Cell Cycle and Mitosis

1. Cell Cycle and Mitosis

2. Cell Cycle and Mitosis Cell Division—process by which a cell divides into 2 new cells 2 Daughter Cells Parent Cell • The original cell is called the parent cell; 2 new cells are called daughter cells 2 Daughter Cells Parent Cell

3. Why do cells need to divide? • Living things grow by producing more cells, NOT because each cell increases in size • Repair of damaged tissue • If cell gets too big, it cannot get enough nutrients into the cell and wastes out of the cell

4. Do you remember? Nucleus 1) Which cell organelle controls all cell functions? 2) What does this cell organelle contain? 3) What do ALL cells need in order to have the directions/code to perform functions correctly? Genetic Information DNA

5. DNA • DNA is located in the nucleus and controls all cell activities including cell division • Long and thread-like DNA in a non-dividing cell is called chromatin • Doubled, coiled, short DNA in a dividing cell is called chromosome • Consists of 2 parts: chromatidand centromere

6. Compare and Illustrate DNA DNA in NON-DIVIDING Cell DNA in a DIVIDING Cell

7. Chromatin to chromosomes illustration: Chromatin Coils up into chromosomes Duplicates itself Why does DNA need to change from chromatin to chromosome? More efficientdivision

8. 2 identical “sister” chromatids attached at an area in the middle called a centromere • When cells divide, “sister” chromatids separate and 1 goes to each new cell

9. Cell Cycle and Mitosis • Before cell division occurs , the cell replicates (copies) all of its DNA, so each daughter cell gets complete set of genetic information from parent cell • Each daughter cell is exactly like the parent cell – same kind and number of chromosomes as the original cell • Every organism has its own specific number of chromosomes • Examples: Human = 46 chromosomes or 23 pairs • Dog = 78 chromosomes or 39 pairs • Goldfish = 94 chromosomes or 47 pairs • Lettuce = 18 chromosomes or 9 pairs

10. All somatic (body) cells in an organism have the same kind and number of chromosomes. • Examples: Human = 46 chromosomes • Human skin cell = 46 chromosomes • Human heart cell = 46 chromosomes • Human muscle cell = 46 chromosomes • Fruit fly = 8 chromosomes • Fruit fly skin cell = 8 chromosomes • Fruit fly heart cell = 8 chromosomes • Fruit fly muscle cell = 8 chromosomes

11. Cell Cycle -- series of events cells go through as they grow and divide • Cell grows, prepares for division, then divides to form 2 daughter cells – each of which then begins the cycle again

12. Cell Cycle Outline • Interphase • G1: Cell Grows • S: DNA Replicates • G2: Growth & prepares for division • Mitosis • Prophase • Metaphase • Anaphase • Telophase • Cytokinesis

13. Cell Cycle and Mitosis Create a sentence to help you remember the order of the cell cycle and mitosis. Use the first letter of each term. Write your sentence in the box provided on your notes. • Interphase • Prophase • Metaphase • Anaphase • Telophase • Cytokinesis

14. Interphase • Interestingthings happen! • Cell preparing to divide • Genetic material doubles • Cells most of their time in Interphase

15. Mitosis –division of the nucleus into 2 nuclei, each with the same number of chromosomes • Mitosis occurs in all the somatic (body) cells Mitosis BeginsProphase, Metaphase, Anaphase, Telephase

16. Prophase Prophase • Chromosomepair up! • Chromosomes become visible • Nuclear membrane disappears • Spindle fibers form

17. Metaphase • Chromosomes meetin the middle! • Spindle Fibers connect to chromosomes Metaphase

18. Anaphase Anaphase • Chromosomes get pulled apart • Spindle fibers pull chromosomes to opposite sides

19. Telophase Telophase • Now there are two! • Chromosomes uncoil • Spindle fibers disappear • Two nuclei are formed

20. Cytokinesis Cytokinesis — the division of the rest of the cell (cytoplasm and organelles) after the nucleus divides In animal cells the cytoplasm pinches in In plant cells a cell plate forms • After mitosis and cytokinesis, the cell returns to Interphase to continue to grow and perform regular cell activities

21. Mitosis is a type of asexual reproduction. • There are two types of reproduction: Asexual Reproduction Sexual Reproduction • parent reproduces by itself • offspring is genetically identical to “mamma” • Offspring is genetically unique • creates diversity within population

22. Asexual Reproduction • Mitosis • Binary Fission • Budding • Spores • Regeneration • Vegetative Propagation

23. 1) Mitosis 2) Binary Fission • a parent cell splits into 2 daughter cells of = size • w/ prokaryotes produce 2 identical daughter cells with the same # of chromosomes as the parent cell. (identical)

24. 3) Budding 4) Spores • spores are surrounded by a tough coat to help them survive harsh conditions. .. Produced and released • a new, duplicate organism forms at the side of the parent and enlarges until an individual is created.

