2. prokaryotic cells and viruses

Question 1

cytoplasm?

Answer 1

no membrane bound organelles (unlike eukaryote)

has ribosomes but smaller than in a eukaryote (70s vs 80s)

Question 2

flagellum?

Answer 2

long hair like structure that rotates to make cell move

not all have a flagellum, some have more than 1

Question 3

nucleus?

Answer 3

no
DNA floats free in cytoplasm 
circular DNA (one coiled up strand) not attached to any histone proteins

Question 4

plasmids?

Answer 4

small loops of DNA
not always present
contain genes for things like antibiotic resistance
can be passed between prokaryotes

Question 5

plasma membrane?

Answer 5

yes

Question 6

cell wall?

Answer 6

yes

supports cell prevents it changing shape. made of polymer murein (a glycoprotein - protein with carbohydrate attached)

Question 7

capsule?

Answer 7

in some prokaryotes
made of slime
helps protect bacteria

Question 8

viruses are

Answer 8

Acellular
nucleic acids surrounded by protein
not alive

Question 9

how are viruses different to bacteria

Answer 9

smaller

have no plasma membrane, cytoplasm, ribosomes

Question 10

why are viruses known as host cells

Answer 10

all viruses invade and reproduce inside cells of other organisms

Question 11

structure of viruses

Answer 11

contain core of genetic material either DNA or RNA
protein coat around core is called capsid
attachment proteins stick out from edge of capsid letting viruses cling to suitable host

Question 12

how to prokaryotic cells replicate?

Answer 12

by binary fission

Question 13

how does binary fission work

Answer 13

1. circular DNA and plasmids replicate. main DNA loop replicated once but plasmids can be replicated lots of times
2. cell gets bigger and DNA loop moves to opposite poles of the cell
3. cytoplasm begins to divide and new cell walls begin to form
4. cytoplasm divides and 2 daughter cells produced. each daughter cell has one copy of DNA but can have variable copies of plasmids

Question 14

how do viruses replicate

Answer 14

1. use attachment proteins to bind to complimentary receptor protein on surface of host cells
2. different viruses have different receptor proteins therefore require different host cells. as a result some viruses can only infect 1 type of cell
3. not alive - don’t undergo cell division. inject DNA or RNA into host cell. the cell then replicates viral particles using its own organelles / proteins