Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

VEM > Bacteria: Intro > Flashcards

Bacteria: Intro Flashcards

(90 cards)

Start Studying
1
Q

What are the main components of bacterial structure?

A

Capsule, cell wall, cell membrane, cytoplasm, nuclear material (chromosome and plasmids), appendages (flagella and pili).

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

What is the function of the bacterial cell wall?

A

Protects the cell from mechanical damage and osmotic lysis; rigidity is imparted by peptidoglycan.

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

What distinguishes Gram-positive and Gram-negative bacteria?

A

Gram-positive bacteria have a thick peptidoglycan layer, while Gram-negative bacteria have a thinner layer and an outer membrane containing lipopolysaccharides.

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

Describe the Gram-staining procedure.

A
  1. Primary stain (crystal violet) penetrates both Gram-positive and Gram-negative.
  2. Mordant (Gram’s iodine) forms a complex with the dye.
  3. Alcohol decolorizes Gram-negative bacteria.
  4. Counterstain (safranin) stains the decolorized Gram-negative bacteria pink.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the role of lipopolysaccharides (LPS) in Gram-negative bacteria?

A

LPS is an endotoxin released upon cell lysis, stimulating immune responses and contributing to pathogenicity.

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

What is the function of the cytoplasmic membrane in bacteria?

A

Regulates the transport of materials in and out of the cell and is the site for energy production and biosynthesis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the composition of bacterial ribosomes?

A

Bacterial ribosomes consist of two subunits: a larger 50S subunit and a smaller 30S subunit.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are plasmids and their significance in bacteria?

A

Plasmids are small circular DNA molecules that replicate independently and can carry genes for antibiotic resistance.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the functions of flagella and pili?

A

Flagella provide motility, while pili assist in adhesion to surfaces and genetic recombination.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are endospores and their importance?

A

Endospores are dormant, highly resistant structures formed by some bacteria to survive adverse conditions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the two types of bacterial toxins?

A

Exotoxins (secreted by living bacteria) and endotoxins (released upon lysis).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the properties of exotoxins?

A

Exotoxins are highly antigenic, can be neutralized by antibodies, and are produced by both Gram-positive and Gram-negative bacteria.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the properties of endotoxins?

A

Endotoxins are less potent, stable to heat, neutralized by antibodies to limited extent, and primarily associated with Gram-negative bacteria.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What microscopy methods are used for bacterial visualization?

A

Bright-field, dark-field, phase-contrast, and electron microscopy.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the steps in preparing a bacterial smear?

A
  1. Prepare a thin smear from a sample.
  2. Fix the smear to the slide.
  3. Stain and observe under a microscope.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the purpose of differential staining?

A

To distinguish between different types of bacteria based on their cell wall properties, such as Gram staining and Ziehl-Neelsen staining for acid-fast bacteria.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the characteristics of mycoplasmas?

A

Mycoplasmas are small, wall-less bacteria that require cholesterol for growth and are resistant to antibiotics that target cell wall synthesis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the importance of pure cultures in bacteriology?

A

Pure cultures allow for the characterization of individual bacterial species and are essential for accurate identification.

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

What are the methods contributing to genetic variation in bacteria?

A

Mutation, genetic recombination (conjugation, transduction, transformation), and transposons.

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

What is the central dogma of molecular biology?

A

The flow of genetic information is unidirectional: DNA → RNA → Protein.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How does bacterial DNA replication occur?

A

Bacterial DNA replication begins at the origin of replication and is semi-conservative, producing two identical daughter molecules.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the phases of the bacterial growth curve?

A

Lag phase, exponential phase, stationary phase, and decline phase.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What factors influence bacterial growth?

A

Genetic, physical, and environmental factors such as temperature, moisture, atmospheric composition, osmotic pressure and nutrient availability.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the function of the capsule in bacteria?

