Topic 2C- Cells and the Immune System (HIV) Flashcards
What does HIV stand for?
What is HIV?
What does HIV eventually lead to and describe?
What is AIDS?
What does this make someone with AIDS?
What is this called?
What does HIV do?
What happens to the immune system without enough of these cells?
Why is this?
When do people with HIV develop AIDS?
Human Immunodeficiency Virus
A virus that infects the immune system
AIDS (Acquired Immune Deficiency Syndrome)
A condition where the immune system deteriorates and eventually fails
More vulnerable to other infections
Opportunistic infections
Infects (and eventually kills) helper T-cells, which act as the host cells for the virus
Without enough helper T-cells, the immune system is unable to mount an effective response to infections
Because other immune system cells don’t behave how they should
When the helper T-cell numbers in their body reach a critically low level.
Describe function (and in some cases the appearance)the following organelles of the structure of HIV:
The core
Capsid
Envelope
Attachment proteins
Contains the genetic material (RNA) and some proteins (including the enzyme reverse transcriptase, which is needed for viral replication)
The outer coating of a protein
The extra outer layer. Made of membrane stolen from the cell membrane of a previous host cell
Stick out from the envelope. They help HIV attach to the host helper T-cell.
Where can HIV only reproduce?
Describe stage one of the life cycle of HIV?
Describe stage two of the life cycle of HIV?
Describe stage three of the life cycle of HIV?
Describe stage four of the life cycle of HIV?
Describe stage five of the life cycle of HIV?
Describe stage six of the life cycle of HIV?
HIV (and all other viruses) can only reproduce inside the cells of the organism it has infected
- The attachment proteins attaches to a receptor molecule on the cell membrane of the host helper T-cell
- The capsid is released into the cell, where it uncoats and releases the genetic material (RNA) into the cell’s cytoplasm
- Inside the cell, reverse transcriptase is used to make a complementary strand of DNA from the viral RNA template
- From this, double-stranded DNA is made and is inserted into the human DNA
- Host cell enzymes are used to make viral proteins from the viral DNA found within the human DNA
- The viral proteins are assembled into new viruses, which bud from the cell and go to infect other cells.
Describe HIV during the initial infection period and what does the infected person show?
What happens after this?
What is this called?
What happens during this period?
In what two ways are people living with HIV classified with having AIDS?
HIV replicated rapidly and the infected person may experience severe flu-like symptoms
HIV replication drops to a lower level
The latency period
(can last for years) the infected person won’t experience any symptoms
- When the symptoms of their failing immune system start to appear
- When their helper T-cell count drops below a certain level.
Describe the initial symptoms of AIDS?
What happens as AIDS progresses?
What are the symptoms of this?
What happens during the late stages of AIDS?
What can patients then develop and give two examples?
What are four factors that affect the progression of HIV to AIDS and survival time?
Include minor infections of mucous membranes (eg the inside of the nose, ears and genitals) and recurring respiratory infections
The number of immune system cells decreases further
Patients more susceptible to more serious infections including chronic diarrhoea, severe bacterial infections and tuberculosis
Patients have a very low number of immune system cells
A range of serious infections such as toxoplasmosis of the brain (a parasite infection) and candidiasis of the respiratory system (fungal infection)
Existing infections; the strain of HIV they’re infected with; age; access to healthcare.
How do antibiotics kill bacteria?
What two things do antibiotics target in bacteria?
Why don’t antibiotics target human cells?
By interfering with their metabolic reactions
Bacterial enzymes and ribosomes used in these reactions
Because bacterial enzymes and ribosomes are different from human enzymes and ribosomes.
Why can’t antibiotics inhibit human viruses?
What are most antiviral drugs designed to target?
What is an example of this?
In this example, what are these drugs called?
Describe cures and vaccines for HIV?
What is the best way to control HIV infection?
Because human viruses use human enzymes and ribosomes to replicate and antibiotics don’t target human processes
The few virus-specific enzymes that exist
eg HIV uses reverse transcriptase to replicate. Human cells don’t use this enzyme so drugs can be designed to inhibit it without affecting the host cell
Reverse-transcriptase inhibitors
There’s currently no cure or vaccine for HIV but antiviral drugs can be used to slow down the progression of HIV infection and AIDS
By reducing its spread.
What are the three ways that HIV can be spread?
What can the taking antiviral drugs during pregnancy reduce?
Via unprotected sexual intercourse; through infected bodily fluids (eg blood from sharing contaminated needles); from a HIV-positive mother to her foetus
The chance of the baby being HIV-positive.
