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BIO 101 > Assignment 1 > Flashcards

Assignment 1 Flashcards

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1
Q

What are the two kinds of cellular life forms on Earth?

A

Prokaryotes and eukaryotes

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2
Q

What organelles evolved from bacteria by endosymbiosis?

A

Mitochondria and plastids

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3
Q

What is the ancestral lineage of mitochondria according to evidence?

A

Alpha-proteobacterial ancestry

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4
Q

What significant role did DNA sequencing play in eukaryotic cell evolution?

A

Solved early problems and framed modern views on endosymbiotic theory

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5
Q

Who first introduced the terms ‘prokaryote’ and ‘eukaryote’?

A

Edouard Chatton

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6
Q

What concept did the Russian botanist Constantin Mereschkowsky contribute to?

A

Symbiogenesis

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7
Q

What does endosymbiosis refer to?

A

The bringing together of distinct cells, one inside the other

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8
Q

What is the ‘eocyte hypothesis’?

A

A revival suggesting eukaryotes emerged from within archaea

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9
Q

What did Lynn Margulis propose about the origin of eukaryotic cells?

A

Eukaryotic cells are the result of ancient symbioses

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10
Q

What is the Serial Endosymbiosis Theory?

A

A theory that describes the evolutionary process of eukaryotic cells through endosymbiosis

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11
Q

What were the two competing models for eukaryotic evolution framed by Max Taylor?

A

Autogenous and xenogenous models

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12
Q

What is the traditional view of the origin of eukaryotic cells?

A

Eukaryotic cellular complexity arose prior to endosymbiotic uptake

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13
Q

True or False: Mereschkowsky believed mitochondria evolved by endosymbiosis.

A

False

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14
Q

What was the significance of the work by Carl Woese in the 1970s?

A

Led to the discovery of archaea and provided early nucleic acid sequences for endosymbiont hypothesis

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15
Q

Fill in the blank: The first explicit case for an endosymbiotic origin for plastids was proposed by _______.

A

Constantin Mereschkowsky

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16
Q

What did the phylogenetic analyses suggest about the relationship between archaea and eukaryotes?

A

Archaea and eukaryotes share a more recent common ancestor than either does with bacteria

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17
Q

What is one of the main questions regarding how eukaryotes evolved?

A

How, how often, and why endosymbiosis occurred

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18
Q

What was a common belief among those who opposed endosymbiotic models for organelle evolution?

A

That eukaryotic cells evolved directly from advanced prokaryotic cells

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19
Q

What was the impact of the molecular biology revolution on endosymbiotic theory?

A

Provided tools to test and validate the theory

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20
Q

What is the endosymbiont hypothesis?

A

It posits that mitochondria and plastids originated from free-living prokaryotes that entered into a symbiotic relationship with ancestral eukaryotic cells.

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21
Q

Who developed the RNA cataloguing technique that contributed to the endosymbiont hypothesis?

A

Carl Woese

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22
Q

What did the early studies of rRNA sequences reveal about algal plastids and cyanobacteria?

A

They demonstrated a strong evolutionary link between them.

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23
Q

What significant discovery was made about mitochondrial rRNA fragments in the 1970s?

A

They were shown to be demonstrably prokaryotic.

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24
Q

What hypothesis did Margulis propose regarding eukaryotic flagella?

A

That they were of endosymbiotic origin.

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25
Q

What led to the acceptance of the endosymbiont hypothesis by the mid-1980s?

A

A wealth of biochemical and molecular biology evidence supporting endosymbiosis.

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26
Q

What are the two models for the evolution of eukaryotic cells discussed in the text?

A

Mitochondrion-late and mitochondrion-early scenarios.

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27
Q

What does the Archezoa hypothesis suggest?

A

It suggests that certain eukaryotes, termed Archezoa, evolved without mitochondria.

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28
Q

What are mitochondrion-related organelles (MROs)?

A

Organelles that evolved from mitochondria but do not resemble them, such as mitosomes and hydrogenosomes.

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29
Q

What was a major reason for the decline of the Archezoa hypothesis?

A

The realization that archezoan protists possess mitochondrion-related organelles.

