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Eco and Evo > Bacteria and Archaea > Flashcards

Bacteria and Archaea Flashcards

1
Q

microbe

A

organisms that cannot be seen with the naked eye (need a microscope)

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2
Q

prokaryote

A

a unicellular organisms that lack a nucleus and (generally) lacks organelles

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3
Q

three domains of life

A

bacteria
archaea
eukarya

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4
Q

last universal common ancestor (LUCA) traits

A

cells

central dogma

  • DNA - RNA - proteins
  • genetic code

adenosine triphosphate (ATP)

organic compounds with carbon-hydrogen bonds

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5
Q

bacteria

A

first classified in 1680s Antony van Leeuwenhoek

yet many species remain unclassified

wide variety of habitats and niches

oldest fossils are about 3.5 billion years old

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6
Q

Antony van Leeuwenhoek

A

he first classified bacteria in 1680s

father of microbiology

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7
Q

cyanobacteria

A

first organisms to perform “oxygen producing” photosynthesis

oldest fossils - 2.6 bya

signatures of oxygen in atmosphere - 2.3 to 2.1 by a

made aerobic respiration possible

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8
Q

archaea

A

first classified in 1977 by Carl Woese and George Fox

best known for living in extreme environments, but are found in a wide variety of habitats

oldest fossils are about 3.5 billion years old

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9
Q

Carl Woese and George Fox

A

first classified Archaea in 1977

phylogenetic trees based on ribosomal RNA sequences

Woese proposed the 3 domain system

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10
Q

bacteria and archaea diversity

A

only about 10,000 species of Bacteria and about 500 species of Archaea have been formally described

difficult to draw boundaries between species due to horizontal gene transfer

estimates of total species range from 1 million to 1 trillion

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11
Q

extremophiles

A

organisms that live in extreme environments

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12
Q

ways to characterize Bacteria and Archaea

A

enrichment culture

metagenomics or environmental sampling

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13
Q

enrichment culture

A

establish specific conditions

e.g. temperature, light, food, grow cells, isolate for further study

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14
Q

metagenomics or environmental sampling

A

has revealed lots of uncharacterized diversity

collect massive amounts of DNA or RNA sequences soils or water

detect species (genomic) or functional (expressed genes) diversity

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15
Q

abundance of Bacteria and Archaea

A

in terms of toal volume, Bacteria and Archaea are the dominant organisms of Earth

estimated 5x10^30

  • chain longer than Milky Way!
  • 50% of all carbon
  • 90% of all nitrogen and phosphorus
  • teaspoon of soil contains billions of cells
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16
Q

evolutionary rates of Bacteria and Archaea

A

reproduction is fast, thus they have short generation times
-E. coli cells divide in about 20 minutes at 37C

lateral gene transfer common, plus higher mutation rates than eukaryotes
-genetic diversity

implications for bacterial resistance and growth of “superbugs”

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17
Q

bacteria characteristics

A

most bacteria are about 1 micrometer in diameter, but some are much smaller

cell volume ranges from 0.15 micrometers^3 to 200 x 10^6 micrometers^3
-1.3 billion times the difference

new study in 2015: new bacteria as small as 0.009 micrometers^3

shape varies from rods to spheres to spirals

motility varies: some bacteria are nonmotile, but swimming and gliding are common

two general types distinguished by gram stain (detects peptidoglycan)

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18
Q

Achaea shapes

A

same rotes, spheres, spirals

also some that look like triangles or squares

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19
Q

reproduction

A

Bacteria and Archaea reproduce by (asexual) binary fission

  • DNA uncoils and duplicates
  • cell grows in size
  • DNA copies move toward opposite poles
  • new cell wall splits cel into two
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20
Q

genetic variation

A

mutation

gene transfer:
transformation
transduction
conjugation

different from sexual reproduction:

