Chapter 27: Bacteria & Archaea

Question 1

Chp 27

Cell-Surface Structures

Answer 1

• eukaryote cell wall is made out of cellulose/chitin
• prokaryotic cell wall contains peptidoglycan (sugar polymers)
• archaea caintain polysaccharides and lack peptidoglycan
• Gram stain is used to classify bacteria by cell wall composition
• Gram (+): large amount of peptidoglycan & gram (-): less peptidoglycan

Question 2

Chp 27

Gram positive bacteria

Answer 2

• include colony forming groups to decompose matter
• include solitary species
• mycoplasms lack cell walls

Question 3

Chp 27

What is the capsule?

Answer 3

• sticky outer layer of polysaccharide/protein present in some prokaryotes
• allows adherence to substrate or other individuas
• can shield pathogenic bacteria from the host immune system

Question 4

Chp 27

What is an endospore?

Answer 4

• they are metabolically inactive formed by many prokaryotes
• can remain viable in harsh conditions for centuries

Question 5

Chp 27

What is the difference between fimbriae and pili?

Answer 5

• fimbriae: hairlike appendages that allow prokaryotes to stick to their substrate/individuals in a colony
• Pili (sex pili): longer than fimbriae; allow prokaryotes to exchange DNA

Question 6

Chp 27

Mobility

Answer 6

• Taxis: The ability to move toward or away from a stimulus
• Flagella are the most common strutures used by prokaryotes for movement
• flagella of prokaryotes & eukaryotes differ in structure, etc…

Question 7

Chp 27

Internal organization and DNA

Answer 7

• prokaryotic cells lack complex compartmentalization
• infoldings of the plasma membrane in these prokaryotic cells perform metabolic functions
• most of the genome consists of a circular chromosome

Question 8

Chp 27

Nucleoid

Answer 8

• where chromosome is located
• has no surrounding membrane

Question 9

Chp 27

Plasmids

Answer 9

• independtly replicating DNA found in typical prokaryotes
• have smaller rings

Question 10

Chp 27

Reproduction

Answer 10

• prokaryotes reproduce by binary fission and can divide every 1-3 hrs

Question 11

Chp 27

what are the key featires of prokaryote biology?

Answer 11

• they are small
• reproduce by binary fisiion
• have short generation times

Question 12

Chp 27

What three things contribute to prokaryotes’ genetic variation?

Answer 12

• rapid reproduction
• mutation
• genetic recombination

Question 13

Chp 27

Rapid reproduction and mutation

Answer 13

• prokaryotes reproduce asexually
• mutation rates are low but they accumulate rapidly (b/c generation times are short & populations are large)
• their cells have rapid adaptation to environmental change meaning that are highly evolved

Question 14

Chp 27

Genetic recombination

Answer 14

• def: combining of DNA from 2 sources that contributes to diveristy
• transformation, transduction, 7 conjugation facilitate this
• horizontal gene transfer: movement of genes among individuals from different species

Question 15

Chp 27

Transformation

Answer 15

when a prokaryotic cell takes up & incorporate foreign DNA from surrounding environment

Question 16

Chp 27

transduction

Answer 16

movement of genes between bacteria by phages (bacteriophages - viruses that infect bacteria)
1. phage infects bacterial donor cell that carries A+ & B+ alleles
2. phage dna is replicated & phage proteins are made
3. fragment of dna w/ A+ allele is packages within a phage capsid
4. phage w/ A+ allele infects bacterial recipient cell
5. incorporation of phage DNA creates recombinant cell with A+ & B-

Question 17

Chp 27

conjugation & plasmids

Answer 17

• conjugation: process where genetic material is transferred between prokaryotic cells
• the transferred DNA is often in the form of a plasmid
• F factor (piece of DNA) required for production of pili

Question 18

Chp 27

F factor as a plasmid

Answer 18

• F plasmid: DNA donors during conjugations
• Cells w/out f factor function as the recipient
• f factor is transferable during conjugation

Question 19

Chp 27

F factor in the chromosome

Answer 19

• cell with f factor in chromosome will be donot during conjugation
• ^^^ called Hfr cells (high frequenct of recombination)
• recipient becomes a recombinant bacterium with DNA from two different cells

Question 20

Chp 27

R plasmids and antibiotic resistance

Answer 20

• r plasmids carry genes for antibiotic resistance
• antibiotics dont kill bacteria with specific r plasmids
• some r plasmids carry genes for resistance to multiple antibiotics

Question 21

Chp 27

how are prokaryotes categorized by how they obtain energy/carbon?

