Lecture 10 Prokaryotes

Question 0

where can prokaryotes thrive?

Answer 0

almost anywhere

-includes very acidic places, high salinity, extreme temperatures

Question 1

what are the two domains that are considered prokaryotes?

Answer 1

bacteria and archaea

Question 2

what are seven characteristics of prokaryotes?

Answer 2

1. no nucleus
2. plasmids
3. lack compartmentalization
4. prok < euk in size
5. cell wall – peptidoglycan
6. 1/2 of prok are motile
7. reproduction and gene transfer in several forms

Question 3

how is genetic material arranged in prokaryotes?

and how much is there?

Answer 3

• diffused, circular ring of DNA not enclosed by a membrane
• located in nucleoid region
• prok genome has less DNA than euk genome

Question 4

what are plasmids?

Answer 4

small rings of DNA containing ‘extra’ genes

Question 5

what is peptidoglycan?

Answer 5

a network of sugar polymers cross-linked by polypeptides

Question 6

what is the function of the cell wall in prokaryotes? (3)

Answer 6

• maintains cell shape
• protects the cell
• prevents bursting in hypertonic environments

Question 7

what are the two types of bacterial cell wall?

Answer 7

• gram +

- gram -

Question 8

what is a gram + wall?

Answer 8

• simpler bacterial cell wall with a lot of external facing peptidoglycan

Question 9

what is a gram - wall?

Answer 9

a bacterial cell wall that has a lipopolysaccharide layer outside of the cell wall which doesn’t absorb the gram stain readily

Question 10

why are bacteria with gram - cell walls usually more pathogenic than gram + bacteria? (2)

Answer 10

can contain toxins and can resist antibiotics

Question 11

what are 3 cell-surface structures of bacteria?

Answer 11

• capsule
• fibrae
• pili / sex pili

Question 12

what is a capsule?

Answer 12

a polysaccharide or protein layer that covers many prokaryotes

Question 13

what is a fimbrae?

what does it allow bacteria to do (2) ?

Answer 13

adaptation that allows the bacteria to stick to substrates or other individuals in a colony

Question 14

how do most bacteria move?

Answer 14

using flagella scattered about the surface of the bacteria or concentrated at one or both ends

Question 15

how are the flagella of bacteria, archaea, and eukarya diffferent?

Answer 15

composed of different proteins and most likely evolved independently

Question 16

what is taxes/taxis?

Answer 16

the ability to move toward or away from a stimulus

ex: phototaxis – movement towards light

Question 17

what form does bacterial reproduction NOT take

Answer 17

mitosis/meiosis

Question 18

how do bacteria reproduce quickly

Answer 18

using binary fission – depends on environment

Question 19

what are 3 factors that contribute to bacterial genetic variation

Answer 19

• rapid reproduction
• mutation
• genetic recombination

Question 20

how is mutation a factor for genetic variation (despite that mutation rates of binary fission is very low)

Answer 20

mutations occur rapidly in a population because of rapid reproduction

Question 21

how is prokaryotic DNA from different individuals brought together? (3)

Answer 21

• transformation
• transduction
• conjugation

Question 22

what is transformation?

Answer 22

the uptake of foreign DNA from surroundings

ex: naked DNA from dead bacteria

Question 23

what is transduction?

Answer 23

movement of prokaryotic genes between bateria by bacteriophages – usually a mistake on phage’s part

Question 24

what is a bacteriophage?

Answer 24

a virus that infects bacteria

Question 25

what is conjugation? (3)

Answer 25

- a process where genetic material is transferred between an donor cell to a recipient cell via PILUS - unidirectional - plasmids are often transferred

Question 26

by which process are plasmids often transferred?

Answer 26

conjugation

Question 27

what is metabolism?

Answer 27

chemical pathways used by living organisms to build up molecules

Question 28

compare anabolism vs catabolism

Answer 28

catabolism is the breakdown of molecules to release energy --think catastrophy anabolism is the breakdown of molecules to release energy

Question 29

what are the four ways to catagorize prokaryotes by how they obtain energy and carbon?

Answer 29

- phototrophs - chemotrophs - autotrophs - heterotrophs

Question 30

what are phototrophs?

