cycle 1

Question 1

principles underlying evolution by natural selection

Answer 1

1. mutation
2. variation
3. heredity
4. non-random survival (selection)
5. change in the genetic composition of the population (evolution)

Question 2

prokaryotic cells

Answer 2

bacteria and archaea (cell surrounded by a lipid membrane with a DNA genome)

Question 3

eukaryotic cells

Answer 3

eukaryotes (has organelles)

Question 4

characteristics of viruses

Answer 4

not made of cells, protein shell with DNA/RNA genome inside (can be single/double-stranded), some are surrounded by a lipid envelope, obligate parasites

Question 5

what type of virus is HIV?

Answer 5

retrovirus ssRNA

Question 6

zoonotic diseases

Answer 6

occur due to spillover events (usually between closely related species), usually more harmful in the new host (e.g. HIV)

Question 7

antiviral drugs

Answer 7

prevent the virus from replicating, more difficult to design than antibiotics

Question 8

how does a virus integrate its genome into a host cell?

Answer 8

converts RNA to DNA by reverse transcription (reverse transcriptase)

Question 9

integrase

Answer 9

inserts viral DNA into host DNA

Question 10

what was the first drug to treat HIV?

Answer 10

AZT, nucleoside analog (almost like thymidine)

Question 11

how does AZT work?

Answer 11

it blocks the addition of more nucleotides (fools reverse transcriptase, stops replication)

Question 12

how does HIV become resistant to AZT?

Answer 12

reverse transcriptase undergoes a mutation that makes it resistant to AZT, mutated reverse transcriptase survives due to natural selection

Question 13

principles of evolution by natural selection

Answer 13

1. variation
2. heritable (mutations are passed on to offspring)
3. variants differ in reproductive success (fitness)
4. some variants are more likely to reproduce
5. population changes over time

Question 14

why are drug cocktails more effective?

Answer 14

resistance to one drug is easy, resistance to many drugs is less likely (inhibits the virus life cycle at many different points)

Question 15

do viruses evolve?

Answer 15

yes, even “non-living beings” evolve

Question 16

theory

Answer 16

an assumption based on limited knowledge

Question 17

scientific theory

Answer 17

a coherent set of testable hypotheses that attempt to explain facts about the natural world

Question 18

falsifiable theory

Answer 18

• points to hypotheses that need testing, gather evidence
• test a theory by attempting to falsify it
• falsification starts a critical discussion
• revise theory

Question 19

non-falsifiable statements

Answer 19

usually needs some sort of exhaustive search to disprove it

Question 20

falsifiable statements

Answer 20

needs just one observation to disprove it, open to the possibility of it being wrong

Question 21

fact

Answer 21

indisputable observation (theories can graduate to facthood)

Question 22

evidence for evolution (Darwin)

Answer 22

• biogeography: similar species are found in far away distant places (islands vs continents)
• comparative morphology: homologous structures (similar structures but perform different functions)
• geology: geological change is slow and gradual (earth is old, so is life), fossils (evidence life on earth today is different than in the past)

Question 23

vestigial structures

Answer 23

structures that have no function, used to be functional in ancestral species (e.g. appendix)

Question 24

theory of evolution by natural selection

Answer 24

1. natural selection is a mechanism to explain how evolution occurs
2. there is variation for traits in a population
3. individuals are favoured whose traits allow them to better survive and leave more offspring (higher fitness) who inherit these traits
4. over time, individuals with these favourable traits become more common in the population

Question 25

gradualism

Answer 25

takes many generations to produce large evolutionary changes

Question 26

when do new species form?

Answer 26

when an ancestral lineage diverges into daughter lineages

Question 27

scala naturae

Answer 27

each organism occupies a step on the ladder that leads from the non-living world and goes up in complexity

Question 28

Linnaeus

Answer 28

classified organisms by a 2 part system (taxonomy)

Question 29

Lamarck

Answer 29

1st theory of evolution, species change over time (“perfecting principle”, simple organism evolve to become more complex), inheritance of acquired characteristics (changes an organism gains in life are passed on

Question 30

Lyell

Answer 30

all features of the earth were developed millions of years ago

Question 31

LUCA

Answer 31

last universal common ancestor, diverged into Archaea, Bacteria, and Eukaryotes

Question 32

relative fitness calculation

Answer 32

grow rate of evolved population/ growth rate of ancestral population (if greater than 1, adaptation occured)

Question 33

virus classification

Answer 33

classified based on size, structure, genome, replication (-viridae at end of family name)

Question 34

how did viruses evolve?

Answer 34

1. escape hypothesis: evolved from escaped genomic fragments from cells
2. before-cell theory: originated in primordial gene pool

Question 35

shapes of viruses

Answer 35

helical, polyhedral, spherical, complex