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Evolutionary Biology > Introduction and Evolution of HIV > Flashcards

Introduction and Evolution of HIV Flashcards

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1
Q

Understanding the processes of evolution is highly relevant to?

A

human health

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2
Q

It is concerned with explaining and understanding the diversity of living things and their characteristics.

A

Evolutionary biology

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3
Q

It extends and amplifies
the explanation of biological phenomena.

A

Evolutionary biology

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4
Q

Evolutionary biology extends and amplifies
the explanation of biological phenomena complementing?

A

proximate causes and ultimate causes

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5
Q

immediate, mechanical causes

A

proximate causes

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6
Q

their historical causes, especially the action of natural selection

A

ultimate causes

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7
Q

Nothing in Biology Make Sense except in the light of Evolution by

A

Theodosius Dobzhansky (1900-1975)

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8
Q
  • The increase in fitness over time due to natural selection, or adaptation
  • The accumulation of mutations, which alter fitness over time
  • The change in allele frequencies (or the heritable expression of
    those alleles) in a population across generations
  • The progression into more complex forms of life
A

Evolution

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9
Q

Evolution is the increase in fitness over time due to ____ _____ or _____ _____

A

natural selection or adaptation

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10
Q

Evolution is the accumulation of ______, which alter fitness over time

A

mutations

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11
Q

Evolution is the change in ____ ______ in a population across generations

A

allele frequencies

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12
Q

the heritable expression of those allele

A

allele frequencies

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13
Q

Evolution is the progression into more

A

complex forms of life

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14
Q

Evolution is change in ______ of genetically different individuals at each generation

A

proportions

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15
Q

I leads to an average change in characteristics of populations over time

A

change in allele frequencies or the heritable change in the expression of those alleles

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16
Q

change in allele frequencies

A

(genetic composition

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17
Q

heritable change in the expression of those alleles

A

epigenetic inheritance

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18
Q

Evolution acts by removing individuals from the population or by allowing some

A

to leave more offspring

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19
Q

A group of interbreeding
individuals and their offspring (in the case of sexual species)

A

population

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20
Q

The change in allele frequencies (or the heritable expression of those alleles) in a population across
generations.

A

evolution

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21
Q

Even if allele frequencies in a population remain the
same across generations, a population is evolving if it goes out of the _____

A

Hardy-Weinberg Equilibrium

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22
Q

It show follow HW expectations, given the allele frequencies

A

genotype frequencies

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23
Q

How does evolution occur?

A

through 5 major mechanisms: genetic drift, mutation, heritable epigenetic modification, migration, and natural selection

