Ch 3: Bacteria Flashcards
What are prokaryotes? What are the types?
Prokaryotes are simple cells without a nucleus The types of prokaryotes are bacteria and archaea
What types of metabolism do Bacteria and Archaea (prokaryotes) have?
Heterotrophic: feed on organic substrates Autotrophic: Utilize inorganic substrates
Pathogenic bacteria use organic molecules of the host for energy and building blocks for reproduction. Bacterial pathogens are?
Heterotrophs
List the following in order from largest to smallest. Virus, yeast, bacterium, white blood cell.
White Blood Cell, Yeast, Bacterium, Virus
What structures are present on all bacterial cells? What structures are only present on some bacterial cells?
All Bacterial Cells:
- Nucleoid Region
- RIbosomes
- Cell Membrane
- Cytoplasm
Some Bacterial Cells:
- Pilus
- Plasmid
- Actin Cytoskeleton
- Flagellum
- FImbria
- Cell Wall
- Glycocalyx
What is the flagellum?
Translates into “Whip”
Only present on some bacterial cells
Basal body acts as motor that rotates flagellum
What is chemotaxis?
chemical gradients influence bacterial movement
- tumble and runs
- rotate counterclockwise: run (straight)
- rotate clockwise: tumble (change direction)
How do we classify motile bacteria?
flagellar arrangement
What is the fimbria?
Protein filaments used for attachment and colonization
What is a pilus?
protein filament used for attachment and colonization
- sex pilus: hollow tube used for conjugation
What is a glycocalyx?
sugar coat
- slime layer or capsule
How does the glycocalyx (slime layer) help bacteria?
Helps bacteria form biofilms (plaque)
The glycocalyx helps form a capsule. What does the capsule do?
Prevents the bacteria from adhering to phagocytes
What do bacteria transfer using a sex pilus?
Transfer plasmids
What is the cell wall
Structural support
- protection
- target for antibiotics
- Peptidoglycan: glycan sugar crosslinks to provide strength
Who is Hans Christian Gram?
Invented Gram Stain
-differential staining technique for classifying bacteria
- Gram-Positive: Stains PURPLE b/c have THICK cell wall
- Gram-Negative: Stains PINK b/c have THIN cell wall
What are the characteristics of the gram-positive cell wall?
composed of a thick peptidoglycan layer with associated teichoic acids
what are the characteristics of a gram-negative cell wall?
composed of a thin peptidoglycan layer
Two membranes (Inner and outer) with:
- porins: prevent entry of antibiotics like penicillin
- lipopolysaccharides: endotoxin that causes inflammation
Which kind of bacteria has an irregular cell wall? What are the characteristics?
Mycobacterium has atypical cell wall
- gram-positive cell wall but doesn’t stain well
- most of the cell wall is mycolic acid (Wax) which repels stains
What is significant about the mycoplasma bacteria?
Has NO CELL WALL
- cell membrane contains sterols to make it stronger
What kind of crosslinks of peptidoglycan gives a bacterial cell wall its strength?
Peptide crosslink
What is contained in the nucleoid region of the bacterial cytoplasm?
Contains bacterial chromosome (single/circular DNA genome)
- some bacteria have extrachromosomal DNA called Plasmids (multiple/circular)
How do bacteria reproduce?
Asexual cellular reproduction called Binary Fission
What are bacterial ribosomes?
Ribosomes perform protein synthesis
- Translation: (mRNA⇒protein)
Contains two subunits
- Large 50S and Small 30S together form the 70S Ribosome
WHat are the various bacterial cell shapes?
Cytoskeleton (actin filaments) produce the following cell shapes:
- Bacillus: rod shaped
- Vibrio: wave
- Spirillum: sprial
- Spirochete: really spiraled
What are the characteristics of the coccus (cocci)?
have no cytoskeleton
speherical shaped
What are the arrangements of cocci bacteria?
arrangements result from cytoplasmic division w/o separation of cell walls of daughter cells
Cell Division in One Plane:
- Diplococcus: two cells
- Streptococcus: variable number
Cell Division in Two Planes:
- Tetrad: 4 cells
- Staphylococcus: irregular cluster
How can you use cell morphology to tell the difference between Streptococcus and Staphylococcus?
Both are Gram-Positive so stained Purple
Streptococcus: chains
Staphylococcus: irregular cluster
What are endospores?
When growth conditions are unfavorable bacteria the vegetative cell** undergoes **sporulation and form endospores
This allows bacteria to survive in a dormant state until conditions change
When conditions are favorable the bacteria undergo germination** and become a **vegetative cell again
The Clostridium genus form endospores. What would occure when Clostridium tetani is introduced into a host via a puncture wound?
endospores will germinate and produce neurotoxins
