2. Why is Reproduction so important? Preserves the continuity of the species Essential to the transmission of hereditary information which is carried in the DNA

3. Cells reproduce for many reasons: In single-celled organisms, the division of ONE cell to form TWO makes a whole NEW organism In multicellular organisms, cell division allows growth and development of the fertilized egg and replacement of damaged or dead cells

4. There are 2 kinds of reproduction: Asexual Reproduction Sexual Reproduction

5. Asexual Reproduction This type of reproduction involves only ONE parent organism (either unicellular or multicellular). MITOSISOccurs by MITOSIS and cytoplasmic division The offspring contains the same DNA as the parent and is therefore a CLONE Ex: An ameba reproduces asexually by splitting in two

6. Three types of Asexual Reproduction: 1.Binary Fission 2.Budding 3.Regeneration

7. Binary Fission Splitting of an organism into 2 or more individuals of EQUAL SIZE Ex: paramecium, bacteria

9. Budding A new individual splits off its parent Split is not of equal size Ex: Hydra, jellyfish

11. Vegetative Propagation This process grows a new PLANT using mitosis or asexual reproduction! It is the production of a new individual plant from horizontal stems and underground roots

12. Regeneration A new individual can grow from a segment or piece of an existing organism Helpful for replacement of injured or lost body parts Ex: Sea Star, worms

13. Mitosis Our body cells, such as skin and hair, reproduce asexually by splitting and dividing through MITOSIS Mitosis is used when cells/tissues need to grow and repair Mitosis creates clones of the parent cell Body cells contain 46 chromosomes (the Diploid number)

14. What is DNA? All the information needed to create an entire organism is encoded in DNA DNA is made up of Genes A single molecule of DNA has thousands of genes lined up like train cars

15. Chromosomes DNA is coiled into a structure called a chromosome When DNA is copied – the exact copy is called a chromatid. Two chromatids are joined by a centromere

16. In humans, the rate of mitosis is about 25 million cells every second! Calculate the number of cells produced by mitosis in 3 minutes. 3 min = 180 seconds (3 x 60) 180 sec x 25 million = 9 x 10 10 cells = 90,000,000,000

18. Single-Stranded Chromosomes

20. Stages of Mitosis

21. Mitosis

22. Cell Division Animation

23. Mitosis in Animal Cell

24. Mitosis in Plant Cell

26. What is Cancer? Sometimes body cells do not respond to normal control mechanisms, and continue to divide as long as nutrients are available Eventually a tumor forms If cancer cells remain at the original site they are considered benign If they spread to neighboring tissues, they are considered malignant

30. Sexual Reproduction This type of reproduction involves the fusion (joining) of nuclei from two parents The cells used during sexual reproduction are called gametes Male gametes are SPERM,Female gametes are EGG cells

31. Gametogenesis The production of gametes by the process of MEIOSIS in males and females. Gametogenesis is the ONLY process that uses MEIOSIS in the body. Production of Sperm is called Spermatogenesis; Production of Egg cells is called Oogenesis

32. Meiosis sex cells 2 parentsMeiosis is the process by which sex cells (sperm and egg) from 2 parents are created HALF the number of chromosomeshaploid number (23 each)These cells contain HALF the number of chromosomes of the parent cell known as the haploid number (23 each) Fertilizationdiploid number (46)Fertilization restores the diploid number (46)

33. Meiosis4 23chromosomes for every ONE that is divided Meiosis creates 4 cells with 23 chromosomes for every ONE that is divided

35. Diploid Number of some Commonly Studied Organisms: Humans – 46 House Mouse – 40 Corn – 20 Fruit Fly – 8 South African clawed Frog – 36 Microscopic Roundworm – 12 Budding Yeast – 32 Domestic Dog – 78 Deer – 23 An Ant –2 Parasitic Roundworm – 2 A Crayfish – 200 Field Horsetail (plant) - 216

36. Crossing Over During meiosis, chromosomes cross over each other This allows for genetic shuffling and increases genetic variability Offspring have a unique combination of genes inherited from both parents

37. Crossing Over

38. Why crossing over is important… A male bird with large wings and weak muscles mated with a female bird with small wings and strong muscles. Describe all the possible characteristics that could occur in their offspring. Would any combination(s) be advantageous? Would any combination(s) be disadvantageous? How could these variations affect the survival of the organisms?

39. Meiosis Animation

44. Single Parent Single parent passes on ALL of its genes to its offspring Offspring are genetically identical to parent Results in a clone No crossing over occurs Two Parents Each parent passes on half its genes to its offspring Offspring have a unique combination of genes inherited from both parents Results in offspring with greater genetic variation Crossing over occurs which increases genetic variability Asexual Reproduction Sexual Reproduction