1. Honors Biology Spring 2013

2.  With your neighbor, discuss the following:  What does “The Cell Cycle” refer to?  What are the main stages?

3.  What are the stages of cell of the cell cycle?

4.  Why reproduce? Why not just get larger?

5. A. Cell Sizes most cells are between 2 and 200 μ m in diameter B. Diffusion limits cell size C. DNA limits cell size D. Surface Area to Volume Ratio limits cell size

6. A. Overview of Reproduction 1. A characteristic of all living things 2. One cell - parent cell - divides and forms new cells called the daughter cells 3. Reproduction of the organism depends on the reproduction of the cell a. unicellular organisms b. multicellular organisms

7. A. Overview of Reproduction 4. When a cell reaches a certain size, it divides into daughter cells which are similar in structure to the parent cell 5. Organisms reproduce in 2 basic ways a. asexual reproduction b. sexual reproduction

8. B. Chromosomes 1. Chromosomes are the carriers of the genetic material  made of sections of DNA known as genes 2. become visible right before mitosis 3. # of chromosomes is characteristic of a species 4. cells contain the diploid number of chromosomes

9.  Structural review  Chromosomes are composed of 2 identical sister chromatids attached by a centromere  Near the centromere is a kinetochore which is important for attaching the chromosome to the spindle during prophase

10.  Diploid- a cell with two of each kind of chromosome; 2n; complete set  Haploid- cell with one of each kind of chromosome; n; ½ set  In mitosis & cytokinesis, 1 diploid cell splits into 2 diploid daughter cells

11. human hapliod number?  23 human diploid number?  46 most all human cells are diploid,  46 chromosomes

13. C. Cell Cycle 1. The sequence of growth and division of a cell 2. Two general periods a. growth – interphase b. division - mitosis & cytokinesis

15.  The pattern of growth, DNA duplication, and cell division that occurs in eukaryotic cells  4 main phases  Gap 1 (G1): interphase  Synthesis (S): interphase  Gap 2 (G2): interphase  Mitosis (M): mitosis and cytokinesis

16.  G1:Cell caries out normal functions and grows  S: DNA is copied (2 sets)  G2: Cell caries out normal functions and grows  A cell spends most of its time in Interphase (90%)  Genetic material is chromatin

17. Phases of Mitosis - cell division of a eukaryotic somatic cell 1. Prophase 2. Metaphase 3. Anaphase 4. Telophase 5. Cytokinesis

18.  Nuclear envelope & nucleolus disappear (prometaphase)  Chromatin condenses into chromosomes  Centrioles move to opposite ends of cells (animals)  Spindle (microtubules) begins to form  Longest part of mitosis

19.  Doubled chromosomes become attached to the spindle by their kinetochores/ centromeres (prometaphase)  The chromosomes are pulled by the spindle and they begin to line up along the equator of the cell

20.  Centromeres split apart  Sister chromatids pull away from each other because of the shortening of the microtubules in the spindle fibers  Each chromatid is now considered a full-fledged chromosome

21.  Chromatids reach opposite ends of the cell  Chromosomes unwind back into chromatin  Spindle breaks down  Nuclear membrane and nucleolus reappear

22.  Division of the cytoplasm  Usually begins before Telophase is complete  Each daughter cells leaves cytokinesis to start interphase again  Differences in plant and animal cells Cleavage furrowCell plate

26.  Result of mitosis= 2 daughter cells that are genetically identical to the 1 original cell  Rate of mitosis varies on the cell and organism  Mitosis is controlled by enzymes

27.  How does mitosis differ in plant and animal cells?

28. plant cells do not have use a cleavage furrow to separate plants use a cell plate to split parent cell in two the cell plate becomes the cell wall of the two daughter cells

29.  Why would control of cell division be important?

30. Prokaryotes have a single circular chromosome B. Binary fission