Lecture 3: Bacteria and Archaea

Question 1

How can Prokaryotic tolerate extreme conditions?

Answer 1

• High Salinity
• Radiation
• Low pH
• Extreme temp (hot/cold)
• In rocks below earth’s surface

Question 2

Who developed Gram Staining?

Answer 2

Hans Christian Gram

Question 3

What is the purpose of Gram Staining?

Answer 3

Determines the type of bacteria

Question 4

Color posses in Gram +

Answer 4

purple

Question 5

Color posses in Gram -

Answer 5

pink

Question 6

What do cell wall contains in Prokaryotes and what purpose does it serve?

Answer 6

Maintains cell shape and contains peptidoglycan

Prevents cell from lysing (cell bursting)

Question 7

Gram + vs Gram -

Answer 7

Gram (+) => - high peptidoglycan
- Stain Purple
- use antibiotics that inhibit peptidoglycan cross- linking

Gram (-) => - thin layer of peptidoglycan
- Outer membrane containing lipopolysaccharides (lipoprotein)

Question 8

Capsule def

Answer 8

Cell wall surround by sticky layer of polysaccharide (protein)

Question 9

Functions of Capsule

Answer 9

• Adhere to substrate
• Protects against dehydration
• Shield pathogenic prokaryotes from attack by their hosts immune system

Question 10

Endospores def

Answer 10

Bacteria develop resistance cells to withstand harsh conditions

Question 11

Function of Fimbriae

Answer 11

Allow prokaryotes to stick to their substrate or to one another

Question 12

Function of Pili

Answer 12

Appendages that pull two cells together prior to DNA transfer from one cell to the other

Also called Sex Pilus (exchange in genetic info)

Question 13

Motility (moving)
How do prokaryotes move?

Answer 13

Half are moved by taxis
Taxis- directed movement toward or away from a stimulus

Stimulus= Chemotaxis (+ or -)

(+) Effect of Chemoattractants => towards
(-) Effect of Chemoattranctants => away

Question 14

Function of Flagella

Answer 14

Common structure that enable prokaryotes to move

• Arose independently
• Analogous structures

Question 15

Internal Organization and DNA (prokaryotes)

Answer 15

• simple
• circular chromosomes (dsDNA)
• Plasmids (smaller rings of independently replicating DNA molecules)
• Replication is similar but ribosomes are different

Question 16

Reproduction of Prokaryotes

Answer 16

Reproduce by Binary Fission (asexual)
- very short generation times

Question 17

Would you expect low or high levels of genetic diversity within prokaryotes?

Answer 17

High levels

Question 18

3 High levels of genetic diversity are due to…

Answer 18

Rapid Reproduction
Mutations
Genetic Recombination

Question 19

The significance of and mechanisms (3) by which recombinant bacteria form

Answer 19

Three mechanisms:
- Transformation
- Transduction
- Conjugation

Significance:
= Transformation- Cell is recombinant; cell surface proteins recognize foreign DNA from a closely related species & transport it to cell

= Transduction- bacteriophages carry prokaryotic genes from one host cell to another

= Conjugation- DNA is transferred b/w 2 prokaryotic cells (usually of the SAME SPECIES) that are temporarily joined; forms temporary “mating bridge” by sex pilus

Question 20

Compare and contrast the mechanisms (3) [great short ans/ essay question]

Answer 20

Transformation deals with taking in foreign DNA (genetic material) through the cell membrane and into its genome.

Transduction is a bacteriophage injecting the foreign DNA into the hosts cell.

Conjugation is DNA being joined by 2 prokaryotic cells (same species) by a temporary “mating bridge” (sex pilus)

Compare: mechanisms that allow DNA to be transfered from one cell to another.

Question 21

F plasmid (F+ cell) vs. Hfr cell (donor)

Answer 21

F plasmid (+) = fertility factor in plasmid
- part of chromosome transferred

Hfr cell= [High Freq recombination] fertility factor is located bacterial chromosome (whole transferred)

Question 22

Nutritional & Metabolic Adaptations
Phototrophs

Answer 22

derive energy from light

Question 23

Chemotrophs

Answer 23

obtain energy from chemicals

Question 24

Autotrophs

Answer 24

need only CO2 or related inorganic compounds as a carbon source (photosynthetic)

Question 25

Heterotrophs

Answer 25

require @ least one organic nutrient (ex: glucose)

Question 26

Role of Oxygen in Metabolism Obligate aerobes

Answer 26

MUST use O2 for cellular respiration and CANNOT grow without it

Question 27

Obligate anaearobes

Answer 27

Poisoned by O2 and some live by fermentation, other extract chemical for anaerobic respiration

Question 28

Facultative anaerobes

Answer 28

use O2 if its present BUT can also carry fermentation or anaerobic respiration

Question 29

Nitrogen Metabolism

Answer 29

- production of AA and nucleic acids - Prokaryotes can metabolize nitrogen in many forms

Question 30

Nitrogen Fixation

Answer 30

- some cyanobacteria can convert to atmospheric nitrogen to AMMONIA - incorporated into AA and other organic molecules

Question 31

Two Domains in Prokaryotes

Answer 31

Domain Archaea Domain Bacteria

Question 32

What plays a key role in the evolution of prokaryotes?

Answer 32

Horizontal gene transfer - genetic diversity is immense

Question 33

Alpha Proteobacteria

Answer 33

Mitochondria may have evolved from aerobic alpha proteobacteria

Question 34

Beta Proteobacteria

Answer 34

Aquatic and soil bacteria as well as the species that causes gonorrhea - Recycling Nitrogen

Question 35

Gamma Proteobacteria

Answer 35

Include Legionnaires' disease, Salmonella, cholera, & E. coli

Question 36

Delta Proteobacteria

Answer 36

slime- secreting myxobacteria

Question 37

Epsilon Proteobacteria

Answer 37

Most are pathogenic to human or other animals - Blood poisoning, stomach ulcers (Helicobacter pylori)

Question 38

Archaea

Answer 38

- Extremophiles (known as loving extreme conditions) halophiles - live in high saline environ Thermophiles- live in very hot environ

Question 39

Importance of Prokaryotes in biosphere

Answer 39

Chemical Recycling - Function as decomposers - Convert molecules to forms that can be taken up by other organisms

Question 40

Symbiosis

Answer 40

Two species live in close contact w/ each other

Question 41

Mutualism

Answer 41

Both species benefit - E. coli in your intestines helps absorb vitamin K

Question 42

Commensalism

Answer 42

One species benefits while other is neither harmed nor helped

Question 43

Parasitism

Answer 43

Eat cell contents, tissues, or body fluids of host - harm but usually don't kill their host

Question 44

Pathogens

Answer 44

disease causing bacteria

Question 45

Cyanobacteria

Answer 45

- Photoautotrophs - Gram (-) - ONLY prokaryotes that perform PLANT-LIKE, O2 producing photosynthesis - ancestral species form which chloroplasts evolved