Bacteria Flashcards
(20 cards)
What are key differences between prokaryotic and eukaryotic cells?
Prokaryotes lack a nucleus and membrane-bound organelles, have circular DNA, and reproduce by binary fission. Eukaryotes have a nucleus, linear DNA, membrane-bound organelles, and reproduce mostly via mitosis.
What are common shapes of bacteria?
Cocci (spheres), Bacilli (rods), Spirilla (spirals), Vibrio (comma-shaped), Spirochetes (tight spirals), Coccobacilli (oval).
What are common bacterial arrangements?
Single, Diplococcus, Streptococcus, Tetrad, Staphylococcus, Streptobacillus.
What is the function of the bacterial capsule?
Protects against desiccation, phagocytosis, and helps in attachment to surfaces.
What is peptidoglycan and where is it found?
A structural polymer found in bacterial cell walls, unique to bacteria, providing strength and rigidity.
What is the function of plasmids in bacteria?
Plasmids carry non-essential but advantageous genes, such as antibiotic resistance, and replicate independently of chromosomal DNA.
What is the role of ribosomes in bacteria?
They synthesize proteins; bacterial ribosomes are 70S in size (smaller than eukaryotic 80S).
What are fimbriae and pili used for in bacteria?
For attachment to surfaces and in the case of pili (e.g., F pilus), transfer of genetic material via conjugation.
What differentiates Gram-positive from Gram-negative bacteria?
Gram-positive has thick peptidoglycan with teichoic acids; Gram-negative has thin peptidoglycan and an outer membrane with lipopolysaccharides.
What are acid-fast bacteria?
Bacteria like Mycobacterium with waxy mycolic acids that resist standard staining; detected using acid-fast stain.
How do bacteria move?
With flagella, which are spiral structures acting like propellers driven by a motor in the basal body.
What is binary fission?
Asexual reproduction in which a bacterial cell replicates its DNA and splits into two genetically identical daughter cells.
What are endospores and their purpose?
Dormant, tough, non-reproductive structures formed by some bacteria to survive extreme conditions.
What are the steps of endospore formation?
- DNA replicates
- Septum forms
- Forespore develops
- Cortex forms
- Spore coat forms
- Cell degrades, releasing the endospore
Name clinically significant endospore-forming bacteria.
Bacillus anthracis, Clostridium tetani, C. difficile, and C. botulinum.
What environmental factors affect bacterial growth?
Temperature, pH, oxygen levels, pressure, nutrient availability, and water/osmotic conditions.
What are different bacterial oxygen requirements?
Obligate aerobe, Facultative anaerobe, Aerotolerant anaerobe, Obligate anaerobe, Microaerophile.
What is meant by bacterial generation time?
The time it takes for a bacterial population to double, often under 20 minutes in ideal conditions.
What is the difference between solid and liquid bacterial culture media?
Solid media (agar) is used for isolation/identification; liquid media (broth) is used for mass growth.
Why are bacterial cultures important in medicine?
They help identify infectious agents and guide effective treatment decisions, especially antibiotic choice.
