Assignment 1 Flashcards
(109 cards)
1
Q
What are the two kinds of cellular life forms on Earth?
A
Prokaryotes and eukaryotes
2
Q
What organelles evolved from bacteria by endosymbiosis?
A
Mitochondria and plastids
3
Q
What is the ancestral lineage of mitochondria according to evidence?
A
Alpha-proteobacterial ancestry
4
Q
What significant role did DNA sequencing play in eukaryotic cell evolution?
A
Solved early problems and framed modern views on endosymbiotic theory
5
Q
Who first introduced the terms ‘prokaryote’ and ‘eukaryote’?
A
Edouard Chatton
6
Q
What concept did the Russian botanist Constantin Mereschkowsky contribute to?
A
Symbiogenesis
7
Q
What does endosymbiosis refer to?
A
The bringing together of distinct cells, one inside the other
8
Q
What is the ‘eocyte hypothesis’?
A
A revival suggesting eukaryotes emerged from within archaea
9
Q
What did Lynn Margulis propose about the origin of eukaryotic cells?
A
Eukaryotic cells are the result of ancient symbioses
10
Q
What is the Serial Endosymbiosis Theory?
A
A theory that describes the evolutionary process of eukaryotic cells through endosymbiosis
11
Q
What were the two competing models for eukaryotic evolution framed by Max Taylor?
A
Autogenous and xenogenous models
12
Q
What is the traditional view of the origin of eukaryotic cells?
A
Eukaryotic cellular complexity arose prior to endosymbiotic uptake
13
Q
True or False: Mereschkowsky believed mitochondria evolved by endosymbiosis.
A
False
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
15
Q
Fill in the blank: The first explicit case for an endosymbiotic origin for plastids was proposed by _______.
A
Constantin Mereschkowsky
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
17
Q
What is one of the main questions regarding how eukaryotes evolved?
A
How, how often, and why endosymbiosis occurred
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
19
Q
What was the impact of the molecular biology revolution on endosymbiotic theory?
A
Provided tools to test and validate the theory
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.
21
Q
Who developed the RNA cataloguing technique that contributed to the endosymbiont hypothesis?
A
Carl Woese
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.
23
Q
What significant discovery was made about mitochondrial rRNA fragments in the 1970s?
A
They were shown to be demonstrably prokaryotic.
24
Q
What hypothesis did Margulis propose regarding eukaryotic flagella?
A
That they were of endosymbiotic origin.
25
What led to the acceptance of the endosymbiont hypothesis by the mid-1980s?
A wealth of biochemical and molecular biology evidence supporting endosymbiosis.
26
What are the two models for the evolution of eukaryotic cells discussed in the text?
Mitochondrion-late and mitochondrion-early scenarios.
27
What does the Archezoa hypothesis suggest?
It suggests that certain eukaryotes, termed Archezoa, evolved without mitochondria.
28
What are mitochondrion-related organelles (MROs)?
Organelles that evolved from mitochondria but do not resemble them, such as mitosomes and hydrogenosomes.
29
What was a major reason for the decline of the Archezoa hypothesis?
The realization that archezoan protists possess mitochondrion-related organelles.
30
What is the hydrogen hypothesis?
It posits that eukaryotic cells and mitochondria evolved together from a symbiotic relationship between an archaeon and a proteobacterium.
31
According to the hydrogen hypothesis, what was the role of the a-proteobacterium?
It produced hydrogen gas and carbon dioxide as waste, fueling the anaerobic metabolism of the archaeon.
32
What argument do Lane and Martin make regarding prokaryotic genome size?
They argue that prokaryotic genome size is constrained by bioenergetics, limiting complexity.
33
What are eukaryotic signature proteins (ESPs)?
Molecular hallmarks of eukaryotic cells that distinguish them from bacteria and archaea.
34
What are the TACK and DPANN taxa?
Groups of archaeal lineages that may provide insights into the evolution of eukaryotes.
