Homework Questions: Exam One

List three elements of an effective hand washing technique or procedure

- Use soap - Wash for 20 to 40 seconds - Scrubbing

Resolving power

The ability to distinguish between two particles

Joesph Lister

promoted the idea of sterile surgery

List in order of largest to smallest of organisms: bacteria, yeast, mold, and protozoa

mold (largest), yeast, protozoa, bacteria, virus (smallest)

What are the two morphological forms of fungi

mold and yeast

simple stain

used to determine cell shape, size, and arrangement (contrast which enables better visualization of cell and cell parts)

gram stain

used to differentiate two large groups of bacteria based on their different cell walls

95% ethanol (gram stain reagent)

(3) decolorizing and destroys lipids of the membrane

safranin (gram stain reagent)

(4) stain pink cells that have already been decolorized

What is the purpose of fixing a slide?

Done by heat to kill the cell so the bacteria don't wash off the slide during the staining process (attachment to slide)

Entamoeba Histolytica: Endospore

Dormant Resistent

Most viruses are too small to be observed using a compound light microscope. Indicate the type of microscope that could be used to view viruses.

Electron microscope

What is meant by the limit of resolution? What is the maximum resolving power of the compound light microscope?

Means that it is restricted by wavelength of visible light. A compound light microscope can have a max of 200x

At what point in history did the medical profession adopt practices consistent with Dr. Semmelweis' practice?

Mid to late 1800s

Entamoeba Histolytica: Trophozote

Moves Cats Reproduces

What is meant by the term parfocal? What is the advantage of the parfocal lens?

Things stay in focus when magnification is changed, this works as an advantage when changing between lower to higher lenses or vice versa.

What do we call the handwashing techniques used by Dr. Semmelweis?

Antiseptic techniques

What is the function of the iris diaphragm?

Controls the amount of light reaching the slide Compares to the cornea in the eye

Why are unstained bacteria more difficult to observe than stained bacteria?

The stained bacteria would be more contrasted than the unstained bacteria

crystal violent (gram stain reagent)

(1) stains the cell

iodine (gram stain reagent)

(2) binds to crystal violet and makes it less soluble

Magnifying power

enlarges the image

What is childbed fever?

A bacterial infection of the female reproductive tract following childbirth or miscarriage

What is the total magnification achieved with the compound light microscope used in lab if one is using the 10x objective lens to view a specimen?

A normal lens is 10x magnification, but 10x low power lens (10x10=100) you have 100x magnification

What did Dr. Ignaz Semmelweis (1818-1865) propose as an effective means of preventing childbed fever?

He had his students wash their hands and this reduced the number of cases signifigantly

What evidence did Dr. Ignaz Semmelweis have as apart of his hypothesis?

He said that the med students carried "cadaver particles" from their autopsy to the delivery rooms and that these particles resulted in puerperal fever

Given the potential difficulty in observing an unstained microbe why would someone bother to view a microbe using a wet mount (where the organism is not stained)

If you wanted to view a live organism you wouldn't stain it; the stain kills the cell

What is the function of the substage condenser?

It focuses light onto a small area

wet mount

allows you to view living organisms (intact structures) and study their movement and behevior

Why is hand washing important?

it is the single most effective measure to prevent the spread of virulent or antibiotic resistant bacteria in hospitals