Week 7 : Plant Hormone

For the final week of reflective journal on week 7, I learn about the plant hormones. In my opinion, for the 7 weeks that I have been doing reflective journal, I think it is a great idea because it enhance myself to understand the topics that I learnt even more, Furthermore, we do the reflective journal by using blog. As you know, in technology era where the information is spread faster, many people can read through my blog and gain knowledge about the informations that I've shared in my blog.The most frequent sources that I've been refer to is lecture note and also Campbell 10th edition in order to make me understand before I begin to share about the topic that I have learn.

Week 6 : Totipotency and Pollination & Development of Plant Embryo

TOTIPOTENCY

ability of  a individual plant cell/tissue/organ to regenerate into a whole plant under right condition.

 

For week 6, I learn about totipotency and pollination and development of plant embryo. As for totipotency, I learn how the explant undergo de-defferentiation to form callus and undergo re-differentiation to undergo re-differentiation to form embryo.

POLLINATION AND DEVELOPMENT OF PLANT EMBRYO  

Another topic that I learn in that week is pollination and development of plant embryo. I learn about plants reproductive organs, life cycle of angiosperms, double fertilizations and  plant embryogenesis (zygotic & somatic embryogenesis). This is an interesting topic because I learn new things which are zygotic and somatic embryogenesis.

Plants reproductive organs    

Female   

Ovule that contain megasporongium -> megaspores -> give rise to female gametophytes

Male

Anther has microsporangium ->microspores -> pollen grain (contain male gametophytes)

Life cycle of angiosperms 

   

Double Fertilization

 

Pollination : transfer of pollen to the part of a seed plant containing the ovule

When pollen grain at anther transfer to the stigma, pollen grain will germinates and give rise to pollen tube that discharges 2 sperms into female gametophyte within the ovule. One sperm nucleus fertilizes egg and generate a 2n diploid zygote.Meanwhile, another sperm nucleus fertilizes a polar cell with two 1n nuclei generating a 3n triploid endosperm that provide nutrients to the developing embryo

Plant embryogenesis

Plant embryogenesis : process that produces a plant embryo from a fertillised ovule by asymmetric cell division and differentiation of undifferentiated cells into tissues and organs

1) Zygotic embryogenesis

2) Somatic embryogenesis

 

 

Week 5 : Endosymbiosis and Cell Cycle

                                                            ENDOSYMBIOSIS

 

On week 5, I learn about endosymbiosis and also cell cycle. In endosymbiosis, I can know about the endosymbiosis theory which is a new thing for me and also about mitochondria and chloroplast. There is also an evidence of endosymbiosis regarding mitochondria and chloroplast.

Endosymbiosis Theory : 

• Eukaryotes is derived from prokaryotes

• Heterotrophic baecteria became mitochondria

• Cyanobacteria became chloroplast

• Host cell is a large eukaryotic cell

Evidence for Endosymbiosis :

• Both mitochondria and chloroplast are naturally from prokaryotes. This is because the organelles has circular DNA that does nothave introns (non coding protein) or histone whereas the eukaryotes have linear DNA and associated with histone proteins.

• The organelles also divide by binary fission which splits the cell into two. 

• The organelles is a membrane bound organelle which has inner membrane and outer membrane. The inner membrane resemble prokaryotes while the outer membrane resemble eukaryotes.    

                                                   CELL CYCLE

 Next topic is I learnt about the cell cycle which I already know since in my secondary school. But, what makes this topic interesting is, there is cyclin that control the cell cycle and also Cdks which is a new topic for me.

The Cell Cycle :
Ordered set of events, resulting in cell growth and division into two daughter cells.

 -> Multicellular cell is divide to replace lost or damage tissues and allow organisms to grow. Unicellular cell divide is to reproduce

Regulation of cell cycle :  

 

Passage of cell through cell cycle is controlled by proteins in cytoplasm (cyclin) 

• G1 cyclin (D cyclin)
• S-phase cyclin (cyclin A)
• Mitotic cyclin (B cyclin) 

Their level in cell will rise and fall with the stages of cell cycle.

Cyclin-dependent kinases (Cdks)    

The level of cell cycle become fluctuated with the activation of cyclin that is bind to the Cdks. Cdks will undergo phosphorylation that will add phosphate group to the protein substrates that control process in cell cycle.

• G1 Cdk (Cdk A)

• S-phase Cdk (Cdk B)

• M-phase Cdk (Cdk b)  

Week 4 : Cell Theory, Prokaryotes, Virus, Prions and Viroids

 On week 4, I learn about the cell theory, prokaryotes, virus, prions and viroids. there are 3 basic cell theory which are all living organisms are made up of one or more cells, cell is derived from pre-existing cell by cell division and cell is the basic unit of structure & function in living organisms.There are addition of 3 for modern cell theory.

