Microbiology Lecture Exam 1

Front 1

What is microbiology?

Back 1

The study of organisms too small to be seen with the human eye

Front 2

Most microorganisms fall under the micrometer range. what fraction of a meter is a micrometer?

Back 2

1 millionth of a meter

Front 3

What is the theory of Spontaneous Generation?

Who are the 2 notable detractors of this theory?

Back 3

"Organisms can arise from nonliving matter"

Detractors:

1) Francesco Redi

2) Louis Pasteur

Front 4

Who is known as the "father of modern microbiology"? Why/what did he do?

Back 4

Louis Pasteur. He demonstrated that the air is filled with preexisting microorganisms by filtering air through a cotton plug and culturing it. Also did the swan-neck flask experiment.

Front 5

What is Francesco Redi known for?

Back 5

his famous experiment in which he put one chunk of meat in a closed container and one chunk of meat in an open container and only observed maggots on the open container, therefore disproving the theory of Spontaneous Generation.

Front 6

What did John Tyndall do?

Back 6

Discovered why some scientists couldn't reproduce Pasteur's results for the swan-neck flask experiment by providing evidence that some microbes have a very high heat resistance and therefore need different boiling times to reach sterility.

Front 7

Who discovered endospores?

Back 7

Ferdinand Cohn

Front 8

What is an endospore?

Back 8

A tough, dormant spore formed within some bacteria as a response to environmental stress to ensure the survival of the organism. They're UV resistant, dessication, antibiotics, temperature, etc. Once formed, the mother cell that produced it dies.

Front 9

What's the difference between prokaryotes and eukaryotes?

Back 9

prokaryotes have no nucleus or mitochondria or other organelles.

Eukaryotes have a nucleus and many complex organelles.

Front 10

Without certain microorganisms, life could not exist as we know it. What 2 things are microorganisms responsible for?

Back 10

1) Production of oxygen

2) Nitrogen fixation

Front 11

What are the 3 main applications of microbiology?

Back 11

1) food production

2) bioremediation (using organisms to degrade environmental waste)

3) synthesis of numerous products (ex: insulin)

Front 12

What is genetic engineering?

Back 12

the process of introducing foreign genes into an organism to allow it to express new traits.

Front 13

What does the term "pathogenic" mean?

Back 13

disease-causing

Front 14

What is the name of the opportunistic fungal pathogen that causes oral thrush?

Back 14

Candida albicans

Front 15

What is the name of the pathogenic bacteria that causes tetanus/lockjaw?

Back 15

Clostridium tetani

Front 16

What is the name of the pathogenic bacteria that causes stomach ulcers in humans?

Back 16

Helicobater pylori

Front 17

What is xanthan gum?

Back 17

a polysaccharide from the slime layer of the bacterium Xarithomonas campestris that acts as a gelling and stabilizing agent in certain foods.

Front 18

What does the term nosocomial mean?

Back 18

Refers to a hospital-borne infection

Front 19

What are the 3 domains of life?

Back 19

1) Bacteria

2) Archaea

3) Eukarya

Front 20

microorganisms from which domain tend to be the most common type in human infection?

Back 20

Domain Bacteria

Front 21

What is the role of the granule in a prokaryotic cell?

Back 21

Stores nutrients

Front 22

What does "coccus" mean regarding prokaryotic morphology?

Back 22

spherical shaped

Front 23

What does "bacillus" mean regarding prokaryotic morphology?

Back 23

rod/cylinder-shaped (not to be confused with the Bacillus genus)

Front 24

What does the term "vibrio" mean regarding prokaryotic morphology?

Back 24

curved rod (kind of like a boomerang)

Front 25

What does the term "spirillum" refer to regarding prokaryotic morphology?

Back 25

Spiral-shaped

Front 26

What does the term "pleomorphic" mean regarding prokaryotic morphology?

Back 26

describes a bacterium that can vary in shape

Front 27

Regarding bacterial arrangement, what does the term "diplo" mean?

Back 27

"occurring in pairs"

Front 28

Regarding bacterial arrangement, what does the term "strepto" mean?

Back 28

"occurring in chains"

Front 29

Regarding bacterial arrangement, what does the term "staphylo" mean?

Back 29

"occurring in clusters"

-note: only cocci bacteria can be staphylo

Front 30

When naming/describing a bacterial cell, what order do you put the term describing shape and the term describing arrangement in?

Back 30

Arrangement --> shape

ex: Staphylococcus aureus,

ex: streptobacilli

Front 31

What molecule makes up the cell wall of bacteria?

