Week 4 lab, Observing Prokaryotic Microorganisms

What flagella arrangement is this?

Monotrichous

What flagella arrangement is this?

Lophotrichous

What flagella arrangement is this?

Amphitrichous

What flagella arrangement is this 

Peritrichous

What are Cyanobacteria

Prokaryotes that can photosynthesize

What does oil immersion do?

Reduce the refraction of light

absorbs the light

What is cocci shape?

small spheres

What is bacilli  shape?

Rod shape 

What is Spirilla shape?

Spiral wiggly rod shape

What is a capsule

A thick, polysaccharide or polypeptide layer outside the cell wall that increases virulence and protects the cell. Seen as white halos around cells

Why is it difficult to visualize spirochetes?

Because they are extremely thin, poorly stained, and require exact fine focus to see.

What is the point of a negative stain?

Negative Space (Background)

Stained with acidic dye 

What are the advantages of negative stain over a positive stain?

You don’t need to heat fix, so organisms keep their size

useful in determing organism size 

What is a positive stain?

Positive space (cell) stained with base dye

What is a simple stain?

One dye is used

Need to smear and heat fix

What is a capsule stain?

Similar to negative Stain, 

What is a Chromophore

Colored part of a dye molecule 

What is a basic chromophore dye?

Positive Chromophore, Gives off Hydrodrixide

Stains the cell, attracted to the negative bacterial components

What is a acidic chromophore dye?

Negative Chromophore, Gives off Hydrogen acid shi

Stains the positive area surrounding cell, repelled by the negative cell

What is a smear?

Bacteria spread onto slide usally mixed with water

Heat fixed onto stick

What is heat fixing?

Gentle heating to make sure bacteria sticks onto slide

What is a capsule?

Thick glycocalyx, it does not absob dye, allows for a white halo effect that surround cell

What is a biofilm

A type of glycocalex that is sticky

What are the steps of a smear

1) Add a drop a water to a slide

2) Aseptically transfer bacteria from isolated colony onto the slide

3) Air dry

4) run it a couple times in front of insintator to heat fix

5

What are the steps of a simple stain?

1) Make smear

2) Apply Positive chromophore basic, 

3) Wait,

4) Blot using bibilus paper

5) now you can see that shit

What is the common dye used in simple stain?

Methylene Blue

In a simple stain how does it differentiate different bacteria?

It’s non differential, all bacteria is the same color

What is the main point of doing a simple stain?

To just see the bacteria in the first place

What are the dyes used a negative stain?

Negative acidic dye

Nigrosin

India Ink

Which stains do you heat fix?

Simple stain, negative and capsule don’t require heat fixing 

What are the steps for a negative stain?

1) Place a drop of your acidic dye onto the slide 

2) Aseptic tranfer colony onto the drop of dye

3) You take another slide and then use it to drag the dye mixture across the slide using capillary action

4) Let the long streak dry completly

5) View under oil immersion lens

What are the main reason why you need to do a negative stain?

Some bacteria are hard to stain

What are the steps of a capsule stain?

1) Place a drop of acidic dye onto slide

2) Aseptic transfer culture onto dye

3)Use another slide to spread dye across slide

4) Allow for it to dry

5) Flood smear with safranin stain (basic positive)

6) Blot dry

7) Visualize under oil lens

How does the capsule stain work, and what is the reason for using it

It combines negative and simple stain

Uses both acidic and basic dyes

Stains background, stains bacteria

Capsule can’t be stained so it will appear as a clear halo

What is the point of a capsule for a bacteria?

Allows for protection

Organized structure

Firmly attached

Strong

Slime layer characteristics

Unorganized

Loosely attached 

Allows for adhesion 

Forms biofilms

Biofilm characteristics

Community of bacteria

Resiliitant

Resistant to antibiotics

How do you know if you are looking at a simple stain?

Background is clear

Bacteria is all one color

How do you know if you are looking at a negative stain?

Background is stained

Cells remain clear/white

How do you know you are looking at a capsule stain?

Background is stained

Bacteria is pink

There are visible halos around the bacteria, those are the capsules