topic 2 - prokaryotic cells and viruses

Question 1

what is a prokaryotic cell

Answer 1

smaller, simpler cells that do not have a nucleus

Question 2

what 7 organelles are found in a prokaryotic cell

Answer 2

(1) cytoplasm
(2) flagellum
(3) circular DNA
(4) Plasmids
(5) capsule
(6) cell wall
(7) plasma membrane

Question 3

how is a cytoplasm in a prokaryotic cells different to a cytoplasm in a eukaryotic cell

Answer 3

it has no membrane bound organelle (unlike a eukaryotic cell) - it has ribosomes, but they’re smaller than those in a eukaryotic cell

Question 4

what is the flagellum

Answer 4

a long, hair like structure that rotates to make the prokaryotes cell move - not all prokaryotes have a flagellum and some have more than one

Question 5

where does the DNA float freely

Answer 5

in the cytoplasm

Question 6

how is the circular DNA presented

Answer 6

as a long coiled up strand and is not attached to any histone proteins

Question 7

what are plasmids, what do they contain

Answer 7

small loops of DNA that can reproduce independently and aren’t part of the main circular DNA molecule - they contain genes for things like antibiotics resistance and can be passed between prokaryotes

Question 8

what is a capsule made from and what does it do

Answer 8

it’s made up of secreted slime - helps to protect bacteria from attack by cells of the immune system

Question 9

what is a cell wall made from and what does it do

Answer 9

from a polymer called murein which is a glycoprotein - supports the cell and prevents it from changing shape

Question 10

what is a glycoprotein

Answer 10

a protein with a carbohydrate attached

Question 11

what is a plasma membrane made from and what does it do

Answer 11

made of lipids and proteins - it controls the movement of substances into and out of the cell

Question 12

why are viruses not cells

Answer 12

because they are just nucleic acids surrounded by protein - they’re not alive

Question 13

what three things do bacteria have that viruses don’t

Answer 13

plasma membrane, cytoplasm, ribosome

Question 14

what is a host cell

Answer 14

a cell that serves as a shelter and a food source to a foreign organism

Question 15

what are 3 features of a virus

Answer 15

(1) core of genetic material
(2) capsid
(3) attachment protein

Question 16

what are the two possibilities of genetic material a virus may contain

Answer 16

DNA or RNA

Question 17

what is the capsid

Answer 17

the protein coat around the core

Question 18

where are the attachment proteins present

Answer 18

sticking out from the edge of the capsids

Question 19

what do the attachment proteins do

Answer 19

they allow the virus bind onto a suitable host cell in order to infect them

Question 20

what is an example of a feature some viruses may have

Answer 20

lipid envelope

Question 21

are viruses bigger or smaller than bacteria

Answer 21

smaller

Question 22

how to prokaryotes replicate

Answer 22

by binary fission

Question 23

what is binary fission

Answer 23

a type of asexual reproduction where the cell replicates its genetic material before physically splitting into two daughter cells

Question 24

what is the first step of binary fission

Answer 24

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

Question 25

what is the second step of binary fission

Answer 25

the cell gets bigger and the DNA loop move to opposite ‘poles’ of the cell

Question 26

what is the third step of binary fission

Answer 26

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

Question 27

what is the fourth step of binary fission

Answer 27

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 plasmids

Question 28

what do viruses use to replicate themselves

Answer 28

host cells

Question 29

why can some viruses only infect one type of cell

Answer 29

because different viruses have different attachment proteins so require different receptor proteins on host cells

Question 30

how do viruses bind to host cells

Answer 30

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

Question 31

why don’t viruses undergo cell division, what do they do instead

Answer 31

because they aren’t alive - instead they inject their DNA and RNA into the host cell - the infected cell then replicates the viral particles