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Life on Earth > origin and evolution of eukaryotes > Flashcards

origin and evolution of eukaryotes Flashcards

1
Q

bacteria species examples

A

proteobacteria
gram positive
cyanobacteria
cytophaga

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2
Q

archaea species examples

A

methanobacterium
thermoproceus
methanoccoules

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3
Q

eukaryota species examples

A 
fungi 
plants
cilliates
slime molds
trichomonodas
microspondia
diplomondiads
flagalletes
animals
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4
Q

leca

A

last eucaryatic common ancestor
(limited genen sampling makes it hard to be accruatee)
was a complex cell with numerous organelles and 300 new gene families

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5
Q

luca

A

last universal common ancestor

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6
Q

bacteria

A

70 s ribosomes
binary fission
unicellular
circular dna
arose 4 bya
explore many chemical different environments (acidic, heat fluctuating, massive population)
large genetic variation (feeding and respiraiton methods)

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7
Q

archea

A

morphologically simlar to bacteria

biochemically and genetically different

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8
Q

eukarya

A 
80-90 rivosomves
membrane bound organelles
can be multicellular
histones
mitosis and mesiosis
cytoskeleon
explore MORPHOLOGICAL space;
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9
Q

euglena

A

complex bacteria that was LECA

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10
Q

compare bacteria and human cell

A

paramecium has 40,000 genes

x2 of the pancreastic acinar cell

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11
Q

origin of eukaryote theories

A
  1. endosymbiosis
  2. autogeneous evolution
  3. hydrogen hypothesis
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12
Q

prokaryotes and respiration

A

compartementalize
respire oxygen
resporotray complexes are main source of oxygen
gram per gram prokaryotes respire faster than one cell eukaryote

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13
Q

what dont prokaryotes do

A

compartmentalize organelles
anerobic esporation
protection against oxygen toxiticity
increase speed of respiration

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14
Q

eukaryote energy per gene

A

1 cell of eukaryotes consume more oxygen per minute than a prokaryote, hence have a larger metabolic rate

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15
Q

endosymbiotic hypothesis

A

proposed by lynn margulis [also knowsn as SET]

multiple different endosymbiotic events gave rise to eukaryotes with multiple different endosymbioints such as

  1. mitochondria
  2. chlorplasts (from cyanobacteria)

false: cytokeleton and flagella didnt.

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16
Q

endysymbiosis hypothesis evidence

A 
mitochondria/chlorplasta and bacteria have similar: 
circular dna
ribosome size
binar fishion
structures
dna processing
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17
Q

autogenous evolution theory

A

Tom Cavalier Smith: gradual evolution of unicellular cells into eukaryotes

  • eukaryotes evolved autogenously by the loss of the cell wall driven by the evolution of phagotrophy
  • mitchondria acquiisiton was LATE and qualitively unimportant
  • mitchondria and chrloplasts evolved in compartmentalized plasmids in vesciles in plasama mebmrane; nucelus and cytosplasm formed by evolution
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18
Q

hydrogen hypothesis

A

bill martin; ‘non parasitic theory’

a singular endoysymbiotic event of 2 bacterial cells;
all eukaryotic traits evolved after the two prokaryotes merged

existence oef the ‘primitive phagocyte’ not true; only a host archeaon however

(hydrogen dependent archea bacteriam + methanogen eubacteriera—> eukaryote)

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19
Q

problems with SET

A

not always consistent

aerobic, heterotrophic prokaryotes enguledb y other cells by endocytosis; provided oxygen utliiation to anerobic host cells to source in oxygen environment and AID in ATP production

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20
Q

phagotrophy

A

invaginations of prokaryotes leading to compartmentalized functions

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21
Q

where can the AET be valid

A

origins of endoplasmic resticulum,
golgi apparatus
nucleur membrane
lysosomes

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22
Q

paradox of autogenous evolution

A

all complex life is eukaryotic; and it only arose once in 4 billion years

  • all eukaryotes share universal traits
  • prokaryotes show no tendency to evoleve into morpholoical complexity with any of these traits

therefore: if each of these traits evolved step by strep and each step has a selective advantage, why did none evolve in prokaryotes? (aka intermediates dont exist)

