DID YOU KNOW THAT? [PART 2]

• Once people have had some viral infections, like chickenpox, it makes them immune from having it again – vaccination creates the same kind of immunity, so can prevent people from getting the viral infections.

The more people who are vaccinated reduces the amount of infection in a population, protecting even those people who are not vaccinated – this is called ‘herd immunity’. Depending on the virus, 85-95% of people need to be vaccinated to protect the rest of the people – this is why vaccination is important.

• Viruses are passed on by sneezing and coughing, or by touching someone who has a viral infection – this is why it is important to cough or sneeze into tissues and wash hands regularly when infected with a cold or other viral infection.

DID YOU KNOW THAT?

• Bacteria are used in making cheese, yogurt and sourdough bread?

• Bacteria produce oxygen – perhaps as much as half of the oxygen in the atmosphere?

• Bacteria (usually dead or weak ones) are used to make vaccines?

• Bacteria are used to clean water in sewage plants?

A Video on BACTERIA!

Bacteria, bacteria, bacteria! ;)

MICROSCOPE ANATOMY

Historians credit the invention of the compound microscope to the Dutch spectacle maker, Zacharias Janssen, around the year 1590.   The compound microscope uses lenses and light to enlarge the image and is also called an optical or light microscope (vs./ an electron microscope).  The simplest optical microscope is the magnifying glass and is good to about ten times (10X) magnification.  The compoundmicroscope has two systems of lenses for greater magnification, 1) the ocular, or eyepiece lens that one looks into and 2) the objective lens, or the lens closest to the object.  Before purchasing or using a microscope, it is important to know the functions of each part.   

Eyepiece Lens:  the lens at the top that you look through.  They are usually 10X or 15X power. 

Tube:  Connects the eyepiece to the objective lenses

Arm:  Supports the tube and connects it to the base

Base:  The bottom of the microscope, used for support

Illuminator:  A steady light source (110 volts) used in place of a mirror.  If your microscope has a mirror, it is used to reflect light from an external light source up through the bottom of the stage.

Stage:  The flat platform where you place your slides.  Stage clips hold the slides in place.  If your microscope has a mechanical stage, you will be able to move the slide around by turning two knobs.  One moves it left and right, the other moves it up and down.

Revolving Nosepiece or Turret:  This is the part that holds two or more objective lenses and can be rotated to easily change power.

Objective Lenses:  Usually you will find 3 or 4 objective lenses on a microscope.  They almost always consist of 4X, 10X, 40X and 100X powers.  When coupled with a 10X (most common) eyepiece lens, we get total magnifications of 40X (4X times 10X), 100X , 400X and 1000X.  To have good resolution at 1000X, you will need a relatively sophisticated microscope with an Abbe condenser.  The shortest lens is the lowest power, the longest one is the lens with the greatest power.  Lenses are color coded and if built to DIN standards are interchangeable between microscopes.  The high power objective lenses are retractable (i.e. 40XR).  This means that if they hit a slide, the end of the lens will push in (spring loaded) thereby protecting the lens and the slide.  All quality microscopes have achromatic, parcentered, parfocal lenses.

Rack Stop:  This is an adjustment that determines how close the objective lens can get to the slide.  It is set at the factory and keeps students from cranking the high power objective lens down into the slide and breaking things.  You would only need to adjust this if you were using very thin slides and you weren't able to focus on the specimen at high power. (Tip: If you are using thin slides and can't focus, rather than adjust the rack stop, place a clear glass slide under the original slide to raise it a bit higher)

Condenser Lens:  The purpose of the condenser lens is to focus the light onto the specimen.  Condenser lenses are most useful at the highest powers (400X and above).  Microscopes with in stage condenser lenses render a sharper image than those with no lens (at 400X).  If your microscope has a maximum power of 400X, you will get the maximum benefit by using a condenser lenses rated at 0.65 NA or greater.  0.65 NA condenser lenses may be mounted in the stage and work quite well.  A big advantage to a stage mounted lens is that there is one less focusing item to deal with.  If you go to 1000X then you should have a focusable condenser lens with an N.A. of 1.25 or greater.  Most 1000X microscopes use 1.25 Abbe condenser lens systems.  The Abbe condenser lens can be moved up and down.  It is set very close to the slide at 1000X and moved further away at the lower powers.  

Diaphragm or Iris:  Many microscopes have a rotating disk under the stage.  This diaphragm has different sized holes and is used to vary the intensity and size of the cone of light that is projected upward into the slide.  There is no set rule regarding which setting to use for a particular power.   Rather, the setting is a function of the transparency of the specimen, the degree of contrast you desire and the particular objective lens in use.

How to Focus Your Microscope:  The proper way to focus a microscope is to start with the lowest power objective lens first and while looking from the side, crank the lens down as close to the specimen as possible without touching it.  Now, look through the eyepiece lens and focus upward only until the image is sharp.  If you can't get it in focus, repeat the process again.   Once the image is sharp with the low power lens, you should be able to simply click in the next power lens and do minor adjustments with the focus knob.  If your microscope has a fine focus adjustment, turning it a bit should be all that's necessary.   Continue with subsequent objective lenses and fine focus each time. 

TYPES OF MICROORGANISMS PART 2

FUNGI

Kingdom of heterotrophic single-celled, multinucleated, or multicellular organisms, including yeasts, molds, and mushrooms. The organisms live as parasites, symbionts, or saprobes (see saprophyte). Previously classified in the plant kingdom, fungi are nonmotile, like plants, but lack the vascular tissues (phloem and xylem) that form the true roots, stems, and leaves of plants. Most coenocytic (multinucleated) or multicelluar fungi are composed of multiple filaments, called hyphae, grouped together into a discrete organism called a mycelium. The cell walls of most fungi are of chitin compounds instead of cellulose; a group fungi known as cryptomycota lack chitinous cell walls. In many ways fungi are more closely related to animals than to plants, and they have been thought to share a common protist ancestor with animals.

ARCHAEA- A group of single-celled microorganisms. A single individual or species from this domain is called anarchaeon (sometimes spelled "archeon"). They have no cell nucleus or any other membrane-bound organelles within their cells.

In the past they had been classed with bacteria as prokaryotes (or Kingdom Monera) and named archaebacteria, but this classification is regarded as outdated.^[1] In fact, the Archaea have an independent evolutionary history and show many differences in their biochemistry from other forms of life, and so they are now classified as a separate domain in the three-domain system. In this system, the phylogenetically distinct branches of evolutionary descent are the Archaea, Bacteria and Eukaryota.

TYPES OF MICROORGANISMS

Bacteria-Bacteria are microscopic organisms whose single cells have neither a membrane-enclosed nucleus nor other membrane-enclosed organelles like mitochondria and chloroplasts. Another group of microbes, the archaea, meet these criteria but are so different from the bacteria in other ways that they must have had a long, independent evolutionary history since close to the dawn of life. 

Virus- A microorganism that is smaller than a bacterium that cannot grow or reproduce apart from a living cell. A virus invades living cells and uses their chemical machinery to keep itself alive and to replicate itself. It may reproduce with fidelity or with errors (mutations); this ability to mutate is responsible for the ability of some viruses to change slightly in each infected person, making treatment difficult. Viruses cause many common human infections and are also responsible for a number of rare diseases. 

OPENING REMARKS!

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Yeast Experiment Hints at a Faster Evolution From Single Cells

click for more info from "New York Times"

Stuff Microbes

Just saw these things for sale! Aren't they cute?

Gush! what a stressful day, we are having difficulty in making our blog but we are doing our best in order to give you the best source of Microbio knowledge :)