slide 1.2 Flashcards
what are microbes
life too small to be seen with human eye
what are the three domains of life
bacteria, archaea— PROKARYOTES
eukaryotic microbes
are viruses cells?
not cells, they lack hallmarks of cellular life
how long ago did eukarya and archaea diverge?
2 bya
how long ago did bacteria and the other domains diverge
3.5 bya
what is the LUCA
last common ancestor between everyone?
where did the RNA world hypothesis occur?
stable compartment with high concentration of organic building blocks ie nucleotides
what forces selected better RNA in RNA world hypothesis
evolutionary forces such as improved replication and stability, also more complex functions
Steps of the RNA world hypothesis
1) simple RNA molecules
2) selected for better RNA ie more stable, self replicating with simple functions
3) bind with and use amino acids and peptides
4) form simple ribosomes
5) ribosomes make protiens and things get complex
6) DNA, membranes, compartmentalization
RNA world hypothesis evidence
- RNA can form intricate and stable structures that carry out reactions and bind molecules
- proteins made using RNA components, tRNA, and catalytic RNA
- there are relics from RNA world
What are the relics from RNA world
ribozymes, riboswitches, the ribosome
what are ribozymes
RNA enzymes
What are riboswitches
mRNA receptors that bind ligands and regulate gene expression
whats common between essential biological molecules
they are mostly nucleotide based`
Last universal common ancestor features
-had DNA replication, transcription, translation, cell division
- ATP was energy intermediate
- lipid bilayer
- anaerobic metabolism, H2 as energy source, CO2 as carbon source
what did LUCA leave in modern organisms
a limited amount of genes like ribosomal RNA
chemotroph
derive energy from releasing bond energy
phototroph
absorb light and transform it into chemical energy
different types of chemotrophy
chemoorganotroph
chemolithotroph
chemolithotroph
chemotrophy of inorganic chemicals
chemoorganotroph
chemotrophy of organic chemicals
describe the rise of oxygen on earth
-first 2 billion years atmosphere was anoxic
-cyanobacteria produced oxygen as a biproduct of oxygenic photosynthesis
what enabled aerobic organisms to live
o2 is good oxygen acceptor, and the ozone layer protects vs UV
explain Endosymbiotic theory
eukarya evolved from archaea like ancestor engulfing aerobic respiring bacterium
-became an endosymbiont and then a mitochondria
-transfered many genes to host organism
