1
Q
Bacteria appendages and function:
A
Flagella and axial filaments: that provides motility
Fimbriae and pili: provide attachment points or channels
2
Q
What are the common shapes of bacteria?
A
Coccus: spheres, oval
Bacillus: Rod-shapes, cylindrical
Spirillum: rigid helix
Spirochete: flexible helix
3
Q
What are the common arrangements of bacteria?
Cocci
A
Arrangements of cocci:
tetrads: groups of four
Staphylococci: irregular clusters
Streptococci: chains of a few to hundreds of cells
Sarcina: cubical packet of 8, 16, or more cells.
4
Q
What are the common arrangements of bacteria?
Bacilli
A
Arrangements of bacilli:
Diplobacilli: pairs of cells with their ends attached
Streptobacilli: chains of cells
Palisades: cells of a chain remain partially attached and fold back, creating a side-by-side row of cells
5
Q
What are the common arrangements of bacteria?
Spirilla
Spirochetes
A
Arrangements of Spirilla occasionally are found in short chains
Arrangements of Spirochetes rarely remain attached after cell division
6
Q
What are the characteristics of plasmids?
A
- Non-essential pieces of DNA
- separate, double stranded circles of DNA
- duplicated and passes onto offspring during replication
- confer protective traits
- important in genetic engineering
7
Q
What is monotrichous?
A
Single flagellum
8
Q
What is lophotrichous?
A
small bunches or tufts
9
Q
What is amphitrichous?
A
Flagella at both poles of the cell
10
Q
What is peritichous?
A
Flagella are dispersed randomly over the surface of the cell
11
Q
What is Gram stain positive?
A
- Thick cell wall composed of peptidoglycan
- Inner cytoplasmic membrane
- Thick, homogenous sheath of peptidoglycan, 20-80 nm thick
12
Q
What is a grain stain negative?
A
- outer membrane
- thin cell wall
- inner cytoplasmic membrane
- single, thin sheet of peptidoglycan 1-3 nm thick
- somewhat rigid structure
- thinness gives gram-negative bacteria greater flexibility and sensitivity to lysis
13
Q
What are the steps in grain staining?
A
- Apply a smear of bacteria on to a slide. Air dry and then heat fix by passing it through a flame a few times. Make sure you air dry the bacteria before heat fixing.
- Add Crystal Violet to the culture. Let stand for one minute. Bacteria will stain purple. Wash briefly with water and shake off excess.
- Add iodine solution to the culture. Let stand for 30 seconds, wash briefly with water and shake off excess.
- Tilt slide and decolorize with solvent (acetone-alcohol solution) until purple color stops running. Be careful not to over-decolorize. Wash immediately (within 5 seconds) with water and shake off excess.
- Add Safranine. Let stand for one minute, wash briefly with water and shake off excess.
14
Q
What is lysozymes effect on a bacterial cell?
A
-involved in intracellular digestion of food and protection against invading microorganisms.
15
Q
What is the function of the ribosome?
A
- Are a cell structure that makes protein.
- synthesize proteins for use throughout the cell
16
Q
What are ribosomes made of?
A
-made of RNA and protein
17
Q
Where are ribosomes located in prokaryotic cells?
A
-since there are no membrane bound organelles in prokaryotes, the ribosomes float free in the cytoplasm.
18
Q
Where are ribosomes located in eukaryotic cells?
A
-ribosomes roam free in the cytoplasm, but can also be bound to the exterior of the endoplasmic reticulum.
19
Q
Where is the ribosomal RNA made in eukaryotic cells?
A
Molecules of rRNA are synthesized in a specialized region of the cell nucleus called the nucleolus, which appears as a dense area within the nucleus and contains the genes that encode rRNA.
20
Q
What is chemotaxis and how does it move?
A
Chemotaxis: movement in response to chemical signals
- Positive chemotaxis: movement of a cell in the direction of a favorable chemical stimulus
- Negative chemotaxis: movement of a cell away from a repellant or potentially harmful compound
21
Q
What are the parts of the flagella?
A
A bacterial flagellum has 3 basic parts: a filament, a hook, and a basal body.
- The filament is the rigid, helical structure that extends from the cell surface
- The hook is a flexible coupling between the filament and the basal body.
