Week 5 - Endosymbiosis, Division Cycle of Plant Cell and Totipotency

This week, we learnt about “Endosymbiosis”. Frankly speaking, i have no idea about endosymbiosis at first. Thus, it is an excitement for me to learn a new thing. Its theory suggests that heterotrophic bacteria became mitochondria and cyanobacteria became chloroplasts. Before this, I already know that mitochondria and chloroplast are little bit special organelles than others as they have their own DNA but it never acrosses my mind about why and what are the functions they are having that specialty. Maybe I thought they are always like that from the beginning. Long time ago, eukaryotic cell was without mitochondria and chloroplast but then the cell engulf them simultaneously. The scientists also found evidences that show mitochondria and chloroplasts are closely related to bacteria prokaryotic cells that support their theory that those two were once free living cells. In the class, we do the Venn Diagram for mitochondria and chloroplasts during SCL activity. This helps me to see clearly about what is different and same between them.

Next, we learn about “Division Cycle of Plant Cell and Totipotency”. Like other students, I am familiar with the cell cycle but the word totipotency is wholely new. About the cell cycle, some part is the same like we learn during the foundation but now we get new things like the passage of a cell through the cell cycle is controlled by proteins in the cytoplasm which is known as Cyclins. Cyclin is like the determining factor because Cdk only activated when binds to it so that they can add phosphate groups to a variety of protein substrates that control processes in the cell cycle. I am amazed that the cell cycle is like a factory. They work efficiently that at some point when they detect damage in the DNA, they repair it and if cannot be repaired, the cell destructs itself by apoptosis. I found it is great to learn about cell cycle. Moreover, I can also learn about cell cycle by playing games. There are a lot of simulations that help me understand better this topic. This week end with our learning about cell cycle. I am impatiently to learn next part especially about totipotency.