Back 31

Peptidoglycan (PTG)

Front 32

What is the basic structure/bonds of PTG in bacterial cell walls?

Back 32

Made of of 2 alternating subunits NAG and NAM (both sugars), joined by peptide bonds (hence the name, peptidoglycan)

Front 33

What are the 3 main differences between gram-positive bacteria and gram-negative bacteria?

Back 33

1) gram-positive bacteria have thick cell walls made up of up to 30 layers of PTG; Gram-negative bacteria have thin PTG layers (1-2 layers)

2) teichoic acid is found as a component of PTG only in gram-positive bacteria

3) Gram-negative bacteria have an outer membrane on their cell walls, linked to the PTG layer via lipoproteins

Front 34

The outer membrane of gram-negative bacteria is made of a bilayer of what?

Back 34

Made of phospholipids on the inner leaflet and Lipopolysaccharides (LPS) on the outer leaflet.

Front 35

What are the 3 components of an individual molecule of LPS from outermost layer to innermost?

Back 35

1) An O-specific polysaccharide on the outside whose length/composition vary with bacteria

2) A Core polysaccharide in the middle

3) Lipid A, which anchors LPS in the lipid bilayer and can cause an immune response in people

Front 36

What is the function of LPS in the outer membrane of gram-negative bacteria?

Back 36

Serves as a barrier to a variety of molecules

Front 37

What is the periplasm in gram-negative bacteria?

Back 37

The region sandwiched between the outer membrane of the cell wall and the cytoplasmic membrane that contains PTG.

Front 38

Some bacteria naturally lack a cell wall. Give an example of one.

Back 38

Mycoplasma, which causes mild pneumonia.

Front 39

What are the 2 kinds of layers that can be found in a bacterium external to the cell wall?

What's the difference between them?

Back 39

1) Capsules--distinct, regular chemical makeup

2) Slime layer--irregular structure

Front 40

What are capsules and slime layers made up of?

Back 40

Glycocalyx, a polysaccharide

Front 41

What are the 2 general functions of a capsule/slime layer?

Back 41

1) Protection of bacterium against host defenses

2) Attachment

Front 42

What are the 2 different kinds of optional protein appendages that can be found in bacteria? What's the difference in their structure?

Back 42

1) Flagella=long tail-like structure used for motion

2) Pili=shorter and thinner than flagella; hairlike

Front 43

What are the 4 different possible kinds of arrangements of flagella in bacteria?

Back 43

1) monotrichous=single flagellum

2) Lophotrichous=small tufts of flagella emerging from the same site

3) Peritrichous=multiple flagella dispersed randomly over the cell

4) Amphitrichous=2 flagella emerging from opposite ends of the cell

Front 44

What are the 3 basic parts of a flagellum from outermost to innermost? What is the role of each part?

Back 44

outer

1) Filament: extends to the exterior

2) Hook: connects filament to cell

3) Basal body: anchors flagellum to cell wall

Front 45

What is the filament of a flagellum made up of?

Back 45

A protein called flagellin

Front 46

What are the 2 functions of Pili?

What is the pili called in each case?

Back 46

1) Attachment (Pili is called fimbriae in this case)

2) Conjugation (AKA DNA transfer) (Pili is called a sex pilus/F-pilus in this case)

Front 47

Ribosomes are found in bacteria. What is their function? What are they made up of?

Back 47

Involved in protein translation.

Made up of a large (50s) subunit and a small (30s) subunit.

Front 48

What form does the chromosome take in bacteria? Where is it found in the bacterium?

Back 48

The chromosome typically takes the shape of a single, double-stranded molecule and is found in the nucleoid space.

Front 49

What are plasmids?

Back 49

Optional, small circular molecules of DNA that are much smaller than the chromosome and can confer special genes that may enhance the survival of the bacterium.

Front 50

Plasmids are extrachromosomal. What does this mean?

Back 50

1) they're outside of the chromosome

2) they replicate independently

Front 51

What are gas vesicles?

Back 51

Small protein compartments found in aquatic bacteria that provide buoyancy to the cell, allowing the organism to reach the ideal position in the environment.

Front 52

What is a gene?

Back 52

A sequence of DNA that carries the information to make a protein

Front 53

What is the term for the process of forming endospores?

Back 53

sporulation

Front 54

Prokaryotes divide via ___________

Back 54

binary fission

Front 55

What is the generation time?

Back 55

The time it takes for a population of cells to double. AKA doubling time

Front 56

In a laboratory setting, bacterial cells are grown in a Closed/Batch System. What does this mean?

What is the opposite of a batch system?

Back 56

There is no new input of nutrients and no release of waste in the system.

