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BIO1339 - Cell > Cell Biology - Evolution of the cell > Flashcards

Cell Biology - Evolution of the cell Flashcards

1
Q

What happened 4.5 billion years ago?

A

Formation of the solar system

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2
Q

What happened 4.0 billion years ago?

A
  • Water condensation as Earth cools down
  • Formation of Earth crust
  • Formation of organic molecules
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3
Q

What happened 3.5 billion years ago?

A

Stromatolites indicate first life

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4
Q

What happened 3.0 billion years ago?

A
  • Photosynthesis developed in cyanobacteria-like microbes

- Oxygen in the atmosphere

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5
Q

What happened 2.0 billion years ago?

A

Development of eukaryotic cell that contain symbiotic prokaryotes

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6
Q

What happened 1.5 billion years ago?

A

Appearance if multi-cellularity

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7
Q

What happened 0.5 billion years ago?

A

Cambrian explosion of multi-cellular life forms symmetrical with antenna and segmented

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8
Q

What happened 0.25 billion years ago?

A

Dinosaurs dominate the Earth

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9
Q

What happened 0.0004 billion years ago?

A

Homo sapiens developed

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10
Q

What can be formed under “Early Earth conditions”?

A

Building blocks of RNA

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11
Q

What can ribonucleotides be formed from?

A

Cyanamide, cyanoacetylene, glycolaldhyde, glyceraldehyde and inorganic phosphate

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12
Q

What is crucial to establish a working protein?

A

Ribosomes

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13
Q

What do ribosomes consist of?

A

Protein and RNA

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14
Q

What do ribosomes do?

A

Translate mRNA into protein

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15
Q

What are ribosomes considered to be?

A

Riboenzymes

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16
Q

What does the riboenzymes of ribosome depend on?

A

Enzymatic activating of ribosomes depend in RNA part of ribosomes

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17
Q

What is the RNA world hypothesis?

A

RNA was at the origin of life

  • stored genetic information
  • catalyse chemical reactions
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18
Q

Who proposed the RNA world hypothesis?

A

Alexander Rich in 1962

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19
Q

How does RNA have enzymatic activity?

A

Single stranded RNA can fold and form molecules that catalyse chemical reactions

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20
Q

What is a catalytic RNA molecule called?

A

Ribozyme

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21
Q

What are examples of ribozymes?

A
  • Class I RNA ligase

- RNA-degrading riboszyme

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22
Q

What can ribonucleotides spontaneously do on clay surfaces?

A

Polymerise

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23
Q

How does replicase ribozymes produce new replicases?

A
  • Ribozyme replicates an un-folded RNA stand of another replicase molecule
  • High temperature, both stands separate; one folds into a new replicase, one serves as template for further synthesis
24
Q

What do some minerals catalyse from hydrogen and carbon monoxide gases?

A

Fatty acids

25
Q

What do polar fatty acids self-organise into?

A

Micelles

26
Q

What happens in water to fatty acids?

A

Hydrophobic chains turn towards each other exposing hydrophilic head

27
Q

What forms vesicles?

A

Micelles

28
Q

What is required to form vesicles?

A

Acidic pH

Micelles

29
Q

Where can vesicles be formed?

A

Clay surfaces

30
Q

What can cause vesicles to grow?

A

Fusion with micelles

31
Q

Are lipids in vesicles membrane rigid or dynamic?

A

Dynamic

32
Q

What is an advantage of lipids in vesicle membranes being dynamic?

A

Flipping of lipids can transport molecules over the membrane

33
Q

What can accumulate with in vesicles?

A

Molecules such as ribonucleotides, ribozymes etc.

34
Q

What results in a protocell?

A

Combining RNA replicase and vesicles

35
Q

Describe the combination of RNA replicase and vesicles to form a protocell:

A
  • RNA replicase use ribonuceotides to make a copy of anther RNA replicase
  • Micelles fuse with the vesicle and enlarge it until it becomes unstable and divides
  • Random mistakes form better replicates, uptake of new RNAs incorporate new ribozymes, make protocell grow and divide faster
  • Protocells compete for resources and faster growing protocols are more competitive
36
Q

What is symbiosis?

A

Interaction between two different organisms, living in close physical association, advantages to both

37
Q

What is cellular endosymbiosis?

A

When a single cell organism lives in host cell

38
Q

What explains cellular complexity?

A

Endosymbiosis theory

39
Q

Who proposed the endosymbiosis theory?

A

Lynn Margulis

40
Q

Overall summary of endosymbiosis theory:

A

Three fundamental organelles: mitochondria, photosynthetic plastids, basal bodies of flagella
Mechanisms

41
Q

What is the mechanism proposed by endosymbiosis theory?

A

1) Phagocytosis of a prokaryote
2) Host cell and endosymbiont reproduce
3) Development of an interdependence

42
Q

What do mitochondria and chloroplast derive from?

A

Engulfed prokaryotes

43
Q

How is the eukaryotic cell established?

A
  • prokaryote
  • Infolding of membrane forms nucleus and endoplasmic reticulum
  • early eukaryote
  • Engulfing of heterotrophic prokaryote results in mitochondria (=fungi/ animal)
  • Engulfing of photosynthetic prokaryote results in chloroplasts (plant cells)
44
Q

What are the arguments that support endosymbiosis theory (chloroplasts and mitochondria derive from prokaryote)?

A
  • They have their own circular genome
  • Contain 70s ribosome
  • Chloroplast use tubulin-like FtsZ for division
  • Chloroplasts and cyanobacteria have thylakoid membrane
  • Both surrounded by double membrane
  • Bacteria and mitochondria share specific membrane lipid
  • Share organisation similarities
45
Q

Explain how the evidence they have their own circular genome support the endosymbiosis theory?

A

Genome of human mitochondria:
-16000 nucleotides encode for: 13 polypeptides, 22 tRNAs, 2 rRNAs
Genome of plant chloroplasts:
-70,000 to 200,000 nucleotides encode for: 120-130 polypeptides, 54 RNAs

46
Q

Explain how the evidence chloroplasts and cyanobacteria have thylakoid membranes support the endosymbiosis theory?

A
  • Contain chlorophyll

- Share cellulose as main component of the cell wall

47
Q

Explain how the evidence both surrounded by a double membrane support the endosymbiosis theory?

A

Derived from incomplete phagocytosis

48
Q

Explain how the evidence bacteria and mitochondria share a specific membrane lipid support the endosymbiosis theory?

A

Cardiolipin

20% of all lipids

49
Q

Explain how the evidence chloroplasts and mitochondria share organisation similarities support the endosymbiosis theory?

A
  • Inner and outer membrane
  • 70S ribosomes
  • Circular DNA
  • Import of nuclear proteins
  • Endogenous membranes that enlarge the surfaces
  • Not part of cellar endomembrane system
50
Q

What do unicellular marine alga Bigelowiella nations contain derived from establishment of a secondary endosymbiosis?

A

Plastids

51
Q

What is a nucleomorph?

A

DNA-containing relict of an engulfed eukaryote

52
Q

What are lichens a symbiosis of?

A

Fungi and uni-cellular algae

53
Q

Where are coral reefs found?

A

Only in clear shallow water

54
Q

What are corals a symbiosis of?

A

Algae and polyp

55
Q

What doe coral polyps and zooxanthellae form?

A

Mutualistic cellular endosymbiosis

BIO1339 - Cell (9 decks)

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