CELLULAR REPRODUCTION

1. CELLULAR REPRODUCTION BINARY FISSION & THE CELL CYCLE (INTERPHASE – MITOSIS – CYTOKINESIS)

2. Vocab you should know… • Cellular reproduction: the way that cells reproduce • Asexual reproduction: reproduction that does not involve the union of gametes; where one parent produces offspring that are genetically identical to it • Sexual reproduction: reproduction where gametes from two parents unite to form offspring

3. More vocab… • Binary fission: division of a prokaryotic cell into two offspring cells • Mitosis: period of nuclear cell division in which two daughter cells are formed, each containing a complete set of chromosomes • Interphase: cell growth phase where a cell increases in size, carries on metabolism, and duplicates chromosomes prior to division

4. More vocab… • Prophase: 1st & longest phase of mitosis where chromatin coils into visible chromosomes • Chromatin: long, tangles strands of DNA found in the eukaryotic cell nucleus during interphase • Chromosomes: cell structures that carry the genetic material that is copied & passed from generation to generation of cells

5. More vocab… • Metaphase: short second phase of mitosis where doubled chromosomes move to the equator of the spindle & chromatids are attached by centromeres to a separate spindle fiber • Chromatids: one of the two strands of a chromosome that become visible during meiosis or mitosis • Centromeres: region of the chromosome that holds the two sister chromatids together during mitosis

6. More vocab… • Anaphase: phase of mitosis where centromeres split and the chromatid pairs of each chromosome are pulled apart by microbtubules • Microtubules: thin, hollow cylinders made of protein that provide structural support for eukaryotic cells

7. More vocab… • Telophase: final phase of mitosis during which nuclear membranes form around each new set of chromosomes • Haploid: cell with one of each kind of chromosome (n) • Diploid: cell with two of each kind of chromosome (2n)

8. More vocab… • Cytokinesis: cell process following mitosis in which the cell’s cytoplasm divides & separates into two new daughter cells • Cell plate: precursor of a new plant cell wall that forms during cell division & divides the cell into two

9. CELLULAR REPRODUCTION - BASICS • Two basic types: • Asexual • Sexual

10. Prokaryotic Reproduction • Binary fission • It’s a form of asexual reproduction • Most prokaryotic cells reproduce this way

11. Binary Fission

12. Eukaryotic Cell Reproduction: The Cell Cycle • Cell cycle: repeating set of events in the life of a cell, made of 3 phases • Interphase: time between cell divisions, duplication of DNA & cell parts • Mitosis: reproduction & division of nucleus • Cytokinesis: division of cytoplasm & formation of new cells • Cell Cycle Simulation

13. INTERPHASE • Longest phase of cell division; divided into 3 phases; After cell division: offspring cells are about ½ the size of the parent cells • G1 phase: cell growth – offspring cells grow to adult size • S phase: DNA is copied • G2 phase: cell growth & preparation for division • Kangaroo rat interphase

14. Interphase • Interphase: organelles double in #, DNA replicates, protein synthesis occurs, chromosomes are not visible b/c DNA appears as uncoiled chromatin.

15. MITOSIS • Divided into 4 different phases • Follows interphase • Is followed by cytokinesis

16. Mitosis: Prophase, step 1 • Nuclear membrane & nucleolus disappear; chromatin condenses & chromosomes become visible as chromatids; sister chromatids pair up; spindle fibers are assembled. • Kangaroo rat prophase

17. Mitosis: Metaphase, step 2 • Sister chromatid pairs line up along the cell's equator; spindle fiber attach to the centromeres holding them together. • Kangaroo rat metaphase

18. Mitosis: Anaphase, step 3 • Sister chromatids split apart at the centromere as the spindle fibers shorten and “pull” them toward opposite poles; cleavage furrow appears. • Kangaroo rat anaphase

19. Mitosis: Telophase, step 4 • nuclear membrane & nucleoli reform, cleavage furrow deepens; spindle fibers disappear; chromatids uncoil to chromatin. Kangaroo rat telophase

20. Cytokinesis; last phase of cell cycle • Follows mitosis; • dividing cell separates into 2 diploid daughter cells • Different in animal and plant cells

21. Cytokinesis in animal cells • animal cells lack a cell wall and are surrounded only by a plasma membrane • Cleavage furrow deepens until the two furrows meet & pinch apart the cytoplasm creating two separate cells • Cytokinesis real time • Kangaroo rat cytokinesis

22. Cytokinesis in Animal Cells

23. Cytokinesis in plant cells • plant cells are surrounded by a cell wall in addition to the plasma membrane • A cell plate is formed along the equator of the cell & separates the cytoplasm into two daughter cells.

24. Cytokinesis in plant cells

25. Cellular Reproduction Quiz • What are the two basic types of cellular reproduction? • Binary fission is a type of _________ reproduction. • What are the 3 phases of the cell cycle in eukaryotic reproduction?

26. Quiz Cont’d • What happens to the DNA during interphase? • What are the 4 phases of mitosis? • During what phases of mitosis do the duplicated chromosomes line up at the equator? • During which phases do the sister chromatids move towards opposite poles?

27. Quiz Cont’d • During which phase does the nuclear membrane reform? • How many cells are there at the end of cytokinesis? • What is different in plant cell cytokinesis than in animal cell cytokinesis?