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Flashcards in Lecture 3 Deck (109):
1

metabolism definition

all of the chemical processes that take place in a cell

2

 

Anabolism definition

process by which a cell takes materials from the environment/catablic reactions (simple nutrients) and converts them to the various components of the cell

Typically, the more nutrients there are readily available, the higher the growth rate of bacterial colonies. 

3

Catabolism definition

process by which various chemicals are broken down, releasing energy. The cell uses this energy to drive other processes (e.g. anabolism)

4

Conservation of energy from chemical reactions involoves:

oxidation-reduction reactions

5

What kind of bonds are formed during an oxidative reduction reaction?

Polar covalent bonds 

ionic bons (e.g. Na+ + Cl→ NaCl)

 

In any case, redox reactions involve a shift in the balance of electrons

6

In a redox reaction, the e- donor becomes ___ and the acceptor becomes ____. 

oxidized

reduced

7

A totally reduced carbon is bound to ____ and a totally oxidized carbon is bound to ____. 

 

Likewise, a totally reduced oxygen is bound to ____.

 

 

4 hydrogens (CH4)

2 oxygens (CO2)

2 hydrogens (water)

8

Are lipids reduced or oxidized? How does this make them useful?

They are very reduced. They contain a lot of energy due to the amount of times they can be oxidized as they are converted to H2O and CO

9

Air in the atmosphere normally contains what percent of O2 and CO2?

O2: 21%

CO2: .04%

 

10

Anaerobic bacteria

cannot grow in the presence of air/molecular O2 (due to a sensitivity to the presence of oxygen)

Or

are able to grow in the absence of O2

11

Obligate aerobes 

require O2?

do they undergo fermentation?

Grow where in thioglycollate broth?

require presence of O2 for energy metabolism;

do not undergo fermentation

-grow at the top of the broth when cultured

12

Molecular oxygen 

can form toxic superoxide radicals (O2-)(has one unpaired electron, making it very reactive)

13

How do aerobic bacteria survive in the presence of O2?

They have enough superoxide dismutase (SOD) and catalase to remove toxic metabolites that result from the incomplete reduction of molecular oxygen

14

Two types of obligate anaerobes

Strict- grow in environments containing no more than 0.5% O2. Can be killed quickly with exposure to air. 

Moderate- most clinically relevant anaerobes. Will grow in environments 2-8% O2

15

Aerotolerant anaerobes 

-grow in presence of O2?

-where do they grow in thioglycollate broth?

Can grow O2 presence, but grow best in an anaerobic environment

-have enough SOD, so they can grow anywhere in the broth (uniform amount throughout broth)

16

Facultative anaerobes 

-can grow in the presence/absence of O2?

-have suffiecient ___ and ____

-grow best in presence or without O2? Why

-Tend to grow where in Tho\ioglycollate broth?

-Can grow in the presence or absence of O2

-They have sufficient SOD and catalase/peroxidase

-Grow best in presence of O2 bc they use it in energy metabolism

-tend to grow more near the top, but can grow anywhere in the broth

17

Facultative anaerobes can change thier ___ to cope with environmental changes. 

metabolism

18

Obligate anaerobes lack 

where do they grow in thioglycollate broth?

catalase and peroxidase or have such small amounts that they die from toxic effect of H2O2

tend to grow at bottom of broth

19

E. Coli (Escherichia Coli... spelling?)

faculatative anaerobe, highly versatile

20

Thoglycollate broth

allows culture of obligate aerobes(top), obligate anaerobes(bottom), facultative anaerobes(tend to be more @top), aerotolerant anaerobes (all over), and microaerophiles (will grow in the middle below the surface)

 

21

Three growth modes for E. coli

aerobic respiration 

anaerobic repspiration

fermentation (mixed acid fermentation)

22

Strict anaerobes lack: 

What does this enzyme do?

