Immmunity

Question 1

Tuberculosis is a disease caused by a bacterial pathogen that is transmitted through coughing and sneezing. It results in the infection of the lung. There are multiple defences involved in stopping ppl from getting the disease. Describe the body’s non-specific defences against tuberculosis

Answer 1

-Mucus traps particles that could contain tuberculosis -cilia moves this mucus up the trachea to be destroyed -phagocytes monitor the lungs and destroy any bacteria they encounter through phagocytosis

Question 2

Once the bacteria is detected inside the body, B cells become activated, describe how a B cell is activated

Answer 2

-An antigen on the bacterium binds to a B cell. -The B cells an antigen-presenting cell and T-lymphocytes bind to the B cell -Which results in the activation of B cells through the release of cytokines.

Question 3

A vaccine for tuberculosis exists, suggest a mechanism that by which this vaccine protects against tuberculosis.

Answer 3

-An inactive form of the bacterium is introduced into the body -This elicits a SPECIFIC immune response -In which antibodies are produces -As well as memory cells. -these retain the ability to reproduce antibodies quickly if the bacterium is detected again.

Question 4

Tuberculosis is much more prevalent in low income individuals, suggest three reasons for this

Answer 4

-vaccinations more difficult to access -more likely to have other diseases which could reduce the ability of the immune system to fight against TB -poorly ventilated living space might increase risk of transmission of disease

Question 5

describe the process of phagocytosis

Answer 5

• phagocyte attracted to pathogen and binds to pathogen via receptors
• pathogen is engulfed by phagocyte via endocytosis to form phagosome
• lysosomes fuse with pathogen and lysozymes break down pathogen to soluble materials
• antiegns on pathogen are [resnted on surface of phag0ocyte so anyigen-presenting cell

-

Question 6

what are B cells and T cells

Answer 6

• B-cells mature in the boen marrow. Involved in humoral response
• T cells mature in the thymus gland, involved in cell-mediated reponse

Question 7

Describe the humoral response

Answer 7

• helped t cells stimulate b cells to rapidly divide by mitosis to forn clones of plasma cells-clonal selection
• plasma cells p[roduce anyyibodies that have a specific tertiary structure to antigen so attach to antigen and destroy the pathogen via agglutination
• agglutination- stick together so pathogn is easily digested by phagocytes

Question 8

describe the primary response VS secondary response

Answer 8

PRIMARY

SECONDARY

• present because once antibodies destroy the pathogem, memory B cells are formed
• Memory B cells remmeber which antibodies to form to kill that specific pathogen should it return
• larger conc of antibodies, faster before it can cause infection and symptoms

Question 9

what is a vaccine?

Answer 9

• a dead, inactive pathogen which initiates a primary response, leading to the formation of memory B cells
• Upon reinfection, secondary reponse is stimulated (high rate etc)
• main purpose os to provide herd immunity- immunise majority of pop etc etc

Question 10

what are the ethical issues surrounding vaccines

Answer 10

• who shoudl vaccine sbe tested on?
• should vaccinations be conmpulsory?
• are they 100% effective long term?

Question 11

whats the difference betwene active and passive immunity

Answer 11

active= immunity that results from antibody production by immune system in response to presence of an antigen e.g vaccination

passive= immunity that results from the introuction of another person or animal e.g antivenom (artificial) or breast feeding (natural)

Question 12

what are monoclonal antibodies

Answer 12

• type of antibody isolated from a sigle clone of B cells
• used in drug targeting- specific to teh target of the drug e.g tumour
• ethical issue is that mice are used to produce monoclonal antibodies
• also used in ELISA tests

Question 13

describe the ELISA test

(detection of antigens)

Answer 13

1) Antigen of interest is immobilised
2) Monoclonal anyibodies added and bind to their appropriate antigen
3) Apparatus is washed to remove unbund antigen swhihc could obscure results
4) More monoclonal antibodies are added, which are linked to colour-changing enzymes and bind to antigens
5) wash to remove unbound antibodies
6) Complementary substyrate to enzyme is added, triggering colour chnage upon binding, therefore showing presence of antigen

Question 14

Describe the sturctyure and its function, of HIV

Answer 14

Glycoprotein- attach to receptors on host cell allowing for genetic materila to injected into host cell

capsid- a protein coat that houses the genetic material and reverse transcriptase enzymes

Reverse transcriptase- converts RNA into DNA or c DNA

Question 15

Describe HIV replication

Answer 15

• HIV attaches to CD4 recptors on helper T cells
• RNA and enzymes enter host T cell
• Viral RNA is copied to c DNA by reverse transcriptase
• cDNA moves into T cell nucleus, where its transcribed and translated using host machinery to produce viral proteins that make new viruses
• new virus particles break off T cell membrane

Question 16

How does HIV cause AIDS

Answer 16

• When Helper T cell dies when new HIV particles break off membrane
• Decreased B cell stimulation, so decreased immunity
• Vulnerable to infections that are fatal
• HIV drugs often target reverse transcriptase

Question 17

Give 2 ways in which pathogens can cause diseases

Answer 17

• release toxins
• kill tissues

Question 18

Answer 18

• not enough vaccine was available
• there were decreased cases of whooping cough
• decreased risk of fear of side effects