First lecture and second lecture : 22/4/2015 and 24/4/2015

Dr. Wan, for the last week lesson I will combine them into one post.

Topic: Bacteria

Notes:

1) We can use different traits to classify bacteria: cell type, morphology, metabolism, reproduction, phage typing, nucleic acid profile and antibiotic resistance profile.

2) Prokaryotes are divided into 4 category. 

 a) Category 1: Gram -ve bacteria with cell wall

Gram -ve bacteria have thin layer of peptidoglycan in between cytoplasmic membrane and outer membrane of cell wall.

 

3) Gram -ve bacteria with cell walls can be divided into 2 groups based on reproduction and light. One of the groups is nonphototrophic. Nonphototrophic bacteria contain 14 subgroups and 6 of the subgroups are pathogens.

a) Enteric groups

- facultative anaerobic short rods

- E.coli O157:H7 causing uninary tract infection 

- 

b) Campylobacter and Helicobacter

- Aerobic, microaerophilic

- motile

- helical/vibriod bacteria

- Campylobacter jejuni causing diarrhea

- Helicobacter pylori causing ulcer

c) Spirochetes

- slender and long with flexible and helical shape

- corkscrew movement

- They have endoflagella that coil around the cell for cork screw movement.

- causing syphilis and lyme disease

d) Chlamydias

- Obligately intracellular parasites

- resemble virus- intracellular parasites and size

- they are different from virus because they have both DNA and RNA, plasma membrane, metabolic pathways, reproduction by binary fission.

- causing eye/genitourinary tract infection.

e) Pseudomonas, Azobacter and Rhibozium

- nonpathogenic

- Pseudomonas sp. degrade complec organic molecule in soil

- Azobacter and Rhibozium do nitrogen fixation in soil

Activity: Do mind map using padlet and each group need to present one of the kingdom in front of the class.

My own Explorace:

1) Facultative anaerobe is an microorganism that makes ATP by aaerobic respiration if oxygen is present, but is capable of switching to fermentation or anaerobic respiration if oxygen is absent.

2) Microaerophile is a microorganism that requires oxygen to survive, but requires environments containing lower levels of oxygen that are present in atmosphere. 

3) Treponema pallidum cause syphilis and Borrelia burgdorferi cause lyme disease. Lyme disease is transmitted to humans by the bite of infected ticks of the Ixodes genus.

4) Chlamydia trachomatis cause eye infection. Chlamydia infections are the most common bacterial sexually transmitted diseases in humans and are the leading cause of infections blindness worldwide.

Reflection:

E-port folio again. I thaught I will never touch this blog anymore. My feeling to this blog is complicated. It took over few hours of my happy weekend to complete e-port folio. But, I admit I can revised again what Dr taught and take initiative to look for the things that I don't understand. There are few things that we have learnt in semester 1 but I already forgot. For example, I have forgot the name of bacteria that caused syphilis. Dr.Wan introduced new apps, pedlet to us in class.  Although Dr have mentioned pedlet before, but this is my first time to use it. I think it is very convenient for group mindmap. 

Semester 2 - Classification, identification, nomanclature and immunology

Dr. Sieo have taught two big topic in this seven weeks - Classification, identification, nomenclature and immunology.
These two links are the mindmap that I did for classification, identification, nomenclature and immunology:

https://www.goconqr.com/en-US/p/2303520
https://www.goconqr.com/en-US/p/1587060

These are the summary for the Immunology topic:

The examples of primary lymphoid organs are bone marrow and thymus. The examples of secondary lymphoid organs are adenoid, tonsils, lymph nodes and spleen.
Mononuclear leucocyte: T cell, B cell, NK cell, monocyte.
Polymorphonuclear leucocyte: neutrophil, eosinophil and basophil.
B cells are mast cells that mature in bone marrow. The function of B cell is to interact antigen, produce antibody and immune memory. T cells are mast cells that mature in Thymus. The function of T cells is to recognise processed antigen presented in MHC molecule on antigen-presenting cells.
CD4 T cells are the T cells that present CD4 glycoprotein on their cell surface while CD8 T cells are T cells that present CD8 glycoprotein on their cell surface.  T helper 1 cells and T helper 2 cells belong to CD4 T cells and T cytotoxic cells belong to CD8 T cells.

