eukaryal and archaea

eukaryal microbes

contains membrane bound organelle (nucleus, mitochondrian, chloroplast, cell wall, flagellum, nucleolus, ER, Golgi, vacuoles

nucleus

double membrane, contains multiple linear chromosome, prokaryotes have one circular chromosome

spatial separation between DNA —> RNA in nucleus; translation RNA —> protein in cytoplasm

nucleolus

ribosome synthesis

mitochondria + chloroplast

mitochondria: site of cellular respiration

chloroplast: site of photosynthesis

semi-autonomous; have their own DNA, ribosomes, replicate independently

most proteins originate from DNA in the nucleus

how did eukaryal microbes originate

around 2.1 billion years ago; endosymbiotic theory

endosymbiotic theory

one primitive microbe ingested another, forming symbiosis (inside lost ability to survive and became dependent)

endosymbiotic hypothesis

mitochondria arose from stable incorporation of an aerobic respiring bacterium into the cytoplasm of early eukaryotic cells; chloroplasts from a cyanobacterium-like cell into cytoplasm of a eukaryote —> eukaryotic photosynthesis

evidence of eukaryal

1. mitochondria + chloroplast resemble bacteria in size and shape

2. arrangement of double membranes around these structures is consistent with ingestion idea

3. has its own DNA

   • proteobacteria: mitochondria DNA

   • cyanobacteria: chloroplast DNA

plasma membrane in eukarya

phospholipid bilayer

sterols for stability (cholesterol)

cell wall in eukarya

cell support + structure

vary widely

eukaryols are with or without

cytoskeleton

complex internal structures: microtubules, intermediate filament, microfilaments

cell shape

cell division

intracellular-trafficking

can’t prove same protections as cell wall

motility structures

cilia and flagella

very different from bacterial fimbria and flagella

replication

sexual: meiosis —> 4 daughter cells w/unique DNA

asexual: mitosis —> 2 daughter cells (identical)

mitosis

one nucleus into two nuclei, followed by cytokinesis for 2 identical cells

meiosis

each has half of genetic info, 1 round DNA replication + 2 rounds cell division, chances for genetic recombination “crossing over”; haploid cell is genetically distinct tyo

types of eukarya

fungi, protozoa, algae, slime mold

fungi

saccharomyces cerevisiae (type of yeast)

unicellular/absorptive heterotroph; cell walls of chitin

reproduce via budding

easy to study eukaryotic structures + gene expression

significant disease to plants and can cause immunocompromised individuals

protozoa

guardia lamblia

same heterotrophic, photosynthetic, variable cell walls, different motility and reproduction

genetically old —> 2 nuclei and lacks mitochondria (has microsome) and it causes human disease

can cause significant human diseases and plant

slime molds

dicytostelium + discoideum

model for studying ecology, motility, cell-cell communication

some types can fuse many cells into a continuous multinucleate, giant cell

algae

chlamydomonas reinharatii

some single-celled, most multicellular

photosynthetic w/cellulose cell walls

ease of growth + durability

2 flagella

primary producer

large amounts of oxygen

biodegraders

degrade cellulose, recycling plant matter better than animals can

archaea

least studied

look like bacteria but genetically different

wildest range of environments [pH 0, high pressure, low nutrients, anaerobic, 2-120 C]

live in the most inhospitable places on Earth

archaea phylogeny

comparing rRNA gene sequences can establish phylogenetic trees

carl woese in 1970s

first: methanogens (group of microbes capable of producing methane)

morphology of archaea

0.5-5 um

N. equitans = 0.4 um

thermoproteus sp. 100 um

archaea structure

similar in size and shape in bacteria

singular, circular chromosome and lack membrane-bound nucleus

diverse picture of molecules can be found in the cytoplasm

plasma structure unique

archaea cell envelope

all have plasma membrane

most have cell wall

both differ from their equivalents in B + E

archaea plasma membrane

ether linkage instead of ester

contain isoprene instead of fatty acid

can be monolayer (often in high temps)

archaea cell wall

physical +osmotic protection

some lack

may be composed of pseudomurein/pseudopeptidoglycan or proteins; NOT peptidoglycan

B-1,3 glycosidic linkage

S layer

layer of identical armor like subunits

protect against predation/viruses and to mediate adhesion

cannulae

hollow glycoprotein tubes that link cells together to form a complex network

flagella

thinner

2 or more different versions of flagellin protein composition

growing from base rather than tip gr

archaea groups

euryarchaeota, crenatchaeota, korarchaeota, nanoarchaeto

crenarchaeota

thermophiles or hyperthermophile

acidophiles or barophiles (high pressure)

possess many adaptations to thrive

lipid monolayers

strong chaperone protein complexes

thermostable DNA-binding proteins

mesophiles: 15-40 C

psychrophiles < 15 C

euryarchaeota

methanogens: reduce CO2 with H2 to produce CH4 and H2O; strict anaerobes (human gut, swamp)

halophiles: require NaCl > 1.5 M; Great salt lake, Dead Sea

halobacterium salinarum: maintain very high intracellular K+ concentration to offset the very high extracellular Na + concentration

• produce energy through photography

• no chlorophyll or election transport chain

• bacteriahodopsin to harness light energy + produce a proton motion force

• reddish hue

korarchaeota

no species cultivated yet

hyperthermophiles: originally detected from 16s rRNA sequences obtained from Yellowstone Obsidian pool (85 C)

nanoarchaeota

nanoarchaeum equitans —> only one in phylum

possibly smallest organism on Earth

not free-living, needs organismal relationship

thermophiles