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BIO106 - Evolutionary Biology > Lesson 1: Introduction to Evolutionary Biology (sir ppt) > Flashcards

Lesson 1: Introduction to Evolutionary Biology (sir ppt) Flashcards

1
Q

Why study evolution?

A
  1. understanding its process is highly relevant to human health
  2. extends and amplifies the explanation of biological phenomena
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2
Q

highly relevant to human health

A

understanding the processes of evolution

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3
Q

understanding the processes of evolution helps us understand:

A
  1. infectious disease outbreaks
  2. antimicrobial resistance
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4
Q

fascilitates the spread of drug resistance

A

gene transfer

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5
Q

what are proximate causes

A

immediate, mechanical causes

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6
Q

ultimate causes of phenomena

A

historical causes, especially the action of natural selection

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7
Q

“Nothing in biology makes sense except in the light of evolution.”

A

Theodosius Dobzhansky (1900-1975)

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8
Q

what is evolution

A

increase in fitness over time due to natural selection, or adaptation

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9
Q

alters fitness over time

A

mutations

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10
Q
  • refers to how common an allele is in a population
  • heritable expression of those alleles
A

allele frequencies

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11
Q

group of organisms that consist of similar individuals capable of interbreeding or exchanging genes among themselves

A

species

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12
Q

defines a species taxon as a group of organisms that can successfully interbreed and produce fertile offspring

A

Biological Species Concept

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13
Q

helped define the modern synthesis of evolutionary theory, proposing the “Biological Species Concept.”

A

Ernst Mayr

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14
Q

can reproduce

A

viable offspring

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15
Q

cannot reproduce

A

sterile offspring

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16
Q
  • descent with inherited modification
  • transmission of traits that increase chance of survival
A

Biological evolution

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17
Q

fitness vs adaptation

A

adaptation - traits
fitness - measure of reproductive success

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18
Q
  • measures of reproductive success of a species
  • produce viable offspring
  • allow continuous passing of genes
A

fitness

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19
Q

heritable change in the expression of alleles

A

epigenetic inheritance

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20
Q

group of interbreeding individuals and their offspring

A

population

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21
Q

Five major mechanisms of evolution

A
  1. genetic drift
  2. mutation
  3. heritable epigenetic modification
  4. migration
  5. natural selection
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22
Q

totally random changes in allele frequency from generation to generation

A

genetic drift

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23
Q

changes in the genetic code, such as errors in DNA replication, gene deletions or duplications, etc

A

mutation

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24
Q

heritable changes that arenot due to changes in DNA sequence itself, but the expression of the DNA

A

epigenetic inheritance

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25
Q

example of changes in epigenetic inheritance

A

DNA methylation and histone modifications

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26
Q

what do epigenetic inheritance change

A

epi-allele not actual alleles (genetic code)

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27
Q

alleles moving from one population to another

A

gene flow (migration)

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28
Q
  • when some alleles favored over others due to an increase in fitness (not random)
  • acts on genetic variation in the population
A

natural selection

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29
Q

isolate species from mating

A

reproductive isolation

30
Q

how can natural selection happen

A

there is genetic variation

31
Q

where does natural selection acts on

A

genetic or epigenetic variation in a population

32
Q

generates genetic variation

33
Q

changes expression of genes

A

epigenetic inheritance

34
Q

reduces genetic variation

A

genetic drift

35
Q

example of sciences where evolutionary concepts permeate

A
  • biotechnology
  • agriculture
  • medicine
  • conservation
36
Q
  • virus that attacks the body’s immune system
  • one of the fastest evolving organism on Earth
A

human immunodeficiency virus (HIV)

37
Q

what does HIV infect

A
  • macrophages
  • helper T-cells
38
Q
  • chronic, potentially life-threatening condition caused by the human immunodeficiency virus (HIV).
  • By damaging your immune system, HIV interferes with your body’s ability to fight infection and disease
A

Acquired immunodeficiency syndrome (AIDS)

39
Q

WHO 2019 estimate on AIDS

A
  • 32.7 million died
  • ~75.7 million infected
  • ~38 million currently living with AIDS
40
Q

mode of transmission of HIV

A

certain body fluids

41
Q

certain body fluids that could transmit HIV

A
  • blood
  • vaginal fluid
  • breast milk
  • pre-seminal fluid
  • rectal fluids
  • semen (cum)
42
Q

how does HIV transmission occur

A

fluids must come in contact with:
- mucous membrane
- damaged tissue
- directly injected into the bloodstream

43
Q

where are mucous membranes found

A
  • rectum
  • vagina
  • penis
  • mouth
44
Q

little to no risk mode of transmission

A
  1. oral sex, biting, spitting
  2. food contamination
  3. deep, open-mouth kissing
  4. touching
  5. tattoos, body piercing
  6. medical care
45
Q

what is HIV

A

retrovirus with two single strand RNA genomes

46
Q

what does HIV use to replicate RNA to DNA

A

reverse transcriptase enzyme

47
Q

incorporates HIV genome to host genome

48
Q

capture vius and present bits of its protein to naive helper T cells

A

Dendritic cells

49
Q

where do Dendritic cells present bits of its proteins

A

naive helper T cells

50
Q

what happens to naive helper T cells once activated

A

divide to produce effector helper T cells

51
Q

what do effector helper T cells stimulate

52
Q

how do effector helper T cells stimulate B cells

A

displaying same bits of viral protein to mature into plasma cells

53
Q

make antibodies that bind and in some cases inactivate the virus

A

plasma cells

54
Q

what do effector helper T cells also help activate that destroy host cells infected with virus

A

killer T cells

55
Q

most effector T cells are short lived, but a few become long-lived what?

A

memory helper T cells

56
Q

problem with HIV

A

fastest mutation rate of any virus or organism

57
Q

How might HIV evolve

A

impose selection on HIV
1. drugs: evolution of drug resistance
2. transmission rate: evolution of virulence
3. host immune system

58
Q

example of HIV drug

A

Azidothymidine (AZT)

59
Q

what is Azidothymidine (AZT)

A
  • thymidine mimic
  • stops reverse transcription
  • impedes viral replication
60
Q

why does AZT work initially but fail in the long run?

A
  1. fast mutation rate of HIV
  2. natural selection favors reverse transcriptase enzyme mutant that can recognize AZT and not use it
61
Q

what would happen when AZT therapy stops?

A

original reverse transcriptase would be favored (fast and sloppy) because they would outgrow the slow

62
Q

selection on virulence of HIV

A

need to keep host alive long enough to get passed on to the next host

63
Q

high transmission rate

A

high virulence

64
Q

low transmission rate

A

low virulence

65
Q

combating HIV

A

must lower transmission rate of HIV so that less fatal strains evolve

66
Q

evolutionary properties of a disease

A
  1. evolutionary history
  2. mutation rate
  3. selective forces
  4. evolutionary tradeoffs
67
Q

HIV evolution in response to AZT

A

slow and accurate vs fast and sloppy replication

68
Q

HIV evolution in response to transmission rate

A

slow growing and less virulent (keep host alive) vs fast growing and more virulent

69
Q

HIV receptors

A

CD4 and a co-receptor

70
Q

co-receptor of HIV predominantly used in vivo

A

chemokine receptor CCR5

71
Q

variants that use another co-receptor, evolve during disease in some AIDS patients

A

co-receptor CXCR4

BIO106 - Evolutionary Biology (20 decks)

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