- The basal body consists of a rod and a series of rings that anchor the flagellum to the cell wall and the cytoplasmic membrane
22
Q
How is a capsule helpful to a bacterium? What is it made of?
A
- protect bacteria against phagocytic white blood cells
- formed by pathogenic bacteria
- more tightly bound to a cell than a slime layer
- denser and thicker than a slime layer
23
Q
Where does ATP synthesis occur in prokaryotic cells?
A
- Prokaryotes have their ATP synthesis machinery embedded in the cell membrane, instead of of the mitochondrial/thylakoid membrane which is the case for eukaryotes.
- Prokaryotes such as anaerobic bacteria rely heavily on the first stages of glucose break down
24
Q
What is the function of bacterial endospores?
A
- is to ensure the survival of a bacterium through periods of environmental stress
25
What are the characteristics of endospores?
-highly durable, dehydrated, thick-walled, and not a means of reproduction
26
What is the endosymbiotic theory?
A theory stating that the eukaryotes evolved through a process whereby different types of free-living prokaryotes became incorporated inside larger prokaryotic cells and eventually developed into mitochondria, chloroplasts, and possibly other organelles.
27
What is the function of the glycocalyx?
- an outermost boundary that comes into direct contact with the environment
-also called an extracellular matrix
-Composed of polysaccharides
Appearance: network of fibers, slim layer, and capsule
28
Which types of organisms have cilia?
Cilia is an organism found in eukaryotic cells.
| -found only in a single group of Protozoa and certain animal cells.
29
Which types of organisms have cell walls?
Fungi and algae
30
Which type of organisms cell wall made of chitin?
Fungi
31
What is chromatin?
the material of which the chromosomes of organisms other than bacteria (eukaryotes) are composed. It consists of protein, RNA, and DNA.
32
What are histones?
Any of several proteins that, together with DNA, make up most of the chromatin in a cell nucleus.
-long, linear DNA molecules bound to histones
33
Which organisms most resemble bacterial cells?
Mitochondria and chloroplasts
34
What are the characteristics of protists?
- any unicellular or colonial organism that lacks true tissues.
- They are eukaryotic, which means they have a nucleus.
- about 65,000 species
- They can be parasites.
- They all prefer aquatic or moist environments.
- responsible for infections in humans
35
What is the trophozoite?
- motile and feeding stage
| - requires ample food and moisture to remain active
36
What are the characteristics of fungi?
.
37
What is used to ID fungi?
.
38
What are saprobes?
-obtain substrates from dead plants and animals
39
What is pseudohyphae?
A chain of easily disrupted fungal cells that is intermediate between a chain of budding cells and a true hypha, marked by constrictions rather than septa at the junctions.
40
What is hyphae?
-long, threadlike cells found in filamentous fungi or molds
41
What is Mycelium?
-the woven, intertwining mass of hyphae that makes up the body or colony of a mold
42
What are characteristics of helminths?
```
Shape
Size
Degree of development of organs
Presence of hooks, suckers, other special structures
Mode of reproduction
Kinds of hosts
Appearance of eggs and larvae
```
43
What are examples of helminths?
-tapeworms
-flukes
-roundworms
Usually large enough to be seen with the naked eye: 1 mm-25 m in length
44
Which system is most developed in helminths and why?
Reproductive tract is the most developed.
45
What are protozoan cysts?
- dormant, resting stage
- formed when conditions become unfavorable for growth and feeding
- important factor in spread of disease
46
What is the difference between definitive and intermediate host?
- intermediate (secondary) host: the host in which larval development occurs
- definitive (final) host: host in which adulthood and mating occur
47
What types of cells are host for viruses?
.
48
What determines host range?
.
49
What are viral spikes?
- found on both. Naked and enveloped viruses
| - project from either the nucleocapsid or envelope
50
What are bacteriophages?
-the viruses that infect bacteria
51
How do bacteriophages attach to the host cells?
the bacteriophage attaches itself to the bacteria's cell wall, specifically on a receptor found on the bacteria's surface. Once it becomes tightly bound to the cell, the bacterial virus injects its genetic material (its nucleic acid) into the host cell.
52
What are characteristics of a prophage?
.
53
What are the sequence of events in viral multiplication?
