(Section C: Bacteriology) Lecture 18: Flashcards by Lucky Cat

Q

3 Domains of Life

A

Bacteria
Archaea
Eukaryotes

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Q

What domains of life are prokaryotes?

A

Bacteria and Archaea

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Q

Characteristics of Prokayotes

A

Small
Simple
Most abundant cells on Earth
Lack a nucleus
Lack complex organelles

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Q

What do bacteria grow by?

A

Binary Fission

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Q

What are the 4 stages of growth for bacteria?

A

Lag phase
Logarithmic growth phase
Stationary phase
Death phase

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Q

What is generation time?

A

Doubling time
* The time needed for one generation

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Q

What are the rates of growth for bacteria?

A

Some are fast (double in ~10 minutes)
Some are slow (double in ~24 hours)

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Q

Bacteria Shape

A

Coccus
Rod
Spirillum

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Q

What are the 5 types of bacterial classification by O2 utilization?

A

Obligate aerobe
Obligate anaerobe
Facultative anaerobe
Aerotolerant anaerobe
Microaerophile

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Q

Bacterial classification by O2 utilization:

Obligate aerobe

A

Requires oxygen for growth

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Q

Bacterial classification by O2 utilization:

Oligate anaerobe

A

Oxygen is toxic for growth

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Q

Bacterial classification by O2 utilization:

Facultative anaerobe

A

Can use oxygen if present, but can also grow without oxygen

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Q

Bacterial classification by O2 utilization:

Aerotolerant anaerobe

A

Doesn’t use oxygen but oxygen is not toxic

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Q

Bacterial classification by O2 utilization:

Microaerophile

A

Grows best with low levels of oxygen

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Q

In taxonomy, what are the three most important groups when talking about bacteria?

A

Genus
Species
Strain

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Q

How is genetic diversity of bacteria compared to humans?

A

Human genome is 99.5% identical

Bacteria genomes are very different even in the same species (e.x. E. coli has only 60% identical genome between same species)

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Q

What is the main components of a bacterial cellular structure?

A

Cytoplasm
Nuceloid
Cytoplasmic membrane
Cell wall

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Q

What comprises of the cell envelope in a bacteria?

A

Cell wall + Cytoplasmic membrane

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Q

Who was the Gram Stain named after?

A

Hans Christian Gram (1853-1938)

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Q

What are the two types of bacteria in Gram Stain?

A

Gram positive = Purple
Gram negative = Pink

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Q

Compare:

Gram positive vs. Gram negative cell envelope

A

Gram positive:
* Cytoplasmic membrane
* Cell wall outside

Gram negative:
* Cell wall sandwiched between two membranes
* Lipoproteins on the outer membrane

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Q

What are bacterial cell walls made up of?

A

Peptidoglycan

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Q

Describe:

Structure of Peptidoglycan

A

Glycan backbone:
* N-acetlyglucosamine (G)
* N-acetylmuramic acid (M)

Peptide cross-linkage

Q

What are defining features and functions of peptidoglycan?

A

Rigid structure
* Prevents osmotic lysis

What is lipopolysaccharide?

An endotoxin

O-specific polysaccharide

Also called O-antigen * Antigenic * Highly variable

Lipid A

Disaccharide with fatty acid groupos * Recognized by innate immune system, causes septic shock * Part of LPS

How is a nucleoid different from a nucleus?

* No surrounding membrane * Single, circular chromosomes (not all bacteria) * Haploid genomes

What does haploid mean?

One set of chromosomes

Plasmids

* Extra-chromosomal genetic elements * Usually not required for bacterial growth

What do plasmids encode for?

Often encode for 'fitness' factors (e.g. antibiotic resistance)

# True or False: Plasmids stay with one bacteria

False, they can be transferred from bacteria to bacteria

What are the 3 forms of host-microbe relationships?

1. Commensalism 2. Mutualism 3. Parasitism

Commensalism

One benefits without helping or hurting the other

Mutualism

Both benefit (the host and the microbe)

Parasitism

One benefits (usually the microbe) at the expense of the other (usually the host)

What factors will make a bacterial pathogen successful?

* Colonization * Invasion/toxicity * Immune evasion * Transmission

Virulence factors

Produced by pathogens * Molecules produced by the pathogen that contribute to disease

What are virulence factors categorized into?

1. Surface 2. Secreted

# Examples: Surface virulence factors

* LPS (endotoxin) * Flagella * Pili and adhesins * Capsules * Secretion systems

# Examples: Secreted virulence factors

Exotoxins

What do flagella allow bacteria to do?

Allows some bacteria to be motile (chemotaxis)

How will a bacteria move depending on the flagella?

* Counterclockwise flagella rotation: Causes run (move forward) * Clockwise flagella rotation: Causes tumble (turning)

When will bacteria have directed movement?

When an attractant is present

What are pili used for?

Attachment to: * Surfaces * Host tissue * Other bacteria

# Describe: Capsules

Usually made of (exo)polysaccharides * Forms biofilms * Can sometimes used in vaccines

What do capsules do?

* Attachment to host tissues * Protection from host immune system

What are the 5 stages of biofilm formation and development?

1. Attachment 2. Microcolony development 3. Biofilm development 4. Maturation 5. DIssolution/Disperal (allows for spread of bacteria from the biofilm)

What are endospores?

Highly differentiated cells formed within the parent cell

What are characteristics of endospores?

High resistant to: * Heat * Harsh chemicals * Radiation

# True or False: Endospores are active

False, they are a "dormant" stage of the life cycle

Where are endospores most common in?

* Soil * Bacillus and Clostridium genera

What are exotoxins secreted from bacteria?

1. Hemolysins 2. Toxins that function inside host cells 3. Extracellular enzymes 4. Superantigens

What can exotoxins be used for?

Inactivated exotoxins can be used as vaccines

How can some bacteria become intracellular pathogens?

1. Taken up and survive within phagocytic cells 2. 'Force' their own uptake into epithelial cells 3. Allows bacteria to hide from different components of the immune system