types of cells, microscopes, gram staining lab

Question 1

cell theory

Answer 1

All organisms are made of one or more cells.
Cells are the basic unit of structure and function in living things
Cells arise by division of pre- existing cells

Question 2

how do we study cells?

Answer 2

cytology

Question 3

2 main types of microscopes

Answer 3

light and electron

Question 4

2 types of electron microscopes

Answer 4

transmission (TEM)
scanning electron (SEM)

Question 5

light microscope features: how does it work? magnification? can specimen be alive? can you see organelles?

Answer 5

Visible light passes through specimen
Refracts light so specimen is magnified
Magnify up to 1000X
Specimen can be alive/moving

Can’t see organelles
other than nucleus

Question 6

electron microscope features: how does it work? magnification? can specimen be alive? can you see organelles?

Answer 6

Focuses a beam of electrons through/onto specimen
Magnify up to 1,000,000 times
Specimen non-living and in vacuum
Can see organelles

Question 7

can light or electron microscopes magnify better?

Answer 7

electron

Question 8

transmission microscope features

Answer 8

2-D, study internal structures of cells
Creates a flat image with extreme detail
Can enhance contrast by staining atoms with heavy metal dyes
Images called a micrograph

Question 9

scanning microscope features

Answer 9

3-D
Used for detailed study of surface of specimen
Gives great field of depth
Sample covered with thin film of gold, beam excited electrons on surface

Question 10

2 main types of cells

Answer 10

eukaryote
prokaryote

Question 11

prokaryotes domain

Answer 11

bacteria and archaea

Question 12

eukaryotes domain

Answer 12

eukarya (protists, fungi, plants, animals)

Question 13

prokaryote features

Answer 13

No nucleus (Nucleoid-DNA concentration)
DNA in a nucleoid
Cytoplasm/Cytosol
No organelles other than ribosomes
Small size
Primitive
i.e. bacteria

Question 14

eukaryote features

Answer 14

Has nucleus and nuclear envelope
Cytoplasm/Cytosol
Membrane-bound organelles with specialized structure/function
Much larger in size
More complex
i.e. plant/animal cell

Question 15

staining

Answer 15

process when color is added to bacteria so you can see it under a microscope

Question 16

gram-staining

Answer 16

almost always the first test performed for the identification of bacteria. the bacteria are identified as gram positive or negative based on the amount of peptidoglycan it has. it is a specific technique invented by Hans Christian Gram

Question 17

what is the cellular difference between gram positive and negative bacteria?

Answer 17

positive: several layers of peptidoglycan
negative: one layer

Question 18

process of gram staining:

Answer 18

1. specimen is heat fixed to the slide
2. use a primary stain on the slide
3. use a counter stain (secondary stain) on the slide
4. mordant is used to seal the stain into the bacteria
5. a decolorizer is used to remove excess stain

Question 19

heat fixing

Answer 19

process of passing the side containing the specimen through heat 2-3 times to make it stick to the glass slide

Question 20

what happens if you heat fix for too long?

Answer 20

the cytoplasm will boil, resulting in the destruction of bacteria cells, making staining and identification impossible

Question 21

what is the primary stain of the gram staining method?

Answer 21

crystal violet (sometimes methylene blue)

Question 22

what is the most common counter stain of the gram staining method?

Answer 22

safranin red/basic fuchsin

Question 23

what colors will the bacteria appear in the gram staining method?

Answer 23

positive: purple
negative: red

reason: all bacteria stained by crystal violet appear purple, all unstained bacteria are affected by safranin red and appear red.

Question 24

mordant

Answer 24

chemical used to seal the stain into the bacteria. this helps so the stain cannot be easily removed

Question 25

what mordant is used in the gram staining method?

Answer 25

gram’s iodine

Question 26

decolorizer

Answer 26

chemical used to remove excess stain

Question 27

what is the decolorizer used in gram staining?

Answer 27

ethyl alcohol

Question 28

what happens if you leave the stain or decolorizer on the bacteria for too long?

Answer 28

too light/dark stain

too little/too much removal of stain

Question 29

true/false: chemicals lose their effectiveness over time

Answer 29

true