Microevolution Flashcards
What is microevolution
evolutionary change that occurs on a time scale of a a few-1000’s of generations. (We can study these evolutionary processes within our lifetime)
Common perception of evolution
a very slow process from simple to complex life forms
Evolutionary biologists use evolution to understand the ___ rather than ____
present, past
AIDS is (on a time scale)
the later stages of a disease cause by HIV
HIV is common in these types of people
Homosexuals (Africa and South/East Asia)Woman in sub-Sahara AfricaIntravenous drug users
Describe the lifecycle of HIV
1) HIV binds to CCR5 and CD4 on host and centers cell2) viral RNA performs REVERSE transcriptase to make viral DNA3)viral DNA inserts into host DNA4) vRNA goes through transcription/translation5)New virus particles form and move out of host
HIV targets ____ which comprises the _______ which then kills the host
The Helper T-cell, immune system
HIV/AIDS kills the host due to
Lack of immune system so any sickness can kill
Describe the number of T-cells vs time of HIV infection graph
1) Initial decline due to HIV killing T-cells2) T-Cell numbers increase greatly to counter and kill most of the HIV virus3) Then slowly declines due to not being able to fight HIV anymore (because it evolves)
What is the minimal number of Helper T-cells needed to fight off general infection
200
When doe AID symptoms begin?
When the number of T-cells goes under the minimal amt.
What was one of the first drugs developed to fight HIV/AIDs?
AZT
What step in the HIV lifecycle does AZT affect?
Reverse transcriptase
AZT is a base analogue, what does that mean?
Its an unnatural base that pretends to be Thymine during reverse transcriptase
Explain how AZT combats HIV
It inserts its analog base so during reverse transcriptase it processes the face base (Z) rather than T and terminates the process
How many years of life does AZT add?
1-3 years
Why does AZT stop working
The virus evolved to make sure it uses T
How does HIV counter AZT so rapidly?
1) High mutation rate2) Fast generation time (2.6 days)All in all, high evolution rate
What permits HIV to persist at LOW levels in the body
Its high mutation rate (sorta stays incognito until its evolved enough to attack)
HIV’s high mutation rate allows it to exist at _______ levels, keeping 1 step ahead of the immune system
Low levels, (and gradually builds up)
What is the Escape Hypothesis?
1) the number of evolving HIV genotypes increases with time2) The immune system works hard to keep up with all the new genotypes3) Immune system becomes overwhelmed and fails to protect the body
HIV is a devastating disease because of its
EVOLUTIONARY POTENTIAL AHHH!
HIV’s evolutionary rate reflects the process of _____ and ___ as well to ___ and ____
Pests and bacteria to pesticides and anti-biotics
To reduce anitbiotic resistance
Reduce unnecessary use of them to slow evolution resistance
Why is it good to reduce the use of antibiotics in non-dire situations?
It reduces the resistance to antibiotics
What is a pandemic
a disease that spreads worldwide
Each pandemic is due to…
the evolution of a radically new viral genotype
Most influenza strains originate in
wild birds
Explain the process of double infection
When two viruses from two different species infect the same species (bridge)
What does a hybrid virus stem from?
A double infection in a species
Give an example that involves double infection and hybrid virus
Bird influenza and human virus both infect livestock and the viral genes come together to make a hybrid virus and everyone is vulnerable to infection
The creation of the hybrid virus leads to the start of a ____
pandemic
