1. Chapter 15: Biological Diversity and Heredity Foundations Ms. Johnson

2. Objectives Living things have developed special characteristics called adaptations, which enable an organism to live in a particular environment or habitat. Reproduction is the process by which an organism produces new individuals of its own kind. Asexual reproduction involves only one parent and produces offspring identical to the parent. Sexual reproduction involves two parents, male and female, and produces offspring not identical to either parent. All cells come from other cells through the process of cell division. Genetic information is passed from one generation to the next through chromosomes during reproduction. When two genes match for a trait, an individual is called pure for that trait. When two genes differ for a trait, the individual is called hybrid for that trait. In a hybrid, often only one trait is visible; this is called dominant trait. The trait that is not exhibited in a hybrid is called a recessive trait. A change in a gene is called a mutation.

3. Vocabulary Adaptations Habitat Reproduction ▫Sexual ▫Asexual Fertilization Cell division Gene

4. Diversity of Life Different environments have promoted different changes in living things. Living things have adaptations that enable them to survive under a given set of conditions. ▫Adapted for life in water, land, soil, air, etc.

5. Diversity of Life Adaptations permit an organism to live in its own particular environment (habitat). Example: ▫Cactus plant has an extensive root system that helps it reach what little water there is in the desert.

6. Diversity of Life OrganismHabitatAdaptationFunction Arctic HareArcticWhite fur in winter Provides camouflage from predators MonkeyRain forestGrasping tailActs as an extra hand to help movement through trees CactusDesertWaxy skinReduces water loss from evaporation There are millions of different types of plants and animals. Scientists classify organisms in various ways to better understand their similarities and differences.

7. Reproduction All living things come from other living things. Reproduction: the process by which an organism produces offspring (new individuals of its own kind) Each particular organism is called a species. There are two types of sexual reproduction: asexual and sexual.

8. Reproduction Asexual reproduction: involves only one parent ▫The offspring created are identical to the parent. Sexual reproduction: involves two parents and ▫Produces offspring that are not identical to either parent. ▫Female parent produces an egg cell and the male produces the sperm cell. The joining together of egg and sperm is called fertilization.

9. Life Cycles Some young animals look like smaller version of their parents. ▫Ex. Puppies, baby elephants, tigers Some animals, however, change dramatically during their life that the young look nothing like the adults. ▫Ex. Frogs, Insects Life cycle: the changes that an organism undergoes as it develops and produces offspring.

10. Life Cycles Eventually the young will look like the adult. Information is carried from the parent to the offspring determining how they will look. This information gets passed on from generation to generation.

11. Cellular Reproduction All cells come from other cells through the process of cell division. ▫One “parent” cell divides into two new “daughter” cells The parent cell passes genetic information on to the daughter cells in the form of chromosomes. ▫Chromosomes are thread-like structures that contain DNA Chromosomes also give the cell (or organism) its individual characteristics called traits.

12. Cellular Reproduction One-celled organisms reproduce through a kind of cell division called mitosis. In this process a cell divides into two identical daughter cells each with the same number of chromosomes as the parent. Multi-cell organisms duplicate themselves to build new tissues and repair damage tissues by mitosis. Any organism that reproduces asexually does so through mitosis.

13. Sexual Reproduction Some organisms reproduce sexually with two parents. ▫Involves the two special reproductive cells, one from each parent. ▫The sex cells (sperm and egg) have only half the number of chromosomes that other cells have. ▫Formed through meiosis The sex cells join together in what is called fertilization.

14. Inheritance of Traits A piece of genetic information that influences a trait is called a gene. These two genes can be the same or different. ▫Example: the type of earlobe you have is determined from the genetic information you received from your parents.  Ears can either be attached or free If both genes match for a trait, the same trait will appear and it is said to be pure. If you have differing genes for a trait (attached and free) you are said to be hybrid.

15. Mendelian Genetics Gregor Mendel (1822-1884) investigated pea plants and determined that some genes could be dominant over others. ▫The gene that is not exhibited is recessive Mendel crossed pure tall pea plants and pure short pea plants ▫He observed all the plants were tall and concluded that tall was dominant. He then crossed two hybrids and observed most were tall with a few short which he concluded some of the plants still had the gene for tall.

16. Mendelian Genetics OrganismTraitDominantRecessive HumanEye colorBrownBlue HumanEarlobeFreeAttached HumanBlood typeA or BO Fruit FlyWingNormalVestigial Fruit flyEye colorRedWhite Pea plantHeightTallShort Pea plantPea colorYellowGreen Pea plantSeed shapeRoundWrinkled

17. Using a Punnett Square We can predict the possibility of an offspring if we know the types of the genes in the parents. The represent a gene, we use a capital letter for the dominant trait. ▫R for red We use a lowercase of the same letter for a recessive trait. ▫r for white Type of GenesRepresentationAppearance Pure redRRRed Hybrid redRrRed Pure whiterrWhite

18. Using a Punnett Square A punnett square can be used to predict the probability of an organism inheriting a given trait. The genes for each parent are placed on the top and the side. R= gene for red eyes r= gene for white eyes Types of GenesAppearanceProbability RR- pure dominantRed eyes¼ (25%) Rr- hybrid dominantRed eyes2/4 (50%) Rr- pure dominantWhite eyes¼ (25%)

19. Mutations Genetics accidents do occur- they are called mutations. ▫Sometimes genetic material does not reproduce properly. ▫Can be caused by a natural accident or by something in the environment. If the mutation is harmful to the organism, it is less likely to survive and reproduce. If the change is beneficial to the organism, it will be better able to survive and reproduce. ▫The new genetic information can be passed on to the new generation.

20. Mutations Natural selection: favors those organisms that that are best able to survive and reproduce. After many generations and mutations that organism may look and behave differently from its ancestors that it has become a new species. ▫This process is called evolution. Evolution accounts for the great diversity among living things.

21. Questions? Homework: Page 181 Page 185-88