13.3 Flashcards
(14 cards)
What does HIV stand for? (1)
What does AIDS stand for? (1)
(1) Human Immunodeficiency Virus
(1) Acquired Immune Deficiency Syndrome
What is the structure of HIV? (5)
(1) Lipid envelope
(2) attachment proteins / glycoproteins embedded into the lipid envelope
(3) Inside the envelope, there’s a protein layer called a capsid
(4) The capsid encloses 2 strands of RNA & other enzymes
(5) the enzymes include = reverse transcriptase, integrase & protease
Why is HIV called a retrovirus? (2)
(1) because it contains reverse transcriptase
(2) and because it makes DNA from RNA
What is the function of reverse transcriptase? (1)
catalyses the production of DNA from RNA
Describe the process of HIV replication. Remember the coffee shop analogy. (6)
(1) HIV binds to CD4 receptors on the T helper cells
(2) The capsid layer fuses with the cell-membrane of the cell & releases its contents into the cell
(3) Reverse transcriptase converts / makes double-stranded DNA from RNA
(4) The DNA moves into the cell’s nucleus & is integrated into the host cell’s DNA
(5) The viral DNA is then transcribed into viral mRNA, which is used to produce viral proteins and particles
(6) The viral particles, RNA & proteins are packaged using a piece of the cell-surface membrane & then the new virus is released.
The replication of HIV often goes into dormancy and only recommences, leading to AIDS. What is dormancy? (2)
(1) a period in an organism’s life cycle..
(2) when growth, development & physical activity are temporarily stopped
How can HIV cause the main symptom of AIDS, which is weakened immunity? (3)
(1) HIV specifically attacks T-helper cells, so it decreases the number of T-helper cells in the blood
(2) This means that the immune system cannot stimulate B-cells to produce antibodies or cytotoxic T-cells or the memory cells
(3) so the body is unable to produce an adequate immune response and becomes more susceptible to other infections & cancers
Do HIV & AIDS cause death? Why? (2)
(1) No
(2) Because it is the secondary disease that are caused by AIDS that ultimately causes death
There is no cure for HIV, but there is a treatment called Anti-Retroviral Therapy (ART). List the 4 types of drugs in ART. (4)
(1) Attachment & entry inhibitors
(2) Reverse transcriptase inhibitors
(3) Integrase inhibitors
(4) Protease inhibitors
Attachment & Entry inhibitors are a part of ART (anti-retroviral therapy). Explain how they work. (1)
(1) they block the attachment points for the HIV protein onto the T-helper cells
Reverse Transcriptase inhibitors are a part of ART (anti-retroviral therapy). Explain how they work. (4)
(2m) TYPE 1 : non-nucleoside inhibitors –> they act as non-competitive inhibitors, as they bind to reverse transcriptase at an area other than the active site
(2m) TYPE 2 : nucleoside inhibitors —> they act as alternative nucleotides in the synthesis of viral DNA, so when they’re integrated into the viral DNA, the polynucleotide chain is terminated
Type 2 is an example of a spy
Integrase inhibitors are a part of ART (anti-retroviral therapy). Explain how they work. (1)
(1) they prevent the integration of the viral DNA into the host cell’s DNA
Protease inhibitors are a part of ART (anti-retroviral therapy). Explain how they work. (1)
(1) they inhibit the enzymes responsible for completing the MODIFICATION of the proteins that are incorporated into new virus particles
Give 3 reasons why antibiotics are ineffective against viral diseases like AIDS (3)
(1) because there are no metabolic mechanisms or cell structures for them to disrupt
(2) because viruses have a protein coat instead of a murein cell wall, so the antibiotics don’t have any sites to work on
(3) When viruses are within a self-cell, antibiotics can’t reach them
