MICR 271 Exam Questions with Correct Answers
3 Domains
1)Archaea
2)Bacteria
3)Eukaryota
Endosymbiont Theory Definition
Eukaryotes evolved from prokaryotes based on similarities found between bacteria and
mitochondria
Microbe Definition
microscopic living organism that may be single celled (prokaryotic) or multicellular
(eukaryotic)
_____________ is abundant in the atmosphere but only a few species of microbes can
use it in this form
Nitrogen
The total biomass on Earth of bacteria is approaching that of ________
plants
There are typically ____________ bacteria in a gram of soil and __________________
bacteria in a mL of fresh water
50 million; 1 million
A human consists of __________ more bacteria cells than human cells and
____________ more microbial genes than human genes
,10x; 100x
Photosynthetic bacteria (cyanobacteria) produce _____________________
50% of the oxygen we breathe
STUDY CHART W DIFFERENCES BW EUKARYOTES & PROKARYOTES
Major difference in structure of eukaryotes vs prokaryotes
Eukaryotes have membrane bound organelles and prokaryotes do not
Explain the endosymbiotic theory
1)Eukaryotes evolved from prokaryotes based on similarities bw bacteria and mitochondria
2)Mitochondria & chloroplasts evolved from free-living bacteria via symbiosis within a
eukaryotic host cell
3)2 key diffs bw bacteria & miochondria= these organelles contain their own DNA & distinct
translation system
What are the 2 theories of mitochondrial symbiosis/endosymbiont hypothesis
1)Archezoan Scenario
2)Symbiogenesis Scenario
Define symbiosis
Living together or close association of 2 dissimilar organisms, each of these organisms being
known as a symbiont
Archezoan Scenario
-one of the theories of mitochondrial symbiosis
-A primitive mitochondrial eukaryote cell phagocytosed an a-proteobacterium which led to
, evolution of mitochondrion
-fallen out of favour
Symbiogenesis Scenario
-theory of endosymbiont theory/mitochondrial symbiosis
1)States complexity of eukaryotic cell and its defining features emerged after mitochondrial
symbiosis, not before
2)Single endosymbiotic event involving the uptake of an a proteobacterium by an archaeal
cell led to generation of mitochondria and then the evolution of nucleus &
compartmentalization of eukaryotic cell occured
Phylogeny definition
The evolution of a genetically related group of organisms as distinguished from the
development of the individual organisms
What did initial efforts to map phylogenetic relationships rely on?
comparing ribosomal RNA data between organisms to create a tree of life
What was the major finding of the older version of the tree of life?
The close relationship between archaea and Eukaryota
Phylogenetic tree vs phylogenomic tree
phylogenetic-compared rRNA sequences
phylogenomic-compared entire genomes
Original tree of life depicted the evolutionary distance between archaea and eukaryotes
to be ___________________ than it actually is
much further
3 Domains
1)Archaea
2)Bacteria
3)Eukaryota
Endosymbiont Theory Definition
Eukaryotes evolved from prokaryotes based on similarities found between bacteria and
mitochondria
Microbe Definition
microscopic living organism that may be single celled (prokaryotic) or multicellular
(eukaryotic)
_____________ is abundant in the atmosphere but only a few species of microbes can
use it in this form
Nitrogen
The total biomass on Earth of bacteria is approaching that of ________
plants
There are typically ____________ bacteria in a gram of soil and __________________
bacteria in a mL of fresh water
50 million; 1 million
A human consists of __________ more bacteria cells than human cells and
____________ more microbial genes than human genes
,10x; 100x
Photosynthetic bacteria (cyanobacteria) produce _____________________
50% of the oxygen we breathe
STUDY CHART W DIFFERENCES BW EUKARYOTES & PROKARYOTES
Major difference in structure of eukaryotes vs prokaryotes
Eukaryotes have membrane bound organelles and prokaryotes do not
Explain the endosymbiotic theory
1)Eukaryotes evolved from prokaryotes based on similarities bw bacteria and mitochondria
2)Mitochondria & chloroplasts evolved from free-living bacteria via symbiosis within a
eukaryotic host cell
3)2 key diffs bw bacteria & miochondria= these organelles contain their own DNA & distinct
translation system
What are the 2 theories of mitochondrial symbiosis/endosymbiont hypothesis
1)Archezoan Scenario
2)Symbiogenesis Scenario
Define symbiosis
Living together or close association of 2 dissimilar organisms, each of these organisms being
known as a symbiont
Archezoan Scenario
-one of the theories of mitochondrial symbiosis
-A primitive mitochondrial eukaryote cell phagocytosed an a-proteobacterium which led to
, evolution of mitochondrion
-fallen out of favour
Symbiogenesis Scenario
-theory of endosymbiont theory/mitochondrial symbiosis
1)States complexity of eukaryotic cell and its defining features emerged after mitochondrial
symbiosis, not before
2)Single endosymbiotic event involving the uptake of an a proteobacterium by an archaeal
cell led to generation of mitochondria and then the evolution of nucleus &
compartmentalization of eukaryotic cell occured
Phylogeny definition
The evolution of a genetically related group of organisms as distinguished from the
development of the individual organisms
What did initial efforts to map phylogenetic relationships rely on?
comparing ribosomal RNA data between organisms to create a tree of life
What was the major finding of the older version of the tree of life?
The close relationship between archaea and Eukaryota
Phylogenetic tree vs phylogenomic tree
phylogenetic-compared rRNA sequences
phylogenomic-compared entire genomes
Original tree of life depicted the evolutionary distance between archaea and eukaryotes
to be ___________________ than it actually is
much further
