Parts of a bacteria Flashcards
What is a capsule in bacteria?
A capsule is a third protective covering made up of polysaccharides that helps keep the bacterium from drying out and protects it from phagocytosis.
What role does the capsule play in pathogenic bacteria?
The capsule is a major virulence factor in disease-causing bacteria like Escherichia coli and Streptococcus pneumoniae. Nonencapsulated mutants are avirulent.
What is the cell envelope composed of?
The cell envelope consists of two to three layers: the cytoplasmic membrane, the cell wall, and, in some species, an outer capsule.
What is the function of the cell wall in bacteria?
The cell wall provides shape, protects the cytoplasmic membrane, and anchors appendages like pili and flagella.
What is the composition of the bacterial cell wall?
The cell wall is composed of peptidoglycan, a protein-sugar molecule.
How does the Gram staining technique differentiate bacteria?
Gram-positive bacteria retain the purple color of the stain due to their thick cell walls, while gram-negative bacteria release the dye when washed.
What is the cytoplasm in bacterial cells?
The cytoplasm is a gel-like matrix where cell growth, metabolism, and replication occur, containing structures like ribosomes and plasmids.
What is the nucleoid in bacteria?
The nucleoid is a region of cytoplasm where the chromosomal DNA is located, not a membrane-bound nucleus.
What are plasmids?
Plasmids are small, extrachromosomal genetic structures made of circular DNA, not essential for survival but provide selective advantages.
How are plasmids transferred between bacteria?
Plasmids are passed on during binary fission or through conjugation via a pilus.
What is the function of flagella in bacteria?
Flagella are hairlike structures that provide locomotion, helping bacteria move toward nutrients or away from toxins.
What are pili and their function?
Pili are small hairlike projections that assist bacteria in attaching to surfaces and other cells, crucial for infection.
What are ribosomes and their role in bacteria?
Ribosomes are structures that translate genetic code into proteins, essential for cell functions.
How do bacterial ribosomes differ from eukaryotic ribosomes?
Bacterial ribosomes are smaller and have a different composition, allowing some antibiotics to target them without affecting eukaryotic cells.
