Chapter 26 and 27 - Bacteria, Archaea, and Eurkaryotes

prokaryotes

no nucleus

* bacteria and archaea

bacteria

unicellular prokaryotes distinguished by cell walls, plasma membrane, ribosomes, and RNA polymerase

archaea

unicellular prokaryotes distinguished by cell walls made of polysaccharides, plasma membranes, ribosomes, and RNA polymerase

eukarya

includes eukaryotes with membrane-bound cell nucleus, numerous organelles, and an extensive cytoskeleton

eukaryotes

includes a nucleus, nuclear envelope, mitochondrial cellular respiration, and organelles (ex - mito, golgi complex, cholorplasts)

* eukarya

what does not contribute to creating new species

migration and gene flow

* gene flow must be stopped in order to allow for speciation and isolate the population from its parent population

similarities between bacteria and archaea

* microscopic
* no nucleus
* similar shape

differences between bacteria and archaea

* genetics
* cell walls (bacteria - peptidoglycan, archaea - polysaccharides)

cell walls in bacteria vs archaea

bacteria

* have peptidoglycan (either gram-positive cell wall or gram-negative cell wall)

archaea

* resistant to all antibiotics

gram-positive cell wall

the cell wall of bacteria that has a thick wall of peptidoglycan

* shows purple since it binds to the bacteria

gram-negative cell wall

the cell wall of bacteria that has a thinner layer of peptidoglycan sandwiched between the outer membrane and plasma membrane (two membranes)

* shows pink

importance of studying bacteria and archaea

* ancient, abundant, ubiquitous and important
* the most diverse organisms on Earth (unique exchange of genetic material, morphology, and metabolism)

prokaryotes as ancient, abundant, ubiquitous and important

* ancient - oldest organisms on earth (3.5 bya)
* abundant - found in human digestion
* ubiquitous - air, soil, water, animals, plants
* extremophiles
* important - cycle nutrients and decomposition with photosynthesis

extremeophiles

extreme lovers; can be some animals too

* psychrophiles - cold
* halophiles - salt
* hyperthermophiles - high temp
* xerophiles - dry
* acidophiles - acid
* endoliths - rocks
* alkaliphiles - alkaline

human microbiome

the total microbial content in and on the human body

* very few are pathogens

bacteria and archaea as diverse entities

prokaryotes are phylogentically diverse, despite being asexual

asexual reproduction

form of reproduction in which offspring inherit DNA from only one parent

* binary fission and cloning

how is genetic variation generated in prokaryotes

lateral gene transfer and mutations

sexual reproduction

form of reproduction in which genes from two parents are combined via fusion of gametes

* offspring that are genetically distinct from parents and diploid

lateral gene transfer

transfer of DNA betweem two different species (not thru genetics)

* ex - change color because of what you are eating; not heritable

types of lateral gene transfer

transformation, transduction, and conjugation

transformation

uptake of dna from the environment

* donor → recipient → recombination

transduction

lateral gene transfer through phages

* donor → phages inject dna to the recipient cell → recombination

conjugation

lateral gene transfer through cell-to-cell contact

* donor to recipient through a conjugation tube → recombination

prokaryotes and shapes

vary in shape, including square

prokaryotes and metabolism

can be phototrophs, chemotrophs, etc

phototrophs

energy from sunlight

* branch into autotrophs and heterotrophs for carbon source

autotrophs

carbon dervies from inorganic sources (such as CO2) with sunlight as energy source (phototroph)

* ex of photoautotrophs - cyanobacteria and vascular plants

heterotrophs

carbon from organic compounds with sunlights as the energy source (phototrophs)

* ex of photoheterotroph - heliobacteria, red aphids, most green non-sulfur bacteria

chemotrophs

energy from chemical compounds as the energy source

\-lithotrophs

“rock feeders” as carbon source

* autotroph or heterotroph
* ex of chemolithoautotrophs - sulfur-oxidizing bacteria
* ex of chemolithoheterotrophs - hydrogen bacteria

\-organotrophs

“carbon feeders”

* autotroph or heterotroph
* ex of chemoorganoautotrophs - methylomonas and most bacteria
* ex of chemoorganoheterotrphs - animals

paraphyletic group

a common ancestor with some of their descendants

* does not include all the descendants of most recent common ancestor, like a monophyletic group

where are protists commonly found

mostly aquatic

* live in the ocean, wet areas on land (lakes), and in animals and plants

example of parasitic protists

malaria

* mosquito bite injects protist into cell → reproduces during mitosis → goes to red blood cells → infected gametes → fertilization and zygotes

food chain

pathway of energy and nutrient flow throughout species from different trophic levels

* primary producer (phytoplankton) → primary consumer (zooplankton) → secondary consumer (anchovies) → tertiary consumer (tuna)
* protists are important primary produers

role of protists in the marine carbon cycle

CO2 goes to primary producers → primary consumers → decomposers and scavengers → dead cell accumulate on the floor → fossil fuels

diversity in protists derive from

* endosymbiosis
* evolution of the nuclear envelop allowed for separation of transcription and translation
* not all protists have/are: chloroplasts, cell wall, or multicellular

endosymbiosis

association between 2 species in which one lives inside the cells of the other

* formation of the first eukaryote = alpha-bacterium enters the archaeal host cell → host cell engulfs bacterium → host cell gives protection and carbon, and bacterium gives ATP
* result - first mitochondria

origin of nuclear envelope

ancestor of eukaryotes with chromosomes and plasma membrane → infoldings of plasma membrane surround the chromosomes → eukaryotic cell arises with infoldings forming nuclear envelope and ER

how did the diversity of protists evolve

primary and secondary endosymbiosis

primary endosymbiosis

1. cyanobacteria enters a eukaryotic cell (protist)
2. the protist host engulds the cyanobacteria
3. host cell gives protection and light; bacterium gives O2 and C6H12O6 to form first chloroplast

* results in photosynthesis in eukaryotes

secondary endosymbiosis

1. photosynthetic protist is engulfed by a predatory protist
2. nucleus from the photosynthetic protist is lost
3. the photosynthetic protist becomes an organelle with 4 membranes

* result - chloroplasts were passed around to other protists

how do protists obtain food

ingestive, absorptive, and photosynthesis

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ingestive feeding

feeding by phagocytosis is possible in protists without a cell wall

* eating live or dead organisms or on scavenging bits of organic debris
* pseudopodia - structures that allow species to swallow prey whole
* made the evolution of mitochondria and chloroplast possible

absorptive feeding

nutrients cross the plasma membrane via transport proteins (common among protists)

* decomposers and parasites

how do protists move

1. swim with flagella
2. drift/swim with cillia
3. amoeboid motion (crawl) with pseudopodia

how do protists reproduced

alternation of generations = alternation of multicellular haploid and diploid forms

steps of alternation of generation

sporophyte (2n) undergoes meiosis → produces spores (n) that undergo mitosis → form male and female gametophytes (n) separately → fertilize to form zygote (2n) → mitosis a lot to form sporophyte

two prominent life cycles

sexual cycle (animals and humans) and alternation of generations cycles

gametophyte

multicellular haploid form

sporophyte

multicellular diploid form

spore

a single haploid cell that divides mitoticaly to form a multicellular, haploid gametophyte