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Biology 15 - General Microbiology > Chapter 4 > Flashcards

Chapter 4 Flashcards

1
Q

What are the three main bacterial shapes, and what are their singular and plural forms?

A

The three main bacterial shapes are:

Rods: Singular - bacillus, Plural - bacilli
Spheres: Singular - coccus, Plural - cocci
Spirals: Bacteria with one or more twists

Pleomorphic: Bacteria that can take on many shapes
Monomorphic: Bacteria that always have one shape

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2
Q
  1. What does “diplo” mean in bacterial cell organization?
  2. What does “strepto” mean in bacterial cell organization?
  3. What does “staphylo” mean in bacterial cell organization?
A
  1. “Diplo” means bacteria that are arranged in pairs.
  2. “Strepto” means bacteria that are arranged in a chainlike fashion.
  3. “Staphylo” means bacteria that are arranged in clusters.
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3
Q

Name the three spiral types of bacteria and describe their shapes.

A
  1. Vibrio: Curved rods
  2. Spirillum: Rigid corkscrew shape
  3. Spirochete: Helical and flexible
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4
Q

What is the external cell membrane of bacteria composed of?

A

The external cell membrane of bacteria is composed of a carbohydrate called peptidoglycan.

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5
Q

How are NAM and NAG involved in the structure of peptidoglycan?

A

NAM (N-acetylmuramic) and NAG (N-acetylglucosamine) are two alternating sugar groups that make up the carbohydrate backbone of peptidoglycan.

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6
Q

What enzyme catalyzes the destruction of the cell walls of certain bacteria?

A

Lysozyme is an enzyme that catalyzes the destruction of the cell walls of certain bacteria.

Lysozyme targets peptidoglycan to destroy the cell wall.

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7
Q

Describe the characteristics of Gram-negative cell walls.

A
  • Gram-negative cell walls have a thin cell wall and two plasma membranes.
  • The space between the membranes is called the periplasmic space, and the outer membrane consists of lipopolysaccharide (LPS). They can be serotyped.
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8
Q

What are the characteristics of Gram-negative bacteria?

A
  • Gram-negative bacteria are very fragile
  • More common in moist protective environments
  • More resistant to immunity and chemicals. An example is Escherichia coli.
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9
Q

Describe the characteristics of Gram-positive cell walls.

A
  • Gram-positive cell walls have a single plasma membrane
  • Produce a thick external cell wall, including a layer of teichoic acid.
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10
Q

What are the characteristics of Gram-positive bacteria?

A
  • Gram-positive bacteria are more stable,
  • Found in open exposed environments
  • Can produce toxins. An example is Clostridium tetani.
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11
Q

What are endospores, and when do they form?

A

Endospores are specialized “resting” cells that form when essential nutrients are depleted. Only found in gram positive bacteria. NOT FOUND IN GRAM NEGATIVE.

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12
Q

Where are true endospores found, and what conditions can they survive?

A

True endospores are found in Gram-positive bacteria and can survive extreme heat, lack of water, and exposure to chemicals.

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13
Q

What is sporulation, and what is germination in the context of endospores?

A

Sporulation is the process of endospore formation, while germination is the process in which an endospore returns to the vegetative state.

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14
Q

What are the characteristics of Mycoplasma bacteria?

A
  • Mycoplasma bacteria have no cell walls, making them the smallest known bacteria that can grow and reproduce outside living host cells.
  • Their plasma membranes have lipids called sterols.
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15
Q

What is unique about the plasma membranes of Mycoplasma bacteria?

A

Mycoplasma bacteria have plasma membranes with lipids called sterols.

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16
Q

Describe the characteristics of Mycobacterium bacteria.

A
  • Mycobacterium bacteria have acid-fast cell walls with waxy lipids, including mycolic acid, bound to peptidoglycan.
  • They stain with carbolfuchsin and exhibit corded growth.
  • An example is Mycobacterium tuberculosis.
17
Q

What is the glycocalyx, and where is it located?

A

The glycocalyx is a viscous, gelatinous polymer external to the cell wall, made of polysaccharides and/or polypeptides.

18
Q

What are the three types of glycocalyx, and how do they differ?

