Evolution & Taxonomy

Question 1

How long ago did water form on earth?

How long ago do we have chemical evidence of microbes?

How long ago do we have fossil evidence of microbes?

Answer 1

1. 4.3 billion years ago
2. 4.2 billion years ago
3. 3.8 billion years ago

Question 2

What are the stromatolites?

Answer 2

• Earliest form of microbial life, that we know of?
• Layers of filamentous prokaryotes.
• Ancient - anoxygenic phototophic filamentous - don’t produce oxygen
• Modern - oxygenic phototrophic cyanobacteria

Question 3

Why must microbes have 1st formed in a biotic environment?

Answer 3

• Physch!
• Both of our theories on the origin of cellular life assume that early microbes formed by abiotic systems.

Question 4

What is the surface origin hypothesis?

Answer 4

• First membrane-enclosed, self-replicating cells arose out of primordial soup rich in organic and inorganic compounds in ponds on Earth’s surface

Question 5

What argues against the surface origin hypothesis?

Answer 5

• The fact that there were: dramatic temperature fluctuations and mixing from meteor impacts, dust clouds, and big ole storms.

Question 6

What is the Subsurface origin hypothesis?

Answer 6

• Life originated at hydrothermal springs on ocean floor
  
  • conditions would have been more stable than at the surface
  • Steady adn abundant supply of energy (h2 and H2S) could have been available at these sites.

Question 7

What was the clay that was rich in nutrients around the hydrothermal vents?

Answer 7

Montmarillamite?

Question 8

What does LUCA stand for?

Answer 8

Last Universal Common Ancestor

Question 9

1. What experiment proved that the original amino acids could have formed spontaneously?
2. What ingredients were used?

Answer 9

• Miller-Urey
• Methan, Ammonia, Hydrogen gas, add eletrical pulse, add heat.

Question 10

What is an example of catalytic RNA, and why is this important?

Answer 10

• 23s RNA
• This has to do with the RNA world theory. RNA was the first genetic material to be formed, and then subsequently proteins and DNA. However, the RNA would have needed to be able to stuff to itself…so it would need catalytic activity. 23s RNA proves that RNA can be catalytic.

Question 11

What is the RNA world theory?

Answer 11

• First self-replicating systems may have been RNA-based
  
  • RNA can bind small molecules (ATP, other nucleotides)
  • RNA has catalytic activity, may have catalyzed its own synthesis.

Question 12

Why is the buildup of lipids in the clay around hydrothermal vents important?

Answer 12

• The build up of lipids could lead to a lipid bi layer - which encloses and protects RNA/DNA/proteins and keeps them close to each other….LUCA??

Question 13

Approximately, how long ago did Archaea and Bacteria split, evolutionarily?

Answer 13

3.8 billion years ago.

Question 14

What bacteria developed the ability to use H20 instead of H2S for generating O2?

Answer 14

Cyanobacteria

Question 15

When is thought that Eukaryotes diverged from Archaea?

Answer 15

1.5- 2.0 billion years ago.

Question 16

What is the great oxidation event?

Answer 16

• ~2.4 billion years ago, O2 concentrations raised to 1 part per million (in atmosphere)
• O2 need to react with reduced materials in ocean to become abundant.

Question 17

[] spurred evolution of organelle-containing eukaryotic microorganisms…

Answer 17

Oxygen

Question 18

Endosymbiotic Theory 1:

• [] began as nucleus-bearing lineage that later acquired [] and chloroplasts by endosymbiosis

Answer 18

1. Eukaryotes
2. mitochondria

Question 19

Endosymbiotic Theory 2) Hydrogen Theory:

• [] cells arose from intracellular association between 02-consuming/ [] -[] bacterium (the []) which gave rise to micochondria, and the [] host.
• The nucleus formed before or after divergement of Archaea and Eukaryotes???

Answer 19

1. Eukaryotic
2. H2-producing
3. Symbiont
4. Archaeal

• before divergement
• Supported:
  
  • Eukaryoties have similar lipids and enrgy metabolism to bacteria
  • Have transcription and translational machinery similar to archaea

Question 20

Both endosymbiont theories suggest teh eukaryotic cell is [] ….?

Answer 20

Chimeric

Question 21

What are 2 reason supporting the Hydrogen Endosymbiotic Theory?

Answer 21

1. Eukaryotes have similar lipid and energy metabolisms to bacteria
2. Eukaryotes have transcription and translational machinery similar ot Archaea

So: The H2 producing ancestor of Arch/Euk engulfed the O2 producing bacteria - energy and lipid…while the nuclue formed after using the existing Arch/Eukk ancestor…so the transcript and translational machinery carried over.

Question 22

What are 5 modes of mutation/genetic change?

Answer 22

1. Single base changes
2. Gene duplication
3. Horizontal gene transfer
4. Gene loss
5. Insertions by mobile elements

Question 23

[] mutations improvie fitness of an organism, increasing its survival.

Answer 23

adaptive

Question 24

[] and [] mutations will be carried on from generation to generation?

Answer 24

Beneficial and Neutral

Deleterious should be lost.

Question 25

Why does evolution occur more quickly in Bacteria/Archaea?

Answer 25

• fast generation time
• Unicellular
• haploid, smaller
• Big population size
• Selection is tronger

Question 26

Genetic [] acts on the changes casued by evolution/mutation?

Positively changes =

Negative changes =

Answer 26

1. Selection
2. Positive change - beneficial mutation creates bacteria with higher fitness.
3. Negative change - eliminates deleterious mutations creating bacteria wiht lower fitness

Question 27

What is Genetic drift?

Answer 27

• Random process that can cause changes in allele frequencies over time.
• Can cause evolutionary divergence of population due to randomness
• Independent of selection.

Question 28

What is a molecular clock?

What is the criteria to be a molecular clock?

Answer 28

1. Certain genes and proteins that are measure of evolutionary change
2. Found in all domains of life
3. Functionally constant
4. Sufficiently conserved
5. Sufficient length

Question 29

Who established the evidence for the 3 domains of life?

Answer 29

Carl Woese

Question 30

What are the currently used molecular clocks?

Answer 30

16s for Archaea and Bacteria

18s for Eukaryotes

Question 31

What are the 3 steps of Comparative rDNA sequencing?

Answer 31

1. Amplification of gene encoding SSU rRNA
2. Sequencing of the amplified gene
3. Analysis of sequence in referene to other sequences

Question 32

What is the cladistic method for constructing a phylogenetic tree?

Answer 32

• define phylogenetic relationships by examining changes in nucleotides at individual positions in the sequence
• Use those characters that are phylogenetically informative and define monophyletic groups.

Question 33

What phylogenetic group of bacteria contain most of the human pathogens?

Answer 33

Proteobacteria.

Question 34

What are the 2 major groups of Archaea?

Answer 34

Crenarchaeota

Euryarchaeota

Question 35

1. There is [] universally accepted concept of species for prokaryotes

Answer 35

NO

Question 36

What are the 3 traits used to define/compare species of bacteria?

Answer 36

1. 70% or greater DNA-DNA hybridization
2. 98.7% or greater 16s rRNA gene sequence identity
3. Share multiple phenotypes

Question 37

What is better in differntiating a “species” of bacteria, 16s rRNA sequencing or MLST?

Answer 37

• Multi-Locus sequence Typing - uses more information.
• 16s is sometimes too conserved and is can be tough to differentiate