Bacteria & Viruses

Question 1

Bacteria

Answer 1

prokaryotic cells - their genetic information is stored in the form of a
circular strand of DNA

Question 2

Viruses

Answer 2

consist of just nucleic acid enclosed in a

protein coat and their genetic material can take the form of DNA or RNA.

Question 3

What is smaller a bacteria or virsuses

Answer 3

Viruses

Question 4

Difference between virususes and bacteria

Answer 4

-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.

Question 5

Example of a Bacterial disease

Answer 5

Tuberculosis also known as TB

Question 6

What is Tuberculosis caused by

Answer 6

TB is caused by a bacteriacalled Mycobacterium tuberculosis which infects phagocytes in the lungs.

Question 7

Tuberculosis (detailed)

Answer 7

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.

Question 8

Tuberculosis (First infection)

Answer 8

The first infection is symptomless as the infected phagocytes are sealed in tubercles as a result of inflammatory response in the lungs.

Question 9

Example of a Viral infection

Answer 9

HIV i.e. Human Immunodeficiency Virus which causes AIDS

Question 10

First symtoms of HIV

Answer 10

• fevers
• tiredness
• headaches.

Question 11

HIV after several weeks

Answer 11

After several weeks HIV

antibodies appear in blood thus making a person HIV positive.

Question 12

HIV after the first period

Answer 12

he symptomsdisappear until the immune system becomes weakened again thus leading to AIDS.

Question 13

AID symptoms

Answer 13

Symptoms of AIDS include:

• weight loss
• diarrhoea
• dementia
• cancers
• opportunistic infections suchas TB.

Question 14

What do enzymes inside the capid include?

Answer 14

Reverse transcriptase and integrase.

Question 15

What is the genetic material in HIV?

Answer 15

Single-stranded RNA

Question 16

How does HIV infect the immune system?

Answer 16

By replicating inside the T helper (TH) cells.

Question 17

Steps of HIV infecting the immune system?

Answer 17

1. HIV binds to the TH cell surface
2. HIV injects capside into TH cell
3. RNA, Reverse transciptase and intergase are relased from the capsid
4. Reverse transcriptase coverts RNA from single-stranged to double
5. Intergase inserts the DNA into TH cell DNA.
6. The genes are expressed and HIV proteins are synthesised.
7. New HIV viruses are released

Question 18

What is the cause of AIDS

Answer 18

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.

Question 19

When are the symptoms of AIDS seen

Answer 19

Within 4 weeks

Question 20

When are the symptoms of AIDS seen

Answer 20

Within 4 weeks. Chill fever

Question 21

Why can’t Antibiotics be used to treat HIV

Answer 21

As viruses use the host enzymes and ribosomes to replicate.

Question 22

How can AIDS be treated

Answer 22

Target drugs for reverse transcriptase

Question 23

What could be the target of anti-HIV drugs?

Answer 23

Reverse transcriptase