Bacterial Structure, Function and Growth Flashcards
Name five things that are distinctly different between eukarya and bacteria.
- Bacteria don’t have membrane bound nucleus
- Bacteria have 70S ribosomes
- Bacterria do not have endoplasmic reticulum
- Bacteria do not have mitotic spindles
- Bacteria do not have chloroplasts or mitochondria
What is the function of the cell wall?
What is it made of?
To prevent lysis due to osmotic pressure
Peptidoglycan
What is a cocci?
Circular shaped bacterium
What is a bacillus?
Rod shaped bacterium
What is a coccobacillus?
A bacterium who’s shape is in between a bacillus and a cocci
What is a vibrio?
boomerang shaped bacterium
What is a spirillum?
S shaped bacterium
What is a spirochete?
A spring shaped bacterium
What two things determine the shape of a bacterium?
Cell wall & Intracellular cytoskeleton
What are the four cytoskeletal elements found in bacteria?
- FtsZ- looks like tubulin
- MreB & ParM- look like actin
- CreS (crescentin)- intermediate filaments
What is the function of FtsZ?
Division
What is the funtion of MreB and ParM?
Shape
Polarity
Chromosome segregation
What is the function of CreS?
Shape
What are the repeating units found in peptidoglycan?
N-acetylglucosamin (GlcNAc) & N-acetylmuramic acid (MurNAc)
aka. NAM—-NAG
Is NAM or NAG linked to tetrapeptide chains that contain amino acids?
NAM
Amino acid chains linked to NAM are crosslinked with other amino acid chains? Which type of cell has more crosslinking, gram (+) or gram(-)?
Gram positive cells
Lysozyme is an enzyme present in many body secretions and which contributes to innate host defenses against bacteria. What is the mechanism of defense?
Lysozyme hydrolyzes peptidoglycan by specific cleabage of the glycosidic bond between MurNac and GlcNAc.
Which cell type contains teichoic acid?
Gram positive
Name three things found in the outer membrane of gram negative cells.
- Lipopolysaccharides
- Lipoproteins
- Porins
What are the three parts of a lipopolysaccharide?
- A-antigen- Endotoxin
- Core polysaccharide
- O-antigen- species specific
Repeating polyglycerol-P or polyribitol-P backbones make up what molecule?
Teichoic acids
What anchors the cell wall to the cell membrane in gram positive bacteria?
Lipoteichoic acids. They are covalently linked to peptidoglycan layer
Are capsular polysaccharides antigenic?
Yes! and they often increase the virulence of the bacterium due to resistance to phagocytosis
What cell surface structure is responsible for forming biofilms?
Glycocalyx
What do polar bacteria look like?
One flagella
What do peritrichous bacteria look like?
Flagella everywhere
If a bacteria is moving towards a chemoattractant is it doing more runs or tumbles?
Chemorepellent?
Runs
Tumbles
The counterclockwise rotation of a flagella produces….
Runs!
Are flagella antigenic?
Yes. H antigen can be used for classification
What is the function of pili?
They are long, slender, proteinaceous antigenic, hair-like structures on the surface of bacteria used for adherence to surfaces and tissues.
Also for bacterial conjugation
Specialized secretion systems are found mostly in what group of bacteria?
Gram negative
Name two differences between cell membranes in eukaryotes and prokaryotes.
- There are no sterols in bacterial cell membranes
2 Bacterial cells have a much higher content of proteins (60-70%)
Name four functions of electron transport system in bacteria.
- Transport of metabolites
- biosynthesis
- DNA replication
- Flagellar rotation
_______ have 70S ribosomes
bacteria
Do bacteria have a true nucleus?
No
Name the types of genomes bacteria have.
Single, double stranded circular DNA
Linear
Some bacteria have more than one chromosome
What are plasmids?
Extra-chromosomal, self-replicating DNA molecules.
Not essential for bacterial viability
Virulence factor
R factor (resistance)
What are temperate bacteriophages?
Viruses that can integrate into bacterial chromosomes and replicate as part of those chromosomes
What is phage conversion?
A change in the phenotype of a host bacterium as a consequence of expression of a gene that is encoded by a bacteriophage
What is the process of cell division in bacteria called?
Binary fission
What are the different phases of bacterial growth curve?
- Lag phase
- Exponential phase
- Stationary phase
- Death phase
What is autolysis?
Spontaneous cell lysis
What are heterotrophic bacteria?
Bacteria that require an organic carbon source
What are autotrophic bacteria?
Bacteria that obtain their carbon exclusively from CO2
What are fastidious bacteria?
Bacteria that require a number of growth factors such as amino acids, vitamins,purines
Bacteria that can grow in the presence of oxygen produce two enzymes. What are they?
Catalase
Superoxide dismutase (SOD)
What are the two forms of “energy currency” in bacteria and higher cells?
ATP
Electrochemical gradients
In the process of fermentation, organic compounds serve as….
Electron acceptor and electron donors
In the process of aerobic respiration molecular oxygen is the….
Final electron acceptor
In the process of anaerobic respiration inorganic substrates act as…..
Final electron acceptor
What two species of bacteria produce spores?
Clostridium and Bacillus
Name three cell wall-active antimicrobials
- B-lactams
- Vancomycin
- Cycloserine
Name an outer and cytoplasmic membrane-active antimircrobial
Polymyxins
Name four inhibitors of protein synthesis at the ribosomal level.
- Aminoglycosides
- Tetracyclines
- Chloramphenicol
- Macrolides
Name two inhibitors of nucleic acid synthesis.
- Quinolones
2. Rifampicin
Name four metabolic inhibitory antimicrobials
- Sulfonamides
- Trimethoprim
- Isoniazid
- Metronidazole
