prokaryotic cells and viruses COPY

Question 1

role of the flagellum in a prokaryotic cell

Answer 1

the flagellum is a long, hair-like structure that rotates to make the prokaryotic cell move.

not all prokaryotes have a flagellum

some have more than one

Question 2

role of the cytoplasm in a prokayotic cell

Answer 2

the cytoplasm of a prokaryotic cell has no membrance-bound organelles

it has ribosomes but they are smaller

Question 3

define a virus

Answer 3

viruses are just nucleic acids surrounded by protein- they are not even alive

they are acellular not cellular

Question 4

describe viruses

Answer 4

they’re even smaller than bacteria

unlike bacteria, viruses have no plasma membrane, no cytoplasm and no ribosomes

all viruses invade and reproduce inside the cells of other organisms. these cells are known as host cells

Question 5

describe the components of viruses

Answer 5

viruses contain a core of genetic material- either DNA or RNA

the protein coat around the core is called the capsid

attachment proteins stick out from the edge of the capsid. these let the virus cling on to a suitable host cell

Question 6

how do prokaryotic cells replicate

Answer 6

by binary fission

Question 7

define binary fission

Answer 7

the cell replicates its genetic material, before physically splitting into two daughter cells

Question 8

describe the process of binary fission in prokaryotic cells

Answer 8

the circular DNA and plasmids replicate. the main DNA loop is only replicated once, but plasmids can be replicated many times

the cell gets bigger and the DNA loops move to opposite poles of the cell

the cytoplasm begins to divide and new cell walls begin to form

the cytoplasm divides and two daughter cells are produced. Each daughter cell has one copy of the circular DNA but can have a variable number of copies of the plasmid

Question 9

explain how viruses use host cells to replicate themselves

Answer 9

viruses use their attachment proteins to bind to complementary receptor proteins on the surface of host cells.

different viruses have different attachment proteins and therefore require different receptor proteins on host cells. As a result, some viruses can only infect one type of cell

because they’re not alive, viruses don’t undergo cell division. instead, they inject their DNA or RNA into the host cell- this hijacked cell then uses its own enzymes and ribosomes to replicate the viral particles