A General Outlook on Meiosis and Mitosis Processes
Compare and contrast mitosis and meiosis. Think phases, starting and ending products, chromosome numbers, the purpose of each, and the cell types that complete each type of division. Be sure to do a DIRECT compare and contrast, and write in paragraph form - Mitosis involves one cellular division resulting in identical daughter cells while meiosis involves two cellular divisions resulting in different daughter cells. Meiosis produces four haploid cells while mitosis produces two diploid cells- this ensures genetic diversity by sexual reproduction in meiosis and cellular reproduction and production of general growth products in mitosis. The chromosome number also remains the same in mitosis but is reduced by half in meiosis.
On the other hand, both processes involve cellular divisions through the different phases of prophase, metaphase, anaphase and telophase.
Describe the differences in Cytokinesis for plant and animal cells - Because animal cells lack a cell wall, cell division occurs by formation of a cleavage which then grows inwards until the cell ultimately divides into two daughter cells. On the other hand, because of the presence of a cell wall in plant cells, Golgi vesicles fuse together at the middle of the cell forming a cell plate which has all the components necessary for the formation of a new cell wall. The cell plate then divides the cell into two.
Draw a pair of replicated homologous chromosomes in metaphase of mitosis. Label the homologous pairs, sister chromatids, centromere, mitotic spindle, and centrosome.
Differentiate between the centromere and kinetochore - The centromere is the central region of a eukaryotic chromosome forming the linkage between sister chromatids while the kinetochore is the protein structure in eukaryotes which develops on the centromere and provides an attachment for spindle fibers during mitosis
Draw a karyotype, 2n=8, with monosomy for chromosome 3. Draw a karyotype for 3n = 9.
2n = 8
3n = 9
Do a Google search and explain why the rate of non-disjunction in meiosis increases with a woman’s age. This leads to a higher incidence of what syndrome? The activities of the spindle assembly checkpoint reduce with age making them less effective as a woman advances in age. The elements holding together chromosomes also weaken with time and this may increase rates of non-disjunction. These lead to a higher incidence of Turner Syndrome.
Explain why human gametes are haploid. Why is this essential for the continuation of our species? - Human gametes are haploid since they are produced by sexual reproduction through meiosis. They thus must be haploid to balance the number of chromosomes from both sexes forming the new sexually reproduced cell. This haploidy and hence sexual reproduction is essential in ensuring variation from parent cells that assures the survival of the human species from generation to another. Diploidy leads to many deleterious traits that can prove detrimental to our survival as humans.
Explain how meiosis is essential for genetic diversity of the human species. Be sure to include the terms crossing over, chiasma, synapse, bivalent, and tetrad - During meiosis homologous chromosomes pair up to form a synapse and they then cross over with each other and often exchange chromosome segments. At this stage, the sister chromatids are tightly aligned side by side along their entire length and the two duplicated chromosomes forming the bivalents are connected at distinct points. Each linkage, known as a chiasma represents a crossover between two non-sister chromatids. The result of the meiotic process is four different daughter cells, also called a tetrad.
Fill in the chart below with respect to what happens in each phase and what you would look for to identify each phase.
On the following image, label one cell showing each phase (Interphase, prophase, metaphase, anaphase, and telophase). Justify your identification
