Topic 7: Prokaryotes

Question 1

what are prokaryotes 2 domains

Answer 1

-Domain Bacteria
-Domain Archaea

Question 2

what the earliest life from

Answer 2

Prokaryotes
they were the first unicellular organisms
-stromatolites:
they are rock-like structures composed of layers of bacteria mats and sediments

Question 3

why are prokaryotes so successful?

Answer 3

advantages include
-their small size meaning they don’t require much energy to function
-use binary fission-meaning rapid rates of reproduction
-short generation time-able to evolve faster due to the accumulation of more DNA replication errors
overall meaning they are adaptable

Question 4

prokaryotic cells are composed of

Answer 4

-fimbriae- protein structures located at the surface of bacterial cells
-plasma membrane and cell wall
-circular DNA
-pilus- used for horizontal gene transfer
-flagellum-long tails enables movement

Question 5

what do prokaryotes lack

Answer 5

-they lack a nucleus, the circular ring of DNA isn’t enclosed by a membrane, like in eukaryotes
-they lack membrane-enclosed organelles like the Golgi apparatus, mitochondria, etc.

Question 6

what happens when u asexual reproduction fission with short regeneration time

Answer 6

high mutation rate which increases genetic diversity

Question 7

How do bacteria exchange genetic information

Answer 7

through horizontal gene transfer-(movement of genetic information between organisms)

Question 8

what are the three types of horizontal gene transfer’s

Answer 8

-transformation: when there is “naked” DNA picked up from the dead bacteria
-transduction: DNA is transmitted from one cell to another via bacteriophage (virus)
-Conjunction-cells make contact via pilus and exchange their DNA

Question 9

How do prokaryotes obtain Nutrients

Answer 9

either
-Autotrophs-they make their energy from inorganic sources
-Heterotrophs-they make their energy by consuming inorder to get organic molecules

Question 10

the 2 types of autotrophs are

Answer 10

-chemoautotrophs-use energy obtained by oxidizing inorganic chemicals and CO2 (these are most prokaryotes)
-Photoautotophs- use light energy and CO2 (these are the primary producers that support the food web)

Question 11

the 2 types of Heterotrophs

Answer 11

-Photoheterotrophs -use light energy and carbon source from organic molecules
-Chemoheterobtrophs- use organic molecules for both energy and carbon source

Question 12

ecological relationships (5)

Answer 12

1. Mutualism-both organisms benefit from the other presence
2. Competition-neither of the 2 organisms benefits from the other presence
   3.Predation(one eats the other) or Parasitism(one steals the nutrients of the other)-one benefits and the other doesn’t
3. Communalism- one is benefiting and the other isn’t harmed not benefiting, just neutral
4. Amensalism- one is harmed and the other is neutral

Question 12

prokaryotes are…

Answer 12

symbiotic
-when inside the host , its an endosymbiotic relationship

Question 13

what is the difference between bacteria and Archaea

Answer 13

-Bacteria have peptidoglycan in the cell wall whereas archaea don’t
-Bacteria respond to antibiotics that inhibit eubacterial growth whereas archaea don’t
-Archaea can live in extremely harsh conditions (extremophiles)

Question 14

domain archaea are extremophiles meaning…

Answer 14

-they can live in extreme conditions…they are:
Methanogens -live in oxygen-free habitats
Halophiles- live in very salty habitats
Thermophiles- live in very hot habitats

Question 15

Domain Bacteria: Systematics of Eubacteria

Answer 15

1. Proteobacteria (important)
2. Chlamydias
3. spirochetes
4. Cyanobacteria (important)
5. Gram-positive bacteria (important)

Question 16

Domain Bacteria’s cell walls contain what?

Answer 16

contain peptidoglycan

Question 17

what does peptidoglycan do

Answer 17

it provides:
-cell shape
-protection
-prevents the cell form from exploding when placed in a hypotonic solution (lower solute than cell contents meaning that solution goes into the cell causing it to overfill)

Question 18

Gram+ve vs. Gram-ve what happens with the gram stain test

Answer 18

the gram stain test is when you expose the bacteria to crystal violet in order to understand whether its Gram +ve or Gram -ve

Gram +ve -have peptidoglycan wall in contact with an external medium which traps purple stains

Gram -ve have a lipopolysaccharide layer outside of the cell wall, thus do not absorb the stain readily- stain pink

Gram -ve are often pathogenic (cause diseases), as the outer lipopolysaccharide layer can contain toxins and resit action of antibiotics

Question 19

Proteobacteria (what evolved form it )

Answer 19

-are Gram -ve bacteria (contain the lipopolysaccharide)
-include endosymbiotic mutualists like Rhizobium (lives in root nodules or leguminous plants and fixes atmospheric nitrogen to make available for the plant and in return gets carbohydrates
-scientist hyporthizied that mitochondria evolved form the aerobic alpha-proteobacteria through endosymbiosis (since it lives in a host )

Question 20

Chlamydias

Answer 20

-a pathogenic bacteria
-it lives within animal cells
-has no peptidoglycan in the cell wall, possibly because they live within other cells

Question 21

Spirochetes

Answer 21

-are pathogenic bacteria
-they are helical bacteria that swim by spiralling

Question 22

Cyanobacteria (what evolved form it )

Answer 22

-they are photoautotrophs ( meaning they make their energy using light energy and co2)
-they are the cause of oxygen being in our atmosphere billions of years ago since the bi production of photoautotrophs is oxygen
-the chloroplast evolved form the cynanobacteria

Question 23

pathogenic bacteria

Answer 23

-Gram +ve pathogenic bacteria
-spirochetes
chlamydias

Question 24

whats the importance of bacteria

Answer 24

-production of cheese and yogurt
-used to decompose sewage treatment
-decompose bioremediation (when an oil spill occurs in order to manage the spill these bacteria are put, and they eat up the oil spill)
-antibiotics
-are essential for the nitrogen and carbon cycle between the atmosphere and water
-makes nutrient available for animals through decomposing

Question 25

whats oxygenic photosynthesis

Answer 25

when water and another molecule is put in a reaction and the by-product in oxygen

Question 26

comapring