Bacteria Flashcards
3 Common shapes of Bacteria
1) coccus: spherical
2) bacillus: rod
3) spiral
i. spirillum: thick, rigid spiral
ii. spirochete: thin, flexible spiral
What is a bacterial cell wall?
An extra layer of peptidoglycan that surrounds the cell membrane.
What’s the difference between gram-positive bacteria and gram-negative bacteria?
-Gram-positive bacteria can be stained crystal violet due to its thick peptidoglycan layer. Ex: staphylococcus (bunch) and streptococcus (line)
-Gram-negative bacteria can’t be stained crystal violet due to its extra lipopolysaccharide layer. Ex: Escherichia and salmonella
What are Flagella?
Flagella are whip-like appendages used for swimming.
Ex: helicobacter pylori
What are bacterial Fimbriae?
Fimbriae are shorter, hair-like extensions that adhere to surfaces.
Ex: Neisseria Gonorrhoeae
What is a bacterial capsule?
A sticky outer layer that adheres to surfaces and serves as a defense barrier.
Ex: Streptococcus mutans
What is a bacterial endospore?
A tough bacterial spore that can resist damage and remain dormant. During dormancy, metabolism halts. When it rehydrates in the proper environment, it resumes metabolism. The endospore can survive UV, desiccation (drying out), high temperatures, freezing, and chemical disinfectants.
Ex: clostridium botulinum
What are bacterial pili?
Appendages that join bacteria to exchange DNA.
What is a nucleoid?
A region of cytosol that contains chromosomes.
What are plasmids?
Small rings of DNA that are separate from the chromosome.
No organelles (3 analogies)
1) Plasma membrane can have complicated folds to create compartments.
2) Thylakoid folds similar to chloroplast for photosynthesis
3) Cristae-like folds like mitochondria for aerobic respiration
2 means of Bacterial Genetic Diversity
1) Rapid reproduction (by binary fission) and mutation
2) Genetic recombination: horizontal gene transfer
3 means of Genetic Recombination
1) Transformation: uptake of foreign DNA from the environment
2) Transduction: uptake of foreign DNA via a virus
3) Conjugation: DNA transfer between 2 prokaryotic cells via a pilus.
2 means of bacterial Conjugation
1) F-Factor (fertility): 25 genes needed to form a pilus
i. F-plasmid - F-factor on a plasmid can
transfer the conjugation ability
2) Antibiotic Resistance: genes that give bacteria the ability to survive specific antibiotics
i. R-Plasmid: plasmid with antibiotic
resistance genes
a. plasmid can contain resistance to
multiple antibiotics
b. plasmid can contain F-factor
3 types of bacteria
1) Autotrophs: “Self-feeding”; make their own food
2) Heterotrophs: “Eat others”; consumes material from living or dead tissue
3) Symbiosis: two different organisms living in close physical association
2 Autotroph examples
1) cyanobacteria: photosynthesis and carbon fixation
2) Nitrogen fixation: convert inorganic N2 into organic NH3
Heterotroph example
-Fermentation : anaerobic method to generate energy
Ex: Lactobacillus bulgaricus
Symbiosis- 3 types and examples
1) Mutualism: Both species benefit
Ex: Rhizobium leguminosarum - nitrogen
fixing root nodule of legume plants
2) Commensalism: One benefits while the other is unaffected
Ex: Staphylococcus aureus
3) Parasitism: One benefits while the other is harmed
Ex: Pathogens
What are pathogens?
Pathogens are toxins that are secreted by bacteria and that interfere with normal bodily functions.
Ex: Treponema pallidum
What are the 2 types of toxins secreted by bacteria (pathogens)?
1) Endotoxins: chemicals secreted by the bacteria cut out of the cell. They still cause symptoms even if the bacteria isn’t there.
2) Exotoxins: chemicals in cell wall released when the bacteria dies. Also causes symptoms even if the bacteria isn’t there.
What are the 2 examples of endotoxins?
1) Vibrio cholera - cholera toxins that causes diarrhea
2) Clostridium botulinum - botulinum toxin causes botulism: muscular paralysis, then respiratory failure (because the diaphragm is paralyzed), and then death.
What are the 2 examples of exotoxins?
1) Salmonella typhi - causes typhoid fever
2) Salmonella enterica
What causes an opportunistic infection (pathogens)?
Commensal bacteria that take advantage of an opening.
Ex: staphylococcus aureus “flesh eating disease” and MRSA, the methicillin-resistant staphylococcus aureus
What are the 6 phylum of Domain Bacteria?
1) Proteobacteria
2) Cyanobacteria
3) Spirochaete
4) Chlamydiae
5) Firmicutes
6) Thermatogae
Domain Bacteria
Phylum: Proteobacteria
Major phylum of gram negative bacteria
-Escherichia, Salmonella, Vibrio, and Rhizobium
Domain Bacteria
Phylum: Cyanobacteria
Photosynthetic bacteria
-Anabaena and Oscillatoria
Domain Bacteria
Phylum: Spirochaete
Spiral, gram-negative bacteria
-Treponema (syphillis)
Domain Bacteria
Phylum: Chlamydiae
Extremely small intracellular pathogen
Ex: Chlamydia
Domain Bacteria
Phylum: Firmicutes
Spore-forming bacteria
Ex: Staphylococcus, bacillus, and clostridium
Domain Bacteria
Phylum: Thermotogae
Thermophilic Bacteria found in hot springs, sulfur pools, and near thermal vents
