Bacteria & Viruses Flashcards
Bacteria
prokaryotic cells - their genetic information is stored in the form of a
circular strand of DNA
Viruses
consist of just nucleic acid enclosed in a
protein coat and their genetic material can take the form of DNA or RNA.
What is smaller a bacteria or virsuses
Viruses
Difference between virususes and bacteria
-Bacteria do not require a host to survive whereas viruses are entirely dependent on their hosts and cannot survive without them.
- Bacteria have a cell membrane, cell wall and cytoplasm as well as other organelles such
as ribosomes, plasmids, flagellum and pili whereas viruses possess no such structures.
Example of a Bacterial disease
Tuberculosis also known as TB
What is Tuberculosis caused by
TB is caused by a bacteriacalled Mycobacterium tuberculosis which infects phagocytes in the lungs.
Tuberculosis (detailed)
The first infection is symptomless as the infected phagocytes are sealed in tubercles as a result of inflammatory response in the lungs. However, the bacteria lie dormant inside the tubercles as they are not destroyed by the immune system due to the tubercles being covered with a thick waxy coat.
When the immune system becomes weakened, the bacteria become active again and slowly
destroy the lung tissue thus leading to breathing problems, coughing, weight loss as well as
fever. TB can potentially lead to death.
Tuberculosis (First infection)
The first infection is symptomless as the infected phagocytes are sealed in tubercles as a result of inflammatory response in the lungs.
Example of a Viral infection
HIV i.e. Human Immunodeficiency Virus which causes AIDS
First symtoms of HIV
- fevers
- tiredness
- headaches.
HIV after several weeks
After several weeks HIV
antibodies appear in blood thus making a person HIV positive.
HIV after the first period
he symptomsdisappear until the immune system becomes weakened again thus leading to AIDS.
AID symptoms
Symptoms of AIDS include:
- weight loss
- diarrhoea
- dementia
- cancers
- opportunistic infections suchas TB.
What do enzymes inside the capid include?
Reverse transcriptase and integrase.
What is the genetic material in HIV?
Single-stranded RNA
How does HIV infect the immune system?
By replicating inside the T helper (TH) cells.
Steps of HIV infecting the immune system?
- HIV binds to the TH cell surface
- HIV injects capside into TH cell
- RNA, Reverse transciptase and intergase are relased from the capsid
- Reverse transcriptase coverts RNA from single-stranged to double
- Intergase inserts the DNA into TH cell DNA.
- The genes are expressed and HIV proteins are synthesised.
- New HIV viruses are released
What is the cause of AIDS
When an HIV virus infects a TH cell and replicates, the cells are killed. As HIV spreads through the body and more TH cells are killed, the immune system weakens.
The weak immune system makes the individual highly susceptible to infection by other pathogens. This is AIDs.
When are the symptoms of AIDS seen
Within 4 weeks
When are the symptoms of AIDS seen
Within 4 weeks. Chill fever
Why can’t Antibiotics be used to treat HIV
As viruses use the host enzymes and ribosomes to replicate.
How can AIDS be treated
Target drugs for reverse transcriptase
What could be the target of anti-HIV drugs?
Reverse transcriptase
