Origin of Cells A2.1 Flashcards

1
Q

What was oxygen like during pre-biotic Earth? What caused it?

A

concentrations very low because it reacted with methane and locked away in the Earth’s core

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2
Q

What was methane like during pre-biotic Earth? What caused it?

A

concentrations very high because of volcanic activity and meteorite bombardment

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3
Q

What was carbon like during pre-biotic Earth? What caused it?

A

concentrations very high because of emissions from volcanoes

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4
Q

What was ozone like during pre-biotic Earth? What caused it?

A

barely existed because of lack of O2, therefore UV radiation would have been higher

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5
Q

How would carbon compounds form during pre-biotic Earth?

A
  • in specialized environments
  • in droplets of water in the atmosphere
  • deposited by rainfall into pools, lakes, seas. creating a “soup” of carbon compounds
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6
Q

What are some examples of carbon compounds that might have formed during pre-biotic Earth?

A
  • carboxylic acid
  • aldehydes
  • amino acids
  • nitrogenous bases
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7
Q

What does MRHGREN stand for and what does it do?

A

metabolism
response
homeostasis
growth
reproduction
excretion
nutrition
- characteristics of life, used to describe what is required to maintain life, not life itself.

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8
Q

How come viruses are not considered living?

A

viruses depend on a host for a living and therefore cannot maintain life on its own.
- cant make energy
- cant maintain stability
- cant grow, etc

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9
Q

What are the two theories for how life formed?

A
  • abiogenesis
  • biogenesis
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10
Q

What is abiogenesis?

A

life developed independently from non-living or inanimate substances. (spontaneous generation)

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11
Q

What is biogenesis?

A

complex life only arise from pre-existing living things through reproduction. (non-spontaneous gen)

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12
Q

What are necessary requirements for the evolution of first cells?

A
  • catalysis
  • self-assembly
  • compartmentalization
  • self-replication of molecules
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13
Q

What is catalysis?

A

to give control over which chemical reactions occur

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14
Q

What is self-assembly?

A

carbon compounds such as amino acids must assemble to form polymers

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15
Q

What is compartmentalization?

A

a membrane must be developed to enclose cell contents

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16
Q

What is self-replication of molecules?

A

as a basis for inheritance and the persistence of successful variants

17
Q

What are some reasons cells could have arisen from non-living things?

A
  • non-living synthesis of simple organic molecules
  • simple organic molecules became assembled into more complex polymers
  • these polymers became packaged into vesicles of diff internal chemistry
  • certain polymers formed capacity to self-replicate (therefore inheritance)
18
Q

What was the Miller-Urey experiment?

A
  • evidence of carbon compounds origin
  • simulated the atmosphere at early Earth
  • created amino acid and carbon from a mixture of methane, ammonia, and hydrogen
19
Q

Explain in steps what the Miller-Urey experiment did

A
  • water boiled to reflect high temp in prebiotic Earth
  • vapor mixed w/ gases (CH4, H2, NH3) to create a reducing atmosphere (no O2)
  • electrical discharge (lightning) as energy source, led to reactions
  • after cooling, a week later, traces of organic molecules are found
20
Q

What are vesicles?

A

small droplets of fluid, enclosed in a membrane
- cell like but not yet proper cells

21
Q

What are the membrane of vesicles composed of?

A

phospholipids

22
Q

What happens when phospholipids mixed with water?

A

the phospholipid naturally self-assembles into bilayers, creating the basis for vesicles.

23
Q

Why is the internal chemistry of vesicles different from its surroundings?

A

movement of polar molecules is limited

24
Q

Why is RNA the presumed first genetic material?

A
  • RNA can store info in the same way as dNA but is both self-replicating AND act as enzyme
  • Replication needs enzyme actions
  • enzymes need genes to be made
  • can form complex 3D structures of polypeptides
25
Q

What is LUCA?

A

the last universal common ancestor, the evolutionary link between the abiotic phase of Earth’s history and the biotic phase

26
Q

How do we know share ancestory?

A
  • using info from DNA alignment studies
  • all living things use the same four letter code which translates onto codon specific same amino acids
27
Q

How come LUCA is the ONE common ancestor?

A

other life forms evolved but likely extinct from competition with LUCA, AKA natural selection

28
Q

What are some evidence for LUCA near hydrothermal vents?

A
  • genes found in bacteria need for anaerobic metabolism and carbon dioxide fixation, conditions preferably around hydrothermal vents
  • 355 genes identified for protein families among bacteria and archaea bacteria.
29
Q

Where are hydrothermal vents found?

A

tissues in the oceanic crust, gushing hot water.

30
Q

What does the water in hydrothermal vents carry and what does it do?

A
  • reduced inorganic chemicals
  • these chemicals used as source of energy for assembly of simple carbon compounds into polymers
31
Q

What does fossilization do for LUCA?

A

extremely rare but contribute to the understanding of the history of life.