Genetics

1. Genetics Populations and Ecosystems Investigation 9

2. Inheritance • Passing on genetic information from one generation to the next is called inheritance.

3. Inheritance • Augustinian monk, Gregor Mendel, was the pioneer of inheritance with his work on pea plants.

4. Mendel’s Observations • There was variation in the color of the flowers of pea plants.

5. Mendel’s Observations • When both parent pea plants had purple flowers, the offspring had purple flowers • When both parent pea plants had white flowers, the offspring had white flowers.

6. Mendel’s Observations • What happened when one parent had purple flowers and one had white flowers? • What color flowers would the offspring have? Purple? White? Pale Lavender? • Make a prediction!

7. Mendel’s conclusions • Mendel found that the flowers were either all purple or all white. There were no pale lavender (purple) flowers.

8. Mendel’s conclusions • Mendel reasoned that the offspring must be inheriting something from each parent that told the pea plan what color

9. Cells role in inheritance • Information describing how to make you resides in the cells. • Inside cells, there are smaller structures called organelles (“little organs”) that perform functions essential to life. • One of the key organelles is the nucleus (a.k.a. “control center” of the cell.)

10. DNA • Inside the nucleus is the inheritance messenger, DNA. • DNA molecules are huge, containing millions of atoms.

11. Chromosomes • In order for them to fit inside the nucleus, they are coiled into structures called chromosomes. • Chromosomes are the structures that carry the message of inheritance.

12. Chromosomes • Chromosomes always come in pairs. • Both chromosomes in a pair have dark areas in exactly the same location called alleles(a version of a gene.) • Different alleles produce variations in inherited characteristics, such as eye color or blood type.

13. Allele

14. Genes • Two alleles on the paired chromosomes work together and constitute a gene.

15. Summarizing notes • Nuclei contain chromosomes. • Chromosomes come in almost identical pairs. • Chromosomes have specific active locations called alleles. • The two alleles in identical locations on paired chromosomes constitute a gene.

16. Gene (continued) • A gene (two alleles working together) controls a trait. • A genes determine eye color, hair color, etc…. • Alleles are the code that determines the traits of an organism.

17. Genotype • The combination of alleles in an organism’s chromosomes is the organism’s genotype. • The genotype lists the paired alleles that are particular to that organism.

18. Dominant and recessive • Most-influential alleles are dominant alleles. • Represented by an uppercase letter. • Less-influential alleles are called recessive alleles. • Represented by a lower case letter.

19. Phenotype • Every organism has its unique genotype, composed of paired alleles on paired chromosomes that produce unique traits in those organisms. • The traits that the genotype produces results in the organism’s phenotype.