- adsorption
- penetration
- uncoating
- synthesis
- assembly
- release from the host cell
54
What occurs during each event in viral multiplication?
- adsorption: the virus attaches to its host cell by specific binding of its spikes to cell receptors
- penetration: the virus is engulfed into a vesicle and its envelope is..(uncoated)
- uncoating: freeing the virus RNA into the cell cytoplasm
- synthesis: Under the control of viral genes, the cell synthesizes the basic components of new viruses: RNA molecules, capsomers, spikes
- assembly: Viral spike proteins are inserted into the cell membrane for viral envelope; nucleocapsid is formed from RNA and capsomers.
- release from the host cell:
55
Where do DNA viruses multiply compared to RNA viruses?
Viruses that are RNA often replicate in the cytoplasm
DNA viruses replicate in the nucleus
56
What are cytopathic effects?
Compacted masses of viruses or damaged cell organelles in the nucleus or cytoplasm
57
What are some examples of cytopathic?
Common examples of CPE include rounding of the infected cell, fusion with adjacent cells to form syncytia, and the appearance of nuclear or cytoplasmic inclusion bodies.
58
What methods can be used to support viral cultivation?
.
59
What are plaques?
- clear, well defined patches in the cell sheet
- develops when viruses released from an infected cell radiate out to surrounding cells and infect them
- infection spreads gradually and symmetrically from the original point of infection.
60
What are pocks?
-discrete, opaque spots indicating localized areas of damage
61
What are latent infections/viruses?
.
62
What are prions?
- common feature of spongiform encephalopathies
| - distinct protein fibrils deposited in the brain tissue of affected animals.
63
What are some examples of diseases caused by prions?
Prion infection
64
What are viroids?
- virus like agent that parasitizes plants
- about one-tenth the size of an average virus
- composed only of naked strands of RNA and lack a capsid or other type of coating
- significant pathogens in economically important plants like tomatoes, potatoes, cucumbers, citrus trees, and chrysanthemums.
65
What are satellite viruses?
-dependent on other viruses for replication
66
What are types of viral nucleic acids?
- Double-stranded DNA
- Single-stranded DNA
- Single-stranded (+) polarity
- Single-stranded (-) polarity
- Double-stranded RNA
- Single-stranded RNA reverse transcriptase
67
How is transcription different in -RNA and +RNA viruses?
- -Negative-sense RNA: RNA genomes that need to be converted into the proper form to be made into proteins
- -Positive-sense RNA: Single-stranded RNA genomes ready for immediate translation into proteins.
68
What is reverse transcriptase?
an enzyme that catalyzes the formation of DNA from an RNA template in reverse transcription.
69
What is transduction?
Transduction is the process by which DNA is transferred from one bacterium to another by a virus.
It also refers to the process whereby foreign DNA is introduced into another cell via a viral vector.
70
How is a primary cell culture made?
-freshly isolated animal tissue is placed in a growth medium
- cells undergo mitosis division, producing a monolayer
- retain the characteristics of the original tissue from which they were derived.
71
What is a naked virus?
-consist only of a nucleocapsid
72
What is an oncovirus?
An oncovirus is a virus that can cause cancer
- It now refers to any virus with a DNA or RNA genome causing cancer and is synonymous with "tumor virus" or "cancer virus."
- often called oncornaviruses
73
What is lysogeny?
(Lysogenic cycle)
| -bacteriophage becomes incorporated into the host cell DNA.
74
What is induction?
Activation of a prophage in a lysogenic cell to undergo the lyric cycle.
75
What is lysogenic conversion?
- the acquisition of a new trait from a temperate phage
| - responsible for diphtheria toxin, cholera toxin, and botulism toxin.
76
What is Creutzfeldt-Jacob disease?
- affects the central nervous system of humans
- causes gradual degeneration and death
- transmissible by an unknown mechanism
- several animals are victims of similar diseases:
- -Scrapie: sheep, mink elk
- -Bovine spongiform encephalopathy: cows
77
How does flagella move?
- Eukaryotes have one to many flagella, which move in a characteristic whiplike manner
- Bacterial flagella are helically shaped structures containing the protein flagellin that rotates in a clockwise or counterclockwise direction, in a motion similar to that of a propeller.
BIO 204 Microbiology
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