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Microbiology > Lecture 3 > Flashcards

Lecture 3 Flashcards

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Biology 101 flashcards
1
Q

Structure of a prokaryotic cell

A

-No nucleus or nuclear membrane
-No membrane bound organelles
-Single, circular chromosome
-Smaller than eukaryotes

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2
Q

Bacterial Cell wall

A

-Made of peptidoglycan
-Provides structure, shape, and prevents osmotic lysis

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3
Q

Peptidoglycan cell wall

A

-polymer of disaccharide and amino acids
-sugar
•NAG
•NAM
•Sugars bound together by B (1,4) glycosidic (peptide) bond

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4
Q

Gram positive

A

-Thick peptidoglycan layer over inner (cytoplasmic) membrane
-90% of gram-positive dry weight is peptidoglycan
Example:
Staphylococcus aureus)

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5
Q

Gram negative

A

Double membrane
-cytoplasmic membrane—peptidoglycan layer—outer membrane
-10% of dry cell weight is peptidoglycan
Example:
E. coli

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6
Q

Gram positive surface membrane features

A

Techoic acid and lipotechoic acid chains in peptidoglycan layer

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7
Q

Gram negative surface features

A

-Porins and polysaccharides in outer membrane
-lipopolysaccharides pop up from outer membrane

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8
Q

Hans Gram

A

-classified bacteria based on cell wall composition

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9
Q

Function of B-lactam

A

-Antibiotic
-inhibits peptidoglycan formation

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10
Q

Penicillin-binding proteins (PBPs)

A

Enzymes involved in the terminal steps of peptidoglycan peptide cross-linking

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11
Q

Lysozyme

A

-innate immune system antibiotic
-breaks B-(1,4) glycosidic bond
-highly cationic and punctures membrane

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12
Q

Gram indeterminants

A

-Some bacteria contain a waxy lipid, mycolic acid, in their cell wall.
-Gram +, but stains weakly
-important examples:
Mycobacterium
Nocardia

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13
Q

Acid- fast stain (what)

A

Staining tests for mycolic acids

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14
Q

Acid-fast stain (Ziehl-Neelsen stain) steps

A
  1. Fix bacteria
  2. Stain (carbon fuschin) must be driven into the cells with heat/phenol
  3. Decolorized with acid-alcohol (3% HCl and 70% ethanol)
    •not acid fast organism decolors
  4. Counterstained with methylene blue
    •gram indeterminate stays pink
    •gram determinant turns blue
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15
Q

Archaea

A

-Almost all archaea have an S-layer
•considered part of the cell wall
-Some have pseudomureins
•similar to peptidoglycan

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16
Q

Pseudomurein

A

-glycosidic bond is B-(1,3) instead of B-(1,4) which makes it lysozyme resistant

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17
Q

Bacterial cell membrane (cytoplasmic membrane)

A

-40% phospholipid and 60% protein
-6-8nm thick
-Highly selective permeable barrier
-Embedded proteins play an important role

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18
Q

mRNA vaccines use what for delivery?

A

Lipid nanoparticles

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19
Q

Cytoplasmic membrane difference between bacteria and Archaea

A
  1. Bacteria
    -Ether (C-O) linkage between side chain and head
    -Disconnected bilayer
  2. Archaea
    -Ester (O=C-O) linkage
    -connected bilayer
20
Q

Permeability Barrier

A

-prevents leakage and functions as a gateway for transport of nutrients into and out of the cell
•small hydrophobic molecules and water can pass through the cell membrane
•Aquaporins

21
Q

Anchoring proteins

A

-Site of many proteins involved in transport, bioenergetics, and chemotaxis
•can accumulate nutrients against a concentration gradient

22
Q

Energy production

A

-Site of generation and use of the Proton Motive Force (PMF)
•There is a charge difference across the membrane
•Accumulation of protons on the outside and hydroxyl ions on the inside)
•Charge separation is a form of potential energy and provides energy for transport, ATP synthesis, and motility

23
Q

Cytoplasmic membrane function

A

Uniporter: one way transporter
Symporter: one way transporter of two nutrients
Antiporter: two way transporter

24
Q

Simple diffusion

A

-Substances move down their concentration gradient

25
Q

Transport proteins

A

Can move substances against their concentration gradient and concentrate them inside the cell
-highly specific
-Requires energy

26
Q

ABC transporter (ATP-binding cassette transporter)

A

Periplasmic binding proteins are involved and energy comes from ATP

27
Q

Group translocation

A

Chemical modification of the transported substance drives import against a gradient

28
Q

Lipopolysaccharide (LPS)

A

LPS is an Endotoxin: the lipid A component of LPS is a heat-stable toxin associated with the outer membranes

29
Q

Porins

A

Porins are transport proteins of the outer membrane that passively import nutrients (and export molecules) but at the cost of protection from the environment/antibiotics

30
Q

Glycocalyx

A

-Secreted to the outside cell wall
-A sticky, viscous, gelatinous, hydrophilic polysaccharide for (1) attachment, (2) prevention of phagocytosis, (3) prevention of drying out, (4) nutrient traps
—Capsule: neatly organized
—Slime layer: unorganized and loose

31
Q

Capsules

A

-only some bacteria have or acquire capsules
•capsules are called K antigen
-capsule is a virulence factor
•hard casing, difficult to have immune cells deal with.

Examples:
Salmonella typhi
Streptococcus pneumoniae

32
Q

Biofilms

A

-Collection of bacteria stick together because of glycocalyx
-Many glycocalyx built up

33
Q

Biofilm examples

A

-Contact lense build up
-pacemaker build up

-chronic sinusitis
-dental plaque

34
Q

Endospores

A

-tough, resistant structure that allows the bacteria to essentially exist in ‘suspended animation’

Example:
C. Difficile
Tetanus
Anthrax

35
Q

Sporulation

A

-formation of endospore
-Some Gram+ cells sporulate when the environment is inhospitable

36
Q

Endospore staining steps

A
  1. Primary stain: Malachite green with steam heat to force dye into the endospore
  2. Wash with water. The green stain trapped in endospore will remain
  3. Counterstain: Safranin (pink) with no heat
37
Q

Motility

A

-Toward a positive stimulus, such as food source or light
-Away from a negative stimulus, such as a toxin or darkness

38
Q

Flagella

A

Complex organ of motility that serves as a “motor”
-80% efficiency
-PMF-driven
Flagella proteins are referred to as a H antigens
-made of chains of flagellin

39
Q

Flagella staining

A

-Dye + Mordant on flagella
•Mordant examples: tannic acid and aluminum potassium phosphates

40
Q

Monotonous flagellation

A

One flagella on the end

41
Q

Amphitrichous flagellation

A

One flagella on each end

42
Q

Lophotrichous flagellation

A

A tuft of flagella is located on one end

43
Q

Peritrichous flagellation

A

The flagella arise all over the cell body

Peritrichous flagella tumble:
-bundled flagella (CCW rotation)
-tumble—flagella pushed apart (CW rotation)
-flagella bundled
(CCW rotation)

44
Q

Polar flagellation

A

The flagella are located on the ends of the cells

45
Q

Microbial taxis

A

Random Walk:
-Random movement, both runs and tumbles

Biased random walk:
-if organism senses it is moving toward a higher concentration of the attractant, runs become longer and tumbles less frequent. The reverse is also true

46
Q

Axial filaments

A

Spiral internal flagella
Found in spirochetes

Microbiology (13 decks)

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