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M1 Micro Bacteriology Quiz 1 > 01_Bacteria Structure > Flashcards

01_Bacteria Structure Flashcards

1
Q

Note: These are just a few cards. In info was mostly review for me.

A

Note: These are just a few cards. In info was mostly review for me.

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2
Q

When stained, what are the colors of gram positives? Gram negatives?

A
  • Positives = violet

* Negatives = red

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3
Q

What are Koch’s postulates?

A
  • find bacteria that causes disease
  • grow bacteria in culture
  • reproduce disease
  • re-isolate bacteria from disease
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4
Q

What are Koch’s Molecular Postulates?

A
  • The phenotype of the specific gene should be associated with a pathogenic strain
  • Knock out should lead to reduced virulence
  • Knock in should restore of virulence
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5
Q 
What are the distinguishing characteristics (cell wall? Pathogenic? Energy source? Nucleus?) of…
Algae
Fungi
Protozoa
Bacteria
A
  • Algae: no pathogens, all photosynthetic, nucleus
  • Fungi: some pathogens, non-photosynthetic; rigid cell wall; (fungi, including pathogenic fungi, will be discussed later in the course); nucleus
  • Protozoa: some pathogens, no rigid cell wall; unicellular, nonphotosynthetic. Some parasites have cysts with a rigid cell wall. Ameba, Paramecium, Euglena; nucleus

• Bacteria:
o many pathogens
o most require organic compounds as energy source
o some of the non-pathogens are photosynthetic
o all (with one exception) have a rigid cell wall
o Nucleus

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6
Q

Explain the differences in movement of eukaryotes and prokaryotes.

A
  • Euks: Cytoplasmic streaming (amoeboid), flagella, cilia

* Proks: flagella (with no microtubules, and does have H-Antigen)

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7
Q

Explain the differences in cell wall of eukaryotes and prokaryotes.

A
  • Euks: Plants and algae have polysaccharide (glucose); fungi have chitin (acetyl glucosamine polymer) and beta1,3 glucan (glucose polymer)
  • Proks: peptigoglycan polymer containing muramic acid (derivative of acetyl glucosamine); D-amino acids
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8
Q

What are the three shapes of bacteria?

A
  • Coccus (round)
  • Bacillus (rod)
  • Spiral
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9
Q

Do bacteria have sterols in the cytoplasm or membrane?

A
  • No. There is only one exception: mycoplasma.
  • Euks do contain sterols.
  • Proks DO NOT contain sterols
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10
Q

What is a diagnostic quality of Streptococci with regard to cell division? What about Staphylococci?

A
  • Streptococci: form long chains

* Staphylococci: form clusters, like grapes

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11
Q

What are the layers of a gram +?

A
  • membrane
  • Thick peptidoglycan (not an antigen) with Teichoic acid (antigen) and Lipoteichoic acid (antigen)
  • Note: Teichoic acid uses the sugar Ribitol
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12
Q

What are the layers of gram -?

A
  • Inner membrane
  • Thin peptidoglycan
  • Outer membrane with Lipopolysaccharide (LPS) (endotoxin and O-antigen) and porins (passively transport
  • Capsule (?)
  • Note: There is the periplasmic space between the inner and the outer membrane
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13
Q

What is the H-antigen? What is the O-antigen?

A
  • H = flagella

* O = LPS

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14
Q

What is the only bacteria without a cell wall?

A

• Mycoplasma (not mycobacteria!

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15
Q

What are the components of the cell wall in bacteria?

A
  • N-acetyl glucosamine (NAG) linked to N-acetyl muramic acid (NAM) (this is a glycosidic bond)
  • Short peptide (4 aa) linked to the lactic acid residue of the NAM
  • Forms a chain linked fence
  • This is called a peptidoglycan
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16
Q

How does penicillin affect the cell wall?

A

• it blocks the chain linking of the fence and the bacteria die

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17
Q

How does lysozyme (in tears) affect the cell wall?

A

• splits the glycosidic bond between NAG and NAM

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18
Q

What are the differences between gram – and gram +?

A

• see A-16 in notebook

19
Q

What are the functions of the gram – outer membrane?

A

• B barrier to antimicrobial agents
• reacts with antibodies
• blocks entry of large molecules
o ex: lysozyme cannot degrade cell wall unless part of the outer membrane is removed
• more resistant to antibiotics and detergents than gram +

20
Q

What is the function of porins in the outer membrane of gram -?

A
  • Porins allow passive transport of small molecules and block other molecules
  • Antibiotics against gram – must pass through porins in order to work on gram –
21
Q

What is lipopolysaccharide (LPS)?

A
  • found in the outer membrane of gram –
  • Know: the Lipid A portion is embedded in the outer membrane, where as the oligosaccharide (the O antigen) is exposed to the environment
  • There are many O antigens even within species of bacteria and are responsible for immunological specificity (different serotypes)
22
Q

What is found in the periplasmic space in gram - ? How do gram + mimic this function?

