How Cells Reproduce

1. How Cells Reproduce Chapter 8

2. Have you ever wondered… • How you grow from one cell to billions? • How your cuts heal? Hair grows? • How some animals regenerate lost parts? The Answer Is _______!!!

3. FUN FACT: ___________________ ______________________ • Rudolph Virchow came up with this great idea in 1858. • Its importance is huge • If you start as one cell and end up with millions… that means there is a lot of cellular division happening… • In that case lets study it!

4. The process of division depends on who you are and what you want… • Prokaryote: • All are unicellular so any _________ is __________ and all reproduction is asexual (called binary fission) • Eukaryote: • Unicellular ones… all reproduction is asexual but they use mitosis • Multicellular • ________ for repair, increasing size, and replacement of damaged cells • ______ for sexual reproduction… making egg and sperm

5. Asexual Reproduction • Like a Xerox machine. • DNA comes only from one parent making variation dependent on ______ _______and __________ • Organisms can be only asexual or both depending on the circumstance • Regeneration • Budding (cactus) • Mitosis (we’ll come back to it)

6. Before we can get to Mitosis we need to start with the chromosome… • For the majority of DNA’s life it exists as _______… chromosomes + protein associated, loosely packed • When a cell is going to divide the DNA packs up tightly into ______________.

7. Cell cycle… INTERPHASE • A cell is undergoing changes at all times • Every moment of a cells life ________ ________ is called INTERPHASE • In this time it gets prepared to divide • Makes proteins, lipids, carbohydrates and organelles. Grows, metabolizes etc (___ or gap 1) • ____________ its DNA (S phase) • Prepares for mitosis(__ or gap 2)

8. Not all cells are destined to divide • Some cells, like adult _______ will _____ _____ __ living life but not ready to divide • Some cells, like skin cells, are _____ _______ though the cell cycle • At the end of G1, G2, and during divisionthere are _________, like stop lights, that must be ‘green’ for the cell to continue though the cycle. • More on this later!

9. Duplicating DNA (S-Phase) • Before it divides it has to duplicate… • Each chromosome makes a Xerox so that it has a _____ of chromatids (we call them _______ _________) • They are joined by a __________ and when the cell divides each new cell grabs its chromatid by the centromere ** NOTE… it’s a chromosome before and after division… when its doubled its called sister chromatids

10. M phase-- MITOSIS • After interphase… • Nuclear Division • P__________ (one and two) • M__________ • A__________ • T__________ • Before cytoplasm division (c____________)

11. Prophase • Early prophase • Time when chromosomes appear • Nucleolus disappears • Late prophase • Nuclear membrane breaks apart • Microtubules grab the centromere making a structure called the kinetochore • Chromosomes begin to move Centriole

12. Metaphase • Spindle fibers line the chromosomes up at the metaphase plate… all ready to break apart

13. Anaphase • Sister chromatids break apart and move to opposite poles (sides) • Make little A looking things… remember A for Anaphase! • The other spindle fibers (that are not forming kinetochores push apart to elongate the cell)

14. Telophase • Reversal of prophase… the nuclear membrane, then nucleolus reappear • The chromosomes go back to chromatin • As the cell begins cytokinesis a cleavage furrow forms

15. BUT WE’RE NOT DONE… cytokinesis • Once nuclear division is over the cytoplasm must be divided • This splits up the _________, _______, _____ and _______… everything but the DNA • Accomplished by the spindle fibers

16. Affecting cell division • Cells will grow more or less based on their surroundings • _________ _______ is when cells won’t grow unless with other cells that are the same. • ________ ______ is when cells stop dividing once they reach their max capacity (like a full room) • Growth factor: when one cell makes and secretes a protein that tells other cells to divide

17. Check-points of Mitosis • What happens if cell division gets out of control? • So what do we do to stop it? Cell cycle control system • 3 major check points • G1 • G2 • M • Each go ahead sends the cell further into dividing • Non- dividing cells such as muscle and nerve receive stop signals at the _____ phase. • If a cell is damaged it will not have the proper signal to divide and thus will abort its reproduction… the mechanism of this is called signal transduction

18. When Mitosis gets out of control • Cells that undergo uncontrolled division are tumor cells • Their divisions cause them to pile up making a tumor • The tumor can be malignant or benign • benign means the cells are okay… like a mole • malignant means the cells kill the good tissue as they go and can break off or metastasize to other cells

19. Cancer Nomenclature • Each cancer is named from where it originated • Carcinoma: from the covering or lining (epithelium) either in the gut or on the skin (includes lung) • Sarcoma: supportive tissue, bone or muscle • Leukemia: of the blood or blood forming tissues • Lymphoma: lymph or lymphatic organs (spleen)

20. Cancer Treatments • Treatments: • Surgery: cut out as much of the tumor as possible • Radiation therapy exposes a localized area to large amounts of radiation which halt cell division in the area • Chemotherapy supplies a poison to the whole individual slowing cell division • it works better…but it also effects many normal cells