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The Cell cycle

The Cell cycle. Ch. 5.1. Lesson Objectives. At the end of this lesson, students will be able to… List the main stages of the cell cycle in order Explain the main function of each stage Describe factors that determine division rate and cell size. Cells: Prokaryotes vs Eukaryotes.

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The Cell cycle

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  1. The Cell cycle Ch. 5.1

  2. Lesson Objectives • At the end of this lesson, students will be able to… • List the main stages of the cell cycle in order • Explain the main function of each stage • Describe factors that determine division rate and cell size.

  3. Cells: Prokaryotes vs Eukaryotes

  4. Cell structure revisited

  5. Cell structure revisited

  6. The nucleus The cell nucleus is where eukaryotes store their DNA DNA is what carries the instructions for how to build a new cell down to every detail – like the blueprints for a house The nucleus is surrounded by a membrane called the nuclear envelope Inside the nucleus is the nucleoluswhich is the site of rRNA transcription

  7. DNA and Chromosomes • Fig 2.2, Pg. 131 • DNA is in the form of double helix strands • If we stretched out human DNA strands from ONE cell it would be 6.5 feet long • In order to organize these strands of DNA, they are wrapped around proteins called histones.

  8. DNA and Chromosomes Wrapping DNA around histones isn’t enough DNA/histone strands are twisted into coils called chromatin Chromatin is twisted tighter and tighter until it forms a neatly packed chromatid Chromatidsduplicate during the cell cycle to form the X shaped chromosomes we generally see

  9. Chromatid, Chromosome

  10. The centromere is the pinched region of the chromosome that holds the sister chromatids together The kinetochores are the attachment point for spindle fibers

  11. The Cell Cycle Definition: The cell cycle is the regular pattern of growth, DNA duplication, and cell division that occurs in EUKARYOTIC cells.

  12. Stages of the Cell Cycle • Interphase includes: • G1 (Gap 1) • S (Synthesis) • G2 (Gap 2) • Mitosis includes: • M (Mitosis) • Cytokinesis

  13. G1 – Gap 1 The cell spends most of its time in G1 This is when the cell carries out its normal functions Cells also GROW in size Organelles replicate The cell gets ready for the S stage

  14. S - Synthesis Synthesis only begins if the cell passes the checkpoint at the end of G1 During the synthesis stage, DNA is duplicated At this point, DNA is still loosely organized in the nucleus

  15. G2 – Gap 2 G2 is another period of cell growth and normal function G2 also includes a checkpoint that the cell must pass to enter mitosis

  16. M - Mitosis • Definition: the division of the cell nucleus and its contents (DNA) • Mitosis is broken in 4 phases we will learn about later

  17. Cytokinesis Cytokinesis is the actual separation of the cell into two identical daughter cells Literally means “splitting of the cytoplasm”

  18. The Cell Cycle - Video • What are the 2 major phases of the cell cycle? • What percentage of time do most cells spend in interphase? • What is the non-dividing state called? • Why do cells enter this state? • What is the function of histones? • How many chromosomes do human cells have to duplicate?

  19. Review:Using one or two words each, list ONE thing that happens in each of these stages:G1 = S = G2 = M =

  20. HOMEWORK: • Catch up: Section 5.1 • **FAQ #5 – Page 129** • Fill in missing notes (powerpoints on website) • For tomorrow: Section 5.2 • FAQ #2 – Page 134

  21. ****SKIP TO 5.2 – MITOSIS AND CYTOKINESIS!!***

  22. Mitosis and Cytokinesis Ch. 5.2

  23. Lesson objectives • At the end of this lesson, students will be able to… • Describe what happens to DNA during cell division • List the phases of mitosis and cytokinesis in order • Explain major events in each phase

  24. Phases of Mitosis The M-Phase, mitosis, can be broken down into four stages

  25. Phases of Mitosis: Activity FIRST: Number off from 1 – 5 SECOND: Find the table in the back with your number and become the “expert” on that phase. THIRD: Mingle with your classmates until you have information on each phase of the worksheet LAST: Once your worksheet is filled in, return to your seats

  26. The phases of Mitosis Prophase Metaphase Anaphase Telophase Cytokinesis

  27. Mitosis Video http://www.youtube.com/watch?v=C6hn3sA0ip0 How long does mitosis typically last? Where do spindle fibers come from? T or F: The nucleolus breaks down in prophase. Where do spindle fibers/microtubules attach to? In what phase are sister chromatids separated? T or F: new nuclear membranes form during telophase. What does the contractile ring cause?

  28. Mnemonic Devices for: Prophase Metaphase Anaphase Telophase - Cytokinesis Pee MAT Parties (on) Mondays Aren’t That Cool Presidents May Admire The Cabinet Please Make A Taco Cake Please Make A Tasty Chicken Play Makes A Toddler Crazy!

  29. Mnemonic devices Personal Money And Time Care Parties Make Aaron Totally Crazy Purple Monkeys Attack The Cat Play Mates Are Totally Cute

  30. Exit Ticket:What is the product of mitosis and cytokinesis?

  31. ***GO BACK TO RATE OF DIVISION AND CELL SIZE***

  32. Different cells divide at different rates • Prokaryote cells divide faster than eukaryotes • Cells that have a short “life span” need to divide faster to replace dead cells • What types of cells die quickly? • What types live a long time?

  33. Good Info DNA packaging (1.75 mins) Cell signals, Growth factors, and Healing (13 min)

  34. Announcements • Hand in mitosis activity packet • Blue mitosis packets – Thursday 2/21 • Powerpoints and flashcards online • Test – probably on Friday 3/1 • Note packet will be collected on test day

  35. Discuss: Would a skin cell have a long or short G1 stage compared to other cell types? Explain.

  36. Cell Size Cells must be BIG enough to include all of the necessary parts, but SMALL enough to have the correct ratio of membrane surface area to volume Membrane surface area allows diffusion and osmosis to take place See fig 1.3 on page 129

  37. Cell Size Demo – How does size affect the cell??

  38. HOMEWORK • Catch up: • 5.1 – FAQ #5 and 5.2 – FAQ #2 • Fill in missing notes (powerpoints on website) • For tomorrow: • Read 5.3 and do FAQ #5 page 139

  39. Cell Size What limits the maximum size of a cell? The minimum size?

  40. Cell Cycle Regulation Ch. 5.3

  41. Lesson Objectives • At the end of this lesson, students will be able to… • Identify factors that regulate the cell cycle • Explain cancer in terms of the cell cycle

  42. Regulation of the Cell Cycle • The cell cycle is like an assembly line at a factory – Quality checks need to be made along the way to make sure everything is being made correctly • Three major checkpoints occur during the cell cycle: at the end of G1, G2, and metaphase • If the cells fail any of these checkpoints they will move into the NON-dividing phase called G0

  43. Regulation • Other things that can regulate cell division are: • Cell to cell contact– when cells come into contact with each other, cell division stops • Apoptosis – programmed cell death. Cells that are defective or no longer needed are shut down and destroyed • Growth factors– proteins and hormones that stimulate growth and division

  44. Regulation External factors – Available nutrients, chemicals from environment Internal factors – Genetics, stress (causes release of chemicals and hormones inside the body) Cell signals, Growth factors, and Healing (13 min)

  45. Regulation • If any methods of regulation become dysfunctional – cell division can run out of control • Uncontrolled cell division is called cancer

  46. Exit Ticket: What causes cancerous cell growth?

  47. CANCER = UNCONTROLLABLE CELL DIVISION!!!!!!!!!!!!!

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