Antigen are the molecules that trigger specific immune response and react with products of response. There are four feature of good antigens:
a) high molecular weight
b) complexity
c) solubility
d) foreigness

Recognition of antigens:
a) B cells - whole antigen
b) Antibody - Antigen's epitope
c) T-cell receptor - processed antigen

There are 5 types of antibodies : IgM, IgG, IgD, IgA, IgE.
Antibody consist of 4 polypeptide chain where 2 light chain and 2 heavy chain. Fab will be the site that bind to the pathogen while Fc will be the part that bind to macrophage.

** If 2 different classes of antibody react with one antigenic determinant, the constant heavy chain will be different but the heavy and light chain will be the same.
**If 2 same classes of antibody react with two different antigenic determinant, the constant havy chain will be the same but the heavy and light chain will be different.

There are two types of immune response : non-specific immune response and specific immune response.
a) non-specific immune response are internal innate imununity and external innate immunity.
External innate immunity include skin, mucuous membrane, normal microbiota. Periodic drying of skin and slightly acidic pH of skin create unfavourable environment for pathogen to survive. Globet cells secrete mucus to trap the bacteria or pathogen to expel out from body. Normal microbiota compete nutrients with pathogen and secrete antimicrobial substances to inhibit the growth of pathogen.
Internal innate immunity include fever, inflammation and phagocytosis. Fever is to create unfavourable temperature in the body to trigger microbiostasis. High amount of pathogen will produce high amount of pyrogen. the pyrogen will send to hypothalamus and produce prostaglandins which will reset the hypothalamic thermostat. Inflammation is due to the phagocytosis not effective. Histamine released and causes vasodilation. Vasodilation will will deliver more blood to infection site and the macrophage will more permeable move from blood vessel into damaged tissue site. Phagocytosis is the engulfment of pathogen by macrophage or neutrophils.

b) Specific immune response are humoral immunity and cell-mediated immunity. Humoral immunity is an immunity mediated by macromolecules that found in serum.
 How does antibody gives protection?
a) Neutralisation
b) Agglutination
c) Oponisation
d) Activation of complement
e) ADCC ( antibody-dependent cell mediated toxicity)
** Antibody do not kill the pathogen but serach the pathogen by others.

How to determine the latent period?
1) Dosage of antigen
2) Adjuvants
3) Chemical and physical nature of antigens

What are the differences between primary antibody response and secondary antibody response?
Secondary antibody response will have short latent period, higher titer, longer persistence of antibody and more rapid increase in antibody titer if compared with primary antibody response.

Cell-mediated immunity is an immunity response that does not involve antibody but rather involve the activation of macrophage, Tc cell and the release of various cytokine in response to antigen.
There are two types of CD8 T cells killing mechanisms:
a) granules exocytosis
When TcR bind to antigen on class 1 MHC, granule is released to activate apoptosis. Granules contain perforin and granzymes.
b) Fas pathway
When TcR bind to antigen on class 1 MHC, granules are release and triggers expression fas-ligand on Tc cell and the Fas on target cell cross-linked with Fas-ligand.

Delayed-type hypersensitivity (DTH)
- against pathogens living inside macrophages themselves
a) Dendritic cells will pick up the antigens that presented on class 2 MHC and move to secondary lymphoid organ.
b) Dendritic cells will process the antigen and preseneted it on the class 2 MHC CD4 T cell in the secondary lymphoid organ will then activated by the antigen.
c) CD4 T cell will then proliferate, differentiate to T helper 1 cell. T helper 1 cell will then migrate back to the site of infection and secrete cytokines to recruit more monocyte or macrophages to phagocyte the pathogen on the infection site.

Reflection:
Obviously, the topics for semester 2 are harder than the topic in semester 1. Luckily we have Dr. Sieo as our lecturer and taught us in very details way so that we can fully understand these two topics. I like the topic of immunology more if compared with classification and identification. The identification method are all practical but we only understand the basic concept of the methods. That's why I feel less interest in this topic. The topic of immunology is interesting because I would like to know how the pathogen gain access to our body and cause infection. Antibody is important to fight with the pathogen and the process of producing antibody is complicated and it take a long time to produce.