Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BMR 605 > Test 1 Intro to Microbiology > Flashcards

Test 1 Intro to Microbiology Flashcards

1
Q

What are the defining characteristics of Bacteria?

A
  • Unicellular Prokaryotes
  • Lack of both nuclei and membrane-bound organelles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What subtype of bacteria do all pathogens fall under?

A

Eubacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the roll of flagella?

A
  • They are required for movement of the cell
    • Toward nutrients
    • Away from a toxic substance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the process of movement by which flagella operate?

A

Chemotaxis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How can researchers use flagella?

A

The position and number are helpful in ID’ing.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are Pili (fimbriae):

A
  • Thin, rigid appendages composed of pilins
  • allows cells to adhere to host cell or other bacterial cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Capsule (glycocalyx):

A
  • Thick viscous layer to thin slime layers
  • Gives colony a smooth and shiny appearance on agar
  • Confers resistance to phagocytosis
  • Usually polysaccharide, but occasionally protein
  • Also, found in Fungi
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Nucleoid details:

A
  • Discrete area containing the bacterial chromosome and plasmid DNA; bacterial DNA is organized by histone-like proteins.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Cytoplasmic inclusion bodies:

A
  • Sites where nutrient macromolecules (usually polysaccharides like glycogen)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Explain 70S Ribosomes?

A
  • Sites of protien synthesis
    • Actively growing cells are packed with ribosomes.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Explain Endospores

A
  • Heat-resistant, dehydrated multi-layered cells that are formed within a bacterial cell
  • Endospores germinate into growing cells when adverse conditions wane.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Explain Sporulation?

A
  • Induced by nutrient starvation
  • Process by which endospores are formed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Explain Calcium-dipicolinate?

A
  • An abundant compound within the endospore, may stabilize and protect the DNA against damage.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the Bacterial Cell Envelope composed of?

A
  • Plasma membrane + Cell wall + Intervening material
    • Some texts include capsule.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Details of plasma membrane

A
  • Cytoplasmic membrane
  • Functions
    • Site of:
      • Active transport (nutrient uptake)
      • Respiratory chain components (electron transport)
      • Synthesis for phospholipids, LPS, peptidoglycan, and capsular polysaccharides.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the results of the Gram stain test?

A
  • Gram positive are blue-purple
  • Gram negative are pink-red
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is peptidoglycan composed of?

A
  • Complex macromolecule consisting of glycan polymers which are cross-linked by peptide chains.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What peptide chains are unique to gram positive bacteria?

A

Pentapeptide bridges (small circles) coupled to NAM (N-acetylmuramic acid).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is Tetrapeptide (of L-alanine, D-Glutamic, L-lysine and D-Alanine) covalently linked to?

A

Carboxyl group of M (NAM).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How is the Sacculus formed?

A
  • Covalent linkage between tetrapeptides allows glycan backbones to be linked together forming the sacculus.
    • Sacculus = mesh or network of peptidoglycan.
21
Q

In gram +, terminal D-alanine of tetrapeptide is covalently linked by?

A

Glycine pentapeptide

22
Q

In gram +, glycine pentapeptide is covalently linked to the what terminal molecule of tetrapeptide?

A

D-Alanine

23
Q

What is Lysozyme, and what is it’s role?

A
  • Widely distributed in human tissues and secretions and is part of the host defense.
  • Cleaves B-1,4 linkages
24
Q

In what dimension does crosslinking of peptidoglycan occur?

A

Horizontal and vertical.

25
Q

What are the functions of peptidoglycan?

A
  • Allows diffusion of small molecules to the plasma membrane
  • Confers rigidity and shape to bacterial cells
  • Interferes with phagocytosis and is mitogenic
26
Q

What is Muramyl dipeptide (MDP) and what does it do?

A
  • Product of peptidoglycan degradation in the host
    • Adjuvant (Stimulates immune response to antigen)
    • Mitogen (Stimulates cell division)
    • Pyrogen (fever-causing)
    • Somnagen (sleep-inducing)
27
Q

What are Teichoic Acids?

A
  • Water-soluble polymers of either ribitol phosphate or glycerol phosphate that are covalently linked to peptidoglycan.
    • Polysaccharides with phosphodiester linkages
28
Q

What is Lipoteichoic acids?

A

Teichoic acids which terminate in a fatty acid that serves to anchor the molecule in the plasma membrane.

29
Q

Both Teichoic acids (TA) and Lipoteichoic acids (LTA) do what?

A

Common surface antigens that promote attachment to specific receptors on cell surfaces.

30
Q

What are the key features of gram negative cell envelopes?

A
  1. Unique outer membrane which contains LPS (outermost layer)
  2. Thin peptidoglycan overlaying plasma membrane
  3. Periplasmic space
  4. Inner (plasma) membrane
31
Q

What is the outer structure of the gram negative membrane?

