Microbiology Chapter 2 Lecture

Front 1

What is a light microscope?

Back 1

A microscope that uses light to illuminate cells

Front 2

What are the 4 types of light microscopes?

Back 2

1) Bright-field

2) Phase contrast

3) Dark-field

4) Fluorescence

Front 3

How does a light microscope display cells?

Back 3

Specimens are visualized because of differences in contrast between specimen and surroundings

Front 4

What are the two sets of lens that form the image?

Back 4

1. Ocular lens

2. Objective lens

Front 5

What is the equation for total magnification?

Back 5

Objective magnification X ocular magnification

Front 6

What is magnification?

Back 6

The ability to make an object larger

Front 7

What is resolution?

Back 7

The ability to distinguish two adjacent objects as separate and distinct

Front 8

Resolution is determined by what two factors?

Back 8

1.) Wavelength of light

2.) Numerical aperture of lens

Front 9

How can you improve the final image?

Back 9

Improve contrast

Front 10

What is one way of improving contrast?

Back 10

Staining (Dyes are organic compounds that bind to specific cellular materials)

Front 11

What are 3 common stains?

Back 11

1. Methylene blue

2. Crystal violet

3. Safranin

Front 12

What do differential stains such as the gram stain provide?

Back 12

Able to separate bacteria into groups

Front 13

What are the two major groups that bacteria can be separated into?

Back 13

Gram-positive and Gram-negative

Front 14

What color do each bacteria gram stain turn?

Back 14

1. Gram-positive bacteria turns purple

2. Gram-negative bacteria turns red

Front 15

What is the procedure for the gram-stain?

Back 15

1) Flood the heat-fixed smear with crystal violet for 1 min (All cells purple)

2) Add iodine solution for 1 min (All cells remain purple)

3) Decolorize with alcohol for 1 min (Gram-positive are purple; gram-negative are colorless)

4) Counterstain with safranin (gram-positive turn purple and gram-negative turn red)

Front 16

What are the important features of phase-contrast microscopy?

Back 16

1) improves the contrast of a sample without the use of a stain

2) Allows for visualization of live samples

Front 17

What are the important features of dark-field microscopy?

Back 17

1) Light reaches the specimen from the sides

2) Light reaching the lens has been scattered by specimen

3) Image appears light on a dark background

4) Excellent for observing motility

Front 18

What are the important features of fluorescence microscopy?

Back 18

1) Used to visualize specimens that fluoresce

2) Cells fluoresce naturally or after they have been stained with a fluorescent dye

Front 19

What are the two types of microscopes used to visualize cells in 3-D?

Back 19

1) Differential interference contrast microscopy (uses a polarizer to create two distinct beams of polarized light)

2) Confocal scanning laser microscopy (laser source to generate 3-D image;

Front 20

What is special about electron microscopes?

Back 20

Use electrons instead of photons to create image of cells

Front 21

What are the two types of electron microscopes?

Back 21

1. Transmission electron microscope (visualization at the molecular level)

2. Scanning electron microscope (very large specimens can be observed)

Front 22

What are the three major cell morphology types?

Back 22

1. Coccus (spherical)

2. Rod or bacillus (cylindrical shape)

3. Spirillum (spiral shaped)

many variations on these types

Front 23

What are the three cell types that have a unusual shape?

Back 23

1. spirochete

2. appendaged bacteria

3. filamentous bacteria

Front 24

Does morphology predict physiology, ecology, phylogeny, etc?

Back 24

No, not a good predictor

Front 25

What can impact and determine the morphology of a cell?

Back 25

Selective forces

1. Optimization for nutrient uptake (small cells with higher surface to volume ratio)

2. Swimming motility in viscous environments or near surfaces (helical or spiral-shaped cells)

3. Gliding motility (Filamentous bacteria)

Front 26

What are the advantages of cells being small?

Back 26

1. Have more surface area relative to cell volume

2. support greater nutrient exchange per unit cell volume

3. Tend to grow faster than larger cells

Front 27

What is the cytoplasmic membrane?

Back 27

Thin structure that surrounds the cell

Vital barrier that separates the cytoplasm from environment

Highly selective permeable barrier; enable concentration of specific metabolites and excretion of waste products

Front 28

What are the features of membrane composition?

Back 28

1. General structure is a phospholipid bilayer

2. Contains both a hydrophilic and hydrophobic layer

3. Can exists in many different forms as a result of variations in the groups attached to the glycerol backbone

Front 29

What forms the hydrophobic region of the cytoplasmic membrane?

