Module 1 Flashcards
connections between eukaryotes and prokaryotes are supported by the ___ theory
endosymbiont
what is the endosymbiont hypothesis
Mitochondria and chloroplasts evolved from free-living bacteria via symbiosis with a eukaryotic host cell
○ These organelles contain their own DNA
○ Have a distinct translation system
name 4 things that are present in a eukaryotic cell and not a prokaryotic cell
membrane bound nucleus (prokaryotes have nucleiod)
lysosomes/peroxisomes
endoplasmic recticulum/golgi apparatus
mitochondria
what are the two ensosymbiont hypotheses and their differences
Archezoan scenario
-The mitochondrial endosymbiosis (the engulfment of an alpha-proteobacterium that became mitochondria) occurred AFTER the development of the basic eukaryotic cell structure.
Symbiogenesis scenario
-proposes that the origin of mitochondria and the origin of the eukaryotic cell were closely linked, and the two events happened together in a symbiotic relationship.
what does the cell wall of bacteria have that archaea and eukaryota do not have
murein/peptidoglycan
what does the web of life emphasize
horizontal gene transfer
which of the domains of life are viruses capable of interacting with
all of them
when not inside of a host, viruses exist as ___ with _____
virions, genetic material/capsit/envelope
viruses rely on
host machinery to replicate and then leave to infect new cells
viral replication strategies
carries genetic info as DNA or RNA and uses host machinery to transcribe it to make progeny
genome integration into host genome
when it leaves cell (lysogeny) it can take host genome with it to new cells - this can be between species
discuss the hypotheses around the origins of viruses
virus first theory
-viruses came before cells
-evolved from a mixture of macromolecules and existed as self replicating units
-self replicating units of RNA that were first in existence may have gained the ability to infect earlier forms of cells (can catalyze chemical reactions using enzymatic like properties
escape theory
-cells came before viruses
viruses come from bits of cellular RNA/DNA that leaked/escaped from cells
-these parts acquired protein coats allowing them to be independent entities - can interact with cells
-retrotransposons (resemble these)
Reduction theory
-cells came before viruses
-viruses come from small primordial cells that lost cellular components over the course of evolution
-maintained genetic material and elements for replication
-infected other cells and now dependent on host cell as they lost their cellular elements
evidence supporting that mitochondria evolved from bacteria
-double membrane (like gram-)
-circular DNA
-Phylogenetic relationships
-binary fission for reproduction
-similar proteins of ribosomes compared to eukaryotic ribosomes
-endosymbiotic relationships
what are some factors to explain the diversity of the microbial world
rapid reproduction
HGT and VGT
varied habitats/selective pressures
metabolic diversity (photosynthesis and the metabolism of sulfur or nitrogen)
evolutionary history
interactions with other organisms
mutations
The 4 phyla of bacteria that dominate the human body
Actinobacteria
○ Gram-positive bacteria that are aerobic and mostly found in soil
Bacteroidetes
○ Gram-negative phylum which have colonized virtually all types of habitats on Earth
○ Bacteroides
§ Predominant in the gut
Firmicutes
○ Gram-positive and can often form endospores
○ Streptococcus predominant in the mouth
Proteobacteria
○ Major Gram-negative phylum includes a diverse array of bacteria
Gene transfer in bactera
conjugation
- direct, via a pilus
transformation
-uptake from environment
transduction
-from viral infefction
transposition
-jumping from one chromosomal location to another
