Regents Biology Thurs. 12/11/13

1. Regents BiologyThurs. 12/11/13 Please take the handouts from the front table and sit down Take out something to write with We are starting Unit 5 today While you are waiting please answer the question of the day: What do you know or remember about Mitosis?

2. Unit 5: Cell Division--Mitosis • All cells come from pre-existing cells. • When cells divide, both the nucleus and the cytoplasm are divided. • One type of nuclear division is called mitosis and another type is called meiosis

3. Part 1: What are some reasons that we must make new cells? • Growth: obviously we are not born with all of the cells we will need throughout our lives. If that were the case, think about how large babies would be! • Healing or Repair: if we were not able to make new cells in this case, we probably wouldn’t survive very long, would we? • Reproduction: division is to make an entirely new organism.

4. Part 2: The Cell Cycle: • This is the life cycle of the cell from the beginning of its formation until it is completely divided into new cells. • By the time the cell is ready to divide, it must have enough organelles for two cells. It must also have copied or duplicated every chromosome so that each new cell gets all of the genetic information it is supposed to have.

5. The Cell Cycle:

6. Important Vocabulary Terms: • Mitosis = cell division that creates two new identical cells • Chromosomes = a piece of DNA that contains specific active areas called genes • DNA Replication = copying the DNA in a cell • Sister Chromatid = identical copies of a chromosome that are joined together

7. Part 3: All About Chromosomes • BEFORE Replication: one strand also called a single chromatid. • After Replication: the single chromatids have been duplicated, and the two sister chromatids are joined together. • The area they are joined is called the centromere • They are made of DNA • They contain areas of important information called genes.

8. All About Chromosomes:

9. All About Chromosomes: • In humans, normal body cells have 46 chromosomes total. • We inherit 23 from each parent. • Here are some comparisons of the number of chromosomes in other organisms: • Fruit Fly = 8 Dog = 78 • Apple = 34 Tomato = 24 • Chimpanzee = 48 Corn = 20 • When a cell replicates its DNA, all of these chromosomes must be copied.

10. Difference Between Sister Chromatids and Homologous Chromosomes: • Sister Chromatids: • are identical • are formed during “S” phase when DNA is replicated • Homologous Chromosomes: • are NOT identical • one is inherited from each of an organism’s parents • Both contain the same genes but NOT the same information within each of the genes

11. Difference Between Sister Chromatids and Homologous Chromosomes:

12. Important Vocabulary Terms: • Asexual Reproduction = reproduction involving one parent making two genetically identical “daughter” cells as offspring • Sexual Reproduction = reproduction involving the combination of genetic information from two parents • Gene = an area within a chromosome that contains the instructions to make a protein

13. Important Vocabulary Terms: • Centromere = the area where two sister chromatids are joined. It has proteins which help move the chromatid along the spindle • Homologous Chromosome = a non-identical pair of chromosomes with the same genes. One is inherited from each parent.

14. Part 4: Types of Organism Reproduction • 1) Asexual Reproduction: • Simple cell divisions • Results in two new, genetically identical cells • Organisms which reproduce this way include bacteria and yeast

15. Part 4: Types of Organism Reproduction • 2) Sexual Reproduction: • More complicated cell divisions • Genetic information is split up so that the resulting offspring receives genetic information from both parents, and not just one • Organisms which reproduce this way include animals (humans) • Some organisms, like plants can use either type of reproduction.

16. Regents Liv. Env. Thurs 12/12/13 • Please Sit down • Take out your notes and something to write with • While you are waiting, answer the question of the day: • What are the three reasons that organisms perform mitosis? Do humans use mitosis for all three reasons?

17. Part 5: The Process of Mitosis • Mitosis is making two new “daughter” cells from one old “parent” cell. • The daughter cells will be identical to the parent cell and to each other.

18. Step 1: Prophase • The chromosomes become visible because they get shorter and thicker • May be able to see both sister chromatids • The nuclear membrane begins to dissolve • The mitotic spindle also forms out of microtubules, which are tubes of protein

19. Step 2:Metaphase • The spindle is now fully formed. • The chromosomes attach to it at their centromere. • The chromosomes line up in the center of the cell this is called the “metaphase plate”.

20. Step 3:Anaphase • Sister chromatidsseparate from move toward opposite ends • Each chromatid is now considered a “daughter” chromosome. • Proteins in the centromere help to pull the chromatid along the spindle

21. Step 4:TelophaseAND Cytokinesis • Telophase is the final stage of mitosis. • The chromosomes have reached opposite ends of the dividing cell. • The spindle disappears • Two new nuclear membranes form around the two separated sets of chromosomes. • Cytokinesis, which is the division of the cytoplasm occurs at the same time as Telophase.

23. At the end of telophase and cytokinesis there are two completely formed daughter cells that formed from one original parent cell. • Remember: The two newly formed cells are genetically identical to the parent cell they came from, and to each other. • ***An easy way to remember the order in which the stages of mitosis happens is the phrase “Please Move All The Chromosomes”, because the order they happen is prophase, metaphase, anaphase, telophase, and cytokinesis

24. Regents LE Monday 12/16/13 • Sit down please and take out your notes and something to write with • Wait quietly for class to begin and answer the following Question of the Day at the top of your notes page: • Why do cells need to perform DNA Replication prior to Mitosis?

25. How is Mitosis in Animal Cells and Plant Cells Different?? • Mitosis is very similar in both types of cells. • Plant cells have a cell wall that is rigid, and animal cells do not. • In plant cells, a structure called a cell plate forms in the middle of the newly dividing cell • It eventually becomes the new cell wall between the two new daughter cells.

26. How is Mitosis in Animal Cells and Plant Cells Different?? • In animal cells there is no cell wall • During cytokinesis the membrane pinches off at the center, • It is as if someone were pulling a drawstring around its middle. • This pinching off of the membrane results in two newly formed cells.

28. Part 6: Other Processes related to Asexual Reproduction and Mitosis: • 1) Regeneration • The ability of an organism to regrow lost body parts. • Is common in small, simple, multicellular organisms, for example planaria, iguanas, and starfish. • Sometimes these organisms can regenerate a whole new organism from pieces. • Humans and other complex organisms are NOT able to replace lost body parts.

29. Part 6: Other Processes related to Asexual Reproduction and Mitosis: • 2) Vegetative Propagation • a type of asexual reproduction in plants • pieces of roots, stems, or leaves are used to form an entirely new, whole plant. • The new plant is genetically identical to the parent. • This is sometimes also called vegetative reproduction. • Examples of vegetative propagation include cuttings, runners, grafting, or bulbs.

30. Part 7: Cell Division and Cancer • Cancer is a disease that results from out of control cell division (mitosis). • It can have many causes: • Exposure to a carcinogen (a chemical that causes cancer) • Example: asbestos or tobacco smoke • Genetic Trait—some people are more likely to get certain types of cancer based on what genes they inherit. • Common cancers that are known to have a genetic link include breast and colon cancers. • Viruses—certain viruses have been linked to causing cancers, but these people probably are more susceptible to the cancer due to genetics also. • Add at the end of the list—Exposure to radiation (ex: UV rays)

31. How does Cancer work? • A normal cell is only supposed to divide at specific times. • Something, for some reason goes wrong and one or a group of cells have a problem with their normal cell cycle, and the cells begin to divide when it isn’t time to do that. • There has been some type of disruption to the mechanism that controls when the cell is supposed to divide. • As the cells continuously divide when they aren’t supposed to, they form a mass of cells, called a tumor

32. Flashcards Due tomorrow (Tues 12/17): • Mitosis • Chromosomes • DNA Replication • Sister Chromatid • Asexual Reproduction • Sexual Reproduction • Centromere

33. Flashcards Due Weds. 12/18/13 • Homologous Chromosome • Spindle • Cancer • Tumor • Metastasis • Carcinogen

34. Regents Liv.Env. Tues 12/11/12 • Please put your flashcards in the box if you did them • Sit down • Take out your notes and something to write with • Answer the Question of the Day at the top of your page: • How is mitosis different in animal cells and plant cells? How is it the same?

35. How does Cancer work? • Benign Tumors: These are formed from normal cells that are dividing out of control. • These tumors are considered benign and are usually removed without any problems. • Malignant Tumors: These are formed when the cells that are dividing have changed in some way so that they are abnormal. • These tumors are considered malignant, and may or may not be easily removed, depending on their location in the body. • Often people with malignant tumors must undergo various types of treatment, including chemotherapy and/or radiation treatments.

36. How does Cancer work? • Metastasis: This is when the tumor cells have spread from their original site to other parts of the body. • Cells from the tumor can spread through the blood stream or the lymph system, and the abnormal cells can begin growing and dividing in the new area, causing new tumors.

37. How does cancer work? • Chemotherapy: This treatment works by sending medicines throughout the body that will hopefully stop the abnormal cells from dividing. • These medicines are often very useful, but have severe side effects, and often make patients very ill. • Radiation Treatment: This treatment works by exposing the tumor cells directly to high doses of radiation, which should kill them so that they can no longer divide. • This has an advantage because you are only treating the cells of the tumor and not the rest of the body, but it also has some severe side effects.

38. How does cancer work? • Researchers are working hard to find new treatments to battle cancer, and to try to pinpoint the causes. • Proper health, including good nutrition, adequate rest and exercise, and avoiding carcinogens all help people ward off cancers.

39. Important Vocabulary Terms: • Cancer = a disease caused by out of control cell division. Cells may be normal or abnormal • Tumor = a mass of genetically identical cells where it does not belong • Benign = not generally harmful. Abnormal cell division of “normal” cells

40. Important Vocabulary Terms: • Malignant = usually harmful. Abnormal cell division of abnormal cells • Metastasis = spread of cancer cells from one part of the body to others through blood stream or lymph system • Carcinogen = a substance that causes cancer after exposure.