35
What does the discovery of Lokiarchaeota suggest?
They may be the closest relatives of eukaryotes and possess many eukaryotic signature proteins.
36
What is a notable feature of Lokiarchaeota that may link them to eukaryotic evolution?
The presence of genes for small GTPases and components of the endosomal sorting complexes.
37
Fill in the blank: The mitochondrion-late scenario suggests that eukaryotes evolved _______ the origin of mitochondria.
before
38
True or False: The hydrogen hypothesis indicates that eukaryotes had an amitochondriate phase.
False
39
What is one of the main barriers to studying Lokiarchaeota?
The lack of cultured representatives.
40
What critical question remains open regarding the evolution from prokaryotes to eukaryotes?
How prokaryotes became eukaryotes and why eukaryotic complexity evolved only once.
41
What is the significance of mitochondrial enzymes for anaerobic energy metabolism in the context of the hydrogen hypothesis?
They should be of a-proteobacterial ancestry and related in evolutionary trees.
42
What is the significance of the Lokiarchaeota in understanding eukaryotic cell biology?
They provide insights into the prokaryote-to-eukaryote transition and are currently defined by genomes from metagenomic data.
## Footnote
The lack of cultured representatives of Lokiarchaeota hinders progress in research.
43
What is the origin of plastids in eukaryotic cells?
Plastids evolved from endosymbiotic cyanobacteria only once in the history of eukaryotic life.
## Footnote
This is a singular event, unlike mitochondria which also evolved once.
44
How does plastid evolution differ from that of mitochondria?
Plastid evolution involves both vertical inheritance and horizontal spread, while mitochondria evolved in a strictly vertical fashion.
## Footnote
This complexity in plastid evolution complicates understanding its acquisition.
45
What are the three eukaryotic lineages that share a common ancestor with primary plastids?
* Red algae
* Glaucophyte algae
* Green algae
## Footnote
Land plants emerged from within the green algae lineage.
46
What is the TIC–TOC complex?
A multi-subunit translocon used by all primary plastid-bearing organisms to direct nucleus-encoded proteins to the organelle.
## Footnote
This supports the idea of a singular origin of primary plastids.
47
What metabolic benefits did cyanobacterial endosymbionts provide to heterotrophic eukaryotes?
* Oxygenic photosynthesis
* Carbohydrates
* Nitrogen fixation
## Footnote
These benefits were crucial for the evolution of plastids.
48
What defines primary plastids?
They reside in the cytosol, surrounded by two membranes derived from cyanobacterial ancestry.
## Footnote
The peptidoglycan layer is retained in glaucophyte algae but lost in red and green algae.
49
What is secondary endosymbiosis?
The process where a primary plastid-bearing alga is ingested by a non-photosynthetic eukaryote, leading to multiple membrane layers.
## Footnote
This process has resulted in ecologically significant algal lineages like diatoms.
50
What are the characteristics of secondary plastids?
They have three or four membranes and reside within the lumen of the host’s endomembrane system.
## Footnote
This contrasts with primary plastids which are surrounded by two membranes.
51
What are nucleomorphs?
Remnants of the endosymbiont nucleus that persist in certain algae like cryptophytes and chlorarachniophytes.
## Footnote
They reside in the periplastidial compartment derived from the engulfed alga.
52
True or False: Plastids are often lost in organisms that evolve to become parasites.
True.
## Footnote
Examples include Cryptosporidium and Hematodinium, both of which are known to have lost their plastids.
53
What is the chromalveolate hypothesis?
It posits a single ancient capture of a red alga by an ancestor of chromist algae and alveolates, followed by multiple plastid losses.
## Footnote
This hypothesis has faced challenges but remains a subject of research.
54
Fill in the blank: The chromatophores of Paulinella chromatophora are considered to be _______.
[photosynthetic organelles]
## Footnote
They evolved from cyanobacteria and divide synchronously with their host.
