Unit 7 Cell Growth & Division

1. Unit 7 Cell Growth & Division Amoeba

2. Something to Think About !!!! • When a living thing grows, what happens to its cells? • 2. Does an animal get larger because each cell increases in size or because it makes more of them?

3. Answers to Think About It: • Living things grow by producing more cells. • The cells of an adult animal are no larger than those of a young animal –there are just more of them.

4. One More Thing To Think About …… Why do cells make so many new cells rather than continuing to grow indefinitely?

5. Answer : One More Thing To Think About: The larger a cell becomes, the more demands the cell places on its DNA and the more trouble the cell has moving enough nutrients and wastes across the cell membrane.

6. DNA Overload 1.The information that controls a cell’s function is stored in DNA 2.DNA is located in the cell’s nucleus 3.DNA is able to meet the cell’s need when cells are small 4.If a cell were to grow too large, there is not enough information in the DNA molecule to control the larger cell

7. Exchanging Materials 1.If cells were to grow larger than normal, the cell’s volume and its surface area would prevent the cell from maintaining homeostasis. It becomes more difficult for the cell to move needed materials in and waste products out

8. When do new cells need to be produced? • Replacement • Cells get damaged and need to be replaced. • Not all cells can be reproduced. • Growth • The addition of more cells to make the organism larger

9. Life Span of Various Human Cells Life Span Cell Division 2-3 days Can divide 1-2 days Can divide 6 days Can divide Less than 120 days Cannot divide 10 hours to decades Cannot divide Long-lived Can divide Long - lived Cannot divide Long-lived Cannot divide Long-lived Most do not divide

10. The Cell Cycle G1 Phase M Phase S Phase G 2 Phase

11. Cell Cycle • It is a series of events that cells go through as they grow and divide. • The cell cycle consists of four phases: • G1 - Cells increase in size • synthesize new proteins • synthesize new cell organelles • S - Chromosomes are copied which gives the cell a duplicate set of DNA • G2 - Preparation for Mitosis 90% of time is spent in interphase I N T E R P H A S E

12. Mitosis (M Phase) • 1. It is the part of the cell cycle where the division of the nucleus and cytokinesis, (division of the cytoplasm), take place. • 2. Mitosis is divided into 4 steps(phases) • Prophase • Metaphse • Anaphase • Telophase(cytokinesis)

14. Sister Chromatids Centromere Spindle Nuclear envelope Prophase • 1st and longest phase of mitosis • Nuclear envelope disappears • Chromosomes condense – • Now, you can see sister chromatids and centromere • Spindle forms(microtubule structure that helps separate the chromosomes.)

16. Spindle centromere Metaphase • Chromosomes move to the equator of spindle • Each chromatid is attached to spindle with centromere

17. Metaphase

18. Sister Chromatids Anaphase • Centromeres split • Sister chromatids are pulled apart to opposite poles of the cell • Each chromatid is now a separate chromosome

19. Anaphase

20. Telophase • Nuclear envelopes (2) reform • Chromosomes begin to uncoil and return to a tangled looking mess.

21. Telophase

22. Pinching in of cell membrane Cytokinesis • Cytoplasm divides • Two new daughter cellsare now separate • Cytokinesis usually occurs at the same time as telophase.

25. Okay, Now it’s your turn!

26. Interphase? Prophase? Metaphase? Anaphase? Telophase? Telophase Metaphase Anaphase Telophase 1 2 3 4 Prophase Anaphase Interphase 5 6 7

28. What is Cancer ? • Cancer is uncontrolled cell division (mitosis) that can’t be stopped. • A mass of cells called a tumor is a result of this uncontrolled cell division. • There are 2 types of tumors: • Benign = non-cancerous • Malignant= cancerous and they invade and destroy other tissues.

29. Malignant Pancreatic Cancer Tumors

30. Benign Facial Tumors (neurofibromatosis)

31. Cancerous Cells Affects Homeostasis • Interferes with nervous system tissue and blocks important nerve connections. • Cancer cells absorb nutrients needed by the healthy cells. • Prevent organs from functioning properly. Lung Cancer

32. Asexual Reproduction It Only Takes One !

33. Characteristics of Asexual Reproduction • Only one parent is involved. • Offspring are genetically identical to their • parents.

34. Asexual Reproduction in single- celled organisms • 1. Binary Fission • The simplest type of asexual reproduction. • A unicellular organism divides by mitosis to form two daughter cells of equal size. • Both the nucleus and cytoplasm divide equally. • Amoebas, paramecia, and bacteria reproduce this way. • All cells that come from a single cell are genetically identical to each other

35. Binary Fission in Paramcecium

36. Binary Fission in Bacteria

37. Regents Practice Question # 1 A pattern of reproduction and growth in a one celled organism is shown below. Which statement best describes this pattern of reproduction? (1) All genetic material comes from one parent. (2) Only some of the genetic material comes from one parent. (3) The size of the parent determines the amount of genetic material. (4) The size of the parent determines the source of the genetic material.

38. Regents Practice Question # 1 ( Answer) A pattern of reproduction and growth in a one celled organism is shown below. Which statement best describes this pattern of reproduction? (1) All genetic material comes from one parent. (2) Only some of the genetic material comes from one parent. (3) The size of the parent determines the amount of genetic material. (4) The size of the parent determines the source of the genetic material.

39. Asexual Reproduction in multi-cellular organisms • It can be a result of wound repair or growth. • There are many different methods for asexual reproduction in multi-cellular organisms. • Budding • Sporulation • Regeneration • Vegetative Propagation

40. 2. Budding • A new organism develops as part of a parent. • The new organism is called the bud • The bud is a duplicate of the parent. It may separate or remain attached to form a colony. • In budding there is an equal division of the nucleus, but unequal division of cytoplasm. So, one of the daughter cells is larger than the other.

41. Yeast Budding Desert Cactus Hydra Budding

42. Regents Practice Question # 2 The diagram below illustrates asexual reproduction in yeast. Yeast produce offspring that usually have (1) genes that are different from those of the parent (2) genes that are identical to those of the parent (3) half of the genetic information of the parent (4) organelles that are not found in the parent

43. Regents Practice Question # 2 (Answer) The diagram below illustrates asexual reproduction in yeast. Yeast produce offspring that usually have (1) genes that are different from those of the parent (2) genes that are identical to those of the parent (3) half of the genetic information of the parent (4) organelles that are not found in the parent

44. Regents Practice Question # 3 Which diagram represents the reproductive process of budding?

45. Regents Practice Question # 3 (Answer) Which diagram represents the reproductive process of budding? Correct Answer

46. 3. Sporulation • Spores are specialized asexual reproductive cells that contain a nucleus and small amount of cytoplasm. • Spores are produced in large numbers by mitosis. • They are surrounded by a tough protective coat that enables them to survive extreme conditions such as heat or cold. • When conditions are favorable, the spores develop into a new organism. • Bread mold, mushrooms, mosses, and ferns reproduce this way

47. Sporulation in Ferns Diagram of Mold Spores

48. Moss Sporulation

49. 4.Regeneration • The development of a new organism from a part of a parent organism • Occurs in starfish, planaria and sponges • Regeneration can also replace lost body parts. For example lobsters can replace a lost claw.

50. P L A N A R I A R E G E N E R A T I O N