WEEK 7 : PLANT GROWTH REGULATOR AND PLANT HORMONES

PLANT HORMONES

       For every part label above have hormone for growth depend on substance produce by the plant (endogenous) or substance that applied to the plant (exogenous). There are 5 hormones classes; Auxins, Cytokinins, Gibberellins, Abscisic Acid and Ethylene.

SUMMARIES

        End of this 7 week I learned many things about Cellular and Development Biology. Thank you to the lecturer Prof. Madya Dr Parameswari that taught us well and gave extra knowledge. 

WEEK 6 - DIVISION CYCLE OF PLANT CELL AND TOTIPOTENCY + POLLINATION AND EMBRYO DEVELOPMENT

DIVISION CYCLE OF PLANT CELL AND TOTIPOTENCY

Cell division and growth

   In this topic, I learned how cells in multicellular organisms divide to replace lost or damaged cells and allow them to grow.There is a cell cycle which is an events, resulting in cell growth and division into two daughter cells.

Cell Cycle

1. GAP (G1) phase-growth and doubling of cell organelles
2. Synthesis (S) phase - DNA replication occurs
3. GAP (G2) phase-Preparation for cell division
4. M phase-division for nucleus and cell
5. In plants, cell division complete in cytokinesis phase

     Besides in lecture through SCL activity, I learned how an organism grow through cell division. 

     Furthermore, I learned how plant grow through meristematic tissue which is found near tips of roots and stems called apical meristems, in the buds and nodes of stem-axillary meristems, in cambium between the xylem and phloem in dicotyledons, under epidermis of dicotyledon and in the pericycle of roots, producing root.

TOTIPOTENCY

    In this topic, i learned the ability of individual plant cell/tissue/organ to generate into a whole plant under right condition. A scientist suggested that this concept that each cell of an organism being derived from the mitotic divisions of a zygote must be able to produce the entire organism. There also some of loss of totipotency due to the genetic or epigenetic.

     Pathway of generation is a ability of a single cell to form a shoot or somatic embryo on the way to producing a whole plant depend on it is competent or recalcitrant which is new thing for me to learn. I learned the development of adventitious organs or primordia  from undifferentiated cell mass in tissue culture through Organogenesis. Besides, 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.

Moreover, there also some factor that affect cellular totipotency:

1. source of explant
2. nutrient media and constituent
3. culture environment

POLLINATION AND DEVELOPMENT OF PLANT EMBRYO

   In this topic, I learned the way how plant reproduce through the reproductive organ in the angiosperm or flower. There some ways how pollination occurs through self pollination or by other thing like insect, wind for cross pollination. The video in the putrablast is very useful for me to understand more about this topic.

cross pollination by insect

      

plant reproductive organs for flower

Life cycle of angiosperm

Zygotic Embryogenesis 

     Plant embryogenesis is the process 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.

     Somatic embryos are formed from plant cells that arenot normally involved in the development of embryos such as ordinary plant tissue.

 

WEEK 5 - ENDOSYMBIOTIC THEORY

ENDOSYSMBIOTIC THEORY

Suggest that :

• Eukaryotes arose from a symbiotic relationship between various prokaryotes
• Heterotropic (aerobic) bacteria became mitochondria
• Cyanobacteria (photosynthetic) became chloroplast
• Hoat cell was a large eukaryotic cell

The origin of eukaryote cell

Evidence of endosymbiosis:

1. mitochondria and chloroplasts are similar in size and marphology to bacterial prokaryotic cells
2. mitochondria and chloroplasts divide by binary fission, just as bacteria do, and not mitosis as eukaryotes do
3. chemical distint membrane systems
4. mitochondria and chloroplasts have their own DNA and their own ribosomes
5. mitochondria arise from pre-existing mitochondria; chloroplast arise from pre-existing chloroplasts 
6. organelle ribosomes are more similar in size to prokaryotic which have 30s and 50s 
7. many antibiotics that kill or inhibit bacteria also inhibit protein synthesis of these organelles
8. phylogenetic studies using comparative ribosomal RNA sequencing demonstrates that both mitochondria and plastids are related to Bacteria    

In class we learned to differentiate the mitochondria and chloroplast using the venn diagram.

WEEK 4 - CELL THEORY + PROKARYOTE AND EUKARYOTE + VIRUSES + PRIONS + VIROIDS

CELL THEORY



Robert Hooke

plant cell

• In 1665, he discovered a honeycomb-like structure in a cork slice by using a primitive microscope
• He saw cell walls as a dead tissue then he started introducing the word cell to world. 
• He also published the first ever scientific bestseller; Micrographia 

drawings of crystal take from
frozen urine

illustration of his compound
microscope

illustration is bee's stings which
have barbs at the end

Anton van Leeuwenhoek 

animalcules, bacteria and spermatozoa

• In 1674, he discovered animalcules meaning tiny animals when he described the algae spirogyra under microscope. He also discovered other cell in his illustration:



a cross- sectional view
of a nerve fiber  

drawings of shape and size
red blood cells

Theodore Schwann

• In 1836, he discovered the pepsin, digestive enzymes
• He also concluded that all animals are made up of cells

animal cells

Rudolf Virchow

• In 1855, he stated the only source for a living cell was from another living cell 

3 main parts of cell theory:

1. all living things are made up from cells
2. the cells can perform all the function of life which is carry out life processes 
3. all cells are came from pre-existing cells

Exceptions to cell theory:

1. viruses
2. prions
3. subcellular organelles which carry info and replicate independently
4. multinucleated single cell;muscle cells

Modern cell theory:

1. the cell contains hereditary information which is passed on from cell to cell during cell division
2. all cells are basically the same in chemical composition and metabolic activities
3. all basic chemical and physiological functions are carried out inside the cells
4. cell activities depends on the activities of subcellular structures within the cell

PROKARYOTE VS EUKARYOTE

VIRUSES

Properties:

• no membranes, cytoplasm, ribosomes or other cellular components
• cannot move or grow but can reproduce inside a host cell-Obligate intracellular parasites
• consist of 2 major parts -  a protein coat and hereditary (DNA or RNA)
• nucleic acid surrounded by a protective protein coat called a capsid
• some also surrounded by an outer membranous layer called envelope, made of lipid and protein
• come in a wide range of shapes
• can infect plants, animals, human and even bacteria and they attack only specific to their host

can be classified according to their:

1. Genetic material                                            
2. Virus shape
3. Symmetry of the capsid
4. Presence or absence of the envelope
5. Type of the host

viruses reproduce in two ways

PRIONS

• an infectious agent that is composed primarily of protein
• propagate by transmitting a mis-folded protein state
• the process is dependent on the presence of the polypeptide in the host organism
• implicated in a number of diseases in a variety of mammals
• prion diseases - alzheimer's and parkinson's diseases, mad cow disease

VIROIDS

viroids can cause severely misshaped potatoes

• small circular RNA molecules without a protein coat
• can contain as few as 250 nucleotides
• infect plants
• induced diseases lead to dramatic economic losses in agriculture and horticulture worldwide