Test 1 - Microbal Diversity Flashcards
What are 3 Domains?
Bacteria, Eukarya, Archaea
Which of the domains contain microorganisms? Specific groups within Eukarya.
Bacteria, Archaea, and Eukarya (within algae, fungi, and protists)
Which two among the 3 domains share the most recent common ancestor?
Archaea and Eukarya.
What characteristics do all 3 domains share?
Information processing (D->R->P) & Chromosomal Material (DNA)
What characteristics do bacteria and archaea share, without eukarya?
Bacteria and Archaea do not have nucleus. They have operons.
What characteristics are unique to eukarya?
Organelles and 80s ribosomes (compared to 70s).
What characteristics do archaea and eukarya share that bacteria do not? What can we conclude?
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.
List the major events surrounding advent of life: (a) 4.5 BYA - (b) 3.4 BYA - (c) 2.7 BYA - (d) 1.5 BYA-
(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
What happened during the Oxygen Crisis? When did it happen?
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.
What is the Endosymbiotic Theory (with Mitochondria)? When did it happen?
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.
What is the Endosymbiotic Theory (with Chloroplast)? When did it happen?
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.
Evidence for Endosymbiotic Theory?
- 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.
Make the renewed tree of life with example organisms.
Common Ancestor
- Bacteria
(ex. cyanobacteria + protobacteria) - Pro-Eukaria
- Archaea
1+ 2 –> Eukaryotes (Plants or Animals and Protists)
What are all bacteria descended from?
Cyano or protobacteria.
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?
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.
What is rate of DNA mutation?
1/106 BP
What is the effect of detrimental mutation?
Immediate death or poor reproduction, both leading to death without reproduction.
What are some types of mutations that may be beneficial?
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)
What is the assumption underlying the theory of the Molecular Clock?
Accumulation of mutations can tell how many years ago the species diverged from each other. (Based on mutations during replication).
How to choose comparative gene for Molecular Clock?
- Function conserved in all organisms. (Same funciton = same selective pressure)
- Generational time between organisms same. (Fast generation time = Rapid mutation accumulation.)
- Mutation rate constant across generations.
Usually small rRNA (16s or 18s)
Why is small rRNA DNA useful as Molecular Clock?
- Conserved across species.
- Some highly conserved parts (++ selective pressure.)
- Some not so highly conserved part (– selective pressure; this part used for Molecular Clock.)
How to make Phylogenic Tree?
- Collect sequences.
- Perform pairwise comparison.
- Measure similarities/divergences.
What does unrooted tree show? What does it not show?
It shows relatedness of different organisms. It does not show evolutionary path (ex. common ancestor)
What does rooted tree show? What can be an outgroup for bacteria?
Relatedness and evolutionary path. Outgroup can be an eukaryote.
