Bacteria and Archaea

Question 1

microbe

Answer 1

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

Question 2

prokaryote

Answer 2

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

Question 3

three domains of life

Answer 3

bacteria
archaea
eukarya

Question 4

last universal common ancestor (LUCA) traits

Answer 4

cells

central dogma

• DNA - RNA - proteins
• genetic code

adenosine triphosphate (ATP)

organic compounds with carbon-hydrogen bonds

Question 5

bacteria

Answer 5

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

Question 6

Antony van Leeuwenhoek

Answer 6

he first classified bacteria in 1680s

father of microbiology

Question 7

cyanobacteria

Answer 7

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

Question 8

archaea

Answer 8

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

Question 9

Carl Woese and George Fox

Answer 9

first classified Archaea in 1977

phylogenetic trees based on ribosomal RNA sequences

Woese proposed the 3 domain system

Question 10

bacteria and archaea diversity

Answer 10

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

Question 11

extremophiles

Answer 11

organisms that live in extreme environments

Question 12

ways to characterize Bacteria and Archaea

Answer 12

enrichment culture

metagenomics or environmental sampling

Question 13

enrichment culture

Answer 13

establish specific conditions

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

Question 14

metagenomics or environmental sampling

Answer 14

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

Question 15

abundance of Bacteria and Archaea

Answer 15

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

Question 16

evolutionary rates of Bacteria and Archaea

Answer 16

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”

Question 17

bacteria characteristics

Answer 17

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)

Question 18

Achaea shapes

Answer 18

same rotes, spheres, spirals

also some that look like triangles or squares

Question 19

reproduction

Answer 19

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

Question 20

genetic variation

Answer 20

mutation

gene transfer:
transformation
transduction
conjugation

different from sexual reproduction:

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

Question 21

transformation

Answer 21

uptake of DNA from the environment

Question 22

transduction

Answer 22

virus picks up and transfers DNA between cells

Question 23

conjugation

Answer 23

direct transfer by cell-to-cell contact

Question 24

metabolic diversity

Answer 24

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…

Question 25

photoautotrophs

Answer 25

energy from light carbon from inorganic CO2 e.g. plants and algae; cyanobacteria, purple sulfur bacteria

Question 26

chemoautotroph

Answer 26

energy from chemical reactions carbon form inorganic CO2 only bacteria and archaea, many types

Question 27

photoheterotroph

Answer 27

energy from light carbon from organic molecules only bacteria and archaea e.g. purple non-sulfur, helicobacteria

Question 28

chemoheterotrophs

Answer 28

energy and carbon from organic material e.g. animals and fungi; many bacteria and archaea

Question 29

decomposers

Answer 29

breakdown of dead organic matter makes organic compounds available for other organisms many have mutualistic relationships with plants and animals (mainly in gut)

Question 30

nitrogen fixation

Answer 30

conversion of atmospheric nitrogen to forms that can be used by plants nitrogen is often a limiting factor of plant growth

Question 31

pathogenic bacteria

Answer 31

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

Question 32

Robert Koch

Answer 32

1843-1910 did a study of causative link between bacteria and disease made Koch's postulates

Question 33

Koch's postulates

Answer 33

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

Question 34

microbiome

Answer 34

a community of microbes that share a particular space

Question 35

human microbiome

Answer 35

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

Question 36

bioremediation

Answer 36

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

Question 37

microbiology

Answer 37

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

Question 38

germ theory of disease

Answer 38

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

Question 39

infectious diseases

Answer 39

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

Question 40

toxin

Answer 40

a poison

Question 41

endospores

Answer 41

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

Question 42

biofilms

Answer 42

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

Question 43

direct sequencing

Answer 43

a technique based on isolating and sequencing a specific gene from organisms found in a particular habitat along with metagenomics/environmental sequencing

Question 44

plasmid

Answer 44

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

Question 45

gram-positive

Answer 45

a plasma membrane surrounded by a cell wall with extensive peptidoglycan

Question 46

gram-negative

Answer 46

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

Question 47

shapes of bacteria

Answer 47

shape varies from rods to spheres to spirals

Question 48

bacteria motility

Answer 48

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