55
How do spheroid bodies in diatoms differ from traditional plastids?
They are no longer photosynthetic and provide fixed nitrogen instead.
## Footnote
Their genomes are reduced and they are metabolically dependent on their diatom hosts.
56
What is a significant feature of the bacterial symbionts in sap-feeding insects?
They synthesize certain amino acids essential for their host's survival and have undergone extreme genome reduction.
## Footnote
Some insects have two symbionts that complement each other's minimal gene sets.
57
What is the impact of endosymbiotic theory on the understanding of eukaryotic evolution?
It has influenced the exploration of how various subcellular entities may have evolved through endosymbiotic relationships.
## Footnote
This includes components like the flagellum, peroxisome, and nucleus.
58
What are mitochondria and plastids thought to be the result of?
Endosymbiotic origin
## Footnote
This theory suggests that these organelles originated from free-living bacteria that were engulfed by ancestral eukaryotic cells.
59
Which other membranebound or membrane-associated components of eukaryotic cells are suggested to have an endosymbiotic origin?
* Flagellum
* Peroxisome
* Endoplasmic reticulum (ER)
* Nucleus
## Footnote
These components have been proposed to have origins similar to mitochondria and plastids.
60
What did de Duve propose about the origin of peroxisomes?
Evolved from an ancient bacterial endosymbiont that lost its genome
## Footnote
This proposal suggests peroxisomes developed differently than mitochondria and plastids.
61
What is the current consensus about the origin of peroxisomes?
Derivations of the endoplasmic reticulum (ER)
## Footnote
Current data on protein import and organelle biogenesis support this notion.
62
Who first proposed the concept of the nucleus as an endosymbiont?
Mereschkowsky in the early 1900s
## Footnote
This idea has evolved over time and has seen various modern interpretations.
63
What challenge do hypotheses regarding the nucleus as an endosymbiont face?
Lack of cell biological realism
## Footnote
Many hypotheses ignore the continuous nature of the nuclear envelope and lack supporting genome sequence data.
64
What is one proposed reason for the evolution of the nucleus?
Invasion of mobile genetic elements, specifically group II introns
## Footnote
This migration from the bacterial ancestor of mitochondria to the archaeal host cell is suggested to have influenced nuclear evolution.
65
What is the typical thought regarding the origin of the nuclear envelope?
Stemmed from invaginations of a prokaryotic host cell’s plasma membrane
## Footnote
Over time, these invaginations became differentiated and connected to the cytoskeleton.
66
What alternative hypothesis was suggested regarding the evolution of eukaryotes?
Eukaryotes evolved from a prokaryotic cell with a single bounding membrane
## Footnote
This hypothesis suggests the cell extended extracellular protrusions that fused to form the cytoplasm.
67
Is there convincing evidence that endosymbiosis played a role in the origin of cytosolic compartments other than mitochondria and plastids?
No convincing evidence supports this notion
## Footnote
Current understanding suggests further exploration of autogenous origins is needed.
68
What is the implication of the rapid spread of introns following the origin of mitochondria?
It may have created selective pressure that led to nucleus-cytosol compartmentalization
## Footnote
This suggests a physical separation of transcription from translation was necessary.
69
What is the main challenge in current research on the evolution of eukaryotic cells?
Formulating testable hypotheses for the autogenous origin of compartments
## Footnote
These hypotheses must align with modern cell biology and genome evolution.
70
What perspectives should researchers consider in studying cell evolution?
Looking back at historical research while applying modern data
## Footnote
This dual perspective can enhance understanding of cell biology problems.
71
What is the main focus of the article by Embley and Martin (2006)?
Eukaryotic evolution, changes and challenges
## Footnote
Discusses the evolutionary history and the challenges faced by eukaryotic organisms.
72
What does Koonin (2010) address in his work?