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30
Q

What is the hydrogen hypothesis?

A

It posits that eukaryotic cells and mitochondria evolved together from a symbiotic relationship between an archaeon and a proteobacterium.

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31
Q

According to the hydrogen hypothesis, what was the role of the a-proteobacterium?

A

It produced hydrogen gas and carbon dioxide as waste, fueling the anaerobic metabolism of the archaeon.

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32
Q

What argument do Lane and Martin make regarding prokaryotic genome size?

A

They argue that prokaryotic genome size is constrained by bioenergetics, limiting complexity.

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33
Q

What are eukaryotic signature proteins (ESPs)?

A

Molecular hallmarks of eukaryotic cells that distinguish them from bacteria and archaea.

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34
Q

What are the TACK and DPANN taxa?

A

Groups of archaeal lineages that may provide insights into the evolution of eukaryotes.

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35
Q

What does the discovery of Lokiarchaeota suggest?

A

They may be the closest relatives of eukaryotes and possess many eukaryotic signature proteins.

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36
Q

What is a notable feature of Lokiarchaeota that may link them to eukaryotic evolution?

A

The presence of genes for small GTPases and components of the endosomal sorting complexes.

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37
Q

Fill in the blank: The mitochondrion-late scenario suggests that eukaryotes evolved _______ the origin of mitochondria.

A

before

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38
Q

True or False: The hydrogen hypothesis indicates that eukaryotes had an amitochondriate phase.

A

False

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39
Q

What is one of the main barriers to studying Lokiarchaeota?

A

The lack of cultured representatives.

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40
Q

What critical question remains open regarding the evolution from prokaryotes to eukaryotes?

A

How prokaryotes became eukaryotes and why eukaryotic complexity evolved only once.

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41
Q

What is the significance of mitochondrial enzymes for anaerobic energy metabolism in the context of the hydrogen hypothesis?

A

They should be of a-proteobacterial ancestry and related in evolutionary trees.

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42
Q

What is the significance of the Lokiarchaeota in understanding eukaryotic cell biology?

A

They provide insights into the prokaryote-to-eukaryote transition and are currently defined by genomes from metagenomic data.

The lack of cultured representatives of Lokiarchaeota hinders progress in research.

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43
Q

What is the origin of plastids in eukaryotic cells?

A

Plastids evolved from endosymbiotic cyanobacteria only once in the history of eukaryotic life.

This is a singular event, unlike mitochondria which also evolved once.

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44
Q

How does plastid evolution differ from that of mitochondria?

A

Plastid evolution involves both vertical inheritance and horizontal spread, while mitochondria evolved in a strictly vertical fashion.

This complexity in plastid evolution complicates understanding its acquisition.

45
Q

What are the three eukaryotic lineages that share a common ancestor with primary plastids?

A
  • Red algae
  • Glaucophyte algae
  • Green algae

Land plants emerged from within the green algae lineage.

46
Q

What is the TIC–TOC complex?

A

A multi-subunit translocon used by all primary plastid-bearing organisms to direct nucleus-encoded proteins to the organelle.

This supports the idea of a singular origin of primary plastids.

47
Q

What metabolic benefits did cyanobacterial endosymbionts provide to heterotrophic eukaryotes?

A
  • Oxygenic photosynthesis
  • Carbohydrates
  • Nitrogen fixation

These benefits were crucial for the evolution of plastids.

48
Q

What defines primary plastids?

A

They reside in the cytosol, surrounded by two membranes derived from cyanobacterial ancestry.

The peptidoglycan layer is retained in glaucophyte algae but lost in red and green algae.

49
Q

What is secondary endosymbiosis?

A

The process where a primary plastid-bearing alga is ingested by a non-photosynthetic eukaryote, leading to multiple membrane layers.

This process has resulted in ecologically significant algal lineages like diatoms.

50
Q

What are the characteristics of secondary plastids?

A

They have three or four membranes and reside within the lumen of the host’s endomembrane system.

This contrasts with primary plastids which are surrounded by two membranes.

51
Q

What are nucleomorphs?

