When Mendel crossed 2 plants that were different in a single trait, he called that a monohybrid cross. The resulting offspring were called the F1

Transcription

1 Genetics

2 Gregor Mendel The father of Genetics Genetics- the study of heredity Heredity- the passing of characteristics or traits from parents to offspring Mendel chose pea plants to research. Pea plants have male and female plants, so each have sex cells or gametes. male = pollen female = egg (in the pistil) Pollination- transfer of pollen to the pistil Fertilization- the uniting of male and female gametes

3 Mendel s Peas

4 When Mendel crossed 2 plants that were different in a single trait, he called that a monohybrid cross. The resulting offspring were called the F1 generation or the first generation. (F stands for filial which means son/daughter) The F1 generation plants were bred to give the F2 generation or the second generation. (the grandkids of the original plants)

5 Alleles Mendel realized that genes controlled traits. Alleles- different forms of the same gene Each organism has 2 alleles for each trait (1 from mom and one from dad) on separate chromosomes

6 Genotype & Phenotype Some alleles are dominant over others; they are the ones that show themselves Dominant = observed trait code (capital letters) Recessive = hidden trait code (lowercase letters) The two allele codes (1 from each parent) make up the organisms genotype. (Bb) Homozygous- the organism has 2 alleles that are the same for a trait; two capital letters or two lowercase letters Ex: TT or tt Heterozygous- the organism has 2 alleles that are different; 1 capital letter and 1 lowercase letter Ex: Tt

7 Concept Check Below each of the following words are choices. Write the choices that are examples of those words. 1. Dominant Gene D e k L N o R S t U 2. Recessive Gene M n d F G I k P l w 3. Pure Dominant AA Gg KK ll pp Rr TT UU Bb SS 4. Pure Recessive ee Ff HH Oo qq Uu ww Bb SS ss

8 Concept Check Below each of the following words are choices. Write the choices that are examples of those words. 5. Offspring combinations where the dominant gene must show AA dd EE ff Jj RR Ss Tt ll Uu 6. Offspring combinations where the recessive gene must show Aa gg Ff KK Oo pp ss Tt tt Mm

9 Genotype & Phenotype The phenotype of the organism is its behavior and physical looks. (brown hair)

10 Law of Segregation Law of Segregation- alleles from the organism separate to produce 2 types of gametes. Ex: An organism with a Bb genotype can produce a gamete carrying the B allele or a gamete carrying the b allele.

11 Law of Independent Assortment Law of Independent Assortmentgenes for different traits are inherited independently of each other. Ex: just because you have brown hair you don t have to be short

12 Concept Check Fill in the blank with the correct missing word. 1. Chromosomes have parts which determine traits. These parts are. 2. A person having two genes which are alike is said to be. 3. The father of genetics is. 4. A gene which prevents other genes from showing is said to be. 5. A gene which is not expressed even though it is there is said to be.

13 Punnett Squares Punnett Squares- used to predict possible genotypes and phenotypes of the offspring. Monohybrid cross- one trait is crossed Ex: Tt x TT Dihybrid cross- 2 traits are crossed Ex: RrYy x RrYy

14 Punnett Squares Probability of a particular genotype or phenotype is determined with punnett squares.

15 Punnett Squares

16 Punnett Squares Cross a pea plant heterozygous yellow seeds with a green homozygous recessive pea plant. Yellow seeds are dominant to green.

17 Punnett Squares Cross a pea plant homozygous dominant for purple flowers with a pea plant that is homozygous recessive for white flowers.