Lecture 7

Question 1

2 prokaryote domains

Answer 1

1. Archaea

2. Bacteria (distinguished by RNA structure)

Question 2

7 characteristics of prokaryotes

Answer 2

1. evolved before evolution of nucleus
2. plasmids
3. reproduction and gene transfer takes several forms, none using mitosis or meiosis
4. cell wall (when present) includes peptidoglycans
5. lack membrane-enclosed organelles
6. smaller than eukaryotic cells
7. half are motile (using flagella)

Question 3

nucleus

Answer 3

genetic material as dense linear chromosomes enclosed by membrane, present in eukaryotes

Question 4

nucleoid region

Answer 4

diffuse, circular ring of DNA not enclosed by membrane, present in prokaryotes

Question 5

plasmids

Answer 5

small rings of DNA containing a few ‘extra’ genes

Question 6

4 types of reproduction and gene transfer in prokaryotes

Answer 6

1. binary fission
2. transformation
3. transduction
4. conjugation

Question 7

binary fission

Answer 7

most common, chromosome duplicates and cell splits

Question 8

transformation

Answer 8

uptake of ‘naked’ DNA released from dead bacteria by a living prokaryote

Question 9

transduction

Answer 9

virus mistake - transportof DNA between prokaryote cells by viruses

Question 10

bacteriophage

Answer 10

virus that infects and replicates with bacteria

Question 11

conjugation

Answer 11

one prokaryote latches on to another with a string-like structure (pilus) and transfers DNA (unidirectional)

Question 12

why can antibiotic resistance spread so quickly?

Answer 12

modes of horizontal gene transfer

Question 13

horizontal gene transfer

Answer 13

between individuals of the same generation - transformation, transduction, conjugation

Question 14

vertical gene transfer

Answer 14

transfer from parent to offspring between generations - binary fission

Question 15

peptidoglycans

Answer 15

not cellulose or chitin, prevents cell from exploding in hypotonic solution

Question 16

plasmolysis

Answer 16

contents of cell shrink in hypertonic solution, not prevented by cell wall

Question 17

Gram + bacteria

Answer 17

have peptidoglycan wall in contact with external medium which traps purple stain

Question 18

Gram - bacteria

Answer 18

have lipopolysaccharide layer outside of cell wall, and thus do not absorb stain readily (more pathogenic)

Question 19

taxis

Answer 19

movement toward or away from stimulus, demonstrated in many prokaryotes

Question 20

metabolic pathways

Answer 20

differ in prokaryotes and eukaryotes

Question 21

metabolism

Answer 21

chemical pathways used by living organisms to build up

or break down molecules

Question 22

anabolism

Answer 22

build up molecules

Question 23

catabolism

Answer 23

break down molecules to release energy

Question 24

3 needs for metabolic activity

Answer 24

1. water
2. carbon
3. energy

Question 25

photoautotrophs

Answer 25

use light energy and CO2 - plants, cyanobacteria

Question 26

chemoautotrophs

Answer 26

use energy obtained by oxidizing inorganic chemicals, and CO2 - many prokaryotes

Question 27

photoheterotrophs

Answer 27

use light energy, but get carbon from organic molecules

Question 28

chemoheterotrophs

Answer 28

use organic molecules for both energy and carbon source - animals, fungi, many prokaryotes, few plants

Question 29

3 Archaea characteristics

Answer 29

1. lack peptidoglycan in cell wall 2. do not respond to antibiotics that limit eubacterial growth 3. extremophiles

Question 30

extremophiles

Answer 30

live in habitats that seem unpleasant from eukaryotic point of view

Question 31

3 Archaea functional groups

Answer 31

1. methanogens 2. halophiles 3. thermophiles

Question 32

methanogens

Answer 32

live in oxygen-free habitats (swamp substrates, cow and termite guts), produce methane as a waste product

Question 33

halophiles

Answer 33

live in very salty habitats

Question 34

thermophiles

Answer 34

live in very hot habitats, many are chemoautotrophs

Question 35

5 major bacteria clades

Answer 35

1. proteobacteria 2. chlamydias 3. spirochaetes 4. gram + 5. cyanobacteria

Question 36

proteobacteria

Answer 36

large and metabolically diverse group of Gram– bacteria, 5 sublineages - alpha to epsilon

Question 37

Rhizobium

Answer 37

live in root nodules of leguminous plants, fix atmospheric nitrogen, in return, host plant gives Rhizobium carbohydrates

Question 38

proteobacteria examples

Answer 38

endosymbiotic mutualists like Rhizobium, causative agents of cholera and gastric ulcers, Escherichia coli

Question 39

Escherichia coli

Answer 39

typically harmless commensal in human intestine, tested for in drinking water because its presence means fecal matter is entering waterway, some strains toxic

Question 40

chlamydias

Answer 40

can live only within the cells of animals, no peptidoglycan in cell walls

Question 41

chlamydia examples

Answer 41

human STI, cause blindness in newborns, blindness in koalas

Question 42

spirochaetes

Answer 42

long helical bacteria, swim by spiraling, many free-living and some nasty parasitic bacteria

Question 43

spirochaetes examples

Answer 43

causative agents of syphilis and Lyme disease

Question 44

gram + bacteria group

Answer 44

only group with Gram+, but also includes numerous Gram- taxa

Question 45

gram + examples

Answer 45

decomposers in soil, sources for many antibiotics, mycoplasmas (smallest known cells), anthrax, Clostridium botulinum

Question 46

anthrax

Answer 46

Bacillus anthracis, can enter resistant endospore state

Question 47

Clostridium botulinum

Answer 47

causes botulism, can devastate waterfowl when accumulated in fly larvae, Botox

Question 48

cyanobacteria

Answer 48

only prokaryotes that produce oxygen through photoautotrophy, like plants

Question 49

cyanobacteria examples

Answer 49

nitrogen fixers, benign, contain toxins that impair liver function, or neurotoxins

Question 50

number of named bacterial+archaean species

Answer 50

7800, many more unnamed

Question 51

ecological importance of prokaryotes

Answer 51

decomposers, produce oxygen, fix nitrogen, primary producers of some food webs, beneficial inhabitants of eukaryotes, cause disease

Question 52

economic importance of prokaryotes

Answer 52

sewage treatment, food production, Taq used in polymerase chain reaction (PCR)

Question 53

Thermus aquaticus aka Taq

Answer 53

enzymes retain activity at very high temperatures, used in PCR to amplify DNA for sequence analysis