Lecture 7 Flashcards
Why do viruses affect evolution
Can introduce any genetic material to bacteria. Arches. Eukaryotic (fungi);
Discovery of a virus
- noticed mosaic pattern of leaf
- crushed and filtered- hoping to isolate infectious material
Contagious fluid
“Virus” = poison
What are viruses
- must infect and take over host cell to replicate
- don’t have chemical machinery to carry out metabolism
What are viruses composed of
No organelles. No cell wall. No cytoplasm. Nucleus. Or nuceloid
Just nucleic acid and surrounding protein coat
Genome is one or more molecules of dna or rna in single,e or double stranded form
What protects virsus from external genome
Protein coat. Capsid.
What’s the difference between envopled and nonenvoloped
Only nucelocapsid. For protection outer elements
Some are enveloped- have the capsid surrounded by membrane
Spikes. Help attach and enter host cell
Three different virus shapes
- Helical
- inside is the virus genome - Icosahedral symmenty
- Various shape
What are virus host range
The cells the virus can attack.
Many very narrow host range. Ex. On,y specific tissue
Viruses can be classified by their genome (DNA)
DNA vs rna virus
- single stranded or double stranded
- nucleocapsid may be enveloped or nonenvloped
RNA smaller genomes.
- rely more on host cell for replication
- more prone to errors while replicated
What genome has strongest mutation rate
RNA.
Smallest
What can animal virus do in genome
Reverse transcription
- use viral RNA to made DNA strand
Cancer
Benign vs malignant
- uncontrolled growth of a single cell
- forming mass. Tumor.
Benign tumour. Body surround tumour with a capsule
If capsule breaks. Spreads throughout body. Cancer- malignant
Causes problems because uncontrollable and large amount of cells
How many cancers genetic factors
65% cancers. Genetic factors
12% because of virus
Others from carcinogens
Theee ways viruses cause tumors
1, some have oncogenes
- infection results in oncogenes in a cell genome. (Genetic material)
- expression of these genes cause normal cell— to cancer cell
(Genes like growth control. Cell division. Chemical signalling.
How does gene expression cause a tumor
- transformation of a cell due to LOSS OF normal gene function
- normal cells contain tumor suppressor genes
Inhibit transformation of the cell
If triggers inactive suppressor gene. Therefore activating tumour gene and uncontrolled cell growth occurs
