It’s the third week of lecture. Today, it was all about cell theory and prokaryotes. We were introduced to 3 cell theories of life:

- All living things are made up of cells.
- The cell is the basic unit of life in all living things.
- New cells arise from the pre-existing cells.

However, modern cell theory has additional 4 statements which are:

- the cell contains hereditary information (DNA) which is passed on from cell to cell during cell division.
-all cells are basically the same in chemical composition and metabolic activities.
- all basic chemical and physiological functions are carried out inside the cells including movement, digestion and homeostasis
-cell activities depends on the activities of subcellular structures within the cell which are the organelles, nucleus and plasma membrane.

Later, Dr. Parames introduced 2 types of cells which are prokaryote and eukaryote. At first, I thought that prokaryotic cell is pretty easy to me because it is just a unicellular organism without membrane bounded organelles. However, when I studied a bit more detail, I found that actually it was not as simple as it looks. Previously, I only knew that cell wall is always composed of cellulose but in fact that is just for plants, while the bacterial cell wall is composed of peptidoglycan.

Besides, the gram-positive bacteria and gram-negative bacteria are new to me as well where the gram-positive bacteria absorb and retain crystal violet stain due to its thick cell wall while gram-negative bacteria appear red because of the thin cell wall and thick outer membrane.
 

Later, we sat in our own group and make a venn diagram on the similarities and differences between archaebacteria and eubacteria. I think that was such as effective way of teaching because through the venn diagram we could see the similarities and differences clearly. In addition, that venn diagram can be part of our notes as well. So why don’t we do this often? In the next lesson, we discussed about viruses, viroids and prion.