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Biology Exam #2 > prokaryotes > Flashcards

prokaryotes Flashcards

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1
Q

what do prokaryotes lack

A
  • nucleus and membrane bound organelles
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2
Q

where is their DNA

A
  • nucleiod
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3
Q

what shape is their DNA

A

circular

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4
Q

do they have a cytoskeleton

A

no, they have cell wall

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5
Q

what is a plasmid

A

small molecule of DNA seperate from chromosome

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6
Q

what are some extra things prokaryotes have to protect themselves

A
  • capsule (large polusac coting)
  • endospores: form in response to bad conditions, bacteria in endospores can lay dormant, until conditions get better , prevent from dying
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7
Q

what is different with archae cell wall compared to bacteria

A

No peptidoglycan , chemical composition is diff

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8
Q

what does archae have in common with bacteria

A
  • no membranous organelles
  • no nucleus
  • circular DNA
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9
Q

what are the different groups of archae

A
  • mathanogens (release methan, found in anaerobic environements)
    -halophiles (found is saline conditions)
  • thermophiles (hot environemtns)
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10
Q

how do bacteria introduce genetic variability

A
  • bacteriel conjugation
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11
Q

what is bacteriel conjugation

A
  • direct transfer of genetic materiel between two physically linked bacteriel cells by pilus
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12
Q

what is the use of plasmids

A
  • constitute an extra pool of genes
  • can be resistant to certain antibiotics, which then makes creation of bacteria resistent to that antibiotic possible
  • when antiobiotic given, kills non resistant bacteria, but the one’s that survive procreate and then more resistant bacteria are formed
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13
Q

what is the ecological significance of bacteria

A
  • decomposers, saphrophytes (organisms that feed on dead organic matter)
  • mutualistic symbionts (two animals life together, in a useful manner)
  • producers in phytoplankton
  • nitrogen fixation
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14
Q

what are different ways they can get their carbon

A
  • autotrophs ; atmospheric CO2 (from air)
  • Heterotrophs ; organic compounds like sugar, ats, amino-acids and proteins
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15
Q

what are different ways they can get their energy

A
  • chemotrophs : energy from chemical bonds (organic or inorganic)
  • phototrophs : radiant energy from the sun
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16
Q

what are the different nutritional modes

A
  • photoautotrophs
  • photoheterotrophs
  • chemoautotrophs
  • chemoheterotrophs
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17
Q

what are photoautotrophs

A
  • most plants, some prokaryotes, some protists
  • energy from sun, carbon from athmosphere
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18
Q

what are photoheterotrophs

A
  • prokaryotes only
  • energy from sun , carbon in organic form (other living things)
19
Q

what are chemoautotrophs

A
  • prokaryotes
  • energy from chemical bonds (organic or inorganic), carbon from athm. CO2
20
Q

what are chemoheterotrophs

A
  • all animals, fungi, many protists and prokaryotes
  • energy from chemical bonds (organic or inorganic) , carbon in organic form
21
Q

what are obligate aerobes

A

need oxygen for cell resp

22
Q

what are obligate anaerobes

A

oxygen is toxic, not used for cell resp

23
Q

what are faculative anaerobes

A

can perform cellular respiration with or without oxygen

24
Q

how do prokaryotes reproduce

A

binary fission

25
Q

how do some bacteria survive hostile conditions

A

produce endospores

26
Q

what are methanogens

A
  • anaerobic environenments
  • release methane as waste product
27
Q

what are halophiles

A
  • found in dead sea
  • extreme saline conditions
28
Q

what are thermophiles

A
  • hot environments (45 to 104 degres)
29
Q

how does archae differ from bacteria regarding DNA and RNA

A
  • they have histones associated to their DNA like eukaryotes
  • have unique RNA sequences
30
Q

what are the different cell shapes

A
  • cocci = sphere
  • bacilli = rods
    Spirilla = spirals
31
Q

what is the prefix for a chain shaped colony

A

strepto

32
Q

what is the prefix for a clumped shaped colony

A

staphylo

33
Q

what is the prefix for a spiral shaped colony

A

spirilla

34
Q

where is the DNA located in prokaryotes

A
  • in the cytoplasm, not surrounded by membrane, nucleiod region
35
Q

what do they have , additionally to their DNA, what is special about it

A
  • plasmids , small fragment of DNA
  • can be transfered during bacteriel conjugation
36
Q

what does bacteria use for the gene transfers ?

A
  • they use a sex pilus
37
Q

check evolutionary importance of plasmids *

A
38
Q

do antibiotics cause resistance ?

A

No, they create an environment that favors the growth of resistant variants , by not killing those variants

39
Q

what is the major role of bacteria in the environment

A
  • ## decomposition of organic materiels and recycling of nutrients
40
Q

what is a saprophyte

A

Organisms that get substances it needs from decomposing organic matter

41
Q

what is another role of bacteria in the environment

A

mutualistic symbionts , they live in the guts of herbivores, who eat plants, but do not produce the enzymes to decompose the cellulose

42
Q

how are bacteria mutual symbionts with humans

A
  • gut symbionts produce essential vitamins like e. coli
  • they also help pathogens from invading
  • symbionts of the skin and mucosas prevent infection
43
Q

what is bacteria’s relationship with nitrogen

A

they are nitrogen fixers , so organisms can use them
- fix nitrogen in nodules on plant roots

44
Q

where does nitrogen fixation occur

A

cyanobacteria colonies have specialised cells, heterocysts, where nitrogen fixation occurs

Biology Exam #2 (23 decks)

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