Back 29

The fatty acids that point inwards

Hydrophilic region remains exposed to the outside environment

Front 30

Does the cytoplasmic membrane contain embedded proteins?

Back 30

Yes

Front 31

How is the cytoplasmic membrane stabilized?

Back 31

Stabilized via hydrogen bonds and hydrophobic interactions

Front 32

What are the two types of proteins on the cytoplasmic membrane?

Back 32

Integral proteins and peripheral proteins

Front 33

Why is the outer surface of the cytoplasmic membrane important?

Back 33

Interacts with a variety of proteins that bind substrates or process large molecules for transport

Front 34

Why is the inner surface of the cytoplasmic membrane important?

Back 34

Interacts with protein involved in energy-yielding reactions and other important cellular functions

Front 35

What is different about archaeal membranes?

Back 35

They contain ether linkages instead of ester linkages

Front 36

What kind of linkage do bacteria and eukaryotic membranes have of their phospholipids?

Back 36

Ester linkage

Front 37

Do archaeal membranes contain amino acids?

Back 37

No; they have isoprenes instead

Front 38

Can archaeal membranes exist as lipid monolayers, bilayer, or mixture?

Back 38

Yes

Front 39

What are the important functions of the cytoplasmic membrane?

Back 39

1. Permeability barrier (polar and charged molecules transported; accumulate solutes against their concentration gradient)

2. Protein anchor (holds transport proteins in place)

3. Energy conservation (generation of proton motive force)

Front 40

What happens when solute concentration gets too high?

Back 40

The transporter gets saturated

Front 41

How does nutrient transport typically occur?

Back 41

Via carrier-mediated transport systems

Front 42

What are the three major transport systems in prokaryotes?

Back 42

1) Simple transport

2) Group translocation

3) ABC system

Front 43

Do all three transport systems require energy? If so, where does it come from?

Back 43

They all require energy and it typically comes from proton motive force or ATP

Front 44

How does simple transport work?

Back 44

Driven by the energy obtained from the proton motive force (transports solute against its concentration gradient)

Front 45

What are the three transport events that are possible?

Back 45

1) Uniport- transport in one direction across the membrane

2) Symport- transport 2 solutes the same direction at the same time

3) Antiport- transport a molecule in one direction while simultaneously transporting another molecule in the opposite direction

Front 46

Does the substance that is transported via group translocation modified or not?

Back 46

The substance is modified

Front 47

How many proteins are involved in the group translocation transport system?

Back 47

5 proteins

Front 48

Where does the energy come from that powers the group translocation system?

Back 48

Phosphoenolpyruvate

Front 49

How does the energy get transported via group translocation?

Back 49

The phosphate group is moved down the 5 proteins of group translocation

Front 50

What happens when the phosphate bond attaches to the enzyme that is the final part of the group translocation transport system?

Back 50

The phosphorylation leads to change in enzyme shape which allows glucose to enter

Front 51

How is the molecule that enters via group translocation modified?

Back 51

The molecule is phosphorylated

Front 52

What does the ABC system typically transport?

Back 52

1. Organic compounds

2. inorganic nutrients

3. trace metals

Front 53

Does the ABC system display high substrate specificity?

Back 53

Yes

Front 54

What kind of ABC transport system do gram-negative bacteria employ?

Back 54

1) Periplasmic-binding proteins

2) ATP-driven transport proteins

Front 55

What kind of ABC transport system do gram-positive bacteria employ?

Back 55

1) Substrate binding proteins

2) Membrane transport proteins

Front 56

Gram-positive and gram-negative bacteria have the same type of cell wall structure

True or False

Back 56

False (have different cell wall structure)

Front 57

What components make up the cell wall of a gram-negative bacteria?

Back 57

Two layers: LPS and peptidoglycan

Front 58

What components make up the cell wall of a gram-positive bacteria?

Back 58

One layer: peptidoglycan

Front 59

What is the peptidoglycan?

Back 59

Ridgid layer that provides strength to cell walls

Front 60

Peptidoglycan is a polysaccharide composed of 3 main components? What are they?

Back 60

1. N-acetylglucosamine and N-acetylmuramic acid

2. Amino acids

3. Lysine or DAP

Front 61

Is the cross-linkage of peptidoglycan the same or different for gram-negative and gram-positive bacteria?

Back 61

Different for both bacterial strains

Front 62

What is the repeating unit in peptidoglycan?

Back 62

Glycan tetrapeptide

Front 63

The glycan tetrapeptide is made up of two components. What are they?

Back 63

A glucose component and a peptide component

Front 64

What gives the cell wall its strength?

