Exam 1 Review:  Chapter 3 - Mitosis and The Cell Cycle

cell division - The process by which a cell replicates to form two essentially identical daughter cells; the process includes the four stage nuclear division, mitosis, and cytoplasmic division = cytokinesis; upon completion of the process, each daughter cell contains the same genetic material, exact copies of the DNA, as the original cell and roughly half of its cytoplasm.

somatic cell division - The process by which all diploid cells in a multicellular organism other than the germ cells, those cells which are the immediate parents of the gametes, divide to form two essentially identical diploid daughter cells which carry the diploid number of chromosomes; the process includes the four stage nuclear division, mitosis, and cytoplasmic division = cytokinesis; upon completion of the process, each diploid daughter cell contains the same genetic material, exact copies of the DNA, as the original cell and roughly half of its cytoplasm.

parent cell - Any cell which divides by either mitosis or meiosis, followed by cytokinesis, to produce two or more daughter cells.

daughter cells - Those cells, usually two in number, which are produced when a parent cell divides by either mitosis or meiosis, followed by cytokinesis.

mitosis - The process of nuclear division within the more complete process of somatic cell division, typically consisting of four stages: prophase, metaphase, anaphase, and telophase, and normally resulting in two new daughter nuclei, each of which contains a complete copy of the parental chromosomes.  aka - karyokinesis.

interphase - The name applied to the normal lifetime and metabolic activity of any cell based on the unchanging appearance of the nucleus during this period and followed by the stages of cell division; in the cell cycle it is subdivided into Growth₁, S (DNA synthesis), and Growth₂ subphases.

prophase - The first stage of mitosis (or meiosis) during which the DNA (chromatin configuration) of the cell begins the process of supercoiling to become visible chromosomes, the centrioles move toward the poles of the cell and the nuclear membrane begins to disappear.

metaphase - The second stage of mitosis (or meiosis) during which the visible chromosomes (maximally supercoiled DNA) line up at the center to form the metaphase or equitorial plate and the spindle apparatus completes its formation and attachment to the chromosomes.

anaphase - The third stage of mitosis (or meiosis) during which the chromosomes are moved away from the metaphase or equitorial plate by the spindle fibers and move toward the centrioles at the opposite poles.

telophase - The final stage of mitosis (or meiosis) during which the chromosomes of daughter cells have completed their movement toward the poles by the action of the nuclear spindle fibers and new daughter nuclei form; during telophase the chromosomes relax into their chromatin configuration and new nuclear membranes form around them.

There are some good animations of the phases of mitosis linked in the table below.  You will need Shockwave Flash software (which may be downloaded from the Internet for free) to view them.

centromere - The most condensed and constricted region of a chromosome, to which the microtubular spindle fiber is attached during mitosis or meiosis; it is also the point on the chromosome where the daughter chromatids are attached to one another; its location varies among different chromosomes in terms of its position along the length of the chromosome.

mitotic spindle - The diamond-shaped or fusiform = spindle-shaped cytoskeletal structure characteristic of a dividing cell, consisting of microtubules, some of which become attached to each chromosome at its centromere and provide the mechanism for chromosomal movement; in most animal cells, its formation begins at a centriole.  aka - nuclear spindle.

metaphase plate = equatorial plane - An imaginary plane, perpendicular to the spindle fibers of a dividing cell, along which chromosomes align in a tight cluster during the second phase of mitosis, metaphase.

equatorial division - The typical pattern of cell division in which the formation of the new cell membrane which will divide the daughter cells in the process of cytokinesis forms along the same dimension or axis as did the metaphase plate during nuclear division.

cytokinesis - The division of the cytoplasm of a cell, usually into roughly equal proportions,  following the division of the nucleus by mitosis or meiosis to produce to separate daughter cells; in animal cells, it is also called cleavage; at the molecular level, the pinching in of the cytoplasm is achieved by the movements of the cytoskeletal elements powered by ATP hydrolysis.

cleavage furrow - The pattern of cytokinesis observed in most animal cells in which elements of the cytoskeleton slide in the plane of the metaphase plate slowly pulling the cell membrane inward, creating an appearance of the outer membrane pinching in, to separate the cytoplasm of the mother cell into the two daughter cells; at the molecular level, the pinching in of the cytoplasm is achieved by the movements of the cytoskeletal elements powered by ATP hydrolysis.

cell cycle - A description of the time course and events in the life of typical cells, divided into four stages, Growth 1, S Phase (DNA synthesis), Growth 2, and cell division (mitosis or meiosis followed by cytokinesis).

G1 = Growth 1 - The first portion of the cell cycle before DNA synthesis is begun, usually the longest portion of the cell cycle, during which the cell grows to its mature size and begins to carry out its specific metabolic activities.

S-phase = Synthesis phase - The second portion of the cell cycle during which DNA synthesis occurs, usually the shortest portion of the cell cycle.

G2 = Growth 2 - The third portion of the cell cycle which takes place after DNA synthesis is complete and before nuclear and then cytoplasmic division begin; G2 is of variable length depending on cell type.

List:

11. two types of nuclear division processes.

          mitosis (in somatic cells) - meiosis (in reproductive germ or stem cells only)

12. eight stages of the cell cycle in the correct sequence.

          Growth1 - [DNA] Synthesis - Growth2 - Prophase - Metaphase - Anaphase - Telophase - Cytokinesis

13. five stages of cell division in the correct sequence.

          Prophase - Metaphase - Anaphase - Telophase - Cytokinesis

Explain:

3. Compare and Contrast the events of mitosis versus meiosis.

4. Summarize how the cells produced by mitosis differ genetically from those produced by meiosis.

5. Describe the difference in the chromosomes of prophase in mitosis compared to the chromosomes in prophase of meiosis.

Sketch and Label:

 5. a homologous pair of chromosomes.

 7. the cell cycle.

 8. mitosis.

     See Mitosis Figures.
 
10. DNA replication.

11. a replicated chromosome in metaphase.

13. a cell in prophase.

     See Mitosis Figures.

14. a cell in metaphase.

     See Mitosis Figures.

15. a cell in anaphase.

     See Mitosis Figures.

16. a cell in telophase.

     See Mitosis Figures.