1 Cell Reproduction

2 Types of Cell Reproduction Asexual reproduction involves a single cell dividing to make 2 new, identical daughter cells Asexual reproduction involves a single cell dividing to make 2 new, identical daughter cells Mitosis & binary fission are examples of asexual reproduction Mitosis & binary fission are examples of asexual reproduction Sexual reproduction involves two cells (egg & sperm) joining to make a new cell (zygote) that is NOT identical to the original cells Sexual reproduction involves two cells (egg & sperm) joining to make a new cell (zygote) that is NOT identical to the original cells

3 Cell Division All cells come from pre-existing cells All cells come from pre-existing cells New cells are produced for growth and to replace damaged or old cells New cells are produced for growth and to replace damaged or old cells Differs in prokaryotes (bacteria) and eukaryotes (protists, fungi, plants, & animals) Differs in prokaryotes (bacteria) and eukaryotes (protists, fungi, plants, & animals)

4 Keeping Cells Identical The instructions for making cell parts are encoded in the DNA, so each new cell must get a complete set of the DNA molecules

5 DNA Replication DNA must be copied or replicated before cell division DNA must be copied or replicated before cell division Each new cell will then have an identical copy of the DNA Each new cell will then have an identical copy of the DNA Original DNA strand Two new, identical DNA strands

6 Identical Daughter Cells Parent Cell Two identical daughter cells

7 Cell Division in Prokaryotes

8 Prokaryotes such as bacteria divide into 2 identical cells by the process of binary fission Prokaryotes such as bacteria divide into 2 identical cells by the process of binary fission Single chromosome makes a copy of itself Single chromosome makes a copy of itself Cell wall forms between the chromosomes dividing the cell Cell wall forms between the chromosomes dividing the cell

9 Binary Fission of Bacterial Cell

10 E. Coli Dividing by Binary Fission

11 Cell Division in Eukaryotes The Cell Cycle

12 Five Phases of the Cell Cycle G 1 – 1 st Growth Phase S - Synthesis Phase G nd Growth Phase M - Mitosis C - Cytokinesis

13 The Cell Cycle G1 - primary growth phase G1G1G1G1 Newly divided cell begins growth Cell is making organelles & starts carrying on its on its normal normal activities activities The Cell Cycle G1 - primary growth phase G1G1G1G1 Newly divided cell begins growth Cell is making organelles & starts carrying on its on its normal normal activities activities G 1 Checkpoint G 1 – Restriction Point

14 The Cell Cycle DNA in the cell makes an identical copy of itself S G1G1G1G1 S – synthesis; DNA replicated

15 The Cell Cycle G1G1G1G1 S G2G2G2G2 G 2 - secondary growth phase Cell has grown to full size Cell is getting ready to divide again The Cell Cycle G1G1G1G1 S G2G2G2G2 G 2 - secondary growth phase Cell has grown to full size Cell is getting ready to divide again G2 Checkpoint 2 nd RestrictionPoint M Checkpoint – all chromosomes aligned DNA & chromosomes must be replicated

16 The Cell Cycle G1G1G1G1 S G2G2G2G2 Collectively these 3 stages are called INTERPHASE

17 Interphase Cells carry on normal functions Copy of DNA (and chromosomes) is made Animal cells only – centrioles replicate also Cell gets ready to divide Original DNA Two identical copies of DNA

18 Interphase – S Stage Synthesis stageSynthesis stage DNA is copied or replicatedDNA is copied or replicated Two identical copies of DNA Original DNA

19 Mitosis “M” Phase

20 Cell divides into 2 identical cells M - mitosis The Cell Cycle Mitosis G1 S G2G2G2G2

21 Mitosis Division of the nucleus only Division of the nucleus only Only occurs in eukaryotes Only occurs in eukaryotes Has four stages Has four stages Doesn’t occur in some cells such as brain cells Doesn’t occur in some cells such as brain cells