Answer 21

• phototrophs obtain energy from light
• chemotrophs obtain energy from chemicals
• autotrophs require carbon dioxide as a carbon source
• heterotrophs require organic nutrient to make organic compounds

Question 22

Chp 27

Photoautotroph

Answer 22

• energy source: light
• carbon source: CO2, HCO3, etc…
• types of organisms: photosynthetic prokaryotes

Question 23

Chp 27

Chemoautotroph

Answer 23

• energy source: inorganic chemicals
• carbon source: CO2, HCO3, etc…
• types of organisms: unique to certain prokaryotes

Question 24

Chp 27

Photoheterotroph

Answer 24

• energy source: light
• carbon source: organic compounds
• types of organisms: unique to certain aquatic & salt-loving prokaryotes

Question 25

# **Chp 27** Chemoheterotroph

Answer 25

* enerygy souce: light * carboon osurce: organic compounds * types of organisms: many prokaryotes

Question 26

# **Chp 27** role of oxygen in metabolism

Answer 26

* obligate aerobes: require O2 for cellular respiration * obligate anaerobes: poisoned by O2 and live by fermentation * facultative anaerobes: can/cant use O2 depending on presence of O2

Question 27

# **Chp 27** nitrogen metabolism

Answer 27

* prokaryotes can metabolize nitrogen via nitrogen fixation * converting atmospheric nitrogen to ammonia

Question 28

# **Chp 27** metabolic cooperation

Answer 28

* allows prokaryotes to use environmental resources they could not use as individual cells * heterocysts: nitrogen-fixing cells * biofilms: surface coaitng colonies where metabolic cooperation between different proakryotes take place

Question 29

# **Chp 27** bacteria

Answer 29

diverse nutrional types are represented among bacteria

Question 30

# **Chp 27** proeobacteria

Answer 30

* gram negative * include photoautotrophs, chemoautotrophs, & heterotrophs * some anaerobic & others aerobic * 5 subgroups

Question 31

# **Chp 27** Alpha proteobacteria

Answer 31

* closely associated w/ eukaryotic hosts * hypothesize that mitochondria evolved from aerobic alpha via endosymbiosis

Question 32

# **Chp 27** Beta proteobacteria

Answer 32

* nutritionally diverse * other members include aquatic species & pathogens

Question 33

# **Chp 27** Gamma proteobacteria

Answer 33

* include sulfur bacteria * some are pathogenic * some can reside in the intestines of many mammals *ex: salmonella, escherichia coil

Question 34

# **Chp 27** Delta proteobacteria

Answer 34

* ex: myxobacteria prodouces drought-resistant myxospores * ex: bdellovibrios: mount high speed attacks on other bacteria

Question 35

# **Chp 27** Epsilon proteobacteria

Answer 35

* most are pathogenic * ex: *campylobacter* which causes blood poisoning & *helopcobacter pylori* which causes stomach ulcers

Question 36

# **Chp 27** Chlamydias

Answer 36

* parasites that live within animal cells

Question 37

# **Chp 27** Spirochetes

Answer 37

* helical gram-negative heterotrops * some are parasites which cause syphilis and lyme disease

Question 38

# **Chp 27** Cyanobacteria

Answer 38

* gram negative photoautotrophs that make oxygen * plant chloroplasts via endosymbiois prob evolved from this * abundant components of freshwater & marine phytoplankton

Question 39

# **Chp 27** Archaea

Answer 39

* share certain traits w/ bacteri & other traits w/ eukaryotes * have many unique characteristics * extreme halophiles: live in highly saline environments * extreme thermophiles: trhive in very hot environments * mthanogens: live in swamps & marshes and produce methan as waste

Question 40

# **Chp 27** Chemical recycling

Answer 40

* prokaryotes recycle chemical elements between components of the environment * decomposers: some chemoheterotrophic; break down dead organisms & waste products

Question 41

# **Chp 27** Ecological interactions

Answer 41

* symbiosis: two species live in close contact: a larger host & smaller symbiont * prokaryotes often do this with larger organisms * parasites that cause disease are called pathogens

Question 42

# **Chp 27** Mutalistic bacteria

Answer 42

they break down food that is undigested by human intestine

Question 43

# **Chp 27** pathogenic bacteria

Answer 43

bacteria cause about half of all human diseases

Question 44

# **Chp 27** exotoxins vs endotoxins

Answer 44

* exotoxin: secreted and cause disease; cell purposely release this to harm/protect cell * endotoxin: released only when bacteria die and cell wall breaks down