Ch. 23- Patterns of Gene Inheritance

1. Ch. 23- Patterns of Gene Inheritance Chl 23.1- Intro to Genetics: Mendel’s Laws

2. Target #1- I can define the term geneticsTarget #2- I can describe heredity • Genetics: the study of biological inheritance patterns and variation in organisms • Heredity: the transmission of characteristics from parents to offspring • A heritable feature is known as a characteristic • Each characteristic occurs twice in an organism • Ex: color or height

3. Traits: a genetically determined variation of a characteristic • Ex: skin color and eye color • Inherited from a parent passed from one generation to the next Target #3- I can describe a trait

4. Target #4- I can describe the scientific contributions of Gregor Mendel • Gregor Mendel • Austrian monk & statistician • Developed laws of heredity after doing crosses between garden pea plants • Used statistics to analyze how characteristics were passed from generation to generation • Concluded that plants transmitted distinct factors, called genes to offspring • Preferred to investigate genetics at the organismal level

5. Target #5- I can describe the two methods of pollination of plants • Mendel used pea plants because of the ease of control over pollination • Pollination: the when pollen grains on one plant are transferred to the ovary of another plant • In nature plants can self-pollinate or cross pollinate • Self-pollination occurs when pollen is transferred from the anthers to the stigma of the same flower • Cross pollination: occurs between flowers of two plants

6. Mendel began his experiments with varieties that were pure bred, or true bred • Means that when the plants self-pollinate, all the offspring are of the same variety • Referred to as the P generation • Chose to study traits that were “either-or” traits • Shape either wrinkled or smooth • Color either white or purple • The pure-bred plants were then cross pollinated • Their offspring are referred to as the F1 generation • The F1 generation was allowed to self-pollinate • Their offspring are referred to as the F2 generation Target #6- I can explain the methodology involved with Mendel’s pea plant experiment

8. Checking for Understanding What was the point of Mendel’s experiments with the pea plant?

9. Target #7- I can explain Mendel’s two laws • Conclusions • Traits are inherited as discrete units, which we now call genes • Law of Segregation: • Organisms inherit two copies of each gene, one from each parent • Organisms donate only one copy of each gene in their gametes • Law of Independent Assortment • Traits are produced by dominant factors that may or may not appear together • Traits separate independently of one another during the formation of gametes

10. Genetics Terms

11. Target #8- I can define gene • Gene: a piece of DNA that provides a set of instruction to a cell to make a certain protein • Each gene has a locus (location) on a chromosome

12. Target #9- I can define allele • Allele: any of the alternative forms of a gene that may occur at a specific locus • Cells have two alleles for each gene

13. Target #10- I can differentiate between homozygous & heterozygous • Homozygous: two of the same allele at a specific locus • Ex: If B = tall in size, then a homozygous allele is BB • Heterozygous: two different alleles at a specific locus • Ex: if B = tall b= short, then a heterozygous allele is Bb

14. Checking for understanding • PP • Gg • tt • QQ • Ww • Homozygous or heterozygous?

15. Target #11- I can define genome • Genome: all of an organism’s genetic material • Determines all traits of an individual

16. Target #12- I can differentiate between genotype & phenotype • Genotype: the genetic make-up of a set of genes • Trait not seen outwardly • Phenotype: the physical characteristics displayed by the genes • What is expressed physically

17. Target #13- I can differentiate between dominant and recessive alleles • Dominant: an allele that is expressed when two different alleles or two dominant alleles are present • Ex: if B = tall and b = short, an organism with Bb or BB will be tall because the capital letter represents the dominant trait • Recessive: an allele that is only expressed when two copies are present • Ex: if B = tall and b= short, an organism will only be short with a bb because the lower case letters represent the recessive trait

18. Checking for Understanding • Dominant or recessive? • Q • H • n • y • A

19. Checking for understanding- combining concepts • Lets use the letter A for practice • Homozygous dominant • Homozygous recessive • Heterozygous