Cells In Their Environment Flashcards
What was Earth’s early atmosphere composed of?
Lots of methane, increased CO2, little oxygen, much higher temperatures, lots of lightning and volcanic eruptions. No UV protection from atmosphere.
What conditions promoted the development of the first cells?
Ideal reaction conditions (high temperature + pressure), presence of catalysts (metals), self-assembly of polymers, and self-replicating molecules (RNA).
What is the significance of RNA in early cellular development?
RNA can store genetic information, is self-replicating, can act as an enzyme, mutates at a higher rate, and undergoes more mutations.
What is LUCA?
LUCA stands for the last universal common ancestor of cells, which evolved from simple chemicals and RNAs that stored information.
What role do nucleic acids play in early cells?
Nucleic acids are encapsulated in lipid membranes (spontaneously form vesicles), and ribosomes synthesize proteins that dominate cellular catalysis.
What is the endosymbiotic theory regarding mitochondria?
It describes a symbiotic relationship between archaea and a bacterium, leading to the engulfment of the bacterium by a eukaryotic cell.
Why do mitochondria have a double membrane?
The inner membrane comes from the bacteria, and the outer membrane comes from the eukaryotic cell.
What are protozoans?
Single-celled eukaryotes that are motile and predatory, but not classified as animals, plants, or fungi.
What is multicellularity?
It involves division of labor where each cell can specialize and perform different functions.
What is parthenogenesis?
A form of sexual reproduction where eggs can give rise to an organism without fertilization, containing only maternal genetic information.
What are the origins of social behavior in single-celled organisms?
Slime molds can smell and find mates, adhere to each other, and display characteristics of multicellular organisms.
What are pathogens?
Pathogens include viruses (non-living), fungi, bacteria, and protozoans. Archaea are not known to cause diseases.
What is a virion?
A virion consists of DNA/RNA, a protein capsid, and a lipid envelope.
What are retroviruses?
Retroviruses convert RNA to DNA in the host cell and can cause mutagenic integration events.
What is an example of a fungal pathogen?
Athlete’s foot.