PROKARYOTES

  

In prokaryotes it has cell wall, capsule, cell membrane, nucleoid region (DNA), flagella and pili

VIRUS

 -has genetic material (DNA & RNA)

-reproduce inside host cell

-nucleic acid surrounded by protective protein coat called capsid

some virus surrounded by outer membrane layer called an envelope made up of lipid and protein.

-Virus reproduce in 2 ways : 

1) Lytic Cycle                                                                2) Lysogeny Cycle

 

PRIONS 

 

-an infectious agent

-specific protein that prion was composed is Prion Protein (PrP)

-PrP found in infectious material

VIROIDS

 

-small circular RNA without protein coat

-contain 20 nucleotides

-infect plants 

Week 3 : History of Life

ORIGIN OF LIFE

 

For this week reflective journal, I learn about the topic of history of life which is I learn how the life is formed 4.2 billion years ago from inorganic compound that has no oxygen.

4 requirements must have existed:

1.  Little/no free oxygen-earth's early atmosphere was strongly reducing.
2. Source of energy to form organic molecules-early earth was a place of high energy
3. Availability of chemical building blocks such as CO2, N2, H2, CO, water vapour. Some NH3, H2S and CH4,little or no O2.
4.  Sufficient time for molecule to accumulate and react

The first prokaryote that I learnt is chemoautotrophs that consume organic molecules for both energy and carbon and the first autotrophs that I have learnt is photoautotrophs. It used light electron from H2O to fix CO2 into sugar. It is happen when the organic compounds from the ocean become depleted, the prokaryotes who able to make their own food can grow (autotrophs) 


As for the topics for week 3-5, I already published a week 4 topic but I republished topic in week 4 or organize my blog so all 3 weeks topic share the same date.

Week 2 : Selection in Action & SCL activities

On week 2, I learn about the topic of selection in action and SCL activities. The topic of selection in action, I learn about the concept and examples of natural and artificial selection where natural selection is a process in which individuals have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits. For example,
Finches evolved with different type of beak. Meanwhile, artificial selection is the selective breeding of domesticated plants & animals to encourage the occurrence of desireable traits. For example, Cat breeding. Cat breed to get a desireable traits.

SCL ACTIVITIES

Variation : Refers to an individual that possesses characteristics different from each other

Example include tortoise : Intermediate, doomed (in wet areas, lots of mosses) and sealed shell

Example include finches : Finches evolved to different size and type of beak.

Adaptation : Process of change by which an organism/species becomes better suited to its environment

Fossil evidence : Coral formation, volcanic island

               KEY TO INSIGHTS LED TO DARWIN'S THEORY

Artificial selection : The selective breeding of domestical plants & animals to encourage the occurance of desireable traits

Heretibility : Ability of traits to be inherited from one generation to one generation.

Struggle for survival : This fittest one who would survive

              4 MAIN PRINCIPLES OF NATURAL SELECTION
-Variation : Refers to an individual that possesses characteristics different from each other
-Overproduction : Ability of species to produce far more offspring than can possibly survive.
-Adaptation :
provides the basis for the population to adapt to environmental changes, such as the volcanic eruption on the island
-Descent with modification : Pass down adaptation from one generation to one generation

           MODERN SYNTHESIS OF EVOLUTIONARY THEORY

DNA sequence analysis
- process of determining the precise order of nucleotides within DNA molecules

Pseudogenes
- non functional sequence of genomic DNA originally derived from functional genes

Homeobox genes
- a large family of similar genes that direct the formation of many body structures during early embryonic development

Protein Comparisons
- different organisms have different protein sequence

I have been introduced to reflective journal on week 2 but I start it a bit late because of holidays and does not have internet connection at my village.

Week 1 : Historical Development of Theory of Evolution

For the topic on this week, I learn and understand about the terminologies which are speciation, species, evolution, fossil, biodiversity, vestigial structures, homologous body structure, mutations, variations. I also learn about the ideas on evolution prior to Darwin

Ideas on Evolution Prior to Darwin

 ARISTOTLE (384-322)                                         

• Arrange organisms from simple to complex.
• Visualized as not perfect but move to perfectness.

JEAN BAPTISTE LAMARK (1744-1829)

• French naturalist.
• Evolution  occur by inheritance of acquired characteristics.
• Organisms subjected to a external force
• Theory : Evolution of modern giraffe.   

CHARLES LYELL

• Book : 'Principles of Geology'
• Earth must be very old
• Subjected to natural processes in past just like present time
• Erosion, earthquakes, volcanoes
• Idea lead Charles Darwin to understand biological evolution. 

 CHARLES DARWIN

•  All species of life have evolved over time from common ancestors through natural selection.
• The long neck of giraffe due to mutation, variation. 

For week 1 topic, I supposed to publish around 7-13 september. But we haven't been introduced to reflective journal on week 1