Lectures: Prokaryotes

Question 1

Prokaryotes

Answer 1

single-celled organism that lacks organelles and does not have nuclei surrounded by a nuclear membrane
e.g. bacteria & archaea

Question 2

Do Prokaryotes comprise a monophyletic group?

Answer 2

No, Prokaryotes are not a great term for understanding the evolution of biodiversity

Question 3

Are Archaea and Bacteria sister taxa?

Answer 3

No, Archaea is sister taxa with Eukarya

Question 4

Anoxic

Answer 4

no molecular oxygen

Question 5

Phototrophs

Answer 5

able to make its own food by converting solar energy to chemical energy

Question 6

Early prokaryotes were ______.

Answer 6

phototrophs

Question 7

What is another name for blue-green algae?

Answer 7

Cyanobacteria
- have oxygenic photosynthesis metabolism
- created oxygen as byproduct
- led to “oxygenation” of atmosphere
- allowed evolution of more efficient aerobic metabolism

Question 8

How is prokaryotes diversity studied and classified?

Answer 8

1. Cultures:
   - Collect samples and try to grow cultures in different mediums and temperatures
   - But, many can not be cultured
2. Metagenomics:
   - Collect massive amounts of DNA or RNA sequences soils or water
   – Detect species (genomic) or functional (expressed genes) diversity

Question 9

What has Metagenomics revealed?

Answer 9

uncharacterized diversity

Question 10

5 characteristics of a Prokaryote cell:

Answer 10

1. Unicellular and lack membrane-bound organelles
2. Circular chromosomes located in nucleoid
3. Protective cell wall
4. Some have capsule around cell wall
5. Some have flagella used for locomotion

Question 11

What are the 3 main shapes of the Prokaryotic cell?

Answer 11

1. cocci (spherical)
2. bacilli (rod-shaped)
3. spirilli (spiral-shaped)
   *archaea also have triangular and square shapes

Question 12

Cell Wall

Answer 12

Protective layer that gives cell shape and rigidity

Question 13

Bacterial cell walls contain _________, which is not in Archaea

Answer 13

Peptidoglycan

Question 14

Peptidoglycan

Answer 14

material composed of polysaccharide chains cross-linked to unusual peptides

Question 15

Bacteria can be split into 2 groups based on their reaction to what?

Answer 15

Gram Staining:
- Gram positive: contains mainly peptidoglycan in cell wall
- Gram negative: cell walls contain little peptidoglycan and an outer membrane

Question 16

How are Bacteria and Archaea reproduce?

Answer 16

Binary Fission (asexual):
- DNA uncoils and duplicates
- Cell grows in size
- DNA copies move towards opposite poles
- New cell wall spilts into two

Question 17

True or False. Binary Fission does not provide the opportunity for Recombination.

Answer 17

True, Recombination is seen in Eukarya and is an important source of genetic variation during sexual reproduction

Question 18

Horizontal Gene Transfer

Answer 18

• gene transfer between already existing organisms (donor & recipient)
• an important way for asexually reproducing organisms like prokaryotes to acquire new traits

Question 19

What are the 3 subtypes of HGT?

Answer 19

1. Transformation: uptake of DNA from the environment
2. Transduction: bacteriophage (virus) transfer DNA between cells
3. Conjugation: direct transfer by cell-to-cell contact

Question 20

How does HGT differ from sexual reproduction??

Answer 20

1. one-way transfer
2. Transfer is limited to a small number of genes

Question 21

What has higher mutation rates? Prokaryotes or Eukaryotes? Why?

Answer 21

Prokaryotes, due to how common HGT = high genetic diversity (e.g. “superbugs”)

Question 22

What are the dominant forms of life on Earth which are able to live in a wide variety or environments?

Answer 22

Bacteria and Archaea, due to wide diversity of metabolism (e.g. heterotroph, phototroph, etc)

Question 23

Photoautotroph:

Answer 23

• Energy from light
• Carbon from inorganic CO2
  e.g. plants. algae, cyanobacteria

Question 24

Photoheterotrophs:

Answer 24

• Energy from light
• Carbon from organic molecule
  e.g. only Bacteria and Archaea

Question 25

Chemoheterotrophs:

Answer 25

• Energy and carbon from organic
  material
  e.g. animals and plants, bacteria and archaea

Question 26

Chemoautotrophs:

Answer 26

• Energy from chemical reactions, carbon from inorganic CO2
  e.g. only Bacteria and Archaea

Question 27

What are Prokaryotic roles in the ecosystem?

Answer 27

1. major roles in the Carbon Cycle & Nitrogen Cycle
2. Photo- and chemoautotrophs
   convert CO2 to organic carbon
3. Together with fungi, prokaryotes
   are main decomposers (make organic compounds available for other organisms)

Question 28

Decomposers

Answer 28

organism that carries out the decomposition of dead organisms

Question 29

Nitrogen fixation

Answer 29

process by which gaseous nitrogen is transformed, or “fixed” into more readily available forms such as ammonia
(exclusive to Prokaryotes)

Question 30

Ammonification

Answer 30

process by which ammonia is released during the decomposition of nitrogen-containing organic compounds

Question 31

What is the focus on prokaryotes for?

Answer 31

For their potential to be pathogens (disease-causing) and how some are responsible for emerging diseases

Question 32

Emerging Diseases

Answer 32

disease making an initial appearance in a population or that is increasing in incidence or geographic range

Question 33

Antibiotic

Answer 33

biological substance that, in low concentration, is antagonistic to the growth of prokaryotes

Question 34

Microbiome

Answer 34

a community of microbes that share a
particular space

Question 35

Bioremediation

Answer 35

use of microbial metabolism to remove pollutants