Chapter 4: Microscopy, Staining and Classification

Question 1

At what size is something microscopic? Not visible to the human eye?

Answer 1

0.1 millimeters(mm)

Anything smaller then a micron, we start to use a light microscope.

Question 2

What does magnification allow us to do?

Answer 2

It allows us to visualize cells that are too small for the human eye.

Question 3

What is resolution?

Answer 3

this is the ability to see two objects as separate. It gives you a clearer picture.

Question 4

What can light microscopes see?

Answer 4

They can identify things that are 2 tenths of a micron. after what is visible to the human eye. (1 tenth of a millimeter)

Question 5

How can you see through a light microscope?

Answer 5

It goes through 2 lens so everything you are looking at is upsides down and backwards.

oil has the same refractive index and helps the light rays pass through instead of having it scattered,

Question 6

Big difference between TEM and SEM?

Answer 6

TEM is best for detailed images of cell interiors and structures while SEM is best for detail images of the whole organism.

Question 7

What does TEM stand for? What does it do?

Answer 7

Transmission Electron Microscope- it is used to visualize the smallest organisms(viruses) They can magnify many more times then light microscope can. You would look at cross-sections, the interior portion of the cell unlike the scanning electron microscope.

Question 8

What does SEM stand for? What does it do?

Answer 8

Scanning Electron Microscope- it is used to visualized the surface of the entire object. Not good at visualizing the interiors like TEM. The samples tend to be coating in something such as gold or platinum.

Question 9

What happens if the sample from a scanning electron microscope isn’t covered with something.

Answer 9

The electrons will pass through.

Question 10

What are the primary form of measurements for microbes ?

Answer 10

Nanometers(nm) and Micrometers(um).

Question 11

what is contrast and staining?

Answer 11

Using stains and light adjustments to enhance microorganisms because they’re usually see through. The stains can be used on the actual cells or the background to make them glow.

Question 12

What are the subunits of the ribsomes?

Answer 12

total of 70s subunits of 50s and 30s

Question 13

what is the most common way to identify microbes

Answer 13

Gram staining.(most commonly used method)

Question 14

what are electron microscopes?

Answer 14

These are microscopes that absorb or deflect the electrons transmitted through a specimen.

Higher magnification then light microscopes.

Question 15

What is the difference between electron microscopes and light microscopes?

Answer 15

Instead of light, the electron microscope absorbs, deflects, or transmits the electrons through or off the specimen.

Question 16

What is the purpose of heat fixing?

Answer 16

This is a crucial step when making stainings because it kills all the bacteria, and sticks it into place. if you don’t heat fix, the auger will dry but then it will melt with the dyes.

Question 17

What are the Dichotomous Keys?

Answer 17

These are a series of yes or no steps that can help you drill down the bacteria to specific keys and catagories.

it is a series of paired statements that eventually lead you to the name of the organism.

Question 18

What is empty magnification?

Answer 18

It is when the image becomes fuzzy because the amount of filters and oils make it look the ability to reveal the images.

Question 19

What are negative stains?

Answer 19

This is a special type of stain that attaches with the anionic. Instead of being attached to the cell wall which is negative, it will be attached to everything else and the bacteria will glow.

Question 20

What is the highest taxonomic layer for a virus?

Answer 20

Most viruses don’t go higher than family.

Question 21

what are the Taxonomic layers?

Answer 21

Highest: Domain
               Kingdom 
               Phylum
               Class 
               Order 
               Family 
               Genus 
               Species

Question 22

Percentages for nucleic acids?

Answer 22

Can range from 20-80%. This is a big way to classify groups.

Question 23

What are the four common tests to identify characteristics?

Answer 23

physical
biochemical
serological
phage typing

Question 24

What are the three domains?

Answer 24

Archaea
Bacteria
Eukarya

Question 25

Who created the three domian system?

Answer 25

Carl Woese.

Question 26

What is Physical?

Answer 26

looks for physical shape and arrangements.

Question 27

What is Biochemical tests?

Answer 27

look for the production of acids and carbohydrate utilization.

Question 28

what is serological?

Answer 28

Study of antibody, antigen reaction.

Question 29

What is phage typing?

Answer 29

look for virus colonies(plaques)

Question 30

Difference between Cationic/basic stains and acidic/anionic stains?

Answer 30

with basic stains the chromophore is attached to the positive cation and attracted to the negatively charged wall while Acidic stains’ chromophores is attached to the negative anion, causing it to repel from the cell wall and staining the background instead.

Question 31

What are chromophore dyes?

Answer 31

They can attach to either the cationic or the anionic part of the stain.