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23
Q

congruent evolution example

A

eyes; humans and octopus eyes are similar but evovled different

morphologically indepedent but SAME genes in common that create them

this is becasue SIGHT is an advantage

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24
Q

eukaryotic super groups

A

5-6; unicellular groups have most genetic diveristy; branch lengths seperating groups much shorter than bacteria within groups

suggests a ‘big bang’ after LECA

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25
Q

SAR

A

stramenophiles
alveolata
rhizaria

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26
Q

what is the black hole in biology

A

all eukaryotes share traits absent from prokaryotes

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27
Q

what traits do ONLY eukaryotes have

A

larger geneomes and cell volumes
dynamic cytoskeleton, motor proteins, flagella and cillia
nucleus, nucleur membrane, pore complexes, nuclelous and straight chromosomes
rericporcal sex, mitotisis and tubilin spindle
phagocytosis
seperation of transcription and translation
endomembrane systems like mitrochondria

‘big bang’ after all these traits evolved in leca

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28
Q

why do only eukaryotes have specific traits

A

selective bottle neck; great oxydation event 2.2. billion years ago;
only the best preadapted groups made it rhough this ‘selecive bottle neck’
- this fixed niches and led to fast evolution and explosive radiation into new forms

29
Q

predictions of selective obottle neck

A

events such as snowball earth, oxygen, ocean temperature and anodic ocean stratificiation

  • if selective; environmental contraits and biolgoically easy organisms should have been a polyphyletic radiation
30
Q

polyphetic radiation

A

different bacteria groups SHOUDL have also given rise to complex life indepenently; traits lack common ancestor

31
Q

paraphyletic radiation

A

semi dependent traits

32
Q

monophyletic radiation

A

clade formation; traits of descenends all have same ancestry

33
Q

leca big bang?

A

intense genetic diversity and short branch lengths

all eukaryotic genes can be traced back to it unlike prokaryotic and archaeic genes

34
Q

what are the eukaryotic supergroups

A

metazoa

ophisthokonta

amoebozoa

excavata

SAR

archae plastidida

35
Q

environmental bottle neck

A

polyphyletic

different lifestyles led to changes

36
Q

serial bottle neck

A

diverse endosymbiosis in different envrionemnts

37
Q

restrictive bottle neck

A

rare change in cell to structure or pylogeny;
if bottle neck were restrictive due to biological contsraints;
what about bacterials trucutred prevented evolution into higher complexity?

leca; had mitochondria= supports mitcohondria acquissiton and eukarotic origin in SAME event

38
Q

eukaryotes and competititors?

A

forms arising later must have been outcompeted to extinction by fully evolved eukaryotes;

if true there were no ecological and evolutionary eukaryotic interdmediates as always became extinct
(one reasons why prokayaryes not more complex?)

39
Q

acheozoa

A

aagainst selective bottleneck;
they could be the missing ‘link’ as evolutionary eukaryotic intermediates

all possess organelles derived from mitchondria
post date leca
are ecological interdmieiesats; underwetn reductive evolution from more complex archea as incentive to dominante was lost

40
Q

ring of life?

A

evidence suggests sukaryotic cell arose via stochastic endosymbiosis between two prokaryotes; search of natural seelection acts on cells over billions of years; does not intrinsigly cause complexity

41
Q

examples of archeoxoa

A

parabasala

microsporindia

42
Q

could archeons be the host cell

A

genetic evidence based on 29 sequnces of protreins

43
Q

whats the closest relative to eukaryotes

A

lokiarcheota

44
Q

lokiarcheota

A

found in loki’s castle in mid atlantic

are a complex archae that might bridge prokaryot-eukearyotic gap

45
Q

domains of life

A

2, not 3?
hot cell for eukaryote was an archeon; phylogentic strucutres place eukaryotes as branching FROM achaea
as a cell within a cel l

46
Q

example of bacteria in a bacteria

A

cyanobacteria

47
Q

bioenergetic constraints of prokaryoates

A
  • respire over cell membrane
  • surface area to volume constraits
  • respoiration effiency half with doubling dimensions
  • dont internalize or compartmentalize
  • oxygen making proteins different to eukaryotes
48
Q

bioenergetic plus of eukaryotes

A

better oyxgen making proteins
need genes in mitchondria to control respiration as they grow larger
merge of 2 prokaryotes allows this

49
Q

cyanobacteria and nitrogen fixing bacteria

A

internal membranes

no organnelle genome out parts

50
Q

e.coli

A

a giant bacteria
respires across plasma membrane; area of biogenetic membrane is massive and nucleoids each govern each other bacterial volume of cytoplasm
exreme polyploid 9gene size)

51
Q

issues with full geneomes and prokaryotic size

A
  1. without intracellular transport networks each egeneome has a fixed volume in the cytoplasm
  2. extreme polyploidy requires massive energy costs to express all genes; hence the energy ber gene is giant and small bacteria
  3. no energetic apactiy to support increase in size and complexity therefore of bacteria
  4. eukaryotes have larger power per haploid gene; hence larger metabolic rate
52
Q

why is endosymbiosis neccessary?

