TOPIC 4 - EUKARYOTES

TOPIC 3 - PROKARYOTES

*INCLUDE WHAT HAVE WE have DONE IN CLASS ALSO

This new entry is for the next topic, Prokaryotes which is topic 3. Before we started to learn topic 3 we all have to do a mindmap on Porkaryotes. It turns out my mindmap is like this;


I have done my best on this mindmap. I put up all that I know into this mindmap. I tried to cramp all the information that I gather about prokaryotes and make a mindmap. 

MINDMAP ON PROKARYOTES

Basically the word prokaryote comes from the Greek πρό (pro) "before" and καρυόν (karyon) "nut or kernel". Prokaryotes are organisms whose cells lack a nucleus and other organelles. Prokaryotes are divided into two distinct groups; the bacteria and the archaea. which scientists believe have unique evolutionary lineages. Most prokaryotes are small, single-celled organisms that have a relatively simple structure. Prokaryotes are called prokaryotic cell.

The learning outcomes for this topic are;
1. To explain, describe, and identify the important structure of prokaryotic cells
2. To explain the characteristics or functions of the structures of prokaryotic cell

PROKARYOTE

This is the basic structure of prokaryotic cell. The size of prokaryotic cell range from 0.2-2.0 um (diameter) and 2-8um (length). prokaryotic cells lack membrane-bound nucleus, cytoskeleton, membrane-bound organelles and internal membranous structures such as endoplasmic reticulum and Golgi apparatus.

There are common bacterial & archaeal structures and their functions

1. Plasma membrane - Selectively permeable barrier, mechanical boundary of cell, nutrient and waste transport, location of many metabolic processes such as respiration and photosynthesis), detection of environmental cues for chemotaxis
2. Gas vacuole -  Buoyancy for floating in aquatic environments
3. Ribosome - Protein synthesis
4. Inclusion - Storage of carbon, phosphate and outer substances
5. Nucleoid - Localisation of genetic material
6. Periplasmic space - Gram positive bacteria: contain hydrolytic enzymes and binding proteins for nutrient processing and uptake ; Gram negative bacteria and archea: small or absent of periplasmic space
7. Cell wall - provides shape and protection from osmotic stress
8. Capsules and slime layers - Resistance to phagocytosis, adherence to surgaces (also presence in archea)
9. Fimbriae and pili - Attachement to surfaces, bacterial conjugation and transformation, twitching and gliding motility
10. Flagella - swimming motility
11. Endospore - survival under harsh environmental conditions (only observed in bacteria)

In this topic we learned about components of prokaryotic cell which is;

1. structure external to the cell wall
2. cell wall 
3. structure internal to the cell wall

The structures external to the cell wall are:

 GLYCOCALYX

• Glycocalyx is a coating secreted by the bacteria. It composed of polysaccharide, polypeptide or can be both. The chemical composition of glycocalyx varies with species. It also hase different terms depending on the structure. 

> Gelatinous -  glycocalyx
> Organized and firmly attached to cell wall - capsule
> Unorganized and loosely attached - slime layer




The functions of glycocalyx are for;

• attachment to surface
• protect against dehydration
• inhibit movement of nutrients out of cells
• source of nutrient

 

 FLAGELLA

 

TOPIC 2 - MICROSCOPY

 

TOPIC 2 – MICROSCOPY

 

The next topic of Microbiology is topic 2 – Microscopy Techniques. The learning outcomes for this topic are:

     a)      To identify the parts of a basic microscope (C3)

Parts of a microscope

                             

     b)      To describe the principle of light, phase-contrast, fluorescence and electron microscope (C2)

Image from electron micoscope

     c)      To select suitable microscope for relevant usage (P1)

Lab microscope that I have used before

     d)      To recognize images produced form different microscope (A2)
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From the learning outcomes listed above, it seems like I have to memorize a lot of things such as the parts of the microscope and its function. Other than that, I also have to know types of different microscope used to detect presence of microbes.

As we all know, we all have to choose an adopted microbe and do an intense research on it and will present our findings later on a three minute talk. So, Dr Wan asked us to put up our microbe’s name on padlet. The microbe that I choose to adopt is Vibrio haemolyticus. Vibrio haemolyticus is a type of bacteria that has a vibrio shape based on its name. Vibrio shape is like a ‘coma’ or curved rods shape. Vibrio haemolyticus is a Gram-negative bacterium found in brackish saltwater, which, when ingested causes gastrointestinal illness in humans. So basically this is a pathogenic bacteria. I chose this bacterium because I found it is interesting and I am enthusiast to know more about this microbe.

Vibrio parahaemolyticus na TCBS agaru

Vibrio haemolyticus

Before we went to the next class, Dr Wan asked us to look for a few terms. They are ‘pleomorphic’, ‘mycoplasma’. ‘thermoplasma’ and ‘vampyrellid’. Honestly, I have never heard any of these terms, thus, I really have to look for the definition of these terms on the internet or in a textbook. The outcome of my findings are; pleomorphic means an ability of some bacteria to alter their shape or size in response to environmental conditions. These environmental conditions usually are not favourable to the microbes, thus, the microbe will have this ability to encounter unusual conditions. Pleomorphism has been observed in some members of Deinococcacae family. They can change shape or size because they lack of cell wall or they have no cell wall. The second term is mycoplasma. Mycoplasma is a genus of bacteria that lack a cell wall around their cell membrane. Without a cell wall, they are unaffected by many common antibiotics such as penicillin that target cell wall synthesis. Most surprising fact about mycoplasma is that mycoplasma is the SMALLEST MICROBE IN THE WORLD! It’s amazing right?! This is the perks of studying microbiology, you get shocked on every facts that you just heard. Haha. :)

