Bacteria

Question 1

What are the different components of bacteria ?

Answer 1

cell wall, cell surface membrane, cytoplasm, circular DNA, ribosomes, flagellum, infolding of surface membrane, capsule, plasmid and pili.

Question 2

What are the structures always present ?

Answer 2

cell wall, cell surface membrane, cytoplasm, circular DNA and ribosome.

Question 3

What are the additional structures sometimes present ?

Answer 3

flagellum, capsule, infolding of cell surface membrane, plasmid and pili.

Question 4

Cell wall of bacteria :

Answer 4

peptidoglycan/murein protects against osmotic pressure.

Question 5

Cytoplasm :

Answer 5

does not contain membrane-bound organelle.

Question 6

Circular DNA :

Answer 6

-found in nucleiod region with no double membrane.
-there may be more than one copy in a given cell.
-associated with proteins and RNA.

Question 7

Ribosomes :

Answer 7

70s.

Question 8

Flagellum :

Answer 8

-ability to swim.
-much simpler than eukaryotic ->simple hollow cylinder of protein molecules.
-rigid ->moves due to wavelike structure and rotating a base. (propeller)
i.e corkscrew motion.

Question 9

Infolding of surface membrane :

Answer 9

-extra surface for biochemical
i.e blue-green bacteria ->photosynthetic pigments/nitrogen fixation.

Question 10

Capsule :

Answer 10

-extra layer outside cell wall.
-capsule ->polysaccharide vs slime layer ->diffuse.
-protect from drying out/antibiotics.

Question 11

Plasmid :

Answer 11

-small circle DNA separate from the main DNA of cell.
-contains genes conferring resistance.
-copy themselves independently and spread rapidly between bacteria.
-no protein therefore ‘naked’ DNA.

Question 12

Pili :

Answer 12

-fine protein rods used for attachment and interactions with other cells or surfaces.
-allow transfer of genes (incl. plasmids) from one bacterium to another during conjugation.