Cell Basics and Microscopy (Lecture 3)

Question 1

What is cell growth the result of?

Answer 1

activities of metabolism

Question 2

What do cells use the metabolic process for?

Answer 2

1. gain mass
2. replicate their DNA
3. divide

Question 3

You have discovered a new ovoid (oval-shaped) microorganism with a nucleus, and genome containing multiple linear chromosomes. The new microorganism is…

Answer 3

most likely a eukaryote

Question 4

Resolution

Answer 4

the smallest distance by which two objects can be separated and still be distinguished

Question 5

What depends on the resolution of the observer’s eye?

Answer 5

the size at which objects become visible

Question 6

Light microscopy has a resolution limit of __________.

Answer 6

200nm

Question 7

What does electron microscopy require ____________________ conditions that can damage or alter cell structures.

Answer 7

fixation/freezing

Question 8

What is the limitation of the naked eye?

Answer 8

resolution is limited to 150 micrometer

Question 9

What is used to observe most microorganisms?

Answer 9

light microscopy

Question 10

What three lenses does light microscopy usually have?

Answer 10

low-power, high-power, and oil-immersion

Question 11

Bright-field

Answer 11

light passing through the cell directly forms the image

Question 12

Phase-contrast and differential-interference-contrast

Answer 12

exploits the phase change of light passing through an object varying thickness and density to produce an image

Question 13

Dark field

Answer 13

illuminating rays are directed from the side so only scattered light enters the microscope lens

Question 14

When is light microscopy useful for?

Answer 14

examining cell when they are alive

Question 15

Phase-contrast, differential-interference-contrast, and dark field are all useful for looking at cells while they ____________________.

Answer 15

1. move around
2. mitosis/cell migration

Question 16

What does staining provide?

Answer 16

contrast

Question 17

What does a simple stain technique involve?

Answer 17

flooding a prepared specimen with basic dye

Question 18

Negative stain technique uses _________ dye.

Answer 18

acidic

Question 19

What does acidic dye repel?

Answer 19

cell walls leaving clear cells on a dark background

Question 20

Fluorescence microscopy

Answer 20

relies on the use of fluorescent chemicals for visualization

Question 21

Fluorescent chemicals absorbs light at one _______________ and emits light at a ______________ longer wavelength.

Answer 21

1. wavelength
2. specific

Question 22

In Fluorescence microscopy what is the specimen stained with?

Answer 22

fluorescent chemical

Question 23

What excites fluorescent chemicals?

Answer 23

light from a mercury lamp

Question 24

How does Fluorescence microscopy work?

Answer 24

chemical emits a specific wavelength of light the light from the sample is passed through a filter so only the emission wavelength from the fluorescent chemical is detected

Question 25

What are some uses of Fluorescence microscopy?

Answer 25

-view a specific cell in a mixture of different cells -view specific cell component in a cell

Question 26

Transmission electron microscopy (TEM)

Answer 26

electrons pass through specimen and it reveals internal structures

Question 27

Scanning electron microscopy (SEM)

Answer 27

electrons scan the specimen surface and reveals external features in 3D

Question 28

What does both SEM and TEM require?

Answer 28

staining with heavy metals this preparation will kill the cell

Question 29

Morphology

Answer 29

cell shape

Question 30

Major cell morphologies

Answer 30

1. coccus 2. rod

Question 31

Cells with unusual shapes are...

Answer 31

1. spirillum (spiral) 2. spirochetes (corkscrew) 3. appendages bacteria 4. filamentous bacteria

Question 32

What are some selective forces that are involved in creating the morphology?

Answer 32

1. optimization for nutrient uptake 2. swimming motility in viscous environments 3. gliding motility

Question 33

Cocci shape

Answer 33

spherically shaped bacteria

Question 34

Where may cocci bacteria grow in?

Answer 34

1. chains 2. clusters 3. tetrads 4. sarcinae

Question 35

Chains

Answer 35

Strepto-

Question 36

Clusters

Answer 36

staph-

Question 37

Bacilli shape

Answer 37

rod-shaped bacteria

Question 38

How can bacilli grow?

Answer 38

1. arrange in pairs 2. chains 3. just short and rounded

Question 39

Bent rods

Answer 39

vibrios

Question 40

Corkscrew

Answer 40

spirilla with rigid cell wall and external flagella

Question 41

Spirochetes are corkscrew-shaped bacteria but are different from spirilla because...

Answer 41

-flexible cell walls -internal flagella

Question 42

Most cultured rod-shaped bacteria are between ________ and ___________ micrometers in width.

Answer 42

0.5 and 5.0

Question 43

Size range for eukaryotic cells

Answer 43

10 to >200 micrometers in diameter

Question 44

Size range for prokaryotes

Answer 44

0.2 to >700 micrometers in diameter

Question 45

Describe smaller cells surface area compared to their cell volume

Answer 45

they have more surface area than their cell volume

Question 46

What does having a larger surface area allow?

Answer 46

1. support greater nutrient exchange per unit cell volume 2. tend to grow faster than larger cells

Question 47

Who's bigger eukaryotes or prokaryotes?

Answer 47

eukaryotes