Viruses - structure Flashcards
What type of particles are viruses?
Viruses are non-cellular infectious particles
Why are viruses not considered alive?
They possess none of the characteristic features used for classifying organisms
What is the size range of viruses?
20 to 300 nm
How can viruses be visualized?
They can only be seen with an electron microscope
What are some structural features common to all viruses?
A small size, few molecules, fixed size, nucleic acid core, protein coat (capsid), no cytoplasm, very few or no enzymes
What is the genome composition of viruses?
DNA or RNA, which can be single or double-stranded
What is the role of attachment proteins in viruses?
They allow viruses to bind to and enter host cells
What is a lipid envelope in viruses?
An additional outer layer formed from membrane-phospholipids of a cell they were made in
How do viruses reproduce?
By infecting living cells and using their protein-building machinery
Do viruses respire?
No, they do not respire
What are the shapes that viruses can take?
Threadlike, polyhedral, and spherical
What determines the type of host cell a virus can infect?
The attachment proteins
What is Bacteriophage lambda?
A bacterial virus that infects Escherichia coli (E.coli)
What type of genome does Bacteriophage lambda have?
A double stranded DNA genome
How does Bacteriophage lambda inject its DNA into the host?
Through its tail
What diseases do coronaviruses cause and how are they transmitted?
Respiratory diseases in mammals and birds, transmitted through respiratory fluids
Describe coronavirus structure
Single stranded RNA
A spherical shape
An envelope outside their capsid
Many glycoproteins that project from their surface, producing a “corona”
What are examples of coronaviruses?
SARS-Cov-2, MERS, and SARS
How is HIV transmitted?
Through intimate human contact, transmitted by direct exchange of bodily fluids
- blood donation
- sharing needles
- sexual intercourse
- mother to child though breast milk or mixing of blood in birth
What type of genetic material does HIV contain?
Two RNA strands
What is the function of reverse transcriptase in HIV?
It allows the production of DNA from the viral RNA
What type of virus is HIV classified as?
A retrovirus
What forms the viral envelope of HIV?
A lipid bilayer derived from the cell membrane of the host helper T cell
