BCH OWL 10/25
Hybridomas, which produce monoclonal antibodies, are made by fusing cells of the immune system with A) cancerous cells. B) viruses. C) bacterial cells. D) ribosomes.
A
A virus life cycle that involves the incorporation of the viral DNA into the host chromosome is A) lysogeny. B) lytic. C) oncogenic. D) non-existent.
A You can think of lysogeny as a cycle in which there is the potential for ("ogeny") cell lysis ("lys"). In contrast, the lytic cycle results in direct cell lysis. It's also important to recognize that some viruses use only one or the other of these cycles - others have options depending on the host cell status.
Dendritic cells A) secrete cytokines, recruiting other cells to destroy microbes. B) display antigens associated with MHC proteins. C) produce antibodies. D) bind to antigens, which leads to their proliferation.
B
Which of the following does not arise from a defect in the immune system? A) Allergies B) Sugar intolerance C) Autoimmune diseases D) Immunodeficiency E) All of these can be caused by defects in the immune system.
B
Which of the following best describes the function of reverse transcriptase? A) It's involved in viral attachment to a host cell. B) It uses an RNA template to make a double-stranded DNA. C) It uses DNA to synthesize an RNA in the 3'→ 5' direction. D) It joins the gene segments that code for antibodies.
B We encountered reverse transcriptase activity in a previous lesson on telomeres and telomerase. Since transcription involves the use of a DNA template to make RNA - this enzyme catalyzes the reverse of this - using an RNA template to make DNA.
The capsid of a virus is composed of A) DNA or RNA B) Protein C) Lipid D) Carbohydrate
B The capsid is the protein coat that protects the genome. All viruses have a capsid but not all also have a membrane envelope.
What is the main function of TH cells? A) They function to stimulate B cells to become antibody-producing cells. B) They function to stimulate TC cells to destroy infected cells. C) Both A and B are true. D) Neither A nor B are true.
C
Which of the following cell types kills cells that have been infected by viruses or that are cancerous? A) dendritic cells B) T cells C) NK cells D) B cells
C
A viral genome is A) always double-stranded B) always single-stranded C) may be double or single stranded D) always made of DNA E) always made of RNA
C The basic lesson here is that there is no "always" when it comes to viral genomes. They may be either DNA or RNA and single-stranded, double-stranded, or partially double-stranded.
How do TC cells bind and recognize antigen on APCs? A) The TCR binds to MHC I and CD8 binds antigen. B) The TCR binds to MHC II and CD8 binds antigen. C) The TCR binds to antigen and CD8 binds B7. D) The TCR binds to antigen and CD8 binds to MHC I. E) The TCR binds to antigen and CD8 binds to MHC II.
D
Which of the following best describes the function of reverse transcriptase? A) It's involved in viral attachment to a host cell. B) It uses an RNA template to make a double-stranded DNA. C) It uses DNA to synthesize an RNA in the 3'→ 5' direction. D) It joins the gene segments that code for antibodies.
D LTRs are part of the viral DNA and enables it to be recognized by the enzyme involved in integrating it into the host DNA.
More than one type of antigen can bind to an antibody, but there is only one type of antibody for each antigen. A) True B) False
F Each antibody is specific for one epitope. The same epitope may be present on different antigens and the same antibody could bind to either. Each antigen carries multiple epitopes and therefore binding sites for antibodies with multiple and variable specificities.
Some viruses can undergo lysis or lysogeny within the same host. Under what conditions might the virus favor lysis instead of lysogeny?
lytic infects primate - if in host, can use resources of host lysogeny infects rodent