Superoxide dismutase (SOD)

Converts a superoxide radical (O2-) to peroxide (H2O2)

 

Note: H2O2 is still toxic

 

23

Catalase/Peroxidase

converts peroxide (H2O2) to nontoxic molecules

24

siderophores

 relatively low molecular weight, ferric ion specific chelating agents elaborated by bacteria and fungi growing under low iron stress

-take iron (from hosts) and concentrate it 

25

Iron

Fe,

important to the functioning of many enzymes, epecially the electron transport chain

26

where is iron found in mamalian tissues? (4 examples)

tightly bound in a variety of proteins: iron is pretty toxic if left by itself

heme- prosthetic group for hemoglobin, myoglobin, and several enzymes

ferratin- inside cells

transferrin- for iron transport between tissues

lactoferrin- in milk, tears, mucosal secretions, and granules of PMNs 

 

27

Where/How do bacteria typically break down macromolecules for nutrients?

They use enzymes to break down large molecules outside of the cell membrane, then bring in the smaller subunits using active or passive transport

28

pyruvic acid 

3 carbon sugar, provides carbon skeleton

converging point for many pathways

29

3 pathways bacteria us to convert glucose to pyruvic adic

Glycolytic (Embden-Meyerhof-Parnas)

Pentose Phosphate

Entner-Dourdoroff 

30

The carbons from pyruvic acid can be: (2)

- further catabolized for energy production

- used in anabolic reactions in the synthesis of new amino acids, lipids, carbs, or precursors for nucleic acids

 

31

How is energy captured in the catabolism of glucose

formation of high energy molecules (ATP) or reduced coenzymes

 

32

What is pyruvate used for? (2)

fermentation products

provide the intermediate that enters into tricarboxylic acid (TCA) or Krebs cycle

33

what are reduced conenzymes used for?

form proton gradient across cell via aerobic/anaerobic respiration

34

Respiration definition

metabolic process that involves electron transport along a series of membrane associated electron carriers to a final inorganic electron acceptor

 

 

35

anaerobic respiration

when the final inorganic electron acceptor is something other than O2

e.g. NO3-2, SO4-2, CO3-2

36

Aerobic respiration

final inorganic electron acceptor is O2

37

Fermentation

 

an organic molecule (often pyruvate) is the terminal electron acceptor. ETC is not used (less energy produced)

38

The Entner-Doudoroff Pathway is used instead of ____ in some bacteria. 

Examples of bacteria that do this: (2)

glycolysis

Pseudomonas aeruginosa (gram -)

Enterococcus faecalis (gram +)

 

39

The reduced coenzymes from the TCA cycle are reoxidized via the ____. 

Electron Transport chain

40

glycolytic pathway:

Where does it occur?

aerobic/anaerobic conditions?

Energy input required?

 

cytoplasmic matrix

reaction occurs in both aerboic and nonaerobic conditions

Needs investment of 2 ATP

41

Net products of glycolysis (per mole of glucose)

2 moles of pyruvate

2 moles of ATP (via chemical/ substrate level phosphorylation)

2 moles of NADH

42

To continue glycolysis, the cell needs a way to ____. How does this happen?

(invlolves NADH)

reoxidize NADH

via repiration or fermentation

 

43

The pentose phosphate pathway is important in : (2)

Can it yield any ATP?

biosynthesis (Source of NADPH) and catabolism (source of 5-carbon sugars for nucleic acids)

Yields 1 net ATP if used for energy

44

Entner-Doudoroff pathway is only seen in?

Products per mole of glucose?

Most bacteria that use this pathway are aerobic/anaerobic?

prokaryotes (that may lack an essental glycolysis enzyme)

1 NADH, 1 NADPH, 1 pyruvate, and 1 ATP net per mole of glucose

aerobes

45

Fermentation 

pyruvate or pyrubate derivative serves as the termianl electron acceptor 

ETC is not used

46

Respiration

uses membrane embedded electron transport chain and usually an inorganic electron acceptor

47

The TCA cycle is for 

Energy production (complete oxidation of pyruvate) to CO2

Biosynthetic Function- provides carbon skeletons for use in biosynthesis

48

In the presence of an inorganic electron acceptor (O2 or NO3-2), the NADH from glycolysis, and the NADH & FADH2 from the TCA cycle are ____. 

oxidized via the electron transport chain

49

What type of respiration uses Oas the final electron acceptor and creates a H+ gradient across the cell membrane?

aerobic respiration

50

NO3-2, SO4-2, or CO3-2 used as terminal electron acceptor. 
Less H+ gradient produced, and lower ATPs