A

Remnants of the endosymbiont nucleus that persist in certain algae like cryptophytes and chlorarachniophytes.

They reside in the periplastidial compartment derived from the engulfed alga.

52
Q

True or False: Plastids are often lost in organisms that evolve to become parasites.

A

True.

Examples include Cryptosporidium and Hematodinium, both of which are known to have lost their plastids.

53
Q

What is the chromalveolate hypothesis?

A

It posits a single ancient capture of a red alga by an ancestor of chromist algae and alveolates, followed by multiple plastid losses.

This hypothesis has faced challenges but remains a subject of research.

54
Q

Fill in the blank: The chromatophores of Paulinella chromatophora are considered to be _______.

A

[photosynthetic organelles]

They evolved from cyanobacteria and divide synchronously with their host.

55
Q

How do spheroid bodies in diatoms differ from traditional plastids?

A

They are no longer photosynthetic and provide fixed nitrogen instead.

Their genomes are reduced and they are metabolically dependent on their diatom hosts.

56
Q

What is a significant feature of the bacterial symbionts in sap-feeding insects?

A

They synthesize certain amino acids essential for their host’s survival and have undergone extreme genome reduction.

Some insects have two symbionts that complement each other’s minimal gene sets.

57
Q

What is the impact of endosymbiotic theory on the understanding of eukaryotic evolution?

A

It has influenced the exploration of how various subcellular entities may have evolved through endosymbiotic relationships.

This includes components like the flagellum, peroxisome, and nucleus.

58
Q

What are mitochondria and plastids thought to be the result of?

A

Endosymbiotic origin

This theory suggests that these organelles originated from free-living bacteria that were engulfed by ancestral eukaryotic cells.

59
Q

Which other membranebound or membrane-associated components of eukaryotic cells are suggested to have an endosymbiotic origin?

A
  • Flagellum
  • Peroxisome
  • Endoplasmic reticulum (ER)
  • Nucleus

These components have been proposed to have origins similar to mitochondria and plastids.

60
Q

What did de Duve propose about the origin of peroxisomes?

A

Evolved from an ancient bacterial endosymbiont that lost its genome

This proposal suggests peroxisomes developed differently than mitochondria and plastids.

61
Q

What is the current consensus about the origin of peroxisomes?

A

Derivations of the endoplasmic reticulum (ER)

Current data on protein import and organelle biogenesis support this notion.

62
Q

Who first proposed the concept of the nucleus as an endosymbiont?

A

Mereschkowsky in the early 1900s

This idea has evolved over time and has seen various modern interpretations.

63
Q

What challenge do hypotheses regarding the nucleus as an endosymbiont face?

A

Lack of cell biological realism

Many hypotheses ignore the continuous nature of the nuclear envelope and lack supporting genome sequence data.

64
Q

What is one proposed reason for the evolution of the nucleus?

A

Invasion of mobile genetic elements, specifically group II introns

This migration from the bacterial ancestor of mitochondria to the archaeal host cell is suggested to have influenced nuclear evolution.

65
Q

What is the typical thought regarding the origin of the nuclear envelope?

A

Stemmed from invaginations of a prokaryotic host cell’s plasma membrane

Over time, these invaginations became differentiated and connected to the cytoskeleton.

66
Q

What alternative hypothesis was suggested regarding the evolution of eukaryotes?

A

Eukaryotes evolved from a prokaryotic cell with a single bounding membrane

This hypothesis suggests the cell extended extracellular protrusions that fused to form the cytoplasm.

67
Q

Is there convincing evidence that endosymbiosis played a role in the origin of cytosolic compartments other than mitochondria and plastids?

A

No convincing evidence supports this notion

Current understanding suggests further exploration of autogenous origins is needed.

68
Q

What is the implication of the rapid spread of introns following the origin of mitochondria?

A

It may have created selective pressure that led to nucleus-cytosol compartmentalization

This suggests a physical separation of transcription from translation was necessary.

69
Q

What is the main challenge in current research on the evolution of eukaryotic cells?

A

Formulating testable hypotheses for the autogenous origin of compartments

These hypotheses must align with modern cell biology and genome evolution.