The origin and early evolution of eukaryotes in the light of phylogenomics
## Footnote
Explores phylogenomic evidence regarding eukaryotic origins.
73
What theory does Martin, Garg, and Zimorski (2015) discuss?
Endosymbiotic theories for eukaryote origin
## Footnote
Examines various endosymbiotic models explaining how eukaryotes originated.
74
What classification system did Cavalier-Smith propose in 1983?
A 6-kingdom classification and a unified phylogeny
## Footnote
A system that categorizes life into six kingdoms and aims for a cohesive evolutionary framework.
75
True or False: Microsporidia are unrelated to Fungi.
False
## Footnote
Evidence suggests a relationship between Microsporidia and Fungi based on RNA polymerase II.
76
What significant discovery did Hirt et al. (1999) make?
Microsporidia are related to Fungi
## Footnote
Found evidence linking Microsporidia to the Fungi kingdom through protein analysis.
77
What hypothesis did Martin and Muller (1998) propose?
The hydrogen hypothesis for the first eukaryote
## Footnote
Suggests that the first eukaryotic cells evolved in a hydrogen-rich environment.
78
What role did horizontal gene transfer play according to Husnik et al. (2013)?
Enabled a tripartite nested mealybug symbiosis
## Footnote
Illustrates how gene transfer from bacteria to an insect genome facilitated complex symbiotic relationships.
79
Fill in the blank: The _______ hypothesis suggests that plastids originated through secondary endosymbiosis.
[secondary endosymbiotic]
## Footnote
This hypothesis posits that plastids in some eukaryotes originated from the engulfment of other photosynthetic eukaryotes.
80
What did Philippe et al. (2000) investigate regarding eukaryotes?
Early-branching or fast-evolving eukaryotes?
## Footnote
A study analyzing the evolutionary relationships and rates of divergence among early eukaryotes.
81
What is the significance of the research by Leger et al. (2013)?
Evidence for a hydrogenosomal-type anaerobic ATP generation pathway in Acanthamoeba castellanii
## Footnote
This research highlights alternative energy metabolism pathways in eukaryotes.
82
What does the term 'phylogenomic' refer to?
The study of evolutionary relationships using genomic data
## Footnote
Utilizes genomic information to trace the evolutionary history and relationships between organisms.
83
What does the concept of 'primary endosymbiosis' entail?
The initial engulfment of a prokaryotic cell by a eukaryotic ancestor
## Footnote
Refers to the process that led to the formation of organelles like mitochondria and plastids.
84
What is the main contribution of Stiller et al. (2014) regarding photosynthesis?
The evolution of photosynthesis in chromist algae through serial endosymbioses
## Footnote
Discusses how multiple endosymbiotic events contributed to the diversity of photosynthetic mechanisms.
85
What are hydrogenosomes?
Organelles that generate ATP anaerobically in certain eukaryotic cells
## Footnote
Similar to mitochondria but adapted to environments lacking oxygen.
86
What is the significance of the article by Eme and Doolittle (2015)?
Discusses microbial diversity and its implications
## Footnote
Highlights the vast diversity of microbial life and the evolutionary significance of various phyla.
87
What does the term 'lateral gene transfer' refer to?
The transfer of genes between organisms in a manner other than traditional reproduction
## Footnote
A key mechanism in microbial evolution that contributes to genetic diversity.
88
What is the focus of the research by Spang et al. (2015)?
Complex archaea that bridge the gap between prokaryotes and eukaryotes
## Footnote
Investigates the evolutionary intermediates that illustrate the transition from prokaryotic to eukaryotic life.
89
What did the research by Deschamps (2014) propose regarding cyanobacteria?
Questions whether cyanobacteria and Chlamydiae ever coexisted in endosymbiosis
## Footnote
Explores the evolutionary relationship and potential interactions between these two groups.
90
What is the main focus of the study by Baurain et al. (2010)?