Anaerobic respiration

51

Bacterial cells replicate using 

binary fission

52

lag phase

the phase when bacteria are first added to a new medium and they require time to adapt their metabolism

No increase in cell numbers in this phase

53

log phase

nutrients begin to be used by bacterial cells and cell growth is exponential

54

stationary phase

cell growth slows due to lack of nutrients and buildup of toxic materials

same # of cells duplicating and dying

55

phase of decline/ death phase

exponential death of bacteria due to a buildup of toxic material and no more resources 

Not as exponential as the log phase

*do not renew/add anything to the medium during the study of population dynamics of a batch culture

56

staphylococcus

species found in the upper respiratory tract and skin of all warm blooded animals

57

What are the cell wall virulence factors of Staphylococcus aureus?

-antiphaogcytic microcapsule

-peptidoglycan and teichoic acids may have endotoxin like activity (stimulate WBC to release cytokines)

-modified penicillin-binding protein provides resistance to penicillins and cephaloporins

58

light microscopy

a concave glass/quartz lens refracts light and is used for magnification of an image at a distance away from the focal point

image is reversed and upside down

59

Protein virulence factors of S. aureus?

-surface proteins that act as adhesins

-surface proteins that subert the immune system

-secreted toxins (cytotoxic alpha-toxin, toxic shock syndrom toxin-1, enterotoxins, exfliative toxins, and panton-Velentine leukocidin (kills WBCs)

-secreted enzymes- promote bacterial spreading through tissues due to tissue destruction

 

60

What regulates the expression of various S. aureus genes? (type of genes)

What is an example of one of these?

Global regulatory genes

The best studied one is a quorum sensing regulatory system that upregulates the expression of surface proteins

-enables the bacteria to optimize virulence gene expression and host colonization

61

surface and secreted proteins in S. aureus are _____ phase dependent. 

Growth

62

Methods to identify microbial agents of disease (4)

-direct microscopic visualization

-culitvation and identification of the organism

-serological and cytological methods (detect microbial antigens, detect the hosts immune response)

-detection of microbial DNA or RNA

63

What color is the shortest visible light wavelength and what is the resolution limit for a light microscopy

blue wavelength is the shortest wavelength and it gives us a resolution limit of ~200nm with light microscopy

64

Shorter wavelengths give ___ resolution

higher 

65

resolution

abitlity to distinguish two closely placed points

66

UV light has a shorter or longer wavelength than visible light?

shorter

67

68

69

brightfield (light) microscopes

field of view is bright if:

Light source is under specimen and light passes through the specimen to then enter into the objective lens

70

brightfield (light) microscopes

objective lens:

usually 4x, 10x, 40x, or 100x power

The 100x needs immersion oil in order to not lose light

71

brightfield (light) microscopes

immersion oil has the same refractive index as the glass of slide and objective lens T/F

What is the function of immersion oil

T

allows more light to enter into the small diameter, high magnification (90x-100x) lens

72

brightfield (light) microscopes

-the microscope has how many ocular lenses?

-Total maginificaiton = ?

-two

-magnification of objective lens x magnification of occular lens

*most modern microscopes also have a condensor lens to direct light through specimen

73

On light microscopes, why do objective lenses have different lengths?

Each lens set has a different focal lengths

74

Darkfield microscopy

Uses the same objective and occular lenses as brightfield microscope T/F

T

75

Darkfield microscopy

A special condensor only allows ____ light to reach the specimen.

This causes the specimen to appear____ against a ___ background. 

oblique, scattered light

Obect looks bright against a dark background

76

Darkfield microscopy

max resolution?

20nm (10x more resolution than brightfield)

77

Phase contrast microscopy creates what kind of image?

It enables visualization of:

3D image

enables visualization of the internal structures of unstained cells

78

differential interference contrast microscopy (DIC) is a techique used to enhance:

contrast in unstained, transparent samples

79

flurochromes (used in flurorescent microscopy) absorb what kind of light?

Then they emit:

short wavelength UV light

Then they emit energy at a higher visible wavelength

80

flurorecent microscopy

direct immunofluorescence

employs a fluorescent dye linked to an antibody. The antibody directly binds with the target antigen

81

82

indirect immunofluorescence

tagged antibody is a second antibody. It binds to another antibody that actually binds the target antigen

83

Transmission electron microscopy

electrons are fired through specimen and create an image on a detector screen. 

