Vaccines, Disease + Monoclonal Antibodies

Question 1

Describe how vaccines provide protection for individuals + populations against disease.

Answer 1

• small amounts of weakened or dead pathogen, or antigens, are introduced in mouth or by injection
• exposure to antigens activate B cell to divide by mitosis (clonal expansion), to make a large NO° of clones
• clones differentiate into plasma cells (produce monoclonal antibodies) or memory B cells (rapidly divide into plasma cells if reinfected w same pathogen to produce lots of antibodies)

Question 2

Describe the concept of herd immunity.

Answer 2

• when a large portion of pop are vaccinated, making it difficult for pathogen to spread amongst pop.
• this protects those not vaccinated (e.g. children + those w a weak immune system)

Question 3

What are the 2 types of immunity?

Answer 3

• active immunity
• passive immunity

Question 4

What are the differences between active + passive immunity?

Answer 4

• active: when exposure to a pathogen, or it’s antigen, triggers organism’s own immune system to create antibodies
• passive: when antibodies are introduced into body, so no plasma cells or memory cells are made, bc aren’t exposed to pathogen, so no LT immunity

Question 5

What are the 2 types of active immunity?

Answer 5

• natural active immunity: naturally infected w pathogen + so produces own antibodies + memory cells
• artificial active immunity: infected w weakened pathogen or antigens via vaccine, stimulating antibodies + memory cells to be produced

Question 6

Describe the structure of the human immunodeficiency virus (HIV).

Answer 6

• core, containing 2 RNA strands + enzyme reverse transcriptase (needed for viral replication)
• capsid (protein coat)
• envelope, made from phospholipids of host’s cell membrane
• attachment proteins on exterior of envelope, enabling virus to attach to host’s helper T cell

Question 7

Describe how HIV replicates in helper T cells.

Answer 7

• HIV is transported around in blood, until it binds to a CD4 receptor on helper T cell
• HIV protein capsule fuses w helper T cell membrane, allowing RNA + enzymes from HIV to enter cell
• HIV enzyme, reverse transcriptase, makes a DNA copy of viral RNA, which moves into nucleus of helper T cell
• viral DNA is then transcribed into mRNA, which helper T cell uses to make new viral proteins used to make new viral particles

Question 8

How does HIV cause symptoms of AIDS?

Answer 8

• HIV destroys + dec NO° of helper T cells
• this interferes w normal functioning of immune system bc host is unable to produce an adequate immune response to other pathogens, + is left vulnerable to infections + cancer

Question 9

Why are antibiotics ineffective against viruses?

Answer 9

• bc they don’t have a cell wall which antibiotics target
• bc they replicate inside host cells, so don’t have a metabolism or cell structures for antibiotics to disrupt

Question 10

What are monoclonal antibodies used for?

Answer 10

• targeted medication (direct + indirect monoclonal antibody therapy)
• medical diagnosis

Question 11

Describe direct monoclonal antibody therapy.

Answer 11

• some cancer can be treated using monoclonal antibodies that have a complementary binding site to antigens on cancer cells
• antibodies are given to cancer patient, which bind to antigens on cancer cells, preventing chemicals, which enable uncontrolled cell division, from binding, so prevents cancer cells growing

Question 12

Describe indirect monoclonal antibody therapy.

Answer 12

• cancer can be treated using monoclonal antibodies that have a complementary binding site to antigens on cancer cells, + drugs attached to them
• so as antibody attaches to cancer cell, drugs are also directly delivered to cancer cell + kills them, dec harmful side effects that traditional chemotherapy + radiotherapy can produce

Question 13

Describe how monoclonal antibodies are used in medical diagnosis.

Answer 13

• via an ELIZA (enzyme linked immunosorbent assay) test
• can test for pregnancy, influenza, hepatitis etc.

Question 14

Describe the use of antibodies in the ELIZA test.

Answer 14

• 1st antibody is mobile + complementary to antigen being tested for, + has a coloured dye attached
• 2nd antibody is complementary to antigen + is immobilised in test
• 3rd antibody is immobilised + is complimentary to 1st antibody

Question 15

Describe how to test for antigens using the ELIZA test.

Answer 15

• add test sample (e.g. blood) to base of beaker, in which antigens bind to base
• wash to remove any unbound antigens in test sample
• add an antibody, complementary to antigen being tested for
• wash to remove any unbound antibodies
• add a second antibody, w enzyme attached, that are complementary + bind to 1st antibodies
• add a colourless substrate, which reacts w enzyme to form a coloured product if antigen is present
• intensity of colour indicates quantity of antigens present

Question 16

Describe the ethical issues associated w the use of vaccines + monoclonal antibodies.

Answer 16

• creating monoclonal antibodies requires mice to produce antibodies + tumour cells, so ethical debates on if use of animals is justified to enable better treatment of cancers in humans + to detect disease