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Microbiology-1 > Bacterial Structure and Classification > Flashcards

Bacterial Structure and Classification Flashcards

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Biology 101 flashcards
1
Q

What are the two major shapes of bacteria?

A

Rods ( Bacilli ) and Spheres ( Cocci )

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2
Q

What are chains of Cocci?

What are pairs of Cocci ?

Grape like clusters of Cocci ?

A

Streptococci

Diplococci

Staphlococci

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3
Q

What are the major features that distinguish prokaryotes from Eukaryotes?

A

A nucleus and membrane bound organelles

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4
Q

What is the bacterial cell wall made of ?

A

Peptidoglycan- The cell wall in bacteria provides rigidity.

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5
Q

What are the major targets for antimicrobial therapy ?

A

The cell wall and its biosynthetic machinery

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6
Q

What is a way you can distinguish between Gram Positive and Gram negative bacteria?

A

The characteristics of the cell wall.
*Thick and heavily cross linked = Gram +

*Thin and lightly cross linked = Gram -

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7
Q

Do bacteria have sterols in their membranes?

A

No

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8
Q

What are some bacterial components that differ in bacteria and animals enough to be targets for antibiotic therapy?

A

Ribosomes ( smaller in bacteria )
RNA Polymerase
Topoisomerase

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9
Q

What is different in the cell membrane between gram + and gram - bacteria ?

A

The gram - bacteria have an extra layer in the cell membrane

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10
Q

Is the peptidoglycan layer external or internal to the cytoplasmic membrane?

A

The peptidoglycan layer is external to the cytoplasmic membrane

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11
Q

What are the two purposes of Pili ?

A

Sex Pili - are used to transfer genetic materal from one bacterium to another in conjugation,

Attach bacteria to the host surface.

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12
Q

What is the purpose of a flagella ?

A

Cell motility

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13
Q

What is a capsule ?

A

External structures composed of either polysaccharide or polypeptide that serve to protect and encapsulate bacteria from phagocytosis

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14
Q

What type of bacteria forms spores?

A

Gram positive rods can form spores in response to stress and nutrient limitation.

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15
Q

Other than pepditoglycan what other compounds compose the bacterial cell wall?

A

Teichoic acid and Lipoteichoic acid

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16
Q

How many layers deep is the gram negative bacterial cell wall?

A

Two

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17
Q

What space is found between the inner and outer bacterial cell walls?

A

Periplasmic space

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18
Q

What is the charge of the outer bacterial membrane and how does this help the bacteria to survive?

A

The outer membrane is negatively charged. This helps the bacteria evade phagocytosis, hinder antibiotic uptake, and avoid the action of complement.

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19
Q

How do nutrients pass through the outer membrane?

A

Porins are molecular sieves that allow substrates such as sugars to be transported across the membrane.

20
Q

Does the periplasmic space contain any enzymes?

A

Yes, degrative enzymes will attempt to degrade antibiotics.

21
Q

What molecule is unique to the outer membrane of gram (-) bacteria

A

Lipopolysaccharide (LPS) which is found in the outer leaflet of the membrane

22
Q

What other molecules are contained in LPS?

3

A

Lipid A- recognized by the innate immune response to elicit a cytokine storm which leads to sepsis or septic shock

Endotoxin- a toxic phospholipid

O-Antigen- major surface antigen of gram negative bacteria.

23
Q

Describe Type 1 secretion from bacteria.

A

In type 1 secretion proteins are secreted directly into the extracellular environment from the cytoplasm.

24
Q

Can Type 1 secretion have any affect on antimicrobial drugs?

A

Yes, The antimicrobial drugs can be directly pumped out of the cell promoting drug resistance.

25
Q

What type of bacteria have Type 1 Protein Secretion Systems ?

A

Gram ( + )

26
Q

What type of bacteria have Type 2 Protein Secretion Systems ?

A

Gram ( - )

27
Q

How does a type 2 Protein Secretion System work?

A

Proteins are first secreted into the periplasmic space then into the extracellular space.

28
Q

Describe type 3 protein secretion systems.

A

Type 3 protein secretion systems acts like a molecular syringe becuase their structure allows for direct injection of toxins and other virulence factors into the cytosol.

29
Q

What is peptidoglycan made up of?

A

Repeating disaccharides of N-Acetylmuramic acid and N-Acetylglucosamine

30
Q

What are the repeating disaccharides of peptidoglycan linked via?

A

Transglycosylase

31
Q

What bridges the sugar backbones of peptidoglycan?

A

Pentapeptide crosslinks formed by transpeptidases and carboxypeptidases.

32
Q

What are penicillin binding proteins?

A

Transpeptidases.

33
Q

What portion of nacetylmuramic acid pentapeptides contain a target for antimicrobials?

A

Terminal D-Alanine Pair which is critical for cross-linking of the bacterial cell wall.

34
Q

What common antibiotic targets the terminal alanine pair?

A

Vancomycin

35
Q

Where is the bacterial cell wall assembled?

A

In the cytoplasm

36
Q

What is a natural defence that targets the bacterial cell wall?

A

Lysozyme which is present in tears, saliva, and in the lysosomes of phagocytic cells

37
Q

What will offer the bacteria antibiotic resistance to vancomycin?

A

Vancomycin resistance occurs when D-Alanine D- Lactone is synthesized.

38
Q

What are the two types of bacteria that do not stain using the gram stain method?

A

Mycoplasma and Chlamydia

39
Q

What composes the cell wall of mycobacterium?

A

A waxy coat of mycolic acid.

40
Q

What happens to anaerobic bacteria in the presence of oxygen?

A

They get killed.

41
Q

What type are the majority of pathogens?

A

Facultative anaerobes

42
Q

What kind of bacteria can grow in the absence of oxygen?

A

Microaerophilic

43
Q

What is a useful technique to classify Fermentative bacteria?

A

The end products of fermentation.

44
Q

What can be used to determine the major pathogenic members of the Streptococcus species?

A

Lancefield Antigen which is commonly referred to as the GAS antigen

45
Q

How can you distinguish between different strains within a genus of bacteria ?

A

Serotyping

Microbiology-1 (6 decks)

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