 

84

Transmission electron microscopy

How must specimen be prepared?

what is the max resolution compared to LM?

ultrathin sectioning and staining with heavy metals such as osnium, uranium, or lead for increased contrast

Max resolution: 1000x greater than LM

85

Scanning electron microscopy

 

surface of specimen is coated with heavy metal and electron beam scans across its suface, rather than passing through.

reflected electrons are collected and form a 3D like image on a high resolution cathode-ray tube

 

86

Wet mount

specimen is placed on a slide and mixed with a salt solution

87

to detect fungi in tissue scrapings (using wet mount technique), what solution should be used?

10% KOH solution and a stain. The KOH solution will dissolve mammalian and non cellular material, leaving the reistant fungal cell walls. 

88

Wet mounts:

What can india Ink used for?

India ink can be used to visualize the thick capsule of Cryptococcus neoformins in freshly obtained cerebrospinal fluid

89

Methods to phentypically classify bacteria 

Morphology (cell shape, cell arragements, staining characteristics)

Growth charcteristics 

90

Basic dyes have what kind of charge? This means they bind easily to __. 

examples of basic dyes (5)

 

positive charge 

They bind easily to negatively charged molecules, such as nucleic acids, many proteins, and surfaces of bacterial cells

 

91

Acid dyes have what kind of charge? Are they used for bacteria typically?

negatively charged/ are not typically used for bacteria

bind to positively charged cell structures

92

Simple stains are used for

to tell cell shape, size, and cell arrangements

 

93

Differential stains are used for:

Examples of differential stains:

divide bacteria into seperate groups based on staining properties 

e.g. gram stain, acid fast stain

 

94

Gram staining process (6 steps)

1. Heat fix specimen to slide & flood w crystal violet solution. Leave for 1 min

2. rinse the slide, then flood with iodine solution. Leave for 1 min

3. Decolorize w acetone for 5 seconds (not too vigorously tho)

4. wash slide in water immediately. Gram neg bacteria wont be visible now

5. apply safranin counterstain for 30 seconds

6. wash with water, blot, and air dry. 

Violet colored bacteria: gram pos

Red colored bacteria: gram neg

95

During the streak plate technique, it is important to __ the loop between successive regions

sterilize 

96

How to fix bacteria to a slide?

spread culture in thin film over slide, let air dry, then pass slide through flame to fix it. 

 

(see slide 69)

97

98

Acid fast stain used to stain (what organisms?)

What color will they stain? What is used as the counter stain?

Acid fast stains used for staining genuses Mycobacterium and Nocardia and oocyts of certain protozoa

They stain red.

Methylene blue is used as counter stain. All other cells will appear blue

 

99

Ziehl-Neelson Stain (same thing as acid fast) (Kinyoun modification)

Organism is suspended in saline soluntion. 

Slide is flooded with carbol fuchsin and phenol (3 min), then rinsed w H2O

Slide decolorized using 3% HCL in 70% water (~2 min)

rinse with water, then slide flooded with methylene blue counterstain (30 sec)

rinse w water and air dry

100

In acid fast staining you can the blue stained cells are always gram positive T/F

every cell besides acid fast bacteria (which will stain red) will appear blue. This includes all gram pos, gram neg bacteria and eukaryotes. 

101

What stain procedure can be used to visualize Klebsiella pneumoniae?

simple stain to stain the cells and a negative stain to demonstrate their capsule

102

Negative (capsule) staining

stains the background and shows true cell size and can demonstrate capsules

103

Spore stainz

allows you to see a green endospore and red vegatative cell 

104

metachromatic stains

Stains volutin (polyphosphate) in Corynebacterium diptheriae

105

Are endospores easily stained?

Nah

106

What are two species of bateria that form endospores that we are concerned with?

Baccillus and Clostridium

107

What compound do you use to stain an endospore?

malachite green

108

metachromasia definition

where is this used?

staining in a different color than that of the dye

Can be use to detect volutin (black) granules within green Corunebacterium cells) (using Albert's stain)

109

Why stain bacterial flagella?

flagella are too slender to be seen with LM, so flagellar stain coats can make them more apparent. Not routinely done, but can provide important taxonomy info.