Chapter 3 Observing Microorganisms Through a Microscope

Question 1

what are the main units of measure for microbes?

Answer 1

micrometers and nanometers

Question 2

what are the conversions of unit measure for micrometers and nanometers?

Answer 2

Question 3

How many mm are in 18 cm?

Answer 3

Question 4

Answer 4

Question 5

What is the difference between a simple and compound microscope?

Answer 5

simple microscope has 1 lens
compound microscope has 2 lenses

Question 6

what is the best resolution for light microscope?

Answer 6

200 nanometers

Question 7

what is the practical limit of resolution for the unaided eye?

Answer 7

20 micrometers

Question 8

Answer 8

Question 9

Answer 9

Question 10

what is a brightfield method of microscopy?

Answer 10

a dark object on a bright background is viewed that can contain dyes or stains

Question 11

what is a darkfield method of microscopy?

Answer 11

a bright object on a dark background is viewed with NO artificial color

Question 12

why can a sample viewed in darkfield not be dyed or stained?

Answer 12

no color can be added to live cells because the chemicals in dyes/stains can kill the specimen

Question 13

why might you use the method of florescence microscopy? How?

Answer 13

to view the presence of antigens/ antibodies
cell is stained with fluorescent dyes, antibodies get dyed and produce visible light if present

Question 14

what is electron microscopy?

Answer 14

uses waves of electrons instead of visible light
allows for greater magnification but smaller resolution

Question 15

why might we use electron microscopy? Cons?

Answer 15

for viewing organelles of sample (ie: golgi body/ mitochondria)

Cons: must be performed in a vacuum
distorts blurred image of cell
can only be used on dead cells

Question 16

what does SEM stand for? What is its use?

Answer 16

Scanning electron microscopy
produces superficial image of surface structures
surface of specimen is covered in thin layer of gold

Question 17

what does TEM stand for? What is its use?

Answer 17

transmission electron microscopy
used to view interior of cell (organelles of cells)
cell is sliced into 3 thing sections and sections are covered with heavy metals

Question 18

what are differences of advantages of SEM and TEM?

Answer 18

SEM: magnification is up to 10,000x
resolution is down to 10 nanometers

TEM: magnification is up to 100,000x
resolution is 10 picometers

Question 19

what is the definition of magnification?

Answer 19

Bringing an object into closer view

Question 20

what is the definition of resolving power /resolution?

Answer 20

Ability to distinguish fine detail

Question 21

what is the best magnification that we can get with a light microscope?

Answer 21

1000x

Question 22

what type of light microscopy do we use in the lab?

Answer 22

compound microscope

Question 23

what will a cell look like under fluorescence microscopy?

Answer 23

glowing green

Question 24

what is used to dye in fluorescence microscopy?

Answer 24

fluorescent dyes called fluorochromes

Question 25

How do fluorocence microscopy works?

Answer 25

fluorescent dye is added to cell
dye bonds with antigens
antigens are visible and you can see the general structure of the bacteria/organism they surround thus making the bacteria visible

Question 26

how does electron microscopy compare to light mircroscopy?

Answer 26

electron microscopy can magnify greater than light microscopy which is great for viewing organelles of sample

Question 27

What is the subscript for micrometers?

Answer 27

Question 28

what is the subscript for nanometers?

Answer 28

Question 29

what is the definition of magnification?

Answer 29

how big an image is displayed

Question 30

what is the definition of resolution?

Answer 30

the ability to distinguish fine detail