70
Q

What perspectives should researchers consider in studying cell evolution?

A

Looking back at historical research while applying modern data

This dual perspective can enhance understanding of cell biology problems.

71
Q

What is the main focus of the article by Embley and Martin (2006)?

A

Eukaryotic evolution, changes and challenges

Discusses the evolutionary history and the challenges faced by eukaryotic organisms.

72
Q

What does Koonin (2010) address in his work?

A

The origin and early evolution of eukaryotes in the light of phylogenomics

Explores phylogenomic evidence regarding eukaryotic origins.

73
Q

What theory does Martin, Garg, and Zimorski (2015) discuss?

A

Endosymbiotic theories for eukaryote origin

Examines various endosymbiotic models explaining how eukaryotes originated.

74
Q

What classification system did Cavalier-Smith propose in 1983?

A

A 6-kingdom classification and a unified phylogeny

A system that categorizes life into six kingdoms and aims for a cohesive evolutionary framework.

75
Q

True or False: Microsporidia are unrelated to Fungi.

A

False

Evidence suggests a relationship between Microsporidia and Fungi based on RNA polymerase II.

76
Q

What significant discovery did Hirt et al. (1999) make?

A

Microsporidia are related to Fungi

Found evidence linking Microsporidia to the Fungi kingdom through protein analysis.

77
Q

What hypothesis did Martin and Muller (1998) propose?

A

The hydrogen hypothesis for the first eukaryote

Suggests that the first eukaryotic cells evolved in a hydrogen-rich environment.

78
Q

What role did horizontal gene transfer play according to Husnik et al. (2013)?

A

Enabled a tripartite nested mealybug symbiosis

Illustrates how gene transfer from bacteria to an insect genome facilitated complex symbiotic relationships.

79
Q

Fill in the blank: The _______ hypothesis suggests that plastids originated through secondary endosymbiosis.

A

[secondary endosymbiotic]

This hypothesis posits that plastids in some eukaryotes originated from the engulfment of other photosynthetic eukaryotes.

80
Q

What did Philippe et al. (2000) investigate regarding eukaryotes?

A

Early-branching or fast-evolving eukaryotes?

A study analyzing the evolutionary relationships and rates of divergence among early eukaryotes.

81
Q

What is the significance of the research by Leger et al. (2013)?

A

Evidence for a hydrogenosomal-type anaerobic ATP generation pathway in Acanthamoeba castellanii

This research highlights alternative energy metabolism pathways in eukaryotes.

82
Q

What does the term ‘phylogenomic’ refer to?

A

The study of evolutionary relationships using genomic data

Utilizes genomic information to trace the evolutionary history and relationships between organisms.

83
Q

What does the concept of ‘primary endosymbiosis’ entail?

A

The initial engulfment of a prokaryotic cell by a eukaryotic ancestor

Refers to the process that led to the formation of organelles like mitochondria and plastids.

84
Q

What is the main contribution of Stiller et al. (2014) regarding photosynthesis?

A

The evolution of photosynthesis in chromist algae through serial endosymbioses

Discusses how multiple endosymbiotic events contributed to the diversity of photosynthetic mechanisms.

85
Q

What are hydrogenosomes?

A

Organelles that generate ATP anaerobically in certain eukaryotic cells

Similar to mitochondria but adapted to environments lacking oxygen.

86
Q

What is the significance of the article by Eme and Doolittle (2015)?

A

Discusses microbial diversity and its implications

Highlights the vast diversity of microbial life and the evolutionary significance of various phyla.

87
Q

What does the term ‘lateral gene transfer’ refer to?

A

The transfer of genes between organisms in a manner other than traditional reproduction

A key mechanism in microbial evolution that contributes to genetic diversity.

88
Q

What is the focus of the research by Spang et al. (2015)?

A

Complex archaea that bridge the gap between prokaryotes and eukaryotes

Investigates the evolutionary intermediates that illustrate the transition from prokaryotic to eukaryotic life.

89
Q

What did the research by Deschamps (2014) propose regarding cyanobacteria?

