Test 1 - Microbal Diversity

Question 1

What are 3 Domains?

Answer 1

Bacteria, Eukarya, Archaea

Question 2

Which of the domains contain microorganisms? Specific groups within Eukarya.

Answer 2

Bacteria, Archaea, and Eukarya (within algae, fungi, and protists)

Question 3

Which two among the 3 domains share the most recent common ancestor?

Answer 3

Archaea and Eukarya.

Question 4

What characteristics do all 3 domains share?

Answer 4

Information processing (D->R->P) & Chromosomal Material (DNA)

Question 5

What characteristics do bacteria and archaea share, without eukarya?

Answer 5

Bacteria and Archaea do not have nucleus. They have operons.

Question 6

What characteristics are unique to eukarya?

Answer 6

Organelles and 80s ribosomes (compared to 70s).

Question 7

What characteristics do archaea and eukarya share that bacteria do not? What can we conclude?

Answer 7

Achaea and Eukarya have histones/nucleosomes, introns, and more than one RNA Polymerase. Hence, ARCHAE AND EUKARYA HAVE A COMMON ANCESTOR MORE RECENT THAN WITH BACTERIA.

Question 8

List the major events surrounding advent of life: (a) 4.5 BYA - (b) 3.4 BYA - (c) 2.7 BYA - (d) 1.5 BYA-

Answer 8

(a) 4.5 BYA - Earth formed (b) 3.4 BYA - 1st Life Forms (anaerobic prokaryotes) (c) 2.7 BYA - The Oxygen Crisis (d) 1.5 BYA - 1st Eukaryote thru Endosymbiotic Theory

Question 9

What happened during the Oxygen Crisis? When did it happen?

Answer 9

2.7 BYA - The Oxygen Crisis - Oxygenic photosynthesis by cyanobacteria->O2 accumulation->POISON TO ANAEROBES - Species in anaerobic environment prevailed, but rest died or became aerotolerant or aerobic.

Question 10

What is the Endosymbiotic Theory (with Mitochondria)? When did it happen?

Answer 10

1.5 BYA - Endosymbiotic Theory - Pre-Eukaryotic anaerobe (fed by engulfing other bacteria) engulfed a Pre-Mitochondria aerobic bacteria. - Pre-Eukaryote received immunity to O2 & ATP - Pre-Mitochondria received shelter and food.

Question 11

What is the Endosymbiotic Theory (with Chloroplast)? When did it happen?

Answer 11

1.5 BYA - Endosymbiotic Theory - Pre-Eukaryotic anaerobe (fed by engulfing other bacteria) engulfed a Pre-Chloroplast aerobic bacteria. - Pre-Eukaryote received immunity to O2 & ATP (as well as IT NO LONGER NEEDED TO HUNT FOR FOOD) - Pre-Chloroplast received shelter and food.

Question 12

Evidence for Endosymbiotic Theory?

Answer 12

• Mitochondria and Chloroplast both have double membranes like bacteria; bacteria wall is the basis for the double membrane - M + C have own ribosomes and genomes that are similar to bacterial ribosomes and genomes.

Question 13

Make the renewed tree of life with example organisms.

Answer 13

Common Ancestor

1. Bacteria
   (ex. cyanobacteria + protobacteria)
2. Pro-Eukaria
3. Archaea

1+ 2 –> Eukaryotes (Plants or Animals and Protists)

Question 14

What are all bacteria descended from?

Answer 14

Cyano or protobacteria.

Question 15

Why is it unreasonable to define species by whether it can mate to produce viable fertile offspring? What methods are used instead? What are the faults of the methods? What is the better method?

Answer 15

Bacteria reproduce asexually. Charateristics are used to differentiate species instead, with the assumption that closely related species look alike. Assumption is faulty becaues charateristics may be adaptive according to environment, and closely related organisms may have ∆characteristics (ex. E.coli are sometimes harmless, sometimes harmful for humans.). Better method is using genomic sequencing.

Question 16

What is rate of DNA mutation?

Answer 16

1/10⁶ BP

Question 17

What is the effect of detrimental mutation?

Answer 17

Immediate death or poor reproduction, both leading to death without reproduction.

Question 18

What are some types of mutations that may be beneficial?

Answer 18

More efficient enzymes or loss of useless gene, both contributing to more efficiency in energy consumption (less E expended for gene replication or life processes)

Question 19

What is the assumption underlying the theory of the Molecular Clock?

Answer 19

Accumulation of mutations can tell how many years ago the species diverged from each other. (Based on mutations during replication).

Question 20

How to choose comparative gene for Molecular Clock?

Answer 20

1. Function conserved in all organisms. (Same funciton = same selective pressure)
2. Generational time between organisms same. (Fast generation time = Rapid mutation accumulation.)
3. Mutation rate constant across generations.
   Usually small rRNA (16s or 18s)

Question 21

Why is small rRNA DNA useful as Molecular Clock?

Answer 21

1. Conserved across species.
2. Some highly conserved parts (++ selective pressure.)
3. Some not so highly conserved part (– selective pressure; this part used for Molecular Clock.)

Question 22

How to make Phylogenic Tree?

Answer 22

1. Collect sequences.
2. Perform pairwise comparison.
3. Measure similarities/divergences.

Question 23

What does unrooted tree show? What does it not show?

Answer 23

It shows relatedness of different organisms. It does not show evolutionary path (ex. common ancestor)

Question 24

What does rooted tree show? What can be an outgroup for bacteria?

Answer 24

Relatedness and evolutionary path. Outgroup can be an eukaryote.