A

The capsule protects the cell, assists in adherence to surfaces, and helps evade phagocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What is the structure of a bacterial flagellum?
A flagellum consists of a filament, a hook, and a basal body anchored to the cell wall. It is made of flagellin
26
What is the role of pili in bacterial cells?
Pili assist in adhesion to host tissues and play a role in genetic recombination.
27
What are biofilms?
Biofilms are bacterial populations that adhere to each other and/or surfaces, enclosed in a biopolymer matrix.
28
What are the characteristics of Gram-positive bacteria?
Gram-positive bacteria have a thick peptidoglycan layer, retain crystal violet during Gram staining, and appear blue.
29
What are the characteristics of Gram-negative bacteria?
Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane with LPS, appearing red after Gram staining.
30
What is the significance of the Gram-staining procedure?
It helps in the classification of bacteria and guides antibiotic treatment by identifying cell wall structure.
31
What are the two types of bacterial reproduction?
Bacteria reproduce asexually through binary fission and can exchange genetic material through conjugation, transformation, or transduction.
32
What is the difference between obligate aerobes and obligate anaerobes?
Obligate aerobes require oxygen for growth, while obligate anaerobes cannot grow in the presence of oxygen.
33
What is the role of the cytoplasm in bacterial cells?
The cytoplasm contains DNA, ribosomes, nutrients, and enzymes necessary for cellular processes.
34
What is the importance of nutrient acquisition for bacteria?
Bacteria acquire nutrients from their environment, requiring carbon and nitrogen for growth and metabolism.
35
What are the different shapes of bacteria?
spherical (cocci): Diplococci (2), streptococci (chain), staphylococci (cluster) rod-shaped (bacilli): Diplobacillus (2) Streptobacillus (chain) Palisades (stack) spiral (spirilla): Spirillum (1) Spirochete (intertwined)
36
What is the significance of mutation in bacterial genetics?
Mutations can lead to genetic variation, allowing bacteria to adapt to changing environments and develop resistance to antibiotics.
37
What are episomes?
Episomes are genetic elements that can replicate independently or integrate into the bacterial chromosome.
38
What is the process of transformation in bacteria?
Transformation involves the uptake of free DNA (from a lysed cell) from the environment by a competent bacterial cell.
39
What is the role of bacteriophages in genetic transfer?
Bacteriophages can transfer DNA between bacteria through transduction, introducing new genetic material.
40
What is the function of transposons?
Transposons are genetic elements that can change their position within the genome, facilitating genetic diversity and adaptation.
41
What are the characteristics of acid-fast bacteria?
Acid-fast bacteria, such as Mycobacterium, resist decolourization by acid-alcohol due to mycolic acids in their cell wall.
42
What methods are used for laboratory identification of bacteria?
Identification methods include examining stained smears, cultural characteristics, biochemical tests, and molecular techniques.
43
What is the significance of selective media in bacteriology?
Selective media allow for the growth of specific bacteria while inhibiting others, aiding in identification.
44
What is the role of catalase and oxidase tests in bacterial identification?
These tests help differentiate bacteria based on their metabolic capabilities regarding oxygen utilization.
45
What are the phases of bacterial growth and their characteristics?
1. Lag phase: adaptation period 2. Exponential phase: rapid division 3. Stationary phase: balanced growth 4. Decline phase: cell death exceeds growth.
46
What is bacterial generation time and what factors affect it?
Generation time is the length of time required for one bacterium to yield 2 daughter cells. It is influenced by nutrient availability, temperature, and the specific bacterial species.
47
What is the role of teichoic acids in Gram-positive bacteria?
Teichoic acids help maintain cell wall structure and play a role in cell division and adherence.
48
What is the function of the outer membrane in Gram-negative bacteria?
The outer membrane provides an additional barrier to protect against antibiotics and detergents.
49
What is the significance of the periplasmic space in Gram-negative bacteria?
The periplasmic space contains enzymes and proteins involved in nutrient acquisition and detoxification.
50
What is the main component of the bacterial capsule?
The capsule is primarily composed of polysaccharides or glycoproteins.
51
What is the significance of using Indian ink in capsule staining?
Indian ink is used to stain the background, allowing the capsule to appear clear against a dark field.
52
What are the characteristics of endospores in terms of viability?
Endospores can remain viable for years and are resistant to extreme environmental conditions.
53
What is the process of sporulation?
Sporulation is the process by which certain bacteria form endospores in response to unfavorable conditions.
54
What are the key features of the bacterial cytoplasmic membrane?
The cytoplasmic membrane is flexible, composed of phospholipids and proteins, and regulates transport and energy production.
55
What is oxidative phosphorylation?
Oxidative phosphorylation is the process of ATP production during cellular respiration, occurring at the cytoplasmic membrane in bacteria.
56
What is the role of ribosomes in bacterial cells?
Ribosomes are the sites of protein synthesis, translating mRNA into polypeptides.
57
What is the structure of bacterial DNA?
Bacterial DNA is typically a single, circular, double-stranded molecule.
58
