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Unit 2 part 1 Flashcards

Origin of cells

1
Q

Atmosphere of prebiotic earth

A

Oparin + haldane suggested that the prebiotic earth’s atmosphere is v different from todays

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2
Q

What was atmosphere of prebiotic earth primarily composed of?

A

nitrogen, carbon dioxide, water vapour w/ smaller amounts of methane and hydrogen

  • No oxygen gas (O2) or ozone (O3)
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3
Q

How was oxygen gas first released?

A

Photosynthesis

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4
Q

What did the lack of ozone cause?

A

High levels of ultraviolet light entering atmosphere

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5
Q

What did high concentration of carbon dioxide cause?

A

Higher temp due to greenhouse effect

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6
Q

What did Oparin and Haldane propose?

A

That energy available from ultraviolet light and higher temp (and lightning + volcanic activity) on prebiotic earth results in spontaneous generation of organic molecule

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7
Q

Organic compounds

A

Carbon containing molecules excluding oxides and carbonates

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8
Q

Inorganic compounds

A

All other compounds that are not organic

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9
Q

Cell theory

A
  1. Cells are the basic unit of life
  2. All organisms composed of at least 1 cell
  3. All cells come from pre-existing cells
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10
Q

What are characteristics all living organisms have?

A
  1. At least one cell
  2. Capable of carrying out metabolism
  3. Maintain homeostasis
  4. Respond to stimuli
  5. Capable of reproduction
  6. Grow and develop
  7. Contain genetic info in the form of DNA
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11
Q

Why are viruses non living organisms?

A

B/c all living organisms should experience all the characteristics and only viruses have genetic material (DNA or RNA), and ability to reproduce

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12
Q

Viruses ability to reproduce

A

Only through replication by host cells

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13
Q

Requirements of first cell

A
  • Catalysis
  • Self replication of molecules
  • Self assembly and emergence of compartmentalization
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14
Q

How was first cell made?

A
  1. Synthesis of small carbon compounds from abiotic (non-living) molecules
  2. Small organic molecules joining to form large chains of molecules (polymers)
  3. Polymers become contained by membranes, creating a protective homeostatic environment
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15
Q

What is the purpose of self replicating molecules?

A

Their development allows inheritance and control to occur

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16
Q

What was the Miller-Urey experiment?

A

Attempted to stimulate the conditions on a pre-biotic earth in a laboratory setting

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17
Q

Gasses used to represent pre-biotic atmosphere

A

Methane, ammonia, hydrogen

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18
Q

What was used to model the ocean?

A

Water

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19
Q

What did the condenser do?

A

Allowed water to return to liquid

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20
Q

What did they use to supply energy?

A

Sparks to represent thunder

  • Lightning and heat source were stimulated to evaporate water
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21
Q

Results of experiment

A

After 1 week water became brownish black

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22
Q

What did the analysis of the experiment show?

A

Many complex organic molecules, including amino acids, were produced

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23
Q

Strengths of experiment

A
  1. Modeled pre-biotic earth and atmosphere
  2. Demonstrated that molecules like amino acids can be spontaneously generated under certain conditions
  3. Design of experiment allow it to be replicated by other scientists
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24
Q

Limitations of experiment

A
  1. Debate on the actual atmosphere of pre biotic earth
  2. Did not produce all organic molecules required for life
  3. The simulation could not account for all conditions on pre biotic earth
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25
Cell membrane (plasma membrane)
Biological membrane that protects interior of a cell from outside environment
26
What does a cell membrane require?
Separation of cytoplasm from external environment
27
What is a cell membrane formed of?
Phospholipid bilayers
28
Fatty acids
Form spontaneously in experiments like Miller and Urey's
29
Coalesces to form what?
coalesce to form vesicles when mixed with water
30
Vesicles
spherical bilayers
31
Hypothesis of first genetic material
Was trapped within a phospholipid vesicle forming a protocell
32
Why is RNA considered to be the first genetic molecule?
B/c can store genetic info, is capable of self replication, and can catalyze reaction so it could have acted as both genetic material and enzymes of earliest cell
33
What is used to catalyze peptide bond
Ribozymes in ribosomes are still used to catalyze polypeptide bond in protein synthesis
34
Last Universal Common Ancestor (LUCA)
Most recent common ancestor for all organisms on earth
35
LUCA features
- There could have been other forms of life at same time but descendants of LUCA out compete them - No fossil remains for LUCA
36
Proof of LUCA
- All organisms sharing same genetic code suggests they are all evolved from LUCA - All living organisms share a number of genes which are assumed to have been inverted from LUCA
37
Cladistics
Allow scientists to assume age of all common ancestors
37
oldest fossils of cells and its age
Cyanobacteria, 3.5 B years
38
Age of earth and LUCA
Earth - 4.6 billion, LUCA appeared aprox 4 B years ago
39
Radioactive dating of uranium
Used to date minerals and rocks around earliest fossils which decays at a steady rate
40
Molecular clocks
mutation rate of biomolecules to figure out the time when two or more life forms diverged
41
What did LUCA evolve near
Hydrothermal vents
42
Organic compounds in Hydrothermal vents
Methane, carbon dioxide, hydrogen
43
Metabolism
All of the chemical reactions that occur within an organism
44
Reproduction
involves hereditary molecules that can be passed to off springs
45
Homeostasis
Maintenance of a constant internal environment
46
Nutrition
source of compounds that has many bonds which can be broken to provide energy for an organism to stay alive
47
Excretion
enables nutrition
48
Carbon compounds (organic)
Contains carbon and is complex meaning it makes life possible and carbon is a keystone element for life on earth
49
Enzyme
proteins that speed up metabolism or chemical reactions in body
50
Non-reducing environment
Hypothesis in which water vapour, carbon dioxide, sulphur dioxide, small amounts of carbon monoxide and hydrogen sulphide produce it
51
Reducing environment
compounds used in miller-urey experiment (methane, amonia, hydrogen)
52
Compartmentalisation
Development of a boundary around vesicle
53
Fossils
remains and/or traces of past life
54
Half life
length of time required for half of the radioactive isotope to change into another stable element
55
Absolute dating
Measuring amount of an isotope in a fossil and comparing it w/amount taken up when the organisms was alive
56
Relative dating of fossils
Utilises sediment layers of earth and index fossil
57
Hydrothermal vents
Places where hot water emanates from below the ocean floor
58
Index fossils
remains of plants and animals that have only existed for limited geological period
59
Paradigm shift
When theories are completely abandoned b/c of conflicting evidence

Biology (27 decks)

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