Week 4
HAI... we meet again for my week four. for the week four i learn about cell division of plant cell and totipotency. Actually about cell division and totipotency i already study it for SPM and in Asasi. It is basic about mitosis and meiosis but for totipotency i already forgot actually. Hahaha.. For what i know totepotency is the ability of single cell of plant to divide and produce all of the differentiated cells in the plant.
Before we go with the totipotency, we discuss first about cell division in plant. For the topic cell division in plant our lecture not discuss in more detail about mitosis and meiosis but we discuss about interphase. For your information interphase is the longest phase.
In interphase we have G1 phase, S phase and G2 phase. The G1 phase, or Gap 1 phase, is the first of four phases of the cell cycle that takes place in eukaryotic cell division. In this part of interphase, the cell synthesizes mRNA and proteins in preparation for subsequent steps leading to mitosis. G1 phase ends when the cell moves into the S phase of interphase. At G1 has checkpoint 1. Cell cycle checkpoints are control mechanisms in eukaryotic cells which ensure proper division of the cell. Each checkpoint serves as a potential point along the cell cycle, during which the conditions of the cell are assessed, with progression through the various phases of the cell cycle occurring when favorable conditions are met. Currently, there are three known checkpoints: the G1 checkpoint, also known as the restriction or start checkpoint; the G2/M checkpoint; and the metaphase checkpoint, also known as the spindle checkpoint. For G1 checkpoint is the main decision point for a cell which it must choose whether or not to divide.
S-phase (synthesis phase) is the part of the cell cycle in which DNA is replicated, occurring between G1 phase and G2 phase. Precise and accurate DNA replication is necessary to prevent genetic abnormalities which often lead to cell death or disease. then it go to G2. G2 phase, or Gap 2 phase, is the third and final subphase of Interphase in the cell cycle directly preceding mitosis. It follows the successful completion of S phase, during which the cell's DNA is replicated. G2 phase is a period of rapid cell growth and protein synthesis during which the cell readies itself for mitosis. As usually in mitosis has 4 phase which is prophase, metaphase, anaphase and telophase.
At mitosis has metaphase checkpoint. During metaphase, the kinetochore microtubules pull the sister chromatids back and forth until they align along the equator of the cell, called the equatorial plane. There is an important checkpoint in the middle of mitosis, called the metaphase checkpoint, during which the cell ensures that it is ready to divide.
Ok we finish about cell cycle. Now we continue with totipotency. Totipotency is used in plants tissue culture. There are two pathways of regeneration: Organogenesis and Somatic embryogenesis
Organogenesis is the development of adventitious organs or primordia( embroid) from undifferentiated cell mass(callus) in tissue culture. Use auxin and cytokinins to lead the development of shoot, root or somatic embyos.
Factors that affect cellular totipotency are source of explant, nutrient media and constituents, and culture environment.
the topic of cell division of plants cell and totipotency i learn on tuesday and on Thursday i have virus, viroid and prion's quiz. I just manage to get 12 out of 20. it so awfull. ARGHHH....
Thats all i want to share with you all about topic that i learn this week. This week is more light because i just need to revise back what i have study in the past years but also there is a few new knowledge that i get from this topic. But for the quiz on virus. viroid and prions is not good at all. I must study more because next week i will have test 1. I hope i can answer the test 1 well.
GOODBYE EVERYONE... Wish me LUCK on my test...
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