  • one-way transfer
  • transfers are limited to small number of genes
21
Q

transformation

A

uptake of DNA from the environment

22
Q

transduction

A

virus picks up and transfers DNA between cells

23
Q

conjugation

A

direct transfer by cell-to-cell contact

24
Q

metabolic diversity

A

bacteria and archaea domains are the dominant forms of life on Earth and are able to live in a wide variety of environments

much of this success is attributed to a wide diversity of metabolism

i.e. photo, chemo, hetero, auto…

25
Q

photoautotrophs

A

energy from light

carbon from inorganic CO2

e.g. plants and algae; cyanobacteria, purple sulfur bacteria

26
Q

chemoautotroph

A

energy from chemical reactions

carbon form inorganic CO2

only bacteria and archaea, many types

27
Q

photoheterotroph

A

energy from light

carbon from organic molecules

only bacteria and archaea
e.g. purple non-sulfur, helicobacteria

28
Q

chemoheterotrophs

A

energy and carbon from organic material

e.g. animals and fungi; many bacteria and archaea

29
Q

decomposers

A

breakdown of dead organic matter

makes organic compounds available for other organisms

many have mutualistic relationships with plants and animals (mainly in gut)

30
Q

nitrogen fixation

A

conversion of atmospheric nitrogen to forms that can be used by plants

nitrogen is often a limiting factor of plant growth

31
Q

pathogenic bacteria

A

only a tiny fraction of bacteria are pathogenic (disease-causing)

32
Q

Robert Koch

A

1843-1910

did a study of causative link between bacteria and disease

made Koch’s postulates

33
Q

Koch’s postulates

A

microbe present in individuals with disease, absent from healthy individuals

microbe is isolated and grown in our culture

microbes from culture injected into animals produces symptoms of disease

microbe again isolated from diseased animal, should be same as original organism

34
Q

microbiome

A

a community of microbes that share a particular space

35
Q

human microbiome

A

lots of research on microbiome of human digestive tact

each person has about 100 different species (trillions of cells) of bacteria and archaea

analysis of gene expression supports physiological role including:

  • digestion of complex carbohydrates
  • synthesis of amino acids and vitamins
36
Q

bioremediation

A

the use of organisms (usually Bacteria Archaea) to degrade environmental pollutants

pollutants often hydrophobic

  • do not dissolve in water, accumulate in sediments
  • can spread through food chain
37
Q

microbiology

A

the study of organisms that can be seen only with the aid of microscope

38
Q

germ theory of disease

A

states that infectious diseases are caused by specific microbes in the body

39
Q

infectious diseases

A

are spread in 3 main ways:

  • person to person
  • by bites from insects or animals
  • ingesting contaminated food or water, or from the surrounding environment
40
Q

toxin

A

a poison

41
Q

endospores

A

tough, thick-walled dormant structures formed during times of environmental stress, often in response to a lack of nutrients

contain a copy of the cell’s DNA, RNA, ribosomes, and essential enzymes that becomes surrounded by a tough resistant wall

resistant to high temps, UV radiation, and even antibiotics

when conditions become favorable, they resume growth as normal, actively dividing cells

bacteria

42
Q

biofilms

A

dense bacterial colonies enmeshed in a polysaccharide-rich matriculates, which helps shield the bacteria from antibiotics

43
Q

direct sequencing

A

a technique based on isolating and sequencing a specific gene from organisms found in a particular habitat

along with metagenomics/environmental sequencing

44
Q

plasmid

A

a small circular piece of DNA

often contain accessory genes that aren’t required for normal growth, but can be advantageous

e.g. antibacterial resistance

45
Q

gram-positive

A

a plasma membrane surrounded by a cell wall with extensive peptidoglycan

46
Q

gram-negative

A

have a plasma membrane surrounded by a cell wall hat has two components:
-a thin gelatinous layer containing peptidoglycan and an outer phospholipid bilayer

47
Q

shapes of bacteria

A

shape varies from rods to spheres to spirals

48
Q

bacteria motility

A

motility varies: some bacteria are nonmotile, but swimming and gliding are common

Eco and Evo (15 decks)

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