22 Four Mitotic Stages ProphaseProphaseProphaseProphase Metaphase Anaphase TelophaseTelophaseTelophaseTelophase

23 Cells Undergoing Mitosis Metaphase Telophase Anaphase Prophase Interphase

24 Prophase Prophase What the cell looks like What’s happening

25 Early Prophase Chromosomes Nucleolus Cytoplasm Nuclear Membrane Chromatin

26 Spindle Fibers The mitotic spindle forms from the microtubules in plants and centrioles in animal cells The mitotic spindle forms from the microtubules in plants and centrioles in animal cells Polar fibers extend from one pole of the cell to the opposite pole Polar fibers extend from one pole of the cell to the opposite pole Kinetochore fibers extend from the pole to the centromere of the chromatids to which they attach Kinetochore fibers extend from the pole to the centromere of the chromatids to which they attach Asters are short fibers radiating from centrioles Asters are short fibers radiating from centrioles

27 Spindle Fiber attached to Chromatids Kinetochore Fiber Chromatids Eukaryotic Chromatid (Doubled Chromosome) Chromatids

28 Metaphase Chromatids, attached to the kinetochore fibers, move to the center of the cell Chromatids, attached to the kinetochore fibers, move to the center of the cell Chromatids are now lined up at the equator Chromatids are now lined up at the equator Equator of Cell

29 Metaphase Chromatids lined at the Equator Asters at the poles Spindle Fibers

30 Metaphase

31 Anaphase Occurs rapidly Occurs rapidly Sister chromatids are pulled apart to opposite poles of the cell by kinetochore fibers Sister chromatids are pulled apart to opposite poles of the cell by kinetochore fibers

32 Anaphase Sister Chromatids being separated Spindle fibers After separation they become individual Chromosomes

33 Telophase Chromosomes reach opposite poles Chromosomes reach opposite poles Spindle breaks down Spindle breaks down Nuclear envelope reforms around each set of chromosomes Nuclear envelope reforms around each set of chromosomes Nucleolus reappears Nucleolus reappears Chromosomes lengthen, get thinner & disappear as chromatin Chromosomes lengthen, get thinner & disappear as chromatin CYTOKINESIS begins CYTOKINESIS begins

34 Cytokinesis Division of the cytoplasm Division of the cytoplasm Division of cell into two, identical halves called daughter cells Division of cell into two, identical halves called daughter cells In plant cells, cell plate forms at the equator to divide cell In plant cells, cell plate forms at the equator to divide cell In animal cells, cleavage furrow forms to split cell In animal cells, cleavage furrow forms to split cell

35 Cytokinesis Cleavage furrow in animal cell Cell plate in plant cell

36 Daughter Cells of Mitosis Have identical chromosome number and kind as the parent cell from which they were formed Have identical chromosome number and kind as the parent cell from which they were formed Identical to each other, but smaller than parent cell Identical to each other, but smaller than parent cell Must grow in size to become mature cells Must grow in size to become mature cells

37 Identical Daughter Cells Chromosome number the same, but cells smaller than parent cell

38 Review of Mitosis

39 1. ____ 2. ____ 3. ____ 4. ____ 5. ____ Name the Mitotic Stages: 7. Name this? 6. Name this?

40 Eukaryotic Cell Division Used for growth and repair Used for growth and repair Produce two new cells identical to the original cell Produce two new cells identical to the original cell Cells are diploid (2n) Cells are diploid (2n) Chromosomes during Metaphase of mitosis ProphaseMetaphase Anaphase Telophase Cytokinesis

41 Mitosis Animation Name each stage as you see it occur?

42 Mitosis in Onion Root Tips Do you see any stages of mitosis?

43 Test Yourself over Mitosis

44 Mitosis Quiz

45 Mitosis Quiz

46 Name the Stages of Mitosis: Interphase Early prophase Mid-Prophase Late Prophase Metaphase Late Anaphase Early Anaphase Early Telophase, Begin cytokinesis Late telophase, Advanced cytokinesis

47 Identify the Stages Early, Middle, & Late Prophase Late Prophase MetaphaseAnaphase Late Anaphase Telophase Telophase & Cytokinesis ? ? ?? ? ??

48 Locate the Four Mitotic Stages in Plants Metaphase Prophase Anaphase Telophase

49 Uncontrolled Mitosis If mitosis is not controlled, unlimited cell division occurs causing cancerous tumors If mitosis is not controlled, unlimited cell division occurs causing cancerous tumors Oncogenes are special proteins increase the chance that a normal cell develops into a tumor cell Oncogenes are special proteins that increase the chance that a normal cell develops into a tumor cell Cancer cells