Microbiology Exam 1 pt 2

Question 1

Dry mount

Answer 1

Fixing bacteria to a slide:
*Heat
*Chemical
Staining:
*Helps to visualize cells
*Cells must be fixed to the plate to stain

Question 2

Dark field Microscopy

Answer 2

A dark background with a light specimen
Often visualized using fluorecent stains
Good for visualizing specific cell parts

Question 3

Phase Contrast

Answer 3

Mid tone between brightfield and darkfield
Often done woth a wet mount
Good for visualizing motility

Question 4

Brightfield

Answer 4

Dark specimen on a light background
Most common
Requires a stain to visualize

Question 5

Types of staining

Answer 5

Simple vs Differential Stains
Gram Staining
Acid Fast Stain
Stains Mycolic Acids
Will work for specimens that won’t gram
stain
Endospore Stain
Malachite Green for endospore stain
Safranin for rest of the cell
Negative Stain
Stains the background
Flagella Stain
Fluorescent

Question 6

Gram Stain Procedure

Answer 6

1. Heat fix cells to slide
2. Stain w/ crystal violet
3. Use a mordant (grams iodine)
4. Wash cells with decolorizer (alcohol)
5. Stain cells w/ Saffranin
   Gram + = purple
   Gram - = pink

Question 7

Nutrition

Answer 7

Essential nutrients
Macro: CHNOPS and Mg2+, Fe2+, Ca2+,
K2+
Micro/Trace: Co, Cu, Mn, Zn, Mo, Ni

Question 8

Growth

Answer 8

Binary fission- exponential
2n, n= number of generations
Budding
Multiple fission
Three Phases:
Growth after cell is “born”
Chromosome replication and partitioning
Cytokinesis

Question 9

Bacterial growth curve

Answer 9

5 distinct phases
1. Lag phase
2. Exponential phase
3. Stationary Phase
4. Death phase
5. Long-term stationary phase

Question 10

Generation time

Answer 10

For binary fission: Nt=No x 2n

Question 11

Cultures and media

Answer 11

Cultures
Liquid or broth: best for singular type of
bacteria
Solid: best for different types of bacteria
Medias
Complex: nutrient-rich but poorly
defined
Synthetic: precisely defined
Enriched: complex media with blood
(fastidious)
Differential: differentiates between
different bacteria
Selective: selects for one bacteria to
survive over others, inhibits certain
bacterial growth

Question 12

Isolating colonies

Answer 12

Dilution streaking: dragging a loop of bacteria across an agar plate
Spread plating: serial dilutions

Question 13

Measurement of cell numbers

Answer 13

Counting chambers
Membrane filters
Pour plate
Optical density

Question 14

Morphology of bacteria

Answer 14

Cocci:
Circular shape
Can be gram +/-
Can have parallel planes, perpendicular
planes, and random planes
Baccili:
Rod shape
Almost all are gram +

Question 15

What makes up the bacterial cell w/ organelles

Answer 15

Thick outer envolope
Compact genome
Coordinated cell functions
No nucleus, nucleoid instead
Organelles:
Cytoplasm
Cell membrane
Cell wall
Nucleoid
Flagella (not all bacteria)

Question 16

Ultracentrifugation

Answer 16

Allows you to look at the components of a cell

Question 17

Cell membrane composed of

Answer 17

The structure that defines the cell
composed of lipid bilayer
proteins embedded
Fulidity
Hydrophillic polar head
Hydrophobic nonpolar tail
ether bonds are what allows archaea to
survive in extreme temps

Question 18

Membrane Proteins functions

Answer 18

Provide structural support
Detect environmental signals (ex. toxins)
Secretion of things in/out of the cell
Transporting ions and energy storage

Question 19

Transportation

Answer 19

Passive:
Moves with the gradient
High to low
No energy required
Ex. simple diffusion, osmosis, facilitated
diffusion
Active:
Requires energy (ATP)
Usually comes in the form of ATP
hydrolysis

Question 20

Cell wall composed of

Answer 20

Most bacteria cell walls contain peptidoglycan.
A target for antiobiotics
Peptidoglycan contains:
N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)
Peptidoglycan layers are bound together by a peptide

Question 21

Gram +

Answer 21

Thick layer of peptidoglycan which is anchored by teichoic acid
Teichoic acid attaches to NAM of
tetrapeptide
Have capsules
protects cells from phagocytosis
Allows organisms to adhere to surface
colonize host
Have an S-layer
in almost all archaea and free-living
bacteria
consisting of a protein or glycoprotein

Question 22

Gram - cell wall composed of

Answer 22

Thin layer of peptidoglycan
LPS (lipopolysaccharides)
O-polysaccharides
Outer Membrane
Inner membrane
Lipoproteins

Question 23

Inclusions

Answer 23

Formed by an aggregate of Organic and Non-Organic Substances
ex. Granules, Crystals, globules
Microcompartments: can house specific
enzymes (ex. rubisco)
Gas vacuoles: important for microbe
buoyancy
Magnetosomes: Will orient the organism to
the Earth’s Magnetic Field

Question 24

Ribosomes

Answer 24

Site of protein Synthesis:
70s Ribosome: Comprised of 30S and 50S (fit together to make 70s)

Question 25

Nucleoid

Answer 25

Region that holds the cell’s Chromosome
Can be observed through microscopy
Some cells have multiple
Is help in tack by supercoiling DNA