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Biology > Unit 2 part 1 > Flashcards

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
Q

Cell membrane (plasma membrane)

A

Biological membrane that protects interior of a cell from outside environment

26
Q

What does a cell membrane require?

A

Separation of cytoplasm from external environment

27
Q

What is a cell membrane formed of?

A

Phospholipid bilayers

28
Q

Fatty acids

A

Form spontaneously in experiments like Miller and Urey’s

29
Q

Coalesces to form what?

A

coalesce to form vesicles when mixed with water

30
Q

Vesicles

A

spherical bilayers

31
Q

Hypothesis of first genetic material

A

Was trapped within a phospholipid vesicle forming a protocell

32
Q

Why is RNA considered to be the first genetic molecule?

A

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
Q

What is used to catalyze peptide bond

A

Ribozymes in ribosomes are still used to catalyze polypeptide bond in protein synthesis

34
Q

Last Universal Common Ancestor (LUCA)

A

Most recent common ancestor for all organisms on earth

35
Q

LUCA features

A
  • There could have been other forms of life at same time but descendants of LUCA out compete them
  • No fossil remains for LUCA
36
Q

Proof of LUCA

A
  • 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
Q

Cladistics

A

Allow scientists to assume age of all common ancestors

37
Q

oldest fossils of cells and its age

A

Cyanobacteria, 3.5 B years

38
Q

Age of earth and LUCA

A

Earth - 4.6 billion, LUCA appeared aprox 4 B years ago

39
Q

Radioactive dating of uranium

A

Used to date minerals and rocks around earliest fossils which decays at a steady rate

40
Q

Molecular clocks

A

mutation rate of biomolecules to figure out the time when two or more life forms diverged

41
Q

What did LUCA evolve near

A

Hydrothermal vents

42
Q

Organic compounds in Hydrothermal vents

A

Methane, carbon dioxide, hydrogen

43
Q

Metabolism

A

All of the chemical reactions that occur within an organism

44
Q

Reproduction

A

involves hereditary molecules that can be passed to off springs

45
Q

Homeostasis

A

Maintenance of a constant internal environment

46
Q

Nutrition

A

source of compounds that has many bonds which can be broken to provide energy for an organism to stay alive

47
Q

Excretion

A

enables nutrition

48
Q

Carbon compounds (organic)

A

Contains carbon and is complex meaning it makes life possible and carbon is a keystone element for life on earth

49
Q

Enzyme

A

proteins that speed up metabolism or chemical reactions in body

50
Q

Non-reducing environment

A

Hypothesis in which water vapour, carbon dioxide, sulphur dioxide, small amounts of carbon monoxide and hydrogen sulphide produce it

51
Q

Reducing environment

A

compounds used in miller-urey experiment (methane, amonia, hydrogen)

52
Q

Compartmentalisation

A

Development of a boundary around vesicle

53
Q

Fossils

A

remains and/or traces of past life

54
Q

Half life

A

length of time required for half of the radioactive isotope to change into another stable element

55
Q

Absolute dating

A

Measuring amount of an isotope in a fossil and comparing it w/amount taken up when the organisms was alive

56
Q

Relative dating of fossils

A

Utilises sediment layers of earth and index fossil

57
Q

Hydrothermal vents

A

Places where hot water emanates from below the ocean floor

58
Q

Index fossils

A

remains of plants and animals that have only existed for limited geological period

59
Q

Paradigm shift

A

When theories are completely abandoned b/c of conflicting evidence

Biology (22 decks)

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