Dawn of Life Flashcards
Three Main Domains of the Tree of Life
Bacteria: Single-celled prokaryotic organisms; Archaea: Prokaryotic organisms distinct from bacteria, often found in extreme environments; Eukarya: Organisms with eukaryotic cells, including animals, plants, fungi, and protists
Differences Between Eukaryotic and Prokaryotic Cells
Prokaryotic Cells: No nucleus, circular DNA, no membrane-bound organelles, generally smaller; Eukaryotic Cells: Contain a nucleus, linear DNA, have membrane-bound organelles (e.g., mitochondria, chloroplasts), and are generally larger
Most Abundant and Genetically Diverse Groups of Organisms
Bacteria, Archaea, Protists
Meteorites and Origin of Life
Meteorites contain organic molecules such as amino acids, providing clues about the building blocks of life and suggesting that life’s ingredients might have come from space
Life’s First Molecule
RNA is thought to be the first molecule to evolve due to its ability to both store genetic information and catalyze chemical reactions (ribozymes)
Gerald Joyce’s RNA Experiments
Joyce’s experiments demonstrated that RNA could self-replicate and evolve, supporting the idea that RNA could have been the first self-sustaining molecule of life
Why DNA is More Reliable Than RNA
DNA is chemically more stable and less prone to mutations, making it better suited for long-term genetic storage and reliable transmission of information
Plasmids
Small, circular DNA molecules found in bacteria, independent of chromosomal DNA. They often carry genes that provide advantageous traits, such as antibiotic resistance
Gene Trading in Early Microbes
Early microbes benefited from exchanging genes because it increased genetic diversity, allowing rapid adaptation to new environments and survival in changing conditions
Carl Woese’s View on the Common Ancestor
Woese suggested that the last universal common ancestor (LUCA) was a simple, community-like group of organisms that exchanged genes freely, rather than a single entity
Evolutionary Advantages of Gene Duplication
Gene duplications provide raw material for evolution by creating genetic redundancy, allowing one copy to mutate and potentially develop a new function without losing the original gene’s function
Symbiosis
An interaction between two different organisms living in close physical association
Endosymbiotic Theory of Eukaryotic Evoltuion
Eukaryotic cells evolved when larger prokaryotic cells engulfed smaller prokaryotes, which then became mitochondria and chloroplasts, resulting in a mutualistic relationship. Mitochondria and chloroplasts have double membranes, reproduce through binary fission, have circular DNA similar to prokaryotes, and contain ribosomes similar to those in bacteria
Rickettsia Prowazekii
A type of bacteria that causes typhus. It shares genetic similarities with mitochondria, supporting endosymbiotic theory. It is found in live and can cause epidemics under unsanitary conditions