A

size;
small cell; retains control of respiration= favoured by selection

large cell= loses control of respiration and dies

giant cell= needs polyploidy to control respireation

but eukaryotes have endosymbiosints; who supporte large host genome size

53
Q

what does nick lane argue

A

all eukaryotes arose from common ancestor and prokaryotes dont evolve to morphological complexity

54
Q

how does the mitonchrida cause the energy change to be permissive not presectiptive in eukaryotes

A
  1. reductive evolution and specializion of endosymbiont;
    - exterme genomic assymetry
    - mitcondrial genome allows expansion of biogenertic membrane
    - overcomes energy contraints in prokaryotic genome cell to allow host cell to expand by 20000
55
Q

why did eukaryotic genome size increase

A
  • genes and intron addition of endosymbiont caused high mutation rate;
    mutations masked by cell fusion and genome duplication resulting in a protosexual cell

therefore eukaryotic basal traits the saem and massive biogenetic expansion/release from geneome size contraits=

protosexual cell cycle and accumulation of eukaryotic traits

56
Q

what do the bioenergetic changes in eukaryotes explain

A

unique origins of eukaryotes
absense of evolutionary intermediates
eovltuion fo sex in eukaryotes

57
Q

when did eukaryotes origin

A

1 common ancestor 4 billio ears ago

58
Q

common traits in eukaryotes and leca

A

intron positions

nuclear pore complex srcutre

synagamy and 2 step

(common ancestry therefore most parimony explanation as opposed to convergent evolution or lateral gene transfer)

59
Q

why was it unlikely that prokaryotes developed repeatadably into eukaryotes, and were just outcompeted to extinction

A
  1. radiations exlore morphological space, not metabolic
  2. animals and plants are large and vulnerable to extinction
  3. no prokaryotes driven to extinction
  4. diverse morphological simple eukaryotes also exist
  5. extinction too esay to explain all complex life on earth sharing one common ancestor
  6. achezoa have lsot mitcondria by reductive evolution to mitosomes and hydrogenosomes
  7. likehoold of prokaryotes evolving up is 1 in 10^3000
  8. heaving selection against prokayotes to evolve to greater complexity
60
Q

why do prokaryotes show no tendency to tlve to greater morphological complexity

A

a. chemical complexity exists (chromosome variation, itnernal membranes, parasitic)
b. dont accumulate all traits at once
c. streamlend for small genoems for fast replication; hence continous loss of uneeded genes by lateral gene transfer
d. accumulation of genes in eukaryotes reduce selection of smal purying popoulation

= hence dont want to explore morphologicla space

61
Q

eukaryogenesis

A

cross of prokaryote to eukaryote

62
Q

how did eukaryotes origin

A

symbiosisb etween prokaryotes

mitcondria ((universal in eukaryotes and a singular event; d-proteobacteria probably the ancestor) +
host cell (tpe of archeon but unclear)
63
Q

how did eukaryotic cells accumulate

A

endosymbiosis

tree of life not branching, but unbranching trunk

repricocal sex and cll fusion

must have been rapdi in small population

instabiliity ould hav eprevented specialization

large stable population after LECA evolved then into eukaryotic supergroups

64
Q

how do mitcondria solve the eukaryotic origins

A

enable bioengertic membrane to cinrease
enable expansion of host cell genome
cause high mutation rate which casues cell fusion and sex

65
Q

energy per gene variations

A

mean metabolic rate per cell: 0.49 pW in bacteria
mean metabolic rate per cell: 2286 pw in eukaryotes

= respire at same rate but eukaryotes produce learger eneger per gram; not restrained to expand by energetic limitations

66
Q

why can only endosymbiosis fashion giant nuclear sizes

A
  • mitochondrial geneome is lost adn transferrred to nucleas
  • fastes replicators are simple= hence comeptition amogn individuals to remain endosymbiotic by simplicity
  • eukaryotes have genomic assymetry as many tiny mitchondrias sustain many genomes; cell division therefore disperes gene
  • gene loss is slow and functions are lost to save host cell atp synthesis
67
Q

what do mitconrida do for eukaryotes

A
  • oxidative phosphorylation for incrsae respiration rate
  • plasmids cant enable caling as they cant replicate; mitchondria can
  • reductive evolution for maximixed function
  • hence reduced need for cell wall; allows cell fusion and growht with mroe easy
68
Q

origin of sex in eukaryotes

A
  • no evolutionary eukaryotic intermediates
  • common ancestory; important to duplicate genome

hence INTRON positions present in LECA; therefore INTRONS cause mutations that forced sex and cell fusion

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