Summary

            Hi!

  From these 7 past weeks, I have recalled and learned new knowledges which is related to Cellular and Developmental Biology that I am currently taking.I  noticed that I am still lacking and that Biology is not just a subject but it is a wide field of knowledge. I love studying Biology since highschool because it tells us about every little living things from the microscopic bacteria to the , historical giant dinosaurs. I have learned about the evolution, history of life ,prokaryote, eukaryote, endosymbiosis theory,  cell cycle in plant, development of plant embryo and plant hormones.
Other than knowledge, when I did this journal I get to do my revision after I have learned the topics.Thus,  this increase my understanding and without realizing I actually started to memorize some of the terms.

                
             I also realize that we need to prepare before entering the lecture. For example,  we could read the note given  before the lecture starts, make a short note, highlight the key points or important informations like terms and process.I also realized that  a video based on the topics can also be a great help for me to understand the topic. Not only that, the SCL activity helps a lot because I can discuss the things that I'm not sure and understand fully in class.This make learning biology much more fun.Although, there are things that I am weak at especially the last 3 topics which is cell cycle in plant, development of plant embryo and plant hormones, I can find a way to understand it. When there 's a will, there 's a way.                  

The regulation of developmental and Differentiation Hormones

 Hello !

This is the last week which is the 7th week. This week is even hectic then before due to class being cancelled due to the haze in Malaysia. We have to discuss the work plan for Training Scientist Programme that should be on 29th October but it being posponed to 5 November due to the terrible haze that affecting the school 's examination period. However, we did learned a bit about hormones in plants.

       From my understanding,hormones in plants are :

•  Auxin- it stimulate elongation of stems and fruit development
• Cytokinin- it stimulate elongation  of cells and delay the aging in plants
• Gibberelins- it is for fruit ripening
• Abscisic acid-Stimulates the closure of stomata ,inhibits shoot growth but will   promote growth of roots and inhibits the affect of gibberellins.
• Ethylene-It can stimulate fruit ripening

  Auxin is mostly found in shoots apical meristem while cytokinin is mostly found in roots, embryo, and fruits.Both of them need each other but ,if cytokinin is higher in the cell, shoots will form and if auxin is higher roots will form. This is what most botanist applied in growing plants that they desired and cultured plant.

               This is the only parts that I have fully understand whereas the rest of it I will watch a video on the topic and maybe I could ask for my friends help and Dr. Parameswari 's guidance.

Pollination and Development of Plant Embyo

         

                            Good Evening!

         This is the 6th week I  am studying in this course. This week is quite hectic but luckily it   did not affect me in a bad way. This week, I have learned about pollination and development of plant embryo. I did recall what I have been taught at secondary school whereas plants undergo pollination which is self-pollination and cross-pollination. Some plants need the help of a pollination agent such as animal and wind according to their own characteristics.

 

 Pollination is the transfer of pollen in the anther to the stigma and then proceed into the part of a seed plant containing the ovules. Initially, the pollen grain sticks to the stigma and germinate. It will divide by mitosis to produce two sperm cell. One sperm cell will fertillize with the egg cell and one sperm cell will fertilize with two polar nulei.This process is called double fertillization.  It was quite easy since I am just recalling the things that I have learned in the past.

The new things that I have learned this week is  plant embryogenesis which is the process that produces a plant embryo from a fertilised ovule by asymmetric cell division and the differentiation of undifferentiated cells into tissues and organs. It occurs during seed development, when the single-celled zygote undergoes a programmed pattern of cell division resulting in a mature embryo.From what I understand is that after the plant fertillized, it divide mitotically until it forms a mature embryo.

For somatic embryogenesis, there will not be a fussion of gametes and they will not form a suspensor which is necessary for normal development of embryo. I will try to search for a more detailed information especially videos since its easier and more convincing. I can't believe that next week is the last class with Dr. Parameswari .

Division Cycle of Plant Cell and Totipotency

                                                         
                                                    Hey there!
                           
          I would like to share what I have learned on the fifth week in Cellular and Developmental Biology classes. On this week, we have learned about Cell Cycle and Totipotency.I have learned about cell cycle in highschool but never heard of totipotency before. I think it was an interesting new knowledge.

