viruses Flashcards
What are the main disease-causing pathogens in humans?
Bacteria and viruses
How do bacteria and viruses differ in terms of genetic material?
Bacteria have circular DNA; viruses have nucleic acid (DNA or RNA) in a protein coat
Do bacteria require a host to survive?
No, bacteria do not require a host; viruses do
Which is smaller, bacteria or viruses?
Viruses are significantly smaller than bacteria
What structures do bacteria possess that viruses do not?
- Cell membrane
- Cell wall
- Cytoplasm
- Organelles (e.g., ribosomes, plasmids, flagellum, pili)
What is tuberculosis also known as?
TB
What bacterium causes tuberculosis?
Mycobacterium tuberculosis
What happens to the infected phagocytes during the first TB infection?
They are sealed in tubercles and remain symptomless
What causes the symptoms of TB to appear when the immune system is weakened?
The bacteria become active again and destroy lung tissue
What virus causes AIDS?
HIV (Human Immunodeficiency Virus)
What are the initial symptoms of HIV?
- Fevers
- Tiredness
- Headaches
What is the role of histamines in inflammation?
They cause vasodilation and increase blood flow to the infected area
What is phagocytosis?
The process where white blood cells engulf and destroy pathogens
What type of immune response relies on lymphocytes?
Specific immune response
Where do B cells mature?
In the bone marrow
What do T helper cells do?
Stimulate B cells and T killer cells to divide
What are memory cells?
Cells that replicate when exposed to a pathogen and remain in lymph nodes for decades
What is the structure of antibodies?
Made of four polypeptide chains forming a Y-shaped structure
What is agglutination?
The clumping of cells by antibodies to make them easier for phagocytes to find
Define active immunity.
Immunity resulting from the production of antibodies by the immune system in response to an antigen
What is passive immunity?
Immunity resulting from the introduction of antibodies from another person or animal
What is herd immunity?
Protection of unvaccinated individuals when enough people in the population are vaccinated
Why might vaccines not always prevent disease outbreaks?
Pathogen antigens can change, removing immunity
What are monoclonal antibodies?
Clones of a single type of antibody produced for medical use
What is one direct therapy use of monoclonal antibodies?
Targeting and destroying cancerous cells
How is HIV identified?
Using an Enzyme Linked Immunosorbent Assay (ELISA)
Why are antibiotics ineffective against viruses?
Viruses do not have cell walls and reproduce within host cells
What type of drugs are used to treat HIV?
Antiretroviral drugs
