What makes the bacteria vibrio cholerae a pathogen?
Flagellum
Pili
Ability to produce toxins
How does a flagellum make vibrio cholerae a pathogen?
It provides high motility thus allowing the bacteria to move through the mucus layer of the small intestine and reach the site of infection.
How does pili make vibrio cholerae a pathogen?
Toxin corregulated pili (hair like structures on the surface)
- act as adhesions to attach to the epithelial cell
- facilitate cell to cell interactions enabling the bacteria to form micro colonies
How does the ability to produce toxins make vibrio cholerae a pathogen?
Bacteria releases toxins which enter the epithelial cells and triggers a series of chemical reactions resulting in the opening of ion channels. Ions eg cl- leave the cell into the lumen. Water leaves the cell in order to decrease the concentration of ions outside of the cells. This causes severe watery diarrhoea leading to severe dehydration which can result in possible organ failure or death.
What characteristics make HIV a pathogen?
HIV functions as a pathogen by utilising characteristics to hijack host cells and cause disease.
- attachment proteins
- reverse transcriptase
- RNA
- lipid envelope
How does the lipid envelope make HIV a pathogen?
The lipid envelope acts as a protective shield and contains fusion proteins necessary to merge with the host cell membrane. The protein capsid is then ejected into the host cell.
How do attachment proteins make HIV a pathogen?
Attachment proteins (on the surface of the virus) bind to CD4 receptors (mainly) on helper T cells.
What happens once the protein capsid is ejected into the host cell?
- The RNA is converted into DNA by the enzyme: reverse transcriptase
- Transcription takes place and viral mRNA is formed
- RNA travels to the ribosome
- Translation occurs and viral proteins are formed
What happens once viral proteins are formed?
They are assembled into new viruses which bud off hence damaging the host cell membrane. This over time causes the destruction of the cell.
What happens to the number of T helper cells?
Decreases so both humoral and cell mediated immunity become less effective resulting in AIDS: Acquired Immune Deficiency Syndrome.
How is Vibrio Cholerae transmitted?
Via the fecal - oral route. Through direct contact or indirectly via contaminated food/water.
What can be done to prevent the spread of cholera?
- safe water systems
- food safety
- proper hygiene and sanitation such as washing hands
What treatment is available for cholera?
- Antibiotics work on bacteria (not viruses as they are hidden in cells)
- Electrolytes
How is HIV transmitted between individuals?
Through direct contact with bodily fluids such as blood, semen or breast milk. Most commonly transmitted through unprotected sex, sharing needles or from mother to child during birth, pregnancy or breast feeding.
How can the spread of HIV be prevented?
- safe sex practises
- regular testing
- medical prevention with pre/post exposure prophylaxis
- harm reduction for drug use
What treatment is there for HIV?
Can be treated with antiviral drugs as it inhibits key enzymes such as reverse transcriptase. Antibiotics are ineffective as viruses have no cellular structure.
What genetic disease is caused by dominant inheritance?
Huntington’s disease
What is Huntingtons disease?
A progressive neurodegeneterive disease caused by dominant inheritance. It causes the breakdown of nerve cells in the cerebral cortex.
What are the symptoms of Huntingtons?
- Huntington’s chorea (uncontrollable dance like movements)
- difficulty swallowing
- problems with speech
- personality changes
What complications can the symptoms of huntingtons lead to?
- falls
- pulmonary aspiration
- pneumonia
- suicide
What is dominant inheritance in this case?
This means only 1 mutated gene needs to be inherited from parent to chid for the child to display full symptoms and develop Huntington’s disease. This is because the mutated gene is dominant.
What genetic disease is caused by recessive inheritance?
Sickle cell anaemia
What is sickle cell anaemia?
Sickle cell anaemia is a genetic disease caused by recessive inheritance. This is where red blood cells become rigid, sticky and crescent shaped causing them to block blood flow and die prematurely. Their lifespan is 10-20 days in comparison to healthy red blood cells with a lifespan of 4 months. It is common in areas rife with malaria as it is an evolutionary advantage.
What are the symptoms of sickle cell anaemia?
- repeated episodes of stabbing pain due to oxygen starved tissue.
- blockage in the:
Lungs -> difficulty breathing
Eyes -> vision problems
Brain -> stroke
