MICR 271 EXAM 3 QUESTIONS AND
CORRECT ANSWERS!!
name the three domains of life
bacteria, archaea, eukaryotes
differences between proks and euks
- euks are more complex
- euks have a membrane-enclosed nucleus; proks have a nucleoid
- functional differences
- steps of transcription and translation
define the endosymbiont hypothesis
proposes that mitochondria and chloroplasts originated as free-living bacteria that were engulfed
by other microbes
a-proteobacteria is ancestor of mitochondria
what is a key difference between mito and chloroplasts?
- contain their own distinct genomes
- contain a distinct translation system
what is the archezoan scenario of ESH?
- archael ancestor with DNA
- primitive euk, with DNA enclosed in the nucleus
- a-proteobacterial insertion occurs
- diversification and mito evolution
why has the archezoan scenario fallen out of favour?
the original phylogenetic analysis incorrectly placed branches of euk protists close to the base of
the tree of life
,what is the symbiogenesis scenario of ESH?
- archael ancestor with DNA; a-proteobacterial insertion
- primitive euk, with DNA and the a-proteobacteria loose
- evolution of the nucleus
- diversification into proto-euks
* essentially states that euk complexity evolved after mito symbiosis
(a) define phylogeny
(b) on what is the phylogenetic analysis of organisms based?
(a) the evolution of a genetically related group of organisms as distinguished from the
development of the individual organisms. the more similar organisms are, the closer their genetic
relationships are
(b) the entire genome (a large data pool) so the assumptions are less problematic than if it were
based on only rRNA sequences
differentiate between bacteria, archaea and euks in terms of
(a) presence of nucleus
(b) number of RNA polymerase subunits
(c) size of ribosomal subunit
(d) presence of murein/PG in cell wall
(a) euks only
(b) bacteria 3-4, archaea 8-12, euks 12-14
(c) bacteria 70s, archaea 70s, euks 80s
(d) bacteria only
what do the links between the web of life symbolize?
horizontal gene transfer that has always occurred between unicellular organisms
define horizontal gene transfer (HGT)
movement of genetic material between organisms other than vertical transmission
, define a virus
an obligate intracellular parasite capable of interacting with the 3 domains of life and carrying
genetic info
virus structure
- protein envelope
- capsid (protein coat) surrounds the DNA
- genetic material, either DNA or RNA
origin of viruses: virus-first theory
- viruses existed as self-replicating units which may have been able to infect
- viruses evolved from macromolecules of nucleic acid and protein
origin of viruses: escape theory
- cells came first
- viruses derived from bits of cellular RNA/DNA that leaked from cells
- when these fragments acquire a protein coat, they can become independent and can interact
origin of viruses: reduction theory
- cells came first
- viruses come from small primordial cells that lost cellular elements over the course of evolution
but maintained their genetic material and certain elements needed for replication
- these reduced cells evolved into viruses, where complex protocells evolved into modern cells
with nuclei
two protocells --> complex protocell --> + virus --> cell with nucleus --> viral lineages
viral replication strategies
- use host cell machinery to replicate viral genome
- incorporate into the host genome
- when the viral genome excises from the host genome, it can pick up host genes which can then
be incorporated into the next host
CORRECT ANSWERS!!
name the three domains of life
bacteria, archaea, eukaryotes
differences between proks and euks
- euks are more complex
- euks have a membrane-enclosed nucleus; proks have a nucleoid
- functional differences
- steps of transcription and translation
define the endosymbiont hypothesis
proposes that mitochondria and chloroplasts originated as free-living bacteria that were engulfed
by other microbes
a-proteobacteria is ancestor of mitochondria
what is a key difference between mito and chloroplasts?
- contain their own distinct genomes
- contain a distinct translation system
what is the archezoan scenario of ESH?
- archael ancestor with DNA
- primitive euk, with DNA enclosed in the nucleus
- a-proteobacterial insertion occurs
- diversification and mito evolution
why has the archezoan scenario fallen out of favour?
the original phylogenetic analysis incorrectly placed branches of euk protists close to the base of
the tree of life
,what is the symbiogenesis scenario of ESH?
- archael ancestor with DNA; a-proteobacterial insertion
- primitive euk, with DNA and the a-proteobacteria loose
- evolution of the nucleus
- diversification into proto-euks
* essentially states that euk complexity evolved after mito symbiosis
(a) define phylogeny
(b) on what is the phylogenetic analysis of organisms based?
(a) the evolution of a genetically related group of organisms as distinguished from the
development of the individual organisms. the more similar organisms are, the closer their genetic
relationships are
(b) the entire genome (a large data pool) so the assumptions are less problematic than if it were
based on only rRNA sequences
differentiate between bacteria, archaea and euks in terms of
(a) presence of nucleus
(b) number of RNA polymerase subunits
(c) size of ribosomal subunit
(d) presence of murein/PG in cell wall
(a) euks only
(b) bacteria 3-4, archaea 8-12, euks 12-14
(c) bacteria 70s, archaea 70s, euks 80s
(d) bacteria only
what do the links between the web of life symbolize?
horizontal gene transfer that has always occurred between unicellular organisms
define horizontal gene transfer (HGT)
movement of genetic material between organisms other than vertical transmission
, define a virus
an obligate intracellular parasite capable of interacting with the 3 domains of life and carrying
genetic info
virus structure
- protein envelope
- capsid (protein coat) surrounds the DNA
- genetic material, either DNA or RNA
origin of viruses: virus-first theory
- viruses existed as self-replicating units which may have been able to infect
- viruses evolved from macromolecules of nucleic acid and protein
origin of viruses: escape theory
- cells came first
- viruses derived from bits of cellular RNA/DNA that leaked from cells
- when these fragments acquire a protein coat, they can become independent and can interact
origin of viruses: reduction theory
- cells came first
- viruses come from small primordial cells that lost cellular elements over the course of evolution
but maintained their genetic material and certain elements needed for replication
- these reduced cells evolved into viruses, where complex protocells evolved into modern cells
with nuclei
two protocells --> complex protocell --> + virus --> cell with nucleus --> viral lineages
viral replication strategies
- use host cell machinery to replicate viral genome
- incorporate into the host genome
- when the viral genome excises from the host genome, it can pick up host genes which can then
be incorporated into the next host
