Heredity, Genetics and DNA

1. Heredity, Genetics and DNA Are my favorite things

2. The science of biological inheritance Genetics

3. Genetics Vocabulary • Genetics is the study of heredity, a study of how certain characteristics are passed on from parents to children. • A monk, Gregor Mendel, discovered the basic principles of heredity in the 19th century. A HISTORY OF GENETICS Part 1 Part 2 Part 3

4. A segment of a chromosome that produces a particular trait. Gene

5. A pair of hereditary factors that make up a gene (different forms of a gene) Alleles

6. A hereditary factor that “takes over” the gene determining the trait Dominant Allele

7. A hereditary factor that is hidden by a dominant allele Recessive Allele

8. Two identical alleles for a particular trait. TT Homozygous

9. Two different alleles for a particular trait. Tt Heterozygous

10. The genetic makeup of an organism due to the genes present Genotype

11. A particular physical appearance produced by genes Phenotype

12. Male and female sex cells gametes

13. A fertilized seed Zygote

14. Genes • Each trait – an expressed characteristic is produced by a pair of hereditary factors collectively know as GENES. Within a chromosome, there are many genes, each of which controls the inheritance of a particular trait. • A GENE is a segment of a chromosome that produces a particular trait. For example, in pea plants, there’s a gene on the chromosome that holds the code for seed coat color.

15. Alleles • A gene usually consists of a pair of hereditary factors called alleles. Each organism carries two alleles for a particular trait, one from the mother and one from the father. Another way to say this is that two alleles make up a gene, which in turn produces a particular trait.

16. Alleles • Dominant and RECESSIVE ALLELES: an allele can be DOMINANT or RECESSIVE. • A Dominant allele – takes over. Written with a CAPITOL letter. T • A Recessive allele – hidden by the dominant. Written with a LOWERCASE letter. t

17. Phenotype and Genotype • When discussing the physical appearance of an organism we refer to its phenotype. • When talking about the genetic makeup of an organism we refer to its genotype. The genotype tells us which alleles the organism possesses.

18. HOMOZYGOUS and HETEROZYGOUS • When an organism has two identical alleles for a given trait, we say the organism is HOMOZYGOUS. For instance TT and tt would both represent the genotypes of homozygous organisms, one homozygous dominant, and one homozygous recessive. • If an organism has two different alleles for a given trai, say Tt, that organism is heterozygous.

19. PARENT and FILLIAL GENERATIONS • The first generation is always called the parent or P1 GENERATION. • The offspring of the P1 generation are called the first fillial or F1 generation. • The offspring of the F1 generation are called the F2 generation.

20. Mendel’s Law of Heredity • Law of Segregation – states that the members of each pair of alleles separate when gametes are formed. A gamete will receive one allele or the other. • Law of Independent Assortment – states that two or more pairs of alleles segregate independently of one another during gamete formation.

21. The display of all the chromosomes in a cell’s nucleus Karyotype