Endosymbiosis -Exam 3 Flashcards
far more complex than prokaryotic cells
Eukaryotic cells
a nucleus housing highly structured chromosomes
Eukaryotic cells
abundant intracellular membranes, including the rough and smooth ER and the Golgi apparatus
Eukaryotic cells
mitochondria
in plants, chloroplasts
Eukaryotic cells
divide by mitosis
Eukaryotic cells
Created 3.45 billion years ago
Fossils of prokaryotes
arose between 1.5 and 2 billion years ago
Eukaryotic cells
define endosymbiotic theory
how eukaryotes could have evolved from pro-karyotes; a larger cell engulfed smaller cells that evolved into the mitochondrion and the chloroplast
“living together inside”; different cells live to-gether, one cell inside another; common among modern-day microbial eukaryotes)
Endosymbiosis
common endosymbionts in marine animals and protozoans
dinoflagellates, photosyn-thetic protists
endosymbiotic theory was proposed by
Lynn Margulis in 1967
5 similarities between mitochondria and bacteria
are 1 to 4 mm in length are surrounded by two membranes use O2 to generate ATP have their own DNA grow and divide by binary fission
3 additional similarities between mitochondria and bacteria
Their genes are similar (and different from the genes in the nucleus
Their ribosomes are similar (and different from the ribosomes in the cytoplasm)
Their enzymes (including DNA and RNA polymerases) are similar (and different from the enzymes in the nucleus and cytoplasm
arose as the environment was changing from anaerobic (O2 absent) to aerobic (O2 present)
Eukaryotic cells
The increase in atmospheric O2 was due to
photosynthesis by cyanobacteria
toxic to anaerobic or-ganisms, so the “Great Oxygenation Event” about 2.3 billion years ago resulted in mass extinction
Molecular oxygen
- evolution of eukaryotic cells
The origin of a flexible cell surface; (The origin of a cytoskeleton)
- evolution of eukaryotic cells
The origin of a nuclear envelope
- evolution of eukaryotic cells
The origin of phagocytosis and the appearance of digestive vesicles or vacuoles
- evolution of eukaryotic cells
The endosymbiotic acquisition of the mitochondria and chloroplasts
The prokaryotic cell wall was lost, allow-ing the cell to grow larger
As cell size increases, the surface area-to-volume ratio decreases
flexible cell surface