76. VIRUSES Flashcards
1
Q
- Define: Phages.
A
- these are viruses that affect bacteria
2
Q
- List 5 characteristics of Viruses.
A
- They are a simpler form of life
- They are Non-Cellular
- They are infectious particles
- They are much smaller than Bacteria
- They do not consist of cells
3
Q
- What is the sizer of Viruses?
A
- they are usually between 10 - 300 nano metres in
diameter
4
Q
- When were Viruses discovered?
A
- after the Electron Microscope was discovered
THIS IS BECAUSE:
- viruses can only be seen with the Electron Microscope
5
Q
- What are the 2 main categories that Viruses are grouped into?
A
- Obligate Intracellular Parasites
- Bacteriophages
6
Q
- Define: Obligate Intracellular Parasites.
A
- they depend on the host cell for replication
- they use enzymes from the host cell to replicate
- they cannot replicate outside of the host cell
7
Q
- What kind of cells do Obligate Intracellular Parasites infect?
A
- eukaryotic cells
- prokaryotic cells
8
Q
- Define: Bacteriophages.
A
- these are also known as Phages
- they are viruses that infect bacteria
- they are important pathogenic agents
- in both animals and plants
9
Q
- What does this image show?
A
- this is a virus
- it is usually 0.05 μm in size
10
Q
- What does this image show?
A
- this is a Bacteriophage
- it is usually 0.1 μm in size
11
Q
- Label this diagram.
A
- Membrane Envelope
- not all viruses have this - Nucleic Acid
- this can be either RNA or DNA - Capsid
- this is a protein saccule
12
Q
- What are the two main molecules that make up Viruses?
A
- Nucleic Acids
- Proteins
13
Q
- Define: Capsid
A
- this is a protein coat
- it encloses the viral genome
- it protects it from the nucleases
IT MAY HAVE FIBRES:
- these help to attach the virus to the host cell
14
Q
- Define: Envelope.
A
- this is only present is some viruses
- these viruses are called Enveloped Viruses
THE ENVELOPE CONSIST OF:
- the membrane
THE ENVELOPE CARRIES:
- glycoproteins
15
Q
- What do Viral Genomes consist of?
A
THEY CAN CONSIST OF:
- double or single stranded DNA
- double or single stranded RNA
16
Q
- What are the two types of Viruses that we get?
A
- DNA Viruses
- RNA Viruses
17
Q
- What are Capsids composed of?
A
- they are made up of Capsomeres
- these are a protein subunit
18
Q
- What is the shape of the Capsid?
A
- the shape varies
IT CAN EITHER HAVE:
- Icosahedral Symmetry
- helical Symmetry
19
Q
- What does this image show?
A
- this is a Helical Capsid
20
Q
- What does this image show?
A
- this is an Icosahedral Capsid
- it is also known as a Spherical Capsid
- it is has 20 sides
21
Q
- What can be said about animal viruses and viral envelopes?
A
- most animal viruses are enveloped
- they have a membranous envelope
- this surrounds their capsid
22
Q
- What is the function of the Viral Envelope?
A
- it helps the virus to infect the host cell
- the viral envelope will fuse with the host cell
membrane
THIS ALLOWS FOR THE CAPSID:
- to be released from the virus
- into the host cell
23
Q
- What is the Origin of Viral Envelopes?
A
VIRAL ENVELOPES:
- are derived from the host cell’s membranes
- this membrane can be cytoplasmic
- this membrane can be nuclear
24
Q
- When is the Viral Envelope formed?
A
- it is formed when the viral particles exit the host cells
25
25. What does the Viral Envelope consist of?
- it consists of a combination
- of the viral and host cell molecules
26
26. What is the Viral Envelope structure made up of?
- Viral Glycoproteins
- these bind to the specific receptor molecules
- this happens on the surface of the Host Cell
27
27. What can be said about different types of Bacteriophages?
- they infect different species of Bacteria
28
28. What shapes can Bacteriophages have?
- they have a spherical symmetry
- they can have a helical symmetry
29
29. What are the components that make up the Bacteriophage?
1. CAPSID HEAD:
- this encloses the nucleic acid of the Bacteriophage
- this Nucleic Acid is typically DNA
2. PROTEIN TAIL:
- this has fibres
- this helps it to attach to itself to the host cell
