prokaryotes and eukaryotes

Question 1

what features do all prokaryotic cells contain

Answer 1

-cell membrane
-circular DNA floating freely in the cytoplasm
-no nucleus DNA is not associated with histone proteins it is ‘naked’
-70 s ribosomes- for translating and assemnling proteins
-cytoplasm -lacks membrane bound organelles such as mitochondria
-much less well developed cytoskeleton with no centrioles
-bacterial cell wall made up of peptidoglycan ( murein) = acts as a physical barrier to protect the cell against mechanical forces and changes in water potential.
glycogen granules and oil droplets (act as an energy store)

Question 2

what process do prokaryotic cells divide by

Answer 2

binary fission

Question 3

in prokaryotic cells, what is binary fission co- ordinated by

Answer 3

the simple prokaryotic cytoskeleton co-ordinates binary fission

Question 4

in order for prokaryotic cells to divide, what needs to happen to the peptidoglycan cell wall

Answer 4

the peptidoglycan cell wall needs to be broken down in order for prokaryotic cells to divide.

Question 5

what features do only SOME prokaryotic cells contain

Answer 5

flagellum- long hair like protusion that rotates, allowing the prokaryotic cell to move
pili- small hairlike projections that extend out of the bacteria enabling them to adhere to to host cells or each other
slimy capsule- made out of secreted slime and helps protect the prokaryotic cell from detection by other cells, it also allows individual bacteria to stick together.
plasmids- small loops of naked DNA they can be replicated and passed on in cell division, can be transferred from one cell to another through pilli this allows for the transfer of useful genes such as antibiotic resistance.

Question 6

DNA in prokaryotic cells

Answer 6

prokaryotic cells do not contain any membrane bound organelles and so do not possess a nucleus. instead prokaryotic cells have a nucleoid

Question 7

what is a nucleoid

Answer 7

a region in the cytoplasm of a prokaryotic cell that contains the main genetic material of the cell
prokaryotic DNA is circular and ‘naked’ not associated with histone proteins

Question 8

some prokaryotic cells may contain plasmids.
what are plasmids?

Answer 8

plasmids are small loops of naked DNA they are not part of the main circular DNA molecule. they can be replicated and passed on in cell division.
plasmids can also be transferred from one prokaryotic cell to another through pili. allowing for the transfer of useful genes such as antibiotic resistance.

Question 9

why do prokaryotic and eukaryotic cells have several different features if they have both originated from the same common ancestor

Answer 9

they have both originated from the same common ancestor however have evolved independently for a long period of time. and therefore may have several different features