6.3 Flashcards
What happens during primary infection of TB
Causes an inflammatory response
Macrophages engulf bacteria
Mass of tissue called granuloma forms - anaerobic and contain dead bacteria and macrophages, called tubercules
Infection controlled as enlarged lymph nodes drain the area
What happens during active tuberculosis
May happen if primary infection cannot be contained, number of bacteria too great or reduced immune activity
Bacteria multiply rapidly creating cavities
What is glandular TB
TB moves through blood stream to other parts of the body
Infects lymph nodes, kidney, reproductive organs, bone and bone marrow
How does TB evade the immune system
Replicate themselves inside macrophages
Can lie dormant for long period of time
Can suppress T cells
What is a fever
Patient has a raised temperature which enhances immune function
Bacteria reproduce slower at higher temps
How is TB treated
With bacteriostatic or bactericidal antibiotics
Combination of 4 for 2 months
2 continued for further 4 months
What is HIV
An enveloped virus - retrovirus Genome composed of RNA GP120 glycoproteins Reverse transcriptase and integrase Capsid contains genome, no cytoplasm
What does reverse transcriptase do
Converts DNA into RNA
What does integrase do
Puts DNA into hosts genome
How does HIV bind to T helper cells
GP120 binds to T helpers CD4 receptors
Virus envelope fuses with cell membrane allowing viral RNA and enzymes into cell
How does HIV exploit a host T helper cell
Reverse transcriptase coverts RNA into DNA
Integrase integrates DNA into hosts genome
Transcription and translation
Virus proteins bud at surface whilst viral envelope proteins are incorporated into cell membrane
Cell lyses as virus takes with it the host cells membrane
What are the symptoms of TB
Coughing, shortness of breath, loss of appetite, weight loss, fever, extreme fatigue
What is AIDS
Acquired Immune Deficiency Syndrome
Final stage of a HIV infection
Three stages to the HIV infection
What does syndrome mean
A collection of symptoms related to the same cause
What does the rate at which AIDS develops depend on?
Health of host
Genetic resistance
Quality of immune system
Availability of anti-retrovirus drugs
What happens during the acute stage of HIV infection
Antibodies appear in blood after 3 - 12 weeks
Symptoms: fever, headache etc or no symptoms
Rapid replication of e virus and loss of T helper cells
T killer cells destroy infected T helper cells
What happens during the chronic stage of HIV infection
Prolonged stage
Virus replication kept in check by immune system
No symptoms or increasing tendency to suffer from colds etc.
Dormant diseases such as shingles and Tb may become active
What happens during the disease stage of HIV infection
Increased viral load and Declining number if T helper signify onset of AIDS
Opportunistic infections
Significant weight loss
Dementia, tumours - Kaposi’s sarcoma
How is HIV/AIDS treated
Anti-retroviral drugs such as Protease inhibitors, reverse transcriptase inhibitors, Integrase inhibitors and fusion inhibitors
What do protease inhibitors do
The catalyst protease from cutting larger proteins into smaller polypeptides for construction of new viruses
What do reverse transcriptase inhibitors do
Prevent the viral RNA from making DNA for Integrase into the hosts genome
What do Integrase inhibitors do
Inhibit the insertion of viral DNA into the hosts DNA and so viral genes cannot be transcribed or translated
What do fusion inhibitors do
Inhibit fusion of the iron with the cell membrane of the host
Outline the steps of transcription
DNA double helix unwinds, breaks H bonds, exposes template
RNA free nucleotides
RNA polymerase and other transcription factors form an initiation complex and intimidate the transcribing of mRNA from a start codon
Complementary base pairing
Cistron codes for a codon
Phosphodiester bonds in condensation reactions
What is splicing
Pre-mRNA contains exons and introns
Introns are spliced out using enzymes during post-transcriptional changes
Exons spliced back together in different orders
Outline the steps of translation
mRNA attaches to smaller subunit of ribosome - 2 codons face binding site
tRNA with complementary anticodon and amino acid binds through H bonding
Enzyme allows formation of peptide bond between amino acids
Process repeated until stop codon reached
What might vaccines contain
Attenuated virus
Killed bacteria
Harmless toxin
Antigen-bearing fragment
What happens during active immunity
Results from exposure to pathogen or antigen
Lymphocytes involved
Antibodies produced in body
B memory cells produced
What happens during passive immunity
Not exposed to pathogen or antigen
Lymphocytes not involved
Antibodies acquired
No memory cells
What are examples of natural immunity
Antibodies from breast milk or placenta
Infected naturally
What are examples of artificial immunity
Antibodies from vaccine
Antigens from vaccine
