Question

Please explain very short and briefly.

1. Describe how ‘sister chromatids’ are different from ‘homologous chromosomes’.

2. Are diploid cells the only cells that can undergo mitosis? What about haploid or tetraploid cells?

3. Genetic variability is created during meiosis. Identify how this variability is created.

4. What is the most challenging aspect of learning about the processes of mitosis and meiosis?

Answer 1

1. All the diploid cells have two sets of chromosomes, one from the father origin and another from the mother's origin, these are called homologous chromosomes as they have same genes at the same location. But there might be variability between the genes present in the same locus of the homologous chromosomes.

On the other hand, at the time of meiosis, each of the chromosomes undergo replication and the produced daughter chromatids are attached together at the centromere region for each of the homologous chromosomes. These two chromatids which are attached together are called sister chromatids of each other. Both the sister chromatids contain identical genetic material.

2. Mitosis is a type of cell division, where the daughter cells contain the similar number of chromosomes as the mother cells.

So, mitosis is not only possible for the diploid cell, it can occur in all kind of cells including haploid, tetraploid, hexaploid etc.

3. At the time of meiosis, crossing over takes place between the non-sister chromatids of the homologous chromosomes and the transfer of the genetic material takes place. As the homologous chromosomes have variability, transfer of the genetic material between the non-sister chromatids will create variability between sister chromatids.

4. In my opinion, both the processes have their own level of complexity and they are intriguing as well. Both the mitosis and meiosis have two phase, one is interphase where the cell prepare for the cell division and make all the cellular organelles double including the genetic material, followed by the cell division. For, the mitosis one round of DNA replication followed by one round of cell division. But for the meiosis, one round of DNA replication followed by two rounds of cell division. I think the most challenging part is, how the cell orchestrated so many things in a very regulated sequencial manner without any or very negligible mistake.