A

Questions whether cyanobacteria and Chlamydiae ever coexisted in endosymbiosis

Explores the evolutionary relationship and potential interactions between these two groups.

90
Q

What is the main focus of the study by Baurain et al. (2010)?

A

Phylogenomic evidence for separate acquisition of plastids in cryptophytes, haptophytes, and stramenopiles

This study highlights the evolutionary history of plastids in various algal lineages.

91
Q

What are tertiary plastid endosymbioses?

A

Endosymbiotic events involving the acquisition of plastids by dinoflagellates

This concept is explored in Gaget et al. (2014).

92
Q

What is the apicoplast?

A

A specialized organelle found in apicomplexan parasites

It is involved in unique metabolic pathways as discussed by Seeber and Soldati-Favre (2010).

93
Q

Which organism’s complete genome was sequenced in Abrahamsen et al. (2004)?

A

Cryptosporidium parvum

This research provided insight into the genetics of this important apicomplexan parasite.

94
Q

What does phylogenomic evidence support regarding Cryptosporidium parvum?

A

Past endosymbiosis, intracellular and horizontal gene transfer

This evidence was presented in Huang et al. (2004).

95
Q

What does the study by Gornik et al. (2015) reveal about parasitic dinoflagellates?

A

Endosymbiosis can be undone by stepwise elimination of the plastid

This study emphasizes the dynamic nature of endosymbiotic relationships.

96
Q

What significant event does Archibald (2015) discuss?

A

The birth and spread of plastids from a genomic perspective

This work provides a comprehensive overview of plastid evolution.

97
Q

What is the focus of the study by Ku et al. (2015)?

A

Endosymbiotic gene transfer from prokaryotic pangenomes

It discusses inherited chimerism in eukaryotes.

98
Q

What is the significance of Stiller’s (2011) work?

A

Experimental design and statistical rigor in phylogenomics of gene transfer

This paper emphasizes the importance of methodological rigor in evolutionary studies.

99
Q

Who was Robert Lauterborn and what was his contribution?

A

A biologist who studied Paulinella chromatophora and its endosymbiotic relationships

His work is discussed by Melkonian and Mollenhauer (2005).

100
Q

What does Nowack (2014) discuss regarding Paulinella chromatophora?

A

The transition from endosymbiont to organelle

This study rethinks traditional views on endosymbiosis.

101
Q

What is the difference between organelles and endosymbionts according to Theissen and Martin (2006)?

A

Organelles are integrated structures within cells, while endosymbionts are independent entities

This distinction is crucial for understanding cellular evolution.

102
Q

Fill in the blank: The cyanobacterial endosymbiont of the unicellular algae Rhopalodia gibba shows _______.

A

reductive genome evolution

This concept is explored by Kneip et al. (2008).

103
Q

What did Nakayama et al. (2014) reveal about a nonphotosynthetic cyanobacterium?

A

It has adapted to an intracellular lifestyle

This was discovered through the complete genome analysis of the cyanobacterium.

104
Q

What is the topic of Moran and Bennett’s (2014) research?

A

The origins and evolution of tiny genomes in symbiotic relationships

Their work discusses the implications of genome size in symbiotic organisms.

105
Q

True or False: McCutcheon and Keeling (2014) argue that protein targeting erodes the distinction between organelles and symbionts.

A

True

This paper discusses how protein targeting complicates the classification of cellular structures.

106
Q

What is the significance of de Duve’s (1982) work on peroxisomes?

A

It provides a historical perspective on peroxisome evolution

This work is foundational in understanding organelle origins.

107
Q

What concept does Cavalier-Smith (2010) explore?

A

The origin of the cell nucleus, mitosis, and sex as roles of intracellular coevolution

This perspective is critical for understanding eukaryotic evolution.

108
Q

What does Rogozin et al. (2012) discuss in their study?

A

The origin and evolution of spliceosomal introns

This research contributes to the understanding of genetic complexity in eukaryotes.

109
Q

Fill in the blank: The study by Baum and Baum (2014) proposes an _______ origin for the eukaryotic cell.

A

inside-out

This concept challenges traditional views on eukaryotic cell evolution.

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