2.4 Immune system ppq

Question 1

Describe how HIV is replicated (4 marks)

Answer 1

• Attachment proteins attach to receptors on T helper cells
• Nucleic acid/ RNA enters cell
• Reverse transcriptase converts RNA to DNA
• Viral protein produced
• Virus assembled and released

Question 2

Describe how HIV is replicated ONCE INSIDE the T helper cell

Answer 2

• RNA converted to DNA using reverse transcriptase
• DNA inserted into T helper cells nucleus
• DNA transcribed into HIV mRNA
• HIV mRNA translated into viral proteins

Question 3

Describe how a phagocyte destroys a pathogen present in the blood

Answer 3

• Engulfs
• Forming a phagosome and fuses with lysosome
• Enzymes/ lysozymes digest

Question 4

Give 2 types of cells, other than pathogens, that can stimulate an immune response

Answer 4

• Cells from transplant
• Tumour cells

Question 5

What is the role of the disulphide bridge in forming the quaternary structure of an antibody

Answer 5

Joins 2 different polypeptides

Question 6

Explain how HIV affects the production of antibodies when AIDS develops in a person

Answer 6

• Less/ no antibodies produced
• Because HIV destroys T helper cells
• So, few/ no B cells activated

Question 7

Determining the genome of the viruses could allow scientists to develop a vaccine

Answer 7

• Could identify proteins/ proteome
• Could then identify potential antigens to use in vaccine

Question 8

Describe how B lymphocytes of a frog would respond to vaccination against Ranavirus, assuming the act the same way as humans- DONOT include details of the cellular response

Answer 8

• B cells bind to complementary antigen
• B cell clone
• Plasma cells release antibodies
• B cells produce memory cells

Question 9

What is a monoclonal antibody

Answer 9

Antibodies with same tertiary structure

Question 10

After a disease is diagnosed, monoclonal antibodies are used in some medical treatments. Give 1 example of using monoclonal antibodies in a medical treatment

Answer 10

Block antigens on cells

Question 11

Describe the role of antibodies in producing a positive result in an ELISA test

Answer 11

• First antibody binds to antigen
• Second antibody with enzyme attached is added
• Second antibody attaches to antigen
• Substrate changes colour

Question 12

Describe and explain the role of antibodies in stimulating phagocytosis - DO NOT include details about the process of phagocytosis

Answer 12

• Bind to antigen
• Antibodies cause agglutination / attract phagocytes