3.6 Prokaryotic cells and viruses

Question 1

How does a prokaryotic cell differ from a eukaryotic cell?

Answer 1

smaller, no true nucleus, no membrane-bound organelles, smaller ribosomes, no chloroplasts, murein cell wall, may have capsule

Question 2

What is the structure of a bacterial cell?

Answer 2

-typically ranges from 0.1-10μm long
-has cell wall (10-80nm thick), made of murein (murein is a polymer of polysaccharides and peptides), protects against mechanical damage and osmotic lysis
-cell-surface membrane, which controls entry and exit of substances
-circular strand of DNA, which is free-floating in the cytoplasm (medium for chemical reaction) and has the genetic information of the bacterium
may also have:
-a mucilaginous slime capsule on exterior, which protects bacterium from other cells and helps stick bacteria together
-plasmids, which are smaller loops of DNA and possess genes that can aid the bacterium’s survival
-a flagellum/flagella, for locomotion

Question 3

What is the structure of a virus?

Answer 3

-20 to 300nm
-contain nucleic acids, enclosed in a protein capsid
-nonliving and acellular; multiply inside living host cells
-some have an additional lipid envelope
-external surface has attachment proteins