Topic 6.2: Cause of Death

Question 1

What type of cell is Bacteria?

Answer 1

A Prokaryotic cell

Question 2

Bacteria

Answer 2

1. No nucleus.
2. Lack of membrane bound organelles.
3. Do not produce a spindle during cell division.
4. Reproduce asexually by binary fission.

Question 3

What happens to Bacteria after replication?

Answer 3

After replication of their DNA they divide into two identical cells.

Question 4

Ribosomes

Answer 4

Site of protein synthesis; occur free in the cytoplasm.

Question 5

Capsule

Answer 5

Mucus layer for protection
To prevent dehydration
Allows bacteria to form colonies

Question 6

Pilus (Plural pili)

Answer 6

Protein tubes that allow bacteria to attach to surfaces

Involved in cell-to-cell attachment

Question 7

Plasmids

Answer 7

Small circles of DNA

Question 8

Mesosome

Answer 8

Infolding of the cell surface membrane

Site of cell respiration

Question 9

Flagellum

Answer 9

Used for cell movement

Question 10

Cell Wall

Answer 10

Does not contain cellulose.

Made of peptidoglycan: polysaccharide that is cross linked by peptide chains.

Question 11

Gram positive bacteria

Answer 11

Walls are thickened with additional polysaccharides and proteins.

Question 12

Gram negative bacteria

Answer 12

Thinner walls but with a surface layer of lipids for protection.

Question 13

What are Viruses?

Answer 13

Strands of nucleic acid (RNA or DNA) enclosed within a protein coat.

Question 14

Viruses

Answer 14

1. Viral DNA can be single stranded or double stranded.
2. Virus outer envelope is taken from the host cells surface membrane. Envelope has lipids and proteins.
3. Viral envelopes have glycoproteins from the virus itself. Antigens.

Question 15

What do antigens do?

Answer 15

Antigen molecules are recognised by the host’s immune system as not being it’s own self.

Question 16

What does the envelope help do?

Answer 16

Envelope helps the virus attach to the cell and penetrate the surface membrane. An example is HIV.

Question 17

What do viruses lack?

Answer 17

Viruses lack some of the internal structures for growth and reproduction. Therefore disrupts normal working of cell.

Question 18

How do viruses reproduce?

Answer 18

1. Virus attaches to the host cell.
2. Virus inserts nucleic acid.
3. Viral nucleic acids replicate.
4. Viral protein coat synthesised.
5. New virus particles are formed.
6. Virus particles released due to lysis.

Question 19

What are pathogens?

Answer 19

Bacteria and viruses that cause disease.

Question 20

How is TB Bacterium transmitted?

Answer 20

Mycobacterium tuberculosis carried is carried in the droplets of mucus and saliva released into the air when an infected person talks.

Question 21

Ways of TB Transmission

Answer 21

1. Inhaling infected droplets. Known as droplet infection.
2. Droplets can remain suspended for several hours in poorly ventilated areas.
3. Close contact with an infected person increases risk of developing the disease: poor health + poor diet and overcrowding conditions.

Question 22

Why is HIV considered a “weak” virus?

Answer 22

Because it cannot survive outside the body for significant time.

Question 23

How is HIV transmitted?

Answer 23

1. Passed only in body fluids, such as blood, vaginal secretions and semen (not saliva or urine).
2. For infection to occur: body fluids have to be transferred directly into the body.

Question 24

Ways of HIV Transmission

Answer 24

1. Sharing needles.
2. Unprotected sex.
3. Blood-to-blood transfer through cuts and grazes.
4. Maternal transmission from mother to unborn.