Topic 9: Origin of Life

Question 1

what is the main three biological polymers?

Answer 1

Nucleic acid, protein and polysaccharides.
(5 nucleotides bases, 20 amino acids and few sugars)

Question 2

what is the six definitions of life, and what are they?

Answer 2

1. organization: made of one or more cells (basic units of life)
2. metabolism: the chemical reaction of body that manage the energy and material
3. Response to stimuli: grow, alteration of chemical reactions, or movement
4. Homeostasis: maintenance of interna chemical and thermal (temp) consistency relative to change of outside
5. Adaptation: availability to change over time in response to the environment
6. reproduction: the ability to produce new individual organisms

Question 3

Are viruses alive?

Answer 3

they are infectious parasitic entities –> located in the boundary between living and non-living

Question 4

what does virus have and not have?

Answer 4

have: nucleic acid –> helpful to replicate, mutate and response to natural selection

don’t have: metabolism & homeostasis. Can’t not reproduce outside of a host cell

Question 5

who is viruses ancestor?

Answer 5

the origin of viruses are unclear since they do not form fossils

Question 6

what is three big geologic record?

Answer 6

1. Archaean
2. Proterozoic
3. Phanerozoic

Question 7

what is Precambrian?

Answer 7

Archaean + Proterozoic

Question 8

what is three big phanerozoic?

Answer 8

it is divided into three eras:
1. Paleozoic
2. Mesozoic
3. Cenozoic

Question 9

how do we distinct the geological record?

Answer 9

major boundaries can defined from mass extinction evens in the fossil

Question 10

Which of the following events are examples of adaptive radiation?

Answer 10

1. Speciation of the Galápagos finches from a single common ancestor
2. Expansion of marine predators following the Permian extinction
3. Diversification of birds
4. Expansion of mammal diversity from the beginning of the Cenozoic Era

Question 11

what is adaptive radiation?

Answer 11

• it caused by mass extinction
• in adaptive species, they evolve in different way by their environment, and they became different species

Question 12

Which of the following features is incorrect for all prokaryotes from domain Bacteria?

Answer 12

Circular chromosome in membrane-enclosed nucleoid region
–> they do have circular chromosome but they don’t have membrane

Question 13

what is the characteristic of procaryote?

Answer 13

1. Single-celled (unicellular).
2. DNA is not contained in a nucleus
3. Lack membrane-bound organelles

Question 14

what is half-life?

Answer 14

the time required for decaying 50% of atoms in a given amount of isotope

Question 15

If the half-life of carbon-14 is about 5,730 years, then a sub-fossil that has one-eighth (1/8) of the original proportion of carbon-14 to carbon-12 should be about how many years old?

Answer 15

1/8 = three half-lives = (1/2 * 1/2 * 1/2)
so, 3 * 5730 = 17190
Answer: 17190

Question 16

carbon-14’s half life

Answer 16

1. carbon-14 made by cosmic radiation’s atmospheric neutrons and nitrogen-14
2. plants consume C-12 & C-14 through “photosynthesis”
   –> animal eats plants
3. C-14 begins to decay (C-14 –> N-14) at the time of death

note:
- C-12 is very stable isotope –> accumulates (living) and unchanged (after death)
- C- 14 half-life = 5730 yrs

Question 17

how to determining the age of fossils?

Answer 17

Absolute dating: by observing radioactive decay of isotopes of various elements

Using half-life!
–> measure the decreasing ratio of C-14 : C-12
–> C-14: for archaeological specimens (up to ~62,000 yr old).

others (older than C-14)
ex)
- potassium-argon dating
(40K half-life 1.25 bil yrs)
- uranium-lead dating
(235U half-life 710 mil yrs)

Question 18

Two domains of procaryotes and what are they?

Answer 18

1. Bacteria

Question 19

How did the life begin?

Answer 19

Chemical and Physical processes

1. Abiotic synthesis of small organic molecules
2. Joining of small organic molecules into polymers (macromolecules)
3. packaging of molecules into Protocells
4. self-replicating

Question 19

how did abiotic synthesis of small organic molecules occur.

Answer 19

Abiotic synthesis: inorganic –> organic

Two possible sources of organic molecules:
1. terrestrial origin: organic molecule synthesis by energy sources
ex) UV light and electrical discharges

2. Extraterrestrial origin: formation of organic molecules in extraterrestrial objects that “bombarded” early Earth
   ex) amino acid and other organic molecule found in comets and meteorites

CH3/NH3/H/H2O (g) /CO2/N –> amino acid, nitrogen bases, sugar, lipids

Question 20

what is Millers and Urey (1950)’s founding

Answer 20

their hypothesis: Earth’s early atmosphere was initially hypothesized to
be a reducing environment.
(ex. rich in hydrogen-containing molecules such as methane
(CH4) and ammonia (NH3).)

–> replicate its condition
- hot seas: Water vapour-rich atmosphere.
−atmosphere: rich in CH4 &NH3.
− Reducing environment: e- adding
− Frequent energy discharge: lightning

Question 21

what happen to procaryote in early Earth?

Answer 21

O2 is toxic to them
–> used anaerobic metabolism (O2 free)
–> only procaryote with aerobic respiration adapt to O2 rich oceans/atmosphere

Question 22

what is GOE?

Answer 22

Great Oxygenation Event = “oxygen revolution” from 2.7 to 2.3 bya

mass extinction of prokaryote
= end of the Archean Eon