A
  • A lipid bilayer composed of phospholipids and a complex molecule called Lipopolysaccharide (LPS).
  • Porins, Braun’s Lipoprotein and omp proteins also present.
32
Q

Where is LPS found?

A

Only in the outer leaflet of Gram Negative outer membrane.

33
Q

What is LPS sometimes called and why?

A

Endotoxin: due to its potent biological/clinical activities

34
Q

General Structure of LPS?

A

Lipid A - Core - O Antigen

35
Q

What is the role of Lipid A?

A
  • Role
    • Responsible for endotoxic activity
    • Anchors LPS molecule in the outer membrane
  • Structure:
    • Phosphorylated disaccharide with esterified fatty acids.
36
Q

What is the structure and function of the Core component of LPS?

A
  • Structure:
    • Core Polysaccharide contains 9-12 sugars
    • Unusual eight carbon sugar 2-keto-3-deoxyoctulosonic acid (KDO)
  • Role:
    • Essential for LPS strucutre and bacterial viability.
37
Q

What is the structure and function of the O Antigen component of LPS?

A
  • Structure:
    • Long linear polysaccharide (50-100 repeating units) attached to the core
    • Extends to the exterior of the cell
  • Basis for serotypes of bacterial strains and therefore useful for identification.
    • Panels A and B
38
Q

What are the biological properties of LPS?

A
  • One of the most powerful immune stimuli
  • Shed into bloodstream during bacteremia
    • Results in complement and coagualation cascades activated.
  • LPS activates B cells and induces macrophages and dendritic cells to release:
    • IL-1
    • IL-6
    • TNF (Pyrogenic)
  • This is done by binding to CD14 and TLR4
39
Q

What are the clinical effects of LPS?

A
  • Sleep (somnagen)
  • Fever (pyrogen)
  • Leukopenia
  • Hypoglycemia
  • Hypotension and shock (can be severe and prolonged)
  • Because high levels of LPS activate a complement cascade, disseminated intravascular coagulation (DIC) can occur and in severe cases, cause death from organ failure.
40
Q

How are Lipopolysaccharide (LPS) and Lipoteichoic Acid (LTA) similar and different?

A

Both are amphipathic

LTA causes coagulation but not fever.

41
Q

Details about Bacteria porins?

A
  • Protein complexes that form channels that allow passive diffusion of small (less than 600 MW) charged molecules.
  • Found only in outer membrane G-bacteria.
42
Q

Details about Braun Lipoprotein?

A
  • Covalently anchors outer membrane to peptidoglycan.
  • Inner leaflet of outer membrane.
43
Q

What is the role of Omp proteins?

A

Stabilize the outer membrane and act as specific receptors.

44
Q

What are the 6 functions of the outer membrane?

A
  • Serve as permeability barrier to hydrophobic or large molecules
  • Maintain structural rigidity of the cell
  • Protects peptidoglycan and plasma membrane
  • Sieve for small water-soluble molecules
  • Presents sites for host cell and phage attachment
  • Possesses LPS and other molecules that serve as molecular signals to host organism.
45
Q

How is Gram negative peptidoglycan different from that of gram positive?

A
  • 1-2 layers, much thinner than G+
  • Glycan polymer is crosslinked via direct covalent bond between terminal D-ala of one tetrapeptide and either lysine or DAP of another tetrapeptide.
  • No Pentapeptide bridging
  • Less overall crosslinking, (more porous than G+)
  • Floats within perplasmic space
46
Q

What is the structure, composition, and role of Periplasmic space?

A
  • Contains a variety of hydrolytic enzymes including:
    • Proteases, lipases, nucleases, and components of sugar transport systems.
  • Gram negative pathogens can also have collagenases, hyluronidase, and beta-lactamases.
  • Contents of periplasm can be released via shedding or cellular delivery mechanism.
  • Plasma or inner membrane is similar to G+ plasma membrane.
47
Q

Phenotypic Classification of Bacterial Species:

A
  • Phenotypic methods rely on “appearance”
    • Cell Structure
      • Cell wall: Gram + or -
      • Lipid Profiles (LPS, LTA, and mycolic acids)
    • Biochemical typing (e.g. growth on carbon sources enzymes +/-)
      • Allows subdivision below species level
      • API strips
      • Oxidative enzymes: e.g. catalase + or -
    • Serotyping, antibodies to specific antigens (e.g. O157/H7)
      • Allows rapid ID without growing the organism
      • O157 refers to the g- O antigen; H is a flagellar antigen
48
Q

Genotypic Classification of bacteria?

A
  1. DNA Hybridization (e.g. Southern Blotting)
  2. Ribotyping (restriction enzyme analysis of 16S rRNA genes)
  3. Sequence Analysis of 16S rRNA
    1. Most reliable for phylogenetic analysis
  4. Whole bacterial genome sequencing is now common.
49
Q

How does one interpret a phylogenetic tree?

A

Distance apart on the branches serves as an indicator of evolutionary relatedness.

BMR 605 (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions