3 Microbial Cell Structure Free Online FlashCards

What shape characterizes vibrios?

Vibrios are curved rods, often shaped like commas.

What are four common arrangements of cocci?

Cocci may form pairs called diplococci, chains called streptococci, clusters called staphylococci, or groups of four called tetrads.

What is peptidoglycan, and what does it do?

Peptidoglycan is a mesh-like polymer of sugar chains cross-linked by short peptides. It strengthens most bacterial cell walls while allowing growth and shape maintenance.

What is characteristic of a Gram-positive cell wall?

Gram-positive bacteria have a thick peptidoglycan layer outside the plasma membrane. Their walls commonly contain teichoic acids.

What distinguishes a Gram-negative cell envelope?

Gram-negative bacteria have thin peptidoglycan in the periplasm and an outer membrane containing lipopolysaccharide (LPS).

What are two key roles of the bacterial plasma membrane?

The bacterial plasma membrane is a selectively permeable phospholipid bilayer with proteins. It regulates transport and hosts important processes such as energy conversion.

How do capsules and slime layers differ?

A glycocalyx is a surface coat. A firmly attached, organized coat is often called a capsule; a loose, easily removed one is often called a slime layer.

How do fimbriae and pili commonly differ?

Fimbriae are typically short and numerous, helping cells attach. Pili are often longer and fewer; some help transfer DNA between bacterial cells.

How do bacterial flagella enable movement?

Flagella are rotating, protein-based appendages that propel many bacteria through liquid.

What is the bacterial nucleoid?

The nucleoid is the region of bacterial cytoplasm where the chromosome is located. It is not enclosed by a membrane.

What are plasmids?

Plasmids are smaller DNA molecules that many bacteria carry in addition to their chromosome.

What is the function of bacterial 70S ribosomes?

Bacterial 70S ribosomes synthesize proteins.