Microbiology Lab Final

What is a bacterial colony?

a cluster of cells and one type of cell growing into even more cells and into millions

What does the word ubiquity mean?

Something that can be found everywhere

What is a pandemic

Spread of infectious diseases from one continent to another

How dohyW you know if there were bacteria in your swab tube?

sediment, broth, and spores

Why is the level of contamination on an agar plate measured as the number of colonies rather than the size of colonies?

Because the size can vary but the number of helps to see how much infections instead of how big it is also helps to identify the cells

Define infectious disease

Disease that infects within the hosts body through the tissue of the host

Where are high rates of disease transmissions?

an office or school

What is one characteristic of a colony that can be sued to differentiate between bacterial species?

size of the colony

What is the purpose of a streak plate?

to help isolate single cells

In regard to the pour plate technique why must the liquified agar be cooled to 50-55 degrees celsius?

So there is no moisture or condensation on the plate

How do you calculate total magnification?

ocular lense x objective lense

Name one important property of agar?

It is indigestible

Define an aseptic technique

A technique to help prevent infection

Name two examples of aseptic techniques we use in lab?

washing out hands, or cleaning off table before lab

Why is it advisable to start with low=power objective lens when viewing a slide?

So that you can find the microorganism/organsim before magnifying in on it.

What is a characteristic of fungi?

It is heterotrophic

How would you distinguish between a cyanobacterium from a protozoan?

cyanobacteria is prokaryotic protozoan is eukaryotic

What would always distinguish between a mold from an alga?

Mold is heterotrophic algae is autotrophic

What is one characteristic of a protozoan?

It is eukaryotic

What would distinguish between a single-celled yeast (fungus) form a protozoan?

Fungus has a cell wall pronoun does not have a cell wall

What would always distinguish a cyanobacterium from a fungus?

Cyanobacteria is unicellular and autotrophic fungus is heterotrophic

What is the purpose of the gram stain that is what it is differentiating?

to help see the cell clearly and the cells structure

What is the difference between a simple and differential stain?

The differences in cell walls that are used and the information provided on the bacteria.

What is the difference between a positive and negative stain?

Their charges and the positive stains stain the cell and have a light background negative stains stain the background but not the cell

What is one of the two purposes of heat fixing a smear preparation?

To kill the surrounding cells to fit the cells onto the slide so they do not get washed away

What color do gram-positive cells stain?

purple

What is an example of a basic dye?

crystal violet

What is the purpose of decolorized in the gram staining process

To help reomove dye form gram negative cells within their colonies

What are two characteristics of a colony on a plate one could describe for cultural characteristics?

growth and opacity

Why would you use an autoclave?

Because it sterilizes equipment and media standard conditions: 121 C, 15 psi and 15-20min

Difference between a positive and negative stain

positive stains the cell and uses a basic dye negative stains the background and uses an acidic dye

Simple vs. Differential Stain

Simple stain is one dye and shows the shape, size, arrangement. Differential stain uses two or more dye and tries to distinguish between different groups of bacteria ex: gram stain

What is the purpose of the gram stain?

It separates bacteria based on cell wall structure

Why would someone perform a smear preparation

Attach bacteria to the slide, kill bacteria

What are the charges of Dyes

basic dies are positive, acidic dyes are negative and repelled by cells

How do you determine motility using SIM Media?

motile: cloudy growth nonmotile: growth stays only on stab line

What are growth characteristics in broths, slants, and plates

broth : sediment, flocculent slant: beaded rhizoid , plates: shape, margin, elevation

Final Dilution formula

tube dilution x plate dilution

What is hypotonic?

water enters cell and animal cells burst

What are hypertonic and isotonic?

hypertonic is outside has more solute, isotonic is an equal concentration

Why does bacteria survive hypotonic conditions?

Because of their rigid peptidoglycan cell walls and animals have no cell wall

Lysozyme relation to peptidoglycan

It breaks down peptidoglycan layer of bacterial cell walls found in tears saliva, mucus,

What does ultraviolet light have to do with cells?

UV light damages DNA by forming thymine dimers

Antiseptic vs. Disinfectant

Antispetic is sage on living tissue and disinfectant is used on nonliving surfaces

Four modes of Action

Damage cell membrane, Damage proteins, Damage DNA/RNA, Damage cell wall

How does alcohol kill cells

denatures proteins, dissolves membrane lipids

Purpose of Enzymes

enzymes are biological catalysts and lower activation energy

Why use microbial Alpha-Amylase?

less expensive, easier to produce, large quantities, consistent quality

Why use Bacillus Subtitles

grows rapidly, produces large amounts of enzyme, is nonpathogenic, easy to culture

Alpha vs Beta Hemolysis

alpha is partial destruction of RBC’s and green discoloration, beta hemolysis is complete destruction of RBC’s