allele is expressed only when two copies are present
6 GeneticsIn the 1800’s, Gregor Mendel laid the groundwork for modern geneticsHe crossed many pea plants and observed traits of offspringDiscovered thatOrganisms inherit two copies of each gene, one from each parent
8 Genetics Another example: Brown (dominant) vs. black (recessive) Genotypes? Phenotypes?
9 Genetics Mendel’s discoveries led to the Punnett square Developed by R.C. PunnettUsed to predict genotypes of offspringExample:Straight (dom.) vs. curly (rec.)Dad-heterozygousMom-homozygous recessive
10 Dihybrid Punnett Square Predicting more than one traitEX. Cross a tall pea plant with green leaves with a short pea plant with yellow leaves.Determine parent genotypes.Find combinations of alleles.Fill out Punnett square.Determine phenotypes of offspring.
11 Dihybrid Punnett Square EX. Cross a tall (homozygous) pea plant with green (heterozygous) leaves with a short pea plant with yellow leaves. (Tall is dominant to short, green is dominant to yellow)
12 Dihybrid Practice Cross the parents SsYy x SsYy SY Sy sY sy SY Sy sY Smooth/Yellow __9____Smooth/Green ___3___Rough/Yellow ____3__Rough/Green _____1_
13 Bellringer: Complete both questions in your notebook 1. In one particular species of cats, long hair is dominant to short hair. If a heterozygous male is crossed with a homozygous recessive female, what is the probability that one of the offspring has long hair?2. A homozygous dominant flower is crossed with a homozygous recessive flower. Purple flowers are dominant to red flowers. What are the genotypes and phenotypes of the offspring?
14 XX XY Sex-linked Genes X Y X X Sex-linked genes- genes located on the sex chromosomesFemale (XX), Male (XY)XYXXXYXX
15 Incomplete DominanceAlleles that show incomplete dominance show both the dominant and recessive traitsNeither allele is completely dominant or recessiveEx. If a homozygous redflower and homozygous whiteflower cross, the offspringhave pink flowers
16 Codominance Both the dominant and recessive alleles are expressed Ex. Red and white flower are crossed, the offspring will be red and white
17 Exit Slip Sex linked genes are located ______________. 2. A dog that shows the phenotypes of both his mother and father would be an example of (incomplete or codominance).3. A blue flower crosses with a yellow flower to produce a green flower. This is an example of (incomplete or codominance).
18 PedigreePedigree- chart that can help trace phenotypes and genotypes in a familyHelps to determine if people carry the recessive allele