Mycobacterium

Thermoplasma on the other hand is an archae which can thrive in acidic and high-temperature environments . Thermoplasma is a microbial biorealm page on the genus Thermoplasmataceae (Thermoplasma acidophilum). Thermoplasma are facultative anaerobes and respire using sulfur and organic carbon. They do not contain a cell wall but instead contain a unique membrane  composed mainly of a tetraether lipoglycan containing atypial archaeal tetraether lipid attached to a glucose and mannose containing oligosaccharide. This lipoglycan is presumably responsible for the acid and thermal stability of the Thermoplasma membrane.  Vampyrellid are a group cercozoans with filose pseudopods and lacking shells. Vampyrella is typical of the group, which also contains such as Platyreta and Arachnula. The term “Aconchulinida” is sometimes used for vampyrellid.

Cultured E.coli O157:H7

New information that I get from this class is about E.coli. Escherichia coli (abbreviated as E.coli) are bacteria found in the environment, foods and lower intestine of warm-blooded organisms. But there are several names for E.coli such as E.coli 0157:H7. The difference in the names is because of the strains of E.coli bacteria. E.coli 0157:H7 can cause severe anemia or kidney failure, which can lead to death. Escherichia coli 0157:H7 is an enterohaemorrhagic serotype of the bacteria E.coli and a cause of illness, typically through consumption of contaminated and raw food including raw milk. Infection with this type of pathogenic bacteria may lead to haemorrhagic diarrhea and to kidney failure.

There’s something unique happened on this week which was Dr Wan asked Radin’s group to figure out how to learn about the parts of the microscope. They must be able to make us understand and have fun while learning it. When Radin’s group present their slides, it is not about the parts of a microscope but rather about how the first microbes was observed under the first microscope. 

Early microscope

  
So basically, it is not what was Dr Wan wanted but I must compliment what they did were weird, funny and interesting. I like their presentation. We all were  laughing because in between their slides they put funny photos and jokes inside the slides. We had a fun time for a moment.

And we also play a quiz on Kahoot.it. This is the first time I heard about Kahoot.it. Very interesting and energetic quiz. We have only 10 seconds for every questions of the quiz and if we answer it correctly, our names will be displayed on the projector screen. I am looking forward to play Kahoot.it again. But maybe that day is not my lucky day, I did not  manage to get my name displayed on the screen.

Kahoot.it

Topic 2 really surprised me in every possible way. I learned a lot about microscope. There are 4 types of microscope which are optical microscope, electron microscope, scanning probe microscope and scanning acoustic microscope.

Optical microscope

The optical microscope can be divided into dark field, bright field, fluorescence microscopy and phase contrast microscopy. These optical microscope or light  microscope are compound microscope. The bright-field microscope produce dark image against brighter background. Bright-field microscope used to enhance observation with bright-field microscope, kill and stain the cells.  Meanwhile the dark-field microscope produce bright image against darker background. Dark-field microscope usually used to observe live specimens which cannot be stained. Phase contrast microscopy light coming in is in phase and when it strikes the image is it thrown out of phase creating more resolution. Phase contrast microscope also enhances contrasts of transparent and colourless objects by influencing the optical path of light. Fluorescence microscope produces image from light that passes through a specimen. Specimen tagged or naturally fluorescing against dark background. The specimen are exposed to uv, violet or blue light.

Electron microscopy can be divided into 2 that are transmission electron microscope to analyse internal structures and scanning electron microscope to analyse surface structures.

Atomic force (scanning probe) microscopy uses electrons and application of small voltage to the specimen. It allows observation and manipulation at molecular and atomic level.

Scanning acoustic microscopy used sound waves and usually for studying larger specimens like bacterial biofilms and cancer cells.

There are different types of stains for specimens. There are simple stains, differential stains, acid fast stains and special stains. Simple stain is a very simple staining procedure involving only ONE stain. Basic stain such as methylene blue, Gram safranin/ Gram crystal violet are useful for staining most bacteria.

Simple stain 

Differential staining

Differential staining is used to stain physical and chemical properties of different groups of bacteria. It allows us to differentiate between different kinds or parts of bacterial cell.

Acid-fast staining 

Acid fast stain or ‘Ziehl-Neelson stain’ is a differential stain used to identify acid-fast organisms such as members of the genus mycobacterium. Acid-fast organisms are characterized by wax-like, nearly impermeable cell wall; they contain mycolic acid and large amounts of fatty acid , waxes and complex lipids. Usually Ziehl-Neelsen stain used to stain bacteria that is very fussy called fastidious microbes (high fatty acid).

Special stains will stain certain structure such as flagella, capsule and endospore. Colostrodium and bacillus (Bacillus anthracis) are types of bacteria that used endospores.

For the next topic, Prokaryotes, Dr Wan asked us to make a mindmap of prokaryote and submit it to Putrablast. Doing a mindmap before going to class helped me to be ready about what to learn next. I have done my mindmap using Popplet.com. I managed to get as many information as possible and put it into my mindmap. I am satisfied with my mindmap. Truly, by doing a mindmap has helped me understand a certain topic better. I will try to do a mindmap for every topic if possible.

Mindmap

Overall, it can be seen that I learned a lot about topic 2 Microscopy Technique. The techniques are all very high technology and very useful for us to see small microbes. We should be thankful to the inventors of various microscope because they help us to learn microbiology easier.