Viruses and bacteria

Question 1

Structure of viruses

Answer 1

• Usually rod-shaped or spherical in shape with a large number of triangular facets on the surface. They are often symmetrical
• Contain a nucleic acid enclosed within a protein coat
• In-plant virus the nucleic acid is usually RNA, and in animal virus, the nucleic acid is usually either RNA or DNA
• The only life function of a virus is reproduction. A virus cannot be regarded as a cell because it does not have a nucleus with chromosome material

Question 2

Life function of a virus

Answer 2

reproduction

Question 3

How do viruses spread

Answer 3

Viruses can spread through food, by direct contact, or through vectors

Question 4

Replication of viruses

Answer 4

they replicate through living cells only.

A bacteriophage attaches itself firmly to the wall of a single bacterial sell or bacterium, thereafter the nucleic acid content of the bacteriophage is injected into the cell, leaving the capsid behind. The DNA of the bacterium is used to replicate the viral DNA and form proteins for the new capsids. When many bacteriophages have formed, the wall of the bacterium busts releasing the new lysis

Question 5

What is it called when a virus replicates within bacteria

Answer 5

bacteriophage

Question 6

Characteristics of viruses

Answer 6

A vu=irus contains either DNA or RNA
cannot grow or replicate by cell division
are obligate parasites, using host cells to generate new viruses
is host specific and can even be tissue specific

Question 7

Characteristics of viruses

Answer 7

A virus contains either DNA or RNA
cannot grow or replicate by cell division
are obligate parasites, using host cells to generate new viruses
is host specific and can even be tissue specific

Question 8

What is Escherichia coli

Answer 8

a rod-shaped bacterial cell living in the colon of homoiothermic animals, such as mammals which are found in water

Question 9

What does Escherichia coli produce

Answer 9

vitamin K which is necessary for blood clotting

Question 10

How do E. coli cause disease

Answer 10

If a hole forms in the colon, the sterile abdominal cavity can be infected by e. Coli bacteria. A serious and potential life-threatening sickness, peritonitis can develop. Usually, an emergency operation will take place where the abdominal cavity is rinsed and the patient is treated with antibiotics and a urine infection can occur

Question 11

Characteristics of bacteria

Answer 11

Bacteria

are prokaryotic
they are tiny and have distinctive cell walls
they lack a true nucleus and the DNA is free floating

Question 12

Characteristics of bacteria

Answer 12

Bacteria

are prokaryotic
they are tiny and have distinctive cell walls
they lack a true nucleus and the DNA is free-floating