Answer 30

organisms that obtain energy from light

Question 31

what are chemotrophs?

Answer 31

organisms that obtain energy from chemicals (usually inorganic)

Question 32

what are autotrophs?

Answer 32

organisms that use CO2 as a carbon source

Question 33

what are heterotrophs?

Answer 33

organisms that use organic nutrients to make organic compounds -- often have to consume things

Question 34

what are the two types of prok autotrophs?

Answer 34

- chemoautotrophs | - photoautotrophs

Question 35

what are the two types of prok hetertrophs?

Answer 35

- photoheterotrophs | - chemoheterotrophs

Question 36

what do archaea lack in their cell wall?

Answer 36

peptidoglycan

Question 37

what kind of philes are archaea?

Answer 37

extremophiles

Question 38

how do archaea respond to antibiotice that inhibit eubacterial growth?

Answer 38

they DON'T

Question 39

what are three types of archaea covered in this course?

Answer 39

- methanogens: live in O2 free environments - halophiles: very salty environments - thermophiles: very hot habitats

Question 40

what are four characteristics of eubacteria?

Answer 40

diverse, numerous, live almost everywhere, can be pathogenic or have positive interactions w/ humans

Question 41

what are the 5 major clades of bacteria?

Answer 41

- proteobacteria - chlamydias - spirochaetes - cyanobacteria - "Gram +" bacteria

Question 42

what are proteobacteria?

Answer 42

- large and metabolically diverse group of gram neg. bacteria - 5 sub linages - two examples: Rhizobium spp & E. coli

Question 43

what is the proteobacteria Rhizobium spp.? | what relationship does it have with plants?

Answer 43

- live in root nodules of leguminous roots | - mutualistic--fix atm. nigtogen to make it available for the host plant to use, plant gives carbohydrates in return

Question 44

what is the proteobacteria E. coli? (5)

Answer 44

- resides in many mammal intestines - not normally pathogenic - aids in digestion - synthesis of vitamins & other nutrients - some are toxic

Question 45

what are chlamydias? | what do the NOT have in their cell wall?

Answer 45

- parasites only living within animal cells - no peptidoglycan in cell walls - ex: chlamydia trachomatis - common human STD, blindness in newborns

Question 46

what are spirochaetes?

Answer 46

- long helical heterotrophic bacteria that swim by spiralling - many free-living - NASTY parasitic bacteria - ex: syphilis & Lyme disease (ticks)

Question 47

what are cyanobacteria/blue-green algae?

Answer 47

- only prokaryotes that produce oxygen via photoautrophy | - often benignt, but some have toxins that impair liver fxns or act as neurotoxins

Question 48

where are plant chloroplasts thought to evolve from?

Answer 48

cynanobacteria via endosymbiosis

Question 49

what is the "Gram +" bacteria clade?

Answer 49

- ONLY group with GRAM + bacteria (but also includes gram - taxa ...?...) - very important decomposers in soil - source of many antibiotics like streptomycin - and mycoplasmas -- smallest known cells - and clostridium botulinum -- botulism - and bacillus anthracis -- anthrax -- that can enter resistant endospore state

Question 50

what is the importance of prokaryotes?

Answer 50

- producers of O2 and fixers of N - major roles in recycling of chemical elements between living and non-living - ex: chemoheterotrophic prok that are decomposers can increase availability of N, P and K for plants

Question 51

what is symbiosis?

Answer 51

ecological relationship between two species that live in close contact specifically a larger host + a smaller symbiont

Question 52

what are 3 types of symbiotic relationships

Answer 52

- mutualism: both benefit, ex methanogens in cow stomach, Rhizobium - commensalism: one benefits, other is neither harmed nor benefits - parasitism: parasite harms but doesn't kill host (maybe eventually it will...)

Question 53

what are parasites that cause disease called?

Answer 53

pathogens

Question 54

what is the economic importance of prok?

Answer 54

- food production - sewage treatment & bioremediation (decomposers) - production of vitamins, antibiotics, hormones, biofuels - ex Thermus aquaticus "taq" -- used in PCR