                Firstly, the cell cycle is an ordered set of events, resulting in cell growth and division into two daughter cells.It happens in both plants and animal cells. It consist of G1 phase, S phase, G2 phase , Mitosis and Cytokinesis.  Mitosis consists of Prophase, Metaphase, Anaphase and Telophase. There are  regulations of the cell cycle which means the passage of a cell through the cell cycle is controlled by proteins in the cytoplasm-Cyclins. This is quite new to me and I did not understand about it before but along the lecture, one by one was explained and I came to some sort of understanding.
 The cytoplasm- cylins are :                  Cyclin-dependent kinases(Cdks)
  •a G1 cyclins (D cyclins)                     •a G1 Cdk (CdkA)
•S-phase cyclins (cyclin A)                    •an S-phase Cdk (CdkB)
•mitotic cyclins (B cyclins)                    •an M-phase Cdk (CdkB)                                  
                                                                     
                                                                     
                          Any damage to DNA before the cell enters S phase inhibits the action of Cdk2 thus stopping the progression of the cell cycle until the damage can be repaired. If the damage is so severe that it cannot be repaired, the cell self-destructs by apoptosis while any damage to DNA after S phase (the G2 checkpoint), inhibits the action of Cdk1 thus preventing the cell from proceeding from G2 to mitosis. 

                

                    After we had finished discussing about cell cycle, we also had learned about totipotency. From my understanding on the topic, totipotency is the ability for a single cell to develop into a whole organism.This happens because it contains the entire genetic information in its nucleus.

If  a we culture a plant cell it can become  a callus which is made up of a group of unorganized loose parenchyma cells which proliferate from parent cells through de-differentiation before becoming an embryo through re-differentiation or it could also from a callus into an organ. A plant cell can also become an organ without being an embryo  or callus.

 Manipulation of the auxin to cytokinin ratio in the medium can lead to the development of shoots, roots or somatic embryos from which whole plants can subsequently

             I am particularly interested in this topic and I am actually excited when I hear that we will eventually do a plant culture in another semester. I think I  still not very clear some parts in cell cycle but I will find a video that will help me learn. The next topic that we will learn next week is pollination and development of plant embryo. I can't wait~

Endosymbiosis

Hi!!

                            Its already 4 weeks.Wow, time flies so quickly!In our lecture, we had already covered the endosymbiosis theory which was new to me. I find that it 's hard to  believe since nobody have seen it happened before and ever since middle school, I 've thought that mitochondria and chloroplast was naturally there like any other organelles.However, now that I've learned endosymbiosis theory, I honestly kinda feels confuse but as a student I will try to understand the concept of it and memorize it accordingly.It is kinda funny because I imaged it like the game 'PacMan' since from my understanding endosymbiosis is about a large ancestral eukaryotic cell engulfed two smaller prokaryotes and became  the eukaryote as it is now. The two smaller prokaryote; one of them were a heterotroph while the other were autotroph.Even though , after being engulfed it did not die and self-replicate in the larger ancestrial  eukaryotic cell itself which then became an eukaryote.

Endosymbiosis theory suggests that:

•eukaryotes arose from a symbiotic relationship between various prokaryotes.

•heterotrophic (aerobic) bacteria became mitochondria.

•cyanobacteria (photosynthetic) became chloroplasts.

•host cell was a large eukaryotic cell.

                         Based on what I have learned,  some scientists have approved of the theory due to some evidences that they have found from their observation. This is because mitochondria and chloroplasts are similar in size and morphology to bacterial prokaryotic cells like reproduction system which is by binary fission, just as bacteria do, their chemically distinct membrane systems and ect. We did discussed all the similarities that linked mitochondria,chloroplast ,eukaryotes and prokaryotes  together in the lecture as shown below and we did an SCL activity which is a Venn Diagram on the similarities and differences of mitochondria and chloroplast.Its easier to understand since it is classified systematically.

 

There are a lot of new things that I have learned this week.  As for next week, Dr.Parameswari is going to teach us cell cycle and totipotency.I hope I will understand the topic better.