A2.3 viruses

Question 1

structural features common to all viruses

Answer 1

-small fixed size
-nucleic acid RNA or DNA
-capsid made of proteins
-no cytoplasm
-few to no enzymes

Question 2

function of capsid

Answer 2

-protection of genetic material
-unique structure determines ability to allow attachment to specific host cells
-unique based on presence specific amino acid and structure they produce produced when bonding, this determines ability in infect particular host cell
-contain specialized sites on capsid that contain specialized proteins that allow genetic material of virus to penetrate host cell

Question 3

diversity in the structure in viruses

Answer 3

-can have either RNA or DNA double or single stranded
-some have an envelope outside capsid
-10-400nm, exceptions as big as bacteria
-wide variation in shape

Question 4

features of bacteriophage lambda

Answer 4

• capsid head protecting double strand DNA
  -tail fibers that allow attachment to cost cell
  -tail sheath made of proteins that drive tail tube through hosts outer membrane
  -DNA is injected through tail

Question 5

features of coronavirus

Answer 5

-spherical shape
-single stranded RNA
envelope outside capsid
-projections of spike proteins on envelope

Question 6

features of HIV

Answer 6

-has an envelope outside capsid
-two identical strands of RNA in capsid
-in viral RNA, reverse transcriptase is encoded which allows production of DNA using model RNA.
-is known as a retrovirus because it makes DNA copies of RNA code
-envelope has spikes of HIV
-host cell specificity is white blood cells

Question 7

what all viruses must do to reproduce

Answer 7

1. attach to a site on a specific host cell
2. incorporate genetic material into cytoplasm of the host cell
3. use the host cell’s processed to produce new components for themselves
4. assemble viral components into functioning virus entities
5. release the new virus entities into the host cells environment

Question 8

steps of the lytic cycle

Answer 8

'’lysis’’= rupturing of cell membranes by an enzyme called lysozyme

1. phage attaches to host cell
2. penetrates host cell wall and injects its DNA
3. Phage DNA, synthesizes viral components by host hell
4. viral components are assembled into virions, which are fully functioning virus particles
5. Host cell lyses and bursts are released

Question 9

steps of the lysogenic cycle