Biol 415: Lecture 1 (8/25/15)

Front 1

Heritable (Genetic) change in biological structure and function in population over time

Back 1

Evolution

Front 2

T/F: Evolution occurs in individuals

Back 2

False, evolution occurs through a group.

Front 3

Aids was recognized in what year?

Back 3

1981

Front 4

HIV has infected over how many people?

Back 4

65 million

Front 5

Which country has highest number of infected individuals with HIV?

Back 5

Africa

Front 6

What country has seen a marked decline in the number of individuals infected with HIV?

Back 6

India

Front 7

What country has seen a marked plateu in the number of individuals infected with HIV?

Back 7

South Africa

Front 8

How many genes does HIV have?

Back 8

9

Front 9

T/F: HIV is a retrovirus

Back 9

True

Front 10

What enzyme does HIV use to convert Viral RNA to Viral DNA?

Back 10

HIV Reverse Transcriptase

Front 11

What enzyme does HIV use to insert viral DNA into host DNA

Back 11

HIV Integrase

Front 12

What host cell receptor does HIV use to enter the cell?

Back 12

CD4

Front 13

What enzyme does HIV use to convert viral DNA to RNA?

Back 13

Host DNA Polymerase

Front 14

What enzyme does HIV use to convert Viral RNA to proteins?

Back 14

Host RNA polymerase

Front 15

What drug is used to interfere with HIV Reverse transcriptase

Back 15

AZT

Front 16

Explain how the drug AZT works

Back 16

Mimics a molecule needed to synthesize HIV DNA. When reverse transcriptase recruits the nucleotide and this drug is used then it can't extend further because it does not have -OH which is needed to build on the DNA chain.

Front 17

What molecule is bonded to AZT which prevents any additional nucleotides to build on the DNA strand?

Back 17

-N3

Front 18

In early tests, AZT worked, halting the loss of cells. After a few years, patients stopped responding to AZT treatment. What became the ultimate reason as to why this occured?

Back 18

Populations of virions changed

Front 19

How does HIV virions become resistant to AZT?

Back 19

Because of the high reproduction HIV has high mutation rates. With high mutations, it is highly likely that at least one of these mutations confers AZT resistance. When AZT is introduced into the environment, those without the mutation succumb to the drug while those with the mutations are free to replicate. This shifts the population of available virions in favor of those with the AZT resistance mutation. Eventually, as AZT continues to be used the number of AZT resistant virions will outnumber those that are susceptible to the point where AZT treatment will become ineffective.

Front 20

T/F: Through random mutations, a reverse transcriptase is produced which happens to be less susceptible to AZT

Back 20

True

Front 21

T/F: As a result of AZT being introduced into the environment, HIV mutated and produced a reverse transcriptase which is resistant to AZT

Back 21

False. Mutations are spontaneous and do not result from environmental conditions. The AZT resistant reverse transcriptase appeared prior to AZT being introduced into the environment

Front 22

T/F: AZT susceptibility is a heritable trait

Back 22

True

Front 23

T/F: Evolution by natural selection occurs automatically

Back 23

True

Front 24

What are the mechanisms of evolution?

Back 24

1. Traits are inheritable

2. Random variations in traits are due to mutation

3. Random variations due to mutations infer a difference in survival & reproduction

Front 25

How can resistance of HIV to drugs appear so quickly?

Back 25

1. Very fast mutation rates

2. Very large population size

3. Very short generation time

Front 26

How have doctors been able to slow down the virus evolution?

Back 26

Highly Active Retroviral Therapy (HAART): a combination of drugs including multiple inhibitors

Front 27

a combination of drugs including multiple inhibitors

Back 27

Highly Active Retroviral Therapy (HAART)

Front 28

T/F: There is only one type of HAART therapy

Back 28

False

Front 29

Are humans also evolving as a result of HIV?

Back 29

While humans have not directly evolved as a result of HIV,some have evolved in a way that has made them immune to HIV.

Front 30

What mutation has made a small population of humans immune to HIV?

Back 30

CCR5-Delta32 allele: a deletion of the 32 nucleotide within the gene CCR5 which prevents the functional expression of CCR5 chemokine receptors normally used by HIV-1 to enter CD4+ T Cells

Front 31

In what part of the world is the frequency of the CCR5-Delta32 allele found in the greates percentage?

Back 31

Old world Europe

Front 32

Why is resistance to HIV not more prevalent in humans?

Back 32

1. Slow mutation rate

2. Small population size

3. Long generation time

Front 33

T/F: Siv is not virulent in monkeys

Back 33

True

Front 34

An Evolutionary tree is also known as

Back 34

Phylogeny

Front 35

Explain how a doctors was convicted of injecting his girlfriend with HIV

Back 35

The HIV found in the girlfriend closely matched samples of the doctor's patience. By using an evolutionary tree, forensic scientists were able to determine that the most likely source of the girlfriend's HIV came from the patient's of the doctor

Front 36

Where does HIV come from?

Back 36

SIV. It is suggested that the virs jumped from monkeys to humans.

Front 37

T/F: There have been many independent transmissions of SIV to HIV from monkeys to humans

Back 37

True

Front 38

At least how many times has HIV been transmitted to humans?

Back 38

3

Front 39

What are the current hypotheses (2) as to how HIV was transmitted from monkeys to humans?

Back 39

1. Blood-blood transmission during killing/butchering/preparing "bush-meat"

2.Close association of humans and non-human primates "Pets"