What is the difference between haploid and diploid in bacterial genetics?
Bacteria are typically haploid, having a single set of chromosomes, unlike diploid organisms that have two sets.
59
What are the functions of plasmids in bacteria?
Plasmids carry genes that can confer advantages such as antibiotic resistance and are capable of independent replication.
60
What is the significance of genetic recombination in bacteria?
Genetic recombination increases genetic diversity and can enhance survival in changing environments.
61
What are the three main mechanisms of genetic transfer in bacteria?
The three mechanisms are conjugation, transformation, and transduction.
62
What is the role of the F pilus in conjugation?
The F pilus facilitates the transfer of plasmid DNA from a donor to a recipient bacterial cell.
63
What is transduction in bacterial genetics?
Transduction is the transfer of genetic material from one bacterium to another via bacteriophages.
64
What is transformation in the context of bacterial genetics?
Transformation is the uptake of naked DNA from the environment by a competent bacterial cell.
65
What is the role of antibodies in response to exotoxins?
Antibodies can neutralize exotoxins and provide immunity by forming antitoxins.
66
What is the importance of the Ziehl-Neelsen stain?
The Ziehl-Neelsen stain is used to identify acid-fast bacteria like Mycobacterium, which resist standard staining methods.
67
What is the role of metabolic tests in bacterial identification?
Metabolic tests determine the biochemical capabilities of bacteria, aiding in species identification.
68
What are the characteristics of obligate anaerobes?
Obligate anaerobes cannot survive in the presence of oxygen and rely on fermentation or anaerobic respiration.
69
What are facultative anaerobes?
Facultative anaerobes can grow in both the presence and absence of oxygen, using aerobic respiration when oxygen is available.
70
What are microaerophilic bacteria?
Microaerophilic bacteria require oxygen but at lower concentrations than are present in the atmosphere.
71
What is the significance of the lag phase in bacterial growth?
The lag phase is a period of adaptation where bacteria acclimate to their environment before starting to divide.
72
What occurs during the exponential phase of bacterial growth?
During the exponential phase, bacteria divide rapidly, and the population size increases logarithmically.
73
What happens during the stationary phase of bacterial growth?
In the stationary phase, the rate of cell division equals the rate of cell death due to nutrient depletion and waste accumulation.
74
What characterizes the decline phase of bacterial growth?
In the decline phase, the number of viable cells decreases rapidly as resources are exhausted and waste products accumulate.
75
What is the role of environmental factors in bacterial growth?
Environmental factors such as temperature, pH, and moisture levels significantly influence bacterial growth rates.
76
What is the significance of nutrient agar in culturing bacteria?
Nutrient agar provides essential nutrients for the growth of a wide variety of bacteria.
77
What is the purpose of blood agar in microbiological studies?
Blood agar is used to culture fastidious organisms and to assess hemolytic activity.
78
What are the characteristics of L forms of bacteria?
L forms are bacteria that lack cell walls and can arise after exposure to antibiotics that inhibit cell wall synthesis.
79
What are the functions of the bacterial cell wall?
The bacterial cell wall provides structural support, protects against osmotic pressure, and helps maintain shape.
80
What is the significance of the peptidoglycan layer?
Peptidoglycan is unique to bacterial cell walls and is crucial for maintaining structural integrity.
81
What are the main components of lipopolysaccharides?
Lipopolysaccharides consist of lipid A, a core oligosaccharide, and an O-antigen polysaccharide chain.
82
What is the role of the complement system in bacterial infection?
The complement system helps opsonize bacteria for phagocytosis and can lyse bacterial cells.
83
What is the function of the Bunsen burner in preparing bacterial smears?
The Bunsen burner is used to sterilize instruments and fix bacterial smears to slides by passing them through the flame.
84
What is the significance of bacterial morphology in identification?
Bacterial morphology, including shape, size, and arrangement, provides initial clues for identification and classification.
85
What is the purpose of the oxidase test?
The oxidase test determines the presence of cytochrome c oxidase in bacteria which plays a role in aerobic respiration positive oxidase test = non-fermenter
86
What is the role of the catalase test in identifying bacteria?
The catalase test identifies bacteria that produce the enzyme catalase, which breaks down hydrogen peroxide into water and oxygen (bubbles). This helps them neutralize toxic byproducts of aerobic respiration. positive catalase test = non-fermenter
87
What are the characteristics of pathogenic bacteria?
Pathogenic bacteria can cause disease in hosts, often possessing virulence factors that enhance their ability to infect and evade the immune system.
88
What is the significance of antibiotic resistance in bacteria?
Antibiotic resistance poses a significant challenge in treating bacterial infections and is often due to genetic mutations or acquisition of resistance genes.
89
What is the role of serotyping in bacterial identification?
Serotyping involves using antibodies to identify specific strains of bacteria based on surface antigens.
90
What are the implications of bacterial genetics for public health?
Understanding bacterial genetics is crucial for tracking outbreaks, developing vaccines, and managing antibiotic resistance.

VEM (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions