Decoding Cell Growth: Understanding Mitosis in Genetics

1. Chapter 5:Cell Growth and Division Mitosis Rap

2. Where is all the genetic information found in a cell? • On the genes on the Chromosomes • Chromosomes are actually strands of DNA and proteins • If cells were the size of a basketball, your DNA would stretch 40 miles • We have 6 feet of DNA in each cell!!!!!

3. Every species has a set number of chromosomes • Chromosome number: • Number of Chromosomes in a body cell • Specific for each species of organisms. List • Human – 46 • Chimpanzee – 48 • Gorilla – 48 • Potato – 48 • Bat – 44 • Fruit fly – 8 • Mosquito – 6 • King Crab – 208 • Dog - 78 • Horse – 64 • Donkey - 62 • Adder’s tongue fern 1,262

4. How would you duplicate a cell exactly to be certain that both new cells have the identical DNA in each cell? • Duplicate the DNA first (this is DNA replication) • Find a way to be certain that the DNA does not get broken or tangled during the process of dividing it into the two new cells • Be certain that the new daughter cells will have the exact same set of DNA in each new cell’s nucleus • Divide up the cell’s contents. (Cytokinesis)

5. What would happen if a cell were to just split into two without any advance preparation? Instead, it is more efficient to shorten up and then organized the replicated DNA prior to dividing the DNA up evenly into two cells. This is what happens in The Cell Cycle • Imagine trying to divide up pieces of yarn by color if they were all just thrown into a pile together. • It would take a long time to do this efficiently and accurately.

6. Chromosome structure • Before cell division occurs, the DNA is loose in the nucleus and known as Chromatin • DNA starts coiling around proteins called histones (like thread on a spool) • DNA shortens up Chromosome Coiling animation • The two identical chromosomes that resulted from DNA replication will find each other and come together. The two “twins” are called chromatids & are held together by a centromere

7. A Paired Chromosome This strand of DNA is identical to this strand of DNA.

8. Chromatid Sister Chromatids

9. Label the structures on the Paired Chromosomes

10. Why do cells need to reproduce? • Necessary for: • Repair and replacement of damaged cells • Growth (remember your first baby picture) • Smaller cells are more efficient than are larger cells.

11. What would happen to a cell if it continued to grow? As the size of the cell increases, its volume increases faster than its surface area. Surface area tovolumeratio would decrease. Makes it difficult to move needed materials in and wastes out of the cell efficiently. Calculate the Surface area (Length x width x 6) and Volume (Length3) then the Surface area to Volume ratio (reduce to lowest terms)

12. The Cell Cycle • Entire process that a cell undergoes in cell division from start to finish. • Cells: • grow • prepare for division • divide to form two daughter cells • begin the cell cycle over again. • Cells such as skin, lining of digestive tract and blood cells go through this process frequently • Introduction

13. Stomach lining cells: 2 days ______________________ Life Spans of Body Cells Platelets: 10 days ______________________ Skin Cells: 20 days ____________________ Red Blood Cells: 120 days ______________________ Brain cells: 30-50 years ______________________ Intestinal lining cells: 3 days ______________________

14. The Cell Cycle

15. Divided into 2 parts • Interphase • G1 - Cell grows from last cell cycle • S – Synthesis of DNA (DNA makes a copy of itself) • G2 – Cell growth and gets ready for cell division • G0 – No cell division – typical of cells like nerve cells that stop dividing at maturity • Mitosis – Mphase • Prophase • Metaphase • Anaphase • Telophase • Cytokinesis

16. How long does the Cell Cycle take in a human cell? Studies have shown that the average cell works on a 24 hr cycle as does typical cell replication. Embryonic cells will divide every 8 minutes!! Liver cells could take up to a year. However, many cells will be in G0 for long periods of time.

17. Interphase • Longest phase in the Cell Cycle – over half the time is spent in this phase

18. Prophase – longest phase in Mitosis • Chromosomes are visible • Chromatids pair up • Centrioles (if animal cell) migrate to poles • Nuclear envelope & nucleolus start to break down • Fibers form

19. PROPHASE Move apart from one another Shorten and Thicken Form between centrioles (in animal cells) Begins to break down

20. Metaphase – shortest part of Mitosis • Sister Chromatids line up on the equator (middle)

21. METAPHASE Become attached to the fibers. Are moved to middle of cell Go from the poles to centromeres At opposite ends of cells Remains dissolved

22. Anaphase – “An away they go!” • Chromatids separate • Go to opposite poles. Now called chromosomes!! • Fibers shorten up

23. ANAPHASE Pulled apart by fibers. Each chromatid is separate from its “sister” Now called a chromosome Still at cell’s poles; Remains dissolved Pull each chromosome toward opposite ends of the cell

24. Telophase • “the end” – Final phase • Chromosomes reach opposite ends • Cell membrane pinches in or Cell plate forms (if plants) • Chromosomes uncoil • Nuclear membrane & nucleolus reappear • Fibers disappear

25. TELOPHASE Each end of cell has a complete set of identical chromosomes. Begins to pinch, forming two new cells Begin to disappear Begins to reform

26. Cytokinesis Dividing up of cellular contents. Occurs simultaneously with Telophase Mitosis and Cytokinesis

27. Cytokinesis • Cytokinesis differs in animal and plant cells. In animal cells, the membrane pinches closed. In plant cells, a cell plate forms.

28. What was the point of Mitosis? • Results in two identical daughter cells • Each cell will have the SAME number of chromosomes as the original cell • Each cell will have the SAME function as the original cells

29. Mitosis animationsTry them all! • http://www.sumanasinc.com/webcontent/animations/content/mitosis.html • cellsalive. • John Kryk • You tube (really good) • Hybrid (love the music) • http://www.csuchico.edu/~jbell/Biol207/animations/mitosis.html • Arizona • Movie Clip • McGraw Mitosis Rap

30. Mitosis Another Interphase Prophase Anaphase Metaphase Late Prophase Telophase

31. Plant Mitosis

32. Checking your understanding Mitosis Starting with Prophase, draw a cell undergoing mitosis. Your original cell has 4 chromosomes. Make certain to include the nuclear membrane, nucleolus, chromatids, centrioles (animal cell), chromosomes and spindles. PROPHASE ANAPHASE METAPHASE TELOPHASE

33. Give the events occurring in each of the stages of the Cell Cycle INTERPHASE ____________________________________________________________ PROPHASE METAPHASE ANAPHASE TELOPHASE ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________

34. Interphase Metaphase Telophase Prophase Anaphase

35. Can You Put These Plant Cells In The Correct Sequence Of Mitosis? 4. Anaphase 1. Interphase 3. Metaphase ___________________ ___________________ ___________________ 2. Prophase 6. Interphase 5. Telophase ___________________ ___________________ ___________________

36. Cancer Abnormal cell growth • Cancer cells are abnormal cell growth due to either a: • malfunction in the Cell Cycle • change in the genes during DNA replication during the S phase of Interphase Cancer cells do not carry out normal, necessary functions.

37. Cancer cells form disorganized clumps called tumors. • Benign tumors remain clustered and can be removed. • Malignant tumors metastasize, or break away, and can form more tumors. Blood cells Normal cells Mutated cell Cancerous cells

39. Cancer • Carcinogens are substances known to promote cancer. • UV radiation • Chemicals such as formaldehyde, asbestos, arsenic, benzene… • Tobacco smoke • Standard cancer treatments typically kill both cancerous and healthy cells.

41. Stem Cells Stem cells are unique body cells. • Stem cells have the ability to • divide and renew themselves • remain undifferentiated in form • develop into a variety of specialized cell types

42. Stem Cells Some people save the placenta or umbilical cord to harvest these

43. Stem Cells • The use of stem cells offers many currently realized and potential benefits. • Stem cells are used to treat leukemia and lymphoma. • Stem cells may cure disease or replace damaged organs. • Stem cells may revolutionize the drug development process.

44. Henrietta LacksThe Immortal Hela cells • Basic Information • Please Do Now: • Write 4 LINES about your reaction to this video • Was the action of the scientists right or wrong? Why? • Include at least 1 fact about cancer from your notes or the video.