A
  • gram - : protective enzymes that degrade foreign molecules (like antibiotics)
  • gram + : extrude degradative enzymes into its immediate environment
23
Q

Explain the gram staining procedure.

A
  • Stain with violet (violet enters the cytoplasm)
  • Treat with iodine (the iodine binds with the violet)
  • Wash with ethanol (the thick peptidoglycan of gram + traps the purple inside; for gram – the purple washes out)
  • Counter stain with red (stains gram – red)
24
Q

What are the exceptions?

A
  • old gram + sometimes lose their purple-stain-retaining property
  • If the cell wall of gram + were removed, it would stain as gram -
  • There are “gram variable” bacteria exceptions. Some of these are medically important
25
Q

What is the capsule made of? Does it stain?

A
  • non-essential secretion of polysaccharide
  • Does not stain
  • Is usually found on gram -, but some gram + also have
26
Q

What is the clinical significance of the capsule?

A
  • can be pathogenic
  • can be antigenic
  • can be found in the urine or spinal fluid (bad)
27
Q

What are flagella made of?

A

• flagellin

28
Q

What are the two types of location for flagella?

A
  • petrichous flagella (all over the cell)

* polar flagella (one side of cell)

29
Q

Note: all motile bacterial have flagella. Not all bacteria are motile. Some motile bacteria with flagella lose their motility (age and/or conditions), but remain viable

A

Note: all motile bacterial have flagella. Not all bacteria are motile. Some motile bacteria with flagella lose their motility (age and/or conditions), but remain viable

30
Q

What are the functions of pili and/or fimbriae? (hint: it gets raunchy) (name a second that is more modest in its function)

A
  • Function in adherence to other cells, conjugation, and small amounts of movement
  • F pili are are “male” donors that tranfer DNA to other bacteria
  • The recipient now becomes an F pili
  • IV pili function in “twitching motility” that can push and pull bacteria across a surface
31
Q

What are pili made of?

A
  • pilins

* Adhesins (on tip) (typically a lectin, which is a protein that binds to carbs)

32
Q

Explain examples of clinical significance of pili.

A

• adherence to epithelial cells
o in urinary tract, bacteria are richly piliated and bind to the urethra
o Gonococci (gonorrhoea)
• formation of microcolony
• bacterial evolution via conjugation and horizontal transfer

33
Q

What other bacterial structures are used for adherence (other than pili)?

A

• glycocalyx in gram + (this is a polysaccharide)

o bind to heart valves, catheters, and teeth

34
Q

What are spores? Are they common? Under what conditions do they form?

A
  • During nutrient deprivation, one spore can form from one bacteria, which contains the essential components of the bacteria, and can be “re-constituted” when environmental conditions return.
  • Trivia: spores can last at least 250 million years
35
Q

What are spores resistant to? What compounds in spores confer resistance? What can kill spores?

A
  • Resistant to drying, heat, and chemical agents (detergents).
  • Dipicolinic acid (calcium chelator)
  • High heat and pressure. They can survive boiling.
36
Q

Spores are rare. What are examples of spore-forming bacteria?

A

• Large Gram +
o Bacillus and clostridia (gangrene)
o Bacillus Anthracis (anthrax) (can germinate in the lungs)

37
Q

Aside from passive diffusion, what are the three transport mechanisms for bacteria membranes?

A

• Facilitated diffusion
o Followed by rapid metabolism of compound. Intracellular concentration is kept low
• Phosphoenolpyruvate: Sugar Phosphotransferase system
o Involves chemical transformation during transport
o PEP + sugar ==> sugar-P + pyruvate
o Sugar-P is trapped in cell and metabolized
• Active transport (in or out)
o Intracellular concentration > extracellular (often)
o Example antibiotic pumps

38
Q

What are some common secreted factors?

A
  • Exotoxins
  • Proteases
  • Amylases and other polysaccharide-specific degradation enzymes
  • Lipases
39
Q

What are examples of exotoxins?

A

• Exotoxin A, pertussis toxin, Anthrax, Hemolysins, and others

40
Q

What are examples of proteases?

A

• elastase

41
Q

What are examples of polysaccharide degradation enzymes?

A
  • rhamnogalacturonate lyase

* alginate lyase

42
Q

What are examples of lipases?

A

• phospholipase C

43
Q

Explain chemotaxis

A
  • sugars, proteins, and other compounds can function as attractants (positive chemotaxis) or repellants (negative chemotaxis0
  • Bacteria have “tasters” that control flagella
  • Flagella counter clockwise ==> move straight
  • Flagella clockwise ==> change direction

M1 Micro Bacteriology Quiz 1 (5 decks)

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