Topic 7- first life: prokaryotes Flashcards

1
Q

prokaryotes have no ______________ unlike eukaryotes

A

membrane bound nucleus/ other organelles

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2
Q

Which domains are prokaryotes?

A

domain bacteria and domain archaea

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3
Q

The first unicellular organisms were ____( first life)

A

prokaryotes

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4
Q

What 3 things makes prokaryotes so adaptable/ successful ?

A
  1. small size (few needs)
  2. reproduce via binary fission (fast, don’t need to find a mate)
  3. short generation time (evolution can occur quickly, but may be inhibited by asexual reproduction)
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5
Q

prokaryotic cells have ____ DNA, and a nucleus that __(is/ isn’t) enclosed by a membrane

A

circular

is not

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6
Q

What does taxes mean? (singular = taxis)

give an example

A

movement away from or towards stimulus

eg. positive phototaxis is movement toward light

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7
Q

Plasmids are present in prokaryotes. Define plasmid

A

small rings of dna containing a few “extra” genes

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8
Q

prokaryotes have/ lack membrane enclosed organelles

some have ____ __ ____ ______

A

lack

infolding of cell membrane

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9
Q

despite reproducing asexually, prokaryotes have high genetic diversity. how?

A
  • short generation time and high mutation rate compared to eukaryotes = increased diversity
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10
Q

how do bacteria exchange genetic info? (modify their genome)

A

genetic recombination via horizontal gene transfer

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11
Q

name and explain the 3 types of horizontal gene transfer

A
  1. transformation: ‘naked’ dna is picked up from dead bacteria in the environment (b/c when a cell dies, dna is released)
  2. transduction: dna transferred by virus (bacteriophage)
  3. conjugation: dna transferred between 2 bacteria
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12
Q

define autotrophs and their 2 varieties

A

autotroph: make their own energy from inorganic sources
- chemoautotroph: use energy obtained by oxidizing inorganic chemicals, and co2 ( doesn’t need sunlight)- many prokaryotes
- photoautotrophs: use light energy and co2 (primary producers that support food web) eg. cyanobacteria–> O2!

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13
Q

define heterotrophs and their 2 varieties

A
  • don’t make their own energy! most bacteria must eat… enzymes digest organic molecules in environment absorbed through membrane
  • photoheterotrophs: uses light energy; C source from organic molecules to help them process energy
  • chemoautotrophs: use organic molecules for both energy and C source (eg animals, fungi, many prokaryotes, a few plants)
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14
Q

many prokaryotes are symbiotic. If inside the host organism it’s ____

A

endosymbiotic

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15
Q

define commensalism

A

A lives on/ with B, but neither harms nor benefits B

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16
Q

define amensalism

A

A harms B, but A does not gain anything from it

17
Q

Studies of ___ structure revealed that there are actually __ very different lineages of prokaryotes

18
Q

bacteria have _____ in their cell walls

A

peptidoglycan

19
Q

archaea have more/ less variety in rna than bacteria

20
Q

why don’t archaea respond to antibiotics?

A

antibiotics act on the peptidoglycan in the cell wall & cause the cell wall to break (inhibits eubacterial growth)
therefore antibiotics only work on bacteria, not archaea

21
Q

most archaea live in ____ environments

22
Q

archaea methanogens live in _______

they produce ___ as a waste product

A

oxygen-free habitats such as swamp substrates and cow guts

methane

23
Q

archaea halophiles live in ____

A

very salty habitats

24
Q

archaea thermophiles live in ____

many are

A

very hot environments

chemoautotrophs

25
cell wall in bacteria contains ____ which provides ___(list 3 things)
peptidoglycan 1. cell shape 2. protection 3. prevents cell form exploding when placed in hypotonic solution (lower in solutes than cell content)
26
explain gram positive bacteria
they have peptidoglycan in cell wall in contact with external medium which traps purple stain
27
explain gram negative bacteria
have lipopolysaccharide layer outside of cell wall, and thus do not absorb stain readily
28
gram - species are often more ___ because the ____ layer can contain ___ and resist the action of ______
pathogenic lipopolysaccharide toxins antibiotics
29
scientists hypothesize that mitochondria evolved from ______ __ ____ through _____
aerobic alpha proteobacteria | endosymbiosis
30
proteobacteria include ____mutualists called ____ | describe the relationship
endosymbiotic rhizobium which live in roots, and fix atmospheric nitrogen for the host to use in its metabolism - the host plant then gives rhizobium carbohydrates
31
e.coli is an example of a ____
proteobacteria | it's a harmless commensal in human intestine
32
______ and ____ are pathogenic bacteria
chlamydias and spirochetes
33
cyanobacteria are ____trophs and produced O2 in atmosphere billions of yrs ago - ___ evolved form cyanobacteria
photoautotrophs | chloroplast
34
gram + pathogenic bacteria include
- clostridium botulinum (botox!) - tuberculosis - anthrax
35
list 4 similarities among both domains of prokaryotes (bacteria and archaea)
- no membrane bound organelles - single, circular chromosome structure - small size - cell wall is present
36
list 4 differences among both domains of prokaryotes (bacteria and archaea)
- peptidoglycan in bacterial cell walls, not archaea - plasma membrane is unbranched, Esther linkage in bacteria, and branched Esther linkage in archaea - bacteria have linked RNA polymerase varieties, archaea have multiple