2 - Human Diseases

Question 1

Cholera Transmission and Symptoms

Answer 1

Transmitted by ingestion of water or food that is contaminated with faecal material containing the pathogen

Symptoms:
Diarrhoea
Dehydration

Question 2

Cholera Cause

Answer 2

Spec ( Cholera bacteria secrete toxins which increase the secretion of chloride ions into the lumen of the intestine.
This affects the water potential gradient across the intestinal epithelium and results in severe diarrhoea.)

Cholera bacteria open the chloride ion channels

Chloride ions from epithelial cells enter lumen of small intestine

Lowers water potential of lumen, so water moves through osmosis into the lumen from surrounding cells

Loss of water through faeces

Question 3

Cholera Treatment

Answer 3

Oral Rehydration Therapy

Just drinking water is ineffective because intestine is not absorbing water and ions are not being replaced

Rehydration solution must contain:
Water
Sodium
Glucose
Potassium
Other electrolytes (ions)

Question 4

HIV Structure

Answer 4

Core:
-Genetic material
-Reverse transcriptase

Capsid:
-Outer protein coat

Viral Envelope:
-Extra outer layer made from host cells membrane
-consists of lipid bilayer made from cell membrane of host helper T cell

Protein attachments:
-Attaches to receptors on host helper T cells

Question 5

Replication of HIV

Answer 5

HIV enters bloodstream and attachment protein on HIV binds to protein called CD4 on helper T cells

Protein capsid fuses with cell surface membrane and releases HIV RNA and enzymes into helper T cell

HIV reverse transcriptase converts virus’s RNA into DNA

New DNA moves into helper T cell’s nucleus and is inserted into cell’s og dna

HIV DnA created mRNA which contains instructions for making new viral proteins

mRNA uses cell’s own protein synthesis to make HIV particles

HIV particles break away from helper T cell

Question 6

Retrovirus

Answer 6

RNA used to synthesise DNA