25. 5) Regeneration 6) Vegetative Propagation stolons • growth of new tissues/organs to replace those injured or lost. • Common in invertebrates, especially Asteroidea (Sea Stars) and Annelida (Worms). * In some multicellular plants * new plants develop from the roots, stems, or leaves of the parent.

26. Sexual Reproduction • Meiosis Cell division that results in haploid gametes; used for sexual reproduction

27. Haploid? • When a gamete (sperm or egg) of an organism has HALF of the full amount of chromosomes • Hap Half • Remember, human cells have 46 chromosomes? Then the haploid # is 23 Sperm Egg

28. Meiosis Meiosis I • All chromosomes make copes of themselves • This doubles the # of chromosomes in the cell Meiosis II • Begins in same two cells created by Meiosis I • Creates FOUR new haploid cells • Occurs in a manner very similar to mitosis • Occurs in the same four phases as mitosis but in two steps: Meiosis I and Meiosis II

29. Outline of Meiosis • Meiosis I • Prophase I • Metaphase I • Anaphase I • Telophase I • Meiosis II • Prophase II • Metaphase II • Anaphase II • Telophase II

30. Prophase I • Homologous chromosomes: • 1 from each parent • carry genes that control the same • inherited traits. Homologous chromosomes from each parent pair up! They form two attached sets of chromatids called a tetrad There are MANY ways the chromatids can line up: this is one source of genetic variation.

31. Metaphase I Each tetrad meetsin the middle! Spindle fibers connect centromeres Crossing over of chromosomes may occur to provide additional genetic variation – 2nd source of genetic variation

32. Anaphase I Tetrads get pulled apart Homologous chromosomes move to opposite ends

33. Telophase I Cells may finish cytokinesis OR proceed immediately with Meiosis II

34. Prophase II Chromosomes did NOT replicate At this point, the cell is haploid because it no longer has one of every kind of chromosome that was in the original cell

35. Metaphase II Sister chromatids line up on individual spindle fibers

36. Anaphase II Sister chromatids are separated into each new cell Each new cell now has only HALF as many chromosomes as the parent cell in Prophase I

37. Telophase II Each of the four new cells completes reforming nuclei and cytokinesis separates the four new hapliod cells

38. How does meiosis lead to genetic variation? • Look back at Prophase I & Metaphase I, what may lead to genetic variation? • There are MANY ways the chromatids can line up • Crossing over of chromosomes may occur • What is another factor that could lead to genetic variation? • Random combinations of sperm and eggs

39. Interphase Interphase Prophase 1 Review! Metaphase 1 Meiosis 1 Anaphase 1 Telophase 1

40. Prophase 2 Metaphase 2 Meiosis 2 Anaphase 2 Cytokinesis Cytokinesis

41. Note.. Male gametes 4 haploid gametes … 4 sperm by way of spermatogenesis Female gametes 4 haploid gametes … 1 Ovum (egg) & 3 Polar Bodies by way of oogenesis

42. Sometimes cell division doesn’t go as planned…

43. Cell Division Regulation Internal and external factors regulate cell division. • Cancer is the uncontrolled growth and division of cells. • Cancer cells can kill an organism by crowding out normal cells, resulting in the loss of tissue function.

44. Benign – cancer cells typically remain clustered together Malignant – cancer cells can break away or metastasize cancer cell bloodstream normal cell Cancer metastasize Benign Malignant

45. Causes of Cancer • Internal Factors • Inheritance • Mutations • External Factors • Carcinogens are substances that are known to produce and promote the development of cancer. • Radiation • Chemical • Viruses Skin Cancer

46. Nondisjunction Mutations • Improper separation of sister chromatids may result in a cell having one too many chromosomes (trisomy) or not having one of a certain chromosome (monosomy) Karyotype – a picture of an individual’s chromosomes so that the types of mutations might be seen

47. Trisomy 21 – Down Syndrome Trisomy 18 - Edward's Syndrome

48. Meiosis Square Dance

49. Darius Goes West • Darius lives with the crippling disease Duchene Muscular Dystrophy (DMD). It wouldn’t be odd for him to give up on himself or his life’s worth but he doesn’t! He had in fact, already lost a brother to the disease. • If you were diagnosed with such a disease, how would you respond? If you were a friend of a person diagnosed with such a disease, how would you respond? What about Darius impressed you? How about how his friends responded to him? Explain your answers! You must have at least 5 sentences!