prokariotic cells and viruses

Question 1

examples of prokariotes

Answer 1

bacteria

Question 2

cytoplasm of prokariotic cells

Answer 2

has no membrane bound organelles but has ribosomes that are smaller than those that are in eukariotes

Question 3

plasma membrane in prokariotic cells

Answer 3

mainly made up of proteins and lipids, controls the movement of substances into and out of the cell

Question 4

cell wall in prokariotic cells

Answer 4

prevents the cell from changing shape
- made of a polymer called murein (protein with a carbohydrate attached

Question 5

capsule in prokariotic cells

Answer 5

• made up of secreted slime
• helps protect the bacteria from attack by cells of the immune system

Question 6

plasmids in prokatiotic cells

Answer 6

• small loops of dna that arent part of the main circular dna molecule
• contain genes for things like antibiotic resistance
• can be passed between prokariotes
• plasmids are not always present

Question 7

do prokariotic cells have nucleus?

Answer 7

• no its dna floats free in the cytoplasm
• its circular dna presents as one long coiled up strand
• its not attached to any histone proteins

Question 8

flagellum in prokariotic cells

Answer 8

• long hair like structure that rotates to make the prokariotic cell move
• not all prokaryotes have a flagelluma and some have more than one (flagella)

Question 9

viruses are acellular - theyre not cells

structure of viruses

Answer 9

• viruses are nucleic acids surrounded by a protein
• theyre smaller than bacteria
• no plasma membrane, no cytoplasm, no ribosomes
• all viruses invade and reproduce inside the cells of other organisms (host cells)

Question 10

organelles within viruses / structure of prokariotic cells

Answer 10

• viruses contain a core of genetic material- either rna or dna
• the protein around the core is called the capsid
• attachment proteins stick out from the edge of the capsid

Question 12

what do attachment proteins do

Answer 12

they let the virus cling on a suitable host cell

Question 13

prokariotic cells replicate by binary fission
how does this happen?

Answer 13

1- the circular dna and plasmids replicate. The main dna loop is only replicated once but the plasmids can replicate loads of times
2- the cell gets bigger and the dna loops move to opposite poles (ends) of the cell
3- the cytoplasm begins to divide (and new cell walls begin to form)
4- 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 14

viruses use host cells to replicate themselves
How does this happen?

Answer 14

1- viruses use their attachment proteins to bind to complimentary receptor proteins on the surface of host cells
2- 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 (others can infect lost of different cells)
3- Because their not alive, viruses dont undergo cell division. Instead they inject their dna and rna into the host cells- this hijacks the cell and uses its own machinery to do the viruses dirty work and replicate the viral particles.