Opposite: Open/Continuous system

Front 57

What is the growth curve of a population of cells in a culture?

Back 57

The predictable pattern of growth and death in a population of cultured cells.

Front 58

What are the 4 typical phases of a bacterial growth curve? What's involved with each phase?

Back 58

1) lag phase=an initial flatline period where the # of cells doesn't change but the cells prepare for growth.

2) Log phase=the rising line after the lag phase in which cells multiply exponentially. Cells produce primary metabolites (anything required for normal growth) during this time.

3) Stationary phase=a plateau where the population is stable because the growth rate equals the death rate. Secondary metabolites (anything designed to kill off competing cells) are produced.

4) Death phase=the declining line where the total number of viable cells decreases. The death rate is exponential during this phase.

Front 59

What are the 4 main factors that can influence bacterial growth?

Back 59

1) Temperature

2) Oxygen presence

3) pH

4) water availability

Front 60

What are Psychrophiles?

Back 60

Prokaryotes living between -5 to 15 degrees celsius. Found in the arctic/antarctic. Mostly Archaea

Front 61

What are Psychotroph? What characterizes it?

Back 61

Prokaryotes living between 20-30 degrees celsius. Typically bacteria involved in food spoilage.

Front 62

What are Mesophiles?

Back 62

Prokaryotes living between 25-45 degrees celsius. More common than psychotrophs and are typically the bacteria that cause disease.

Front 63

What's the difference between Thermophiles and Hyperthermophiles?

Back 63

Both belong to the domain Archaea.

Thermophiles live between 45-70 degrees celsius and are common in hot springs.

Hyperthermophiles live between 7-110 degrees celsius and are found in hydrothermal vents.

Front 64

What are Obligate Aerobes?

Back 64

Prokaryotes that absolutely require oxygen for cell division and energy production.

Front 65

What are Obligate Anaerobes?

Back 65

Prokaryotes that cannot grow in the presence of oxygen; the opposite of obligate aerobes.

Front 66

What are Facultative Anaerobes?

Back 66

Prokaryotes that grow better in the presence of oxygen but can use fermentation in the absence of oxygen.

Front 67

What are Microaerophiles?

Back 67

Prokaryotes that require oxygen, but in low concentrations and will actually become inhibited if oxygen concentration is too high.

Front 68

What are Aerotolerant Anaerobes?

Back 68

Prokaryotes who do not use oxygen to produce energy and whose growth is not affected either way by the presence or absence of oxygen.

Front 69

pH is a factor that can affect bacterial growth and bacteria can be classified based on this. What are the 3 terms that are used to classify bacteria based on how pH affects their growth?

Back 69

1) Acidophiles=thrive at pH below 5.5

2) Neutrophiles=thrive between pH of 5-8

3) Alkalophiles=thrive at pH above 8.5

Front 70

All organisms need carbon to live and can be classified based on where they get carbon from. What are the 2 classification terms for this?

Back 70

1) Heterotrophs: use organic carbon sources (ex: glucose)

2) Autotrophs: use inorganic carbon (CO2) as their carbon source

Front 71

All organisms can be classified based on where they derive their energy from. What are the 2 classification terms for this?

Back 71

1) Phototrophs: derive energy from sunlight

2) Chemotrophs: derive energy from chemical compounds

Front 72

What are Photoautotrophs?

What kind of organisms are photoautotrophs?

Back 72

Photoautotrophs: use sunlight and atmospheric carbon (CO2) as carbon source.

Think: plants

Front 73

What are Chemoheterotrophs?

What kind of organisms are chemoheterotrophs?

Back 73

Chemoheterotrophs: use organic compounds for both energy and as a carbon source.

Think: animals and humans

Front 74

What does the term "planktonic" mean?

Back 74

Refers to bacteria that exist in a free-floating, single cell form.

Front 75

What is a biofilm?

Back 75

A cooperative association of many species of microorganisms that forms a film/layer on the surface of something. Each member of the biofilm community has a special niche.

Front 76

How do biofilms form?

Back 76

First, a pioneer bacterium that colonizes a surface.

Next, other microbes either attach to the pioneer bacteria or to the sugar/protein substance that the pioneers produce. These organisms start secreting stuff too and in turn more and more organisms accumulate until a complex community forms.

Front 77

What is quorum sensing?

Back 77

The regulation of bacterial gene expression in response to cell population density. Bacteria sense cell population density by releasing and sensing chemicals released by other cells.

Front 78

True or false: microbes in a biofilm behave much differently and express different genes than they would if living planktonically?

Back 78

TRUE