Back 64

Cross linkage

Front 65

Gram-negative bacteria contain cross linkages made up of what?

Back 65

Peptide bonds

Front 66

Gram-positive bacteria contain cross linkages made up of what?

Back 66

Interbridges

Front 67

What gives the cell wall its strength?

Back 67

Cross-linkages

Front 68

How much peptidoglycan layer do gram-positive bacteria have?

Back 68

90 percent

Front 69

Do gram-positive or gram-negative bacteria have teichoic acid?

Back 69

Gram-positive bacteria

Front 70

What are lipoteichoic acids?

Back 70

Teichoic acids covalently bonded to membrane lipids

Front 71

What are the two types of prokaryotes that lack a cell wall?

Back 71

1. Mycoplasmas

2. Thermoplasma

Front 72

How much of the cell wall in gram-negative bacteria contains peptidoglycan?

Back 72

About 10 percent

Front 73

What is most of the gram-negative cell wall made up of?

Back 73

Outer membrane called the lipopolysaccharide layer (LPS)

Front 74

LPS consists of two major components. What are they?

Back 74

Core polysaccharide and O-polysaccharide

Front 75

What is a special feature of the LPS layer?

Back 75

Contains endotoxin which is the toxic portion of the LPS layer

Front 76

What component of the LPS layer acts as a endotoxin?

Back 76

Lipid A

Front 77

What is the periplasm in a gram-negative bacteria?

Back 77

Space between the cytoplasmic membrane and outer membrane (LPS layer)

Front 78

What are porins in gram-negative bacteria?

Back 78

Channels for movement of hydrophilic low-molecular weight substances

Front 79

What is special about archaeal cell walls?

Back 79

No peptidoglycan layer and no outer membrane

Front 80

What is unique and belongs only to archaeal cell walls?

Back 80

Pseudomurein (polysaccharide similar to peptidoglycan)

Front 81

What is the most common cell wall type in the archaea domain?

Back 81

S layers which consists of proteins or glycoprotein

Front 82

Why are capsules and slime layers important?

Back 82

Polysaccharide layers which assist in attachment to surfaces and protect against phagocytosis

Front 83

What is the importance of fimbriae as a cell surface structure?

Back 83

It is a filamentous protein structure that enables organisms to stick to surfaces

Front 84

What is the special function of the cell surface structure called pili?

Back 84

Assist in surface attachment and facilitate genetic exchange between cells

Front 85

What are cell inclusions?

Back 85

Used for energy storage and position cells in a environment that is optimal for survival

Front 86

What are the two proteins that make up gas vesicles?

Back 86

GvpA and GvpC

Front 87

Are endospores present in all bacteria?

Back 87

No, present in just some gram-positive bacteria

Front 88

What are the two common bacteria that generate endospores?

Back 88

Bacillus and Clostridium

Front 89

What gives the endospore its heat resistance property?

Back 89

Calcium and dipicolinic acid

Front 90

What is the flagella?

Back 90

The motility structure that allows bacteria to move

Front 91

What is the flagella structure of bacteria?

Back 91

1) Filament composed of flagellin

2) Move by rotation

Front 92

What is the flagella structure of archaea?

Back 92

1) Composed for several different proteins

2) Move by rotation

Front 93

What are the three main components of the flagella?

Back 93

Filament, hook, and rod

Front 94

What are the 4 rings that make up the flagella basal body?

Back 94

1. L Ring

2. P Ring

3. MS Ring

4. C Ring

Front 95

How many flagella rings do gram-positive bacteria have?

Back 95

Only 2 rings due to missing of outer membrane

Front 96

What is the importance of MOT proteins as part of the flagella rod?

Back 96

Allow protons to cross the membrane and come in

Front 97

Why are the hydrogen ions that use the MOT protein to come in so important?

Back 97

Negative charges on the rod are attracted to the positive charges of the hydrogen ions which allows the MS ring to revolve and create rotational force

Front 98

What component is made first in flagellar synthesis?

Back 98

The MS ring (other proteins and hook are made next)

Front 99

What determines flagella rotation speed?

Back 99

The strength of the proton motive force

Front 100

What is gliding motility?

Back 100

Flagella independent motility

Requires surface contact

Front 101

What is taxis?

Back 101

Directed movement in response to chemical or physical gradients

Front 102

What is chemotaxis?

Back 102

Bacteria respond to chemical stimulus

Front 103

What do bacteria do when no attractant is present?

Back 103

Random movement

Front 104

What do bacteria do when attractants are present?

Back 104

Directed movement