16) Which complex, extra-cellular, contaminates surfaces? prokaryotic structure

Question

16) Which complex, extra-cellular, contaminates surfaces? prokaryotic structure complicates antibiotic treatment and Pilus 17) How can a bacterium directly uptake a DNA molecule from the surrounding environment Conjugation Flagellum Transduction Transformation 18) Which slimy structure enables some individual bacteria to attach to host cells, reduce dehydration, and avoid the human immune system? Capsule Cell Wall Envelope Fimbriae 19) After perceiving unfavorable environmental conditions, what rotating structure enables prokaryotes to move away from such conditions? Capsule Envelope Gas Vesicle 20) Which statement is true? Prokaryotic micro-compartments are surrounded by membranes Eukaryotic organelles typically are surrounded by a protein shell Eukaryotic cells typically are larger than most prokaryotic cells Prokaryotic cell membranes dont perform intra-cellular functions None of the above

Explanation / Answer

16) Biofilm

Biofilms are formed by a group of microorganisms, where cells stack to each other and on to surfaces. Here, the microbes produce extracellular polymeric substance (composed of DNA, proteins and polysaccharides).

17) Transformation

It is the genetic alteration of a cell by direct uptake of genetic material from surrounding through the cell membrane. This is one of the three processes by which the genetic material enters a bacterial cell. Conjugation (transfer of genetic material occurs during direct contact between two bacterial cells) and transduction (genetic material is injected to a bacterium by a bacteriophage virus) are the other two processes.

18) Capsule

Capsules are extracellular material secreted by bacteria, polymers of simple sugars. They are hydrophilic and help the bacteria to prevent water loss. It also protects the bacteria from destruction by host cell (by escaping phagocytosis) possibly due to the slippery nature.

19) Endospore

Endospores are seed-like, dormant, tough and non-reproductive structures. This helps the bacteria to survive through harsh environmental conditions. They are resistant to temperature, chemical disinfectants, UV rays, gamma rays etc.

20) Eukaryotic cells are typically larger than prokaryotic cells.

Eukaryotic cells have a diameter of 10-100 µm and prokaryotic cells have a diameter of 0.1-5 µm

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