3.2.1.2 prokaryotic cells and viruses

Question 1

what are the organelle structures in prokaryotic cells?

Answer 1

• nucleoid (region where circular DNA is found).
• 70s ribosomes.
• flagellum (in some).
• cytoplasm.
• pili (in some).
• plasmids, circular DNA (in some).
• cell wall made of murein.
• cell membrane.
• slime capsule (in some).

Question 2

what is the size difference in prokaryotic cells verses eukaryotic cells?

Answer 2

prokaryotic cells are much smaller.

Question 3

what’s the function of the cell wall?

Answer 3

offers structural support to cell and protects cell against damage. cell wall made of murein.

Question 4

what’s the function of the cell membrane?

Answer 4

controls the exchange of materials between the internal cell environment and external. semi-permeable.

Question 5

what’s the function of the cytoplasm?

Answer 5

site of chemical reactions. lacks membrane bound organelles.

Question 6

what’s the function of 70s ribosomes?

Answer 6

site of translation (protein synthesis). composed of rRNA and proteins. prokaryotes have 70s ribosomes whereas eukaryotes have 80s ribosomes.

Question 7

what’s the function of the nucleoid?

Answer 7

contains genetic information to be transcribed. region where circular DNA is found, free in the cytoplasm and not associated with histone proteins (no nucleus).

Question 8

what’s the function of the plasmids?

Answer 8

small loops of DNA that are separate from the main circular DNA molecule. contains genes that can be passed between prokaryotes. not present in all prokaryotes. aids survival in different conditions e.g. antibiotic resistance.

Question 9

what’s the function of the capsule?

Answer 9

some prokaryotes are surrounded by a finial outer layer called the slime capsule. protects bacteria from drying out and from attacking cells of the immune system of the host organism.

Question 10

what’s the function of the flagella?

Answer 10

long, tail like structure that allows movement. some prokaryotes have more than one.

Question 11

what’s the function of the pili?

Answer 11

for attachment to other cells or surfaces - involved in sexual reproduction.

Question 12

what is binary fission in prokaryotic cells?

Answer 12

it is different from mitosis as there is no nuclear envelope to break down and no spindle fibres present.
it’s the division of cells/bacteria.

Question 13

what’s the process of binary fission?

Answer 13

1) the single, circular DNA molecule undergoes DNA replication and any plasmids present also undergo DNA replication too.
2) the parent cell divides into two cells, with the cytoplasm roughly halved between the two daughter cells.
3) the daughter cells each contain a single copy of the circular DNA molecule and the variable number of plasmids.

Question 14

what structures are in viruses?

Answer 14

• protein coat (capsid).
• enzymes.
• attachment proteins = 3d specific shape.
• phospholipid membrane.
• single/double stranded DNA/RNA nucleic acid core.

Question 15

what type of species is a virus?

Answer 15

non-cellular infectious particle, which is very small.

Question 16

how do viral particles replicate?

Answer 16

• do not undergo cell division as they are non-cellular.
• viruses are parasitic = only reproduce by infecting living cells (host cells).

Question 17

what is the process of viral particle replication?

Answer 17

1) virus uses its attachment proteins to bind to the complementary receptor proteins on the surface of host cell. the virus injects its DNA or RNA into the host cell nucleus, alongside the rest of its contents into the cytoplasm.
2) host cell replicates viruses genetic information = new viral particles. using host cells ribosomes.
3) virus cells released via the cell either by bursting or particles leaving individually through budding.
4) damages host cell, causing disease.