34. Viruses Flashcards
Virus shapes
Rod
Round
Complex
Virus structure
- Surrounded by a protein coat (chemical component)
- Inside is nucleic acid, either DNA or RNA
- No organelles-so no metabolic reactions, so require host cells to carry out these reactions
Why are viruses not seen as living or non living
- Have either DNA or RNA-living have both, non living have neither
- Have no organelles- living things have organelles
- Cant reproduce by themselves-need a host-obligate parasite
Disadvantages of viruses
Economic importance
- Causes contagious human diseases: Measles, mumps, rubella, colds
- Causes plant diseases, causes spots on plants- potato and tomato mosaic diseases
- Causes animal diseases-foot and mouth, rabies
Advantages of viruses
Economic importance
- Control bacterial infections
2. Mosaic patterns give new variety to garden plants
How to control viral infections
- Antibiotics have no effect on them.
- Controlled by body’s own defence system-production of antibodies
- Vaccine
How do viruses reproduce
They can only reproduce using a host cell-obligate parasites
Obligate parasite def.
An organism which can only reproduce using a host cell
Process of viral reproduction
step 1
- Attachment and entry:
virus attaches to host cell and inserts its nucleic acid into the hosts cytoplasm
Process of viral reproduction
Step 2
Synthesis and Assembly:
Viral nucleic acid breaks down the hosts DNA and forces the host to make viral DNA (Synthesis) and new copies of the virus (Assembly)
Process of viral reproduction
Step 3
Release:
The new virus bursts out of the host cell to infect further cells
What is a bacteriophage
Virus that infects a bacteria
What is a bacterium
Bacteria that is infected
What is the biochemical component of the Virus
DNA or RNA
What is the chemical component of the virus
Protein coat