Phylogenomic evidence for separate acquisition of plastids in cryptophytes, haptophytes, and stramenopiles
## Footnote
This study highlights the evolutionary history of plastids in various algal lineages.
91
What are tertiary plastid endosymbioses?
Endosymbiotic events involving the acquisition of plastids by dinoflagellates
## Footnote
This concept is explored in Gaget et al. (2014).
92
What is the apicoplast?
A specialized organelle found in apicomplexan parasites
## Footnote
It is involved in unique metabolic pathways as discussed by Seeber and Soldati-Favre (2010).
93
Which organism's complete genome was sequenced in Abrahamsen et al. (2004)?
Cryptosporidium parvum
## Footnote
This research provided insight into the genetics of this important apicomplexan parasite.
94
What does phylogenomic evidence support regarding Cryptosporidium parvum?
Past endosymbiosis, intracellular and horizontal gene transfer
## Footnote
This evidence was presented in Huang et al. (2004).
95
What does the study by Gornik et al. (2015) reveal about parasitic dinoflagellates?
Endosymbiosis can be undone by stepwise elimination of the plastid
## Footnote
This study emphasizes the dynamic nature of endosymbiotic relationships.
96
What significant event does Archibald (2015) discuss?
The birth and spread of plastids from a genomic perspective
## Footnote
This work provides a comprehensive overview of plastid evolution.
97
What is the focus of the study by Ku et al. (2015)?
Endosymbiotic gene transfer from prokaryotic pangenomes
## Footnote
It discusses inherited chimerism in eukaryotes.
98
What is the significance of Stiller's (2011) work?
Experimental design and statistical rigor in phylogenomics of gene transfer
## Footnote
This paper emphasizes the importance of methodological rigor in evolutionary studies.
99
Who was Robert Lauterborn and what was his contribution?
A biologist who studied Paulinella chromatophora and its endosymbiotic relationships
## Footnote
His work is discussed by Melkonian and Mollenhauer (2005).
100
What does Nowack (2014) discuss regarding Paulinella chromatophora?
The transition from endosymbiont to organelle
## Footnote
This study rethinks traditional views on endosymbiosis.
101
What is the difference between organelles and endosymbionts according to Theissen and Martin (2006)?
Organelles are integrated structures within cells, while endosymbionts are independent entities
## Footnote
This distinction is crucial for understanding cellular evolution.
102
Fill in the blank: The cyanobacterial endosymbiont of the unicellular algae Rhopalodia gibba shows _______.
reductive genome evolution
## Footnote
This concept is explored by Kneip et al. (2008).
103
What did Nakayama et al. (2014) reveal about a nonphotosynthetic cyanobacterium?
It has adapted to an intracellular lifestyle
## Footnote
This was discovered through the complete genome analysis of the cyanobacterium.
104
What is the topic of Moran and Bennett's (2014) research?
The origins and evolution of tiny genomes in symbiotic relationships
## Footnote
Their work discusses the implications of genome size in symbiotic organisms.
105
True or False: McCutcheon and Keeling (2014) argue that protein targeting erodes the distinction between organelles and symbionts.
True
## Footnote
This paper discusses how protein targeting complicates the classification of cellular structures.
106
What is the significance of de Duve's (1982) work on peroxisomes?
It provides a historical perspective on peroxisome evolution
## Footnote
This work is foundational in understanding organelle origins.
107
What concept does Cavalier-Smith (2010) explore?
The origin of the cell nucleus, mitosis, and sex as roles of intracellular coevolution
## Footnote
This perspective is critical for understanding eukaryotic evolution.
108
What does Rogozin et al. (2012) discuss in their study?
The origin and evolution of spliceosomal introns
## Footnote
This research contributes to the understanding of genetic complexity in eukaryotes.
109
Fill in the blank: The study by Baum and Baum (2014) proposes an _______ origin for the eukaryotic cell.
inside-out
## Footnote
This concept challenges traditional views on eukaryotic cell evolution.
