Genetic Variation

1. Genetic Variation www.alsa.org

2. Goal • To learn the basic genetic mechanisms that determines the traits expressed by individuals in a population

3. Natural Selection Theory • Variation in a population of organisms • Results of Mutations • Results of Immigration • Result of survival features of individual organisms

4. Natural Selection Theory • Environments are dynamic • Changing resources • Climate (long term weather) • Natural disasters

5. Natural Selection Theory • Selective Pressure • Environmental changes can cause pressure • Organisms unable to adapt quickly enough will die • Organisms that adapt are able to pass on their successful traits to future generations

6. Natural Selection Theory • Isolation • If one portion of a population is separated from another portion then a new species may evolve

7. Natural Selection Theory • Mechanisms for population change • Key to change is variation among the individuals in the population • Individuals are unique due to their genes

8. Genetics

9. Genetics • Nucleic Acids • Huge molecules that hold information • DNA (deoxyribonucleic acid) is the nucleic acid that holds all the genetic information for organisms ghr.nlm.nih.gov

10. DNA • Genetic code of all living things • Complete set of blueprints and operating instructions for assembling and managing one particular kind of organism • Has four basic building blocks • Adenine (A) • Thymine (T) • Guanine (G) • Cytosine (C)

11. DNA • A and T can only bond with each other • G and C can only bond with each other • When four bases bond together in a long chain they form a double helix (ladder) • Typical DNA molecule may be about 5 cm long

12. DNA • DNA found in the nucleus of the cell • DNA is coiled into a compact structure called a chromosome • Every cell in every plant and animal has a completed set of chromosomes that define the organism • Every time the cell divides to produce two daughter cells the complete set of chromosomes is produced

13. Chromosome, Gene, DNA www.phoenix5.org

14. Genes determine traits • Genes: are the units of heredity that is a sequence of bases (A,T,G,C) that give instructions on how to assemble a certain protein • Genes are the sugars, phosphates, and bases along the DNA strand in the chromosome • The proteins go to the cells to make things such as fats, bone, muscle, nerves, and everything else in a living organism

15. Alleles www.monteweston.com

16. Alleles • Each gene has two copies which are called the alleles. • (2 alleles= 1 gene) • Dominant allele the allele that controls what will happen or which trait will be exhibited (Capital Letter) • Recessive allele the allele that is “overruled” and this trait or function will not be seen because of the dominant allele (Lower case letter).

17. Punnett Squares • A technique for predicting the characteristics of offspring • Example of Punnett Square

18. Punnett Square • Always put the dominant allele (G) before the recessive allele (g) so you would write Gg • Results: • One homozygous dominant (GG) • Two heterozygous (Gg) • One homozygous recessive (gg)

19. Discovery of Heredity • Gregor Mendel • Scientist pioneer to work with pea plants to show how a species can exhibit certain characteristics from one generation to the next. • He was the scientist to support the idea of dominant (capital letter) and recessive (lower case letter) traits. history.nih.gov kentsimmons.uwinnipeg.ca

20. Genotype • Genotype • Genotype is the genetic makeup of the organism (genes/letters) • Example: (letters represent trait…color in this case) • Pea flower color B=dominant allele (purple), b=recessive allele (white) • A purple offspring would have either a BB or Bb genotype • A white offspring would only have a bb genotype www.eastbaymom.com

21. Phenotype • Phenotype: how the organisms looks (trait/picture) • Example: purple flower, white flower, tall plant, short plant

22. Inheritance • Inheritance is passing genetic information from one generation to the next • You inherited alleles from your parents