A

The three types of glycocalyx are:

  1. Capsule: Neatly organized and firmly attached.
  2. Slime Layer: Unorganized and loose.
  3. Extracellular polymeric substance (EPS): Helps form biofilms.
19
Q

How does the capsule contribute to the virulence of pathogenic bacteria?

Virulence: The severity of harmfulness of a disease or poison.

A

The capsule protects pathogenic bacteria from immune cell phagocytosis.

20
Q

What is the significance of extracellular polymeric substance (EPS) in biofilms?

A

EPS protects cells within biofilms, facilitates communication among cells, and increases cell survival by attaching to various surfaces.

21
Q

What is the function of flagella in bacteria?

A

Flagella are long filaments used for motility, propelling bacteria.

22
Q

What are the three parts of a bacterial flagellum?

A

A bacterial flagellum consists of three parts:
1. Filament: The outermost region.
2. Hook: Attaches to the filament.
3. Basal Body: Consists of a rod and pairs of rings; it anchors the flagellum to the cell wall and membrane.

23
Q

What are the four types of flagella arrangements of flagella?

A
  1. Peritrichous (Flagellum all around cell)
  2. Monotrichous and polar (One flagella on one side of the cell)
  3. Lophotrichous and polar (Many flagella on one side of the cell)
  4. Amphitrichous and polar (Two Flagella on each side of the cell)
24
Q

What does it mean when a flagella will “run” or “tumble” ?

A
  • Run/swim: moves in one direction
  • Tumble: Periodic, abrupt, random changes in direction
25
Q

What are the two types of active transport mechanisms, and what do they require?

A

Active transport: Requires a transporter protein and ATP; moves substances against their concentration gradient (from low to high concentration).

Group translocation: Requires a transporter protein and phosphoenolpyruvic acid (PEP); the substance is altered as it crosses the membrane. This mechanism is exclusively found in prokaryotes.

26
Q

What is the primary function of the cytoplasm in a cell?

A

The cytoplasm is a watery environment inside the cell where metabolic reactions occur.

27
Q

List three structures found in the cytoplasm of prokaryotic cells.

A

In prokaryotic cells:

  1. the cytoplasm houses the nucleoid (chromosome and plasmids)
  2. ribosomes for protein synthesis
  3. inclusions for reserve deposits.
28
Q

What is the bacterial chromosome, and what does it contain?

A

The bacterial chromosome is a circular DNA strand containing crucial genetic information needed for the cell’s functions.

29
Q

Explain the role of plasmids in bacteria and their advantages.

A

Plasmids are extrachromosomal genetic elements in bacteria. They provide advantages like antibiotic resistance, tolerance to toxins, toxin production, enzyme synthesis, transferability, and utility in gene manipulation.

NOT NEEDED for survival but can be useful.

30
Q

What is the function of ribosomes in a cell?

A

Ribosomes are essential for protein synthesis. In prokaryotes, they consist of 50S and 30S subunits, forming a 70S ribosome. Eukaryotes have larger ribosomes (80S).

31
Q

How do antibiotics affect protein synthesis in cells?

A

Antibiotics can disrupt protein synthesis by binding to ribosomal units, interfering with the process.

32
Q

Explain the endosymbiotic theory and its supporting evidence.

A

The endosymbiotic theory proposes that eukaryotic cells originated from larger cells engulfing smaller cells. Evidence includes organelles like mitochondria and chloroplasts have their own circular DNA (like prokaryotes), mitochondria and chloroplasts divide like prokarytoes, 70S ribosomes (like prokaryotes), and antibiotic targeting of organelles’ ribosomes.

33
Q

What is the difference between pilli and fimbrae?

A
  • Pili is longer than fimbrae and is involved in DNA transfer from one cell to another. One or two per cell
  • Fimbrae allows for attachment and is used for colonization and biofilms. Few to several hundred per cell.
34
Q

What are axial filaments?

A
  • Bundles of fibrils that sprial around a cell.
  • Found in spriochetes
  • Rotation of axial filaments causes cell to move like a corkscrew
35
Q

What are inclusions of a prokaryotic cell?

A
  • Reserve deposit in the cytoplasm of a prokaryotic cell

Can be:
1. Polysaccharide granules: energy reserve
2. Volutin: phosphate reserve
3. Gas Vacuoles: protein- covered cylinders that maintain buoyancy

Biology 15 - General Microbiology (29 decks)

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