Cell Division and Mitosis

Cell Division and Mitosis

1. Cell division in eukaryotic cells is mitosis.

2. The stages of the cell cycle are Growth 1, synthesis, Growth 2 and mitosis.

3. The stages that make up interphase are growth 1, synthesis and growth 2.

   • ANAPHASE: The spindle fibres pull on the centromere until they split; spindle pulls the sister chromatids to opposite poles of the spindle.
   • TELOPHASE: The spindle disintergrates, chromosomes unwinds to form chromatin and the nucleus and nucleolus reappear.
   • CYTOKINESIS: The division of the cytoplasm occurs, producing two new cells.

4. During interphase, DNA replication happens.

5. The four stages of mitosis are prophase, metaphase, anaphase, telophase (including cytokinesis).

6. The role of the spindle fibres during mitosis is to attach to the centromeres in the separation of chromatids.

7. PROPHASE: The nucleolus and nuclear envelope disappear, chromatin condenses into chromosomes and spindle forms.

8. METAPHASE:The chromosomes are lined up across the equator of the spindle.

9. If cell division becomes uncontrolled this can lead to the formation of tumours and of cancers. Many cancer treatments are directed at uncontrolling rate of cell division.

10. The name for cell division in prokaryotic cells is binary fission.

    • In binary fission, the replication of circular DNA and of plasmids. Division of the cytoplasm to produce two daughter cells, each with a single copy of the circular DNA and a variable number of copies of plasmids.

11. Because viruses are non living, they do not undergo cell division. Following the injection of their nucleic acid, the infected host cell replicates the virus particles.

12. The cell cycle is the three stages of cell division/growth: interphase, mitosis and cytokinesis.

13. To function of meiosis is to make gametes and produce genetic variation.

14. A gene is a section of DNA that codes for a protein.

    • A locus is the position of a gene on a chromosome.

15. An allele is a different form/version of a particular gene.

16. During crossing over the chromosomes twist around each other and exchange equivalent sections of DNA.

17. Mitosis produces two identical clone diploid daughter cells where as meiosis produces four individual haploid cells.

18. A mutation is a change to the base sequence of DNA.

19. A substitution is when one base/nucleotide is replaced with another.

20. Deletion is when a base/nucleotide is removed from the sequence.

21. Polyploidy is where an organism has three or more sets of whole chromosomes instead of the usual two pairs.

22. Non-disjuntion is where there are more or fewer chromosomes on one set such as 1 or 3 instead of a pair.