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24
Q

Totally random changes in allele frequency from generation to generation

A

Genetic Drift

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25
Changes in the genetic code, such as error in DNA replication, gene deletions or duplications, etc.
Mutation
26
heritable changes that are not due to changes in DNA sequence itself, but the expression of the DNA, such as changes in DNA methylation and histone modifications, etc. >> changes “epi-alleles” not the genetic code (actual alleles
Epigenetic inheritance
27
Alleles moving from one population to another
Gene flow (Migration)
28
When some alleles favored over others due to an increase in fitness (not random); acts on genetic variation in the population
Natural Selection
29
How does evolution occur?
Natural Selection
30
What are the sources of genetic variation?
- mutation - epigenetic inheritance - genetic drift
31
It generates genetic variation
mutation
32
It changes expression of genes
Epigenetic inheritance
33
It reduces genetic variation
Genetic drift
34
It acts on genetic or epigenetic variation in a population
Natural Selection
35
Without it, natural selection cannot occur
genetic or epigenetic variation
36
Evolutionary concepts permeate all aspects of biology
- Biotechnology - Agriculture - Medicine - Conservation
37
Many of our food is a product of intense
artificial selection or human-induced evolution
38
It is the fastest evolving organism on Earth
HIV
39
It infects macrophages and T-cells
HIV
40
It is among the deadliest epidemics in human history
AIDS
41
WHO estimates in 2019 that _____ have died and ___ have been infected, and ___ people currently living with AIDS
- 32.7 million - 75.7 million - 38 million
42
What are the body fluids that transmit HIV?
- blood - semen(cum) - rectal fluids - pre-seminal fluid - breast milk - vaginal fluids
43
Only certain ____ ____ from a person who has HIV can transmit HIV
body fluid
44
This fluid must ______ from a needle or syringe for transmission to occur
- come in contact with a mucous membrane or damaged tissue - be directly injected into the bloodstream
45
Mucous membranes are found inside the
- rectum - vagina - penis - mouth
46
Mode of transmission HIGH RISK
- sexual intercourse - injection drug use
47
Mode of transmision LITTLE NO RISK
- oral sex, biting, spitting - food contamination - deep, open-mouth kissing - touching - tattoos, body piercing - medical care
48
Likely mode of transmission in year 2002 of Cambodia, Honduras, Russia, Indonesia, and Kenya (1998)
- injection drug use - sex work - heterosexual sex with a partner at high-risk - male-male sex - casual heterosexual sex
49
Likely mode of transmission in US (2006), Canada (2005), and UK (2007)
- male-male sex - MMS & IDU - Injection drug use (IDU) - heterosexual sex
50
- Retrovirus with two single strand RNAgenomes - Uses the enzyme reverse transcriptase to replicate RNA → DNA - Has an integrase to incorporate its genome to the host genome - Attacks host immune system: infects macrophages and helper Tcells
Human Immunodeficiency virus or HIV
51
HIV is a ___ with two single strand RNA genomes
Retrovirus
52
HIV uses the enzyme ____ ____ to replicate DNA
reverse transcriptase
53
HIV has an ___ to incorporate its genome to the host genome
integrase
54
HIV attack ____ and infects ____
- attack host immune cells - infects macrophages and helper T cells
55
It capture the virus and present bits of its proteins to naive helper T cells
Dendritic cells
56
This cells divide to produce effector helper T cells
Naive cells
57
It stimulates B cells displaying the same bots of viral protein to mature into plasma cells, which make antibodies that bind and in some cases inactive the virus
Effector helper T cells
58
It also activate killer T cells, which destroy host cells infected with the virus
Effector helper T cells
59
It destroy host cells infected with the virus
killer T cells
60
Mots of it are are short, but a few become long-lived memory helper T cells
effector T cells
61
HIV has the ____ _____ ___ of any virus or organism observed to date
fastest mutation rate
62
It evolves more rapidly than humans and more quickly than the ability of humans to produce new drugs
HIV
63
These are unlikely to work on all strains of the virus and unlikely to work on a given strain in the long run
AIDS vaccines
64
HOW might HIV evolve?
Drugs impose selection on HIV ----> transmission rate imposes selection on HIV -------> host immune system also imposes selection
65
evolution of drug resistance
Drugs impose selection on HIV
66
evolution of virulence
transmission rate imposes selection on HIV
67
it also imposes selection on HIV
host immune system
68
It is a thymidine mimic which stops reverse transcription and impedes viral replication
Azidothymidine (AZT)
69
Example of an HIV drug
AZT
70
Why does AZT work initially but fail in the long run?
fat mutation rate natural selection
71
Lots of mutations arise, including in the reverse transcriptase gene of HIV---->
Fast Mutation rate -----> genetic variation
72
It favors reverse transcriptase enzyme mutant that can recognize AZT and not use it
Natural selection
73
an enzyme thatnis slow, but the virus is now resistant to AZT
careful reverse transcriptase enzyme
74
The careful reverse transcriptase enzyme is slow, but the virus is now resistant to AZT
evolutionary tradeoff between fast & sloppy vs. slow & careful enzyme
75
It favors mutants that are resistant to AZT
Natural selection
76
Mutations in the viral reverse transcriptase gene of HIV arises
Fast mutation rate
77
Favors reverse transcriptase enzyme that can recognize AZT and not use it
Natural Selection
78
These mutations slow down the virus (as it becomes more careful), but makes the virus resistant to AZT
tradeoff between speed vs. accuracy of reverse transcription
79
Why does fast & sloppy are favored?
because fast replicating mutants would outgrow the slower
80
What would happen when AZT therapy stops?
Back mutations that restore the amino acid sequence to the original state are then favored by selection so that reverse transcription could speed up again
81
Evolutionary tradeoff between fast viral population growth versus keeping the host alive
Need to keep host alive long enough to get passed on to the next host
82
can grow fast and jump to the next host; ok if host dies; the genetic strain that grows faster will win
High transmission rate: High virulence
83
More virulent strains would die with the host and get selected out; less virulent strain that does not kill the host will win
Low transmission rate; low virulence
84
will select for high virulence
High Transmission rate
85
If the virus is likely to move to a new host, the faster growing (and more virulent) strain is likely to overtake the slower strains and “win”
High Transmission rate
86
Kill the host since the chance of jumping to a new host is high
High transmission rate
87
It favors the more virulent strain
Natural selection
88
Will select for low virulence
Low transmission rate
89
If the virus is not likely to move to a new host the slower growing (and less virulent) strain is likely to “win
Low transmission rate
90
since the chances of jumping to a new host is low. If the virus kills the host, it will kill itself
It's not ok to kill the host
91
will favor the less virulent strain
Natural selection
92
How to combat HIV
- must lower transmission rate of HIV so that less fatal strains evolve - must understand evolutionary properties of a disease
93
Must understand evolutionary properties of a disease
- evolutionary history - mutation rate - selective forces - evolutionary tradeoffs
94
evolution in response to AZT
slow and accurate vs fast and sloppy replication
95
Evolution in response to transmission rate
slow growing & less virulent (keep host alive_ vs fast growing & more virulent

Evolutionary Biology (1 decks)

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