Lecture 40- Evolution Of Eukaryotes Flashcards
What is Unity of the Universe and diversity of the Universe/
Living things come from one common ancestor (unity)
Living things are diverse because each species is adapted to their way of life
What are the 4 main stages scientists believe thst lead to simple cells?
- Abiotic synthesis of small organic molecules, such as amino acids
- Joining of the small molecules into polymers, such as proteins and Nucleic acids
- Packaging of molecules into protobionts; droplets with membranes that can maintain an internal chemistry different from the environment
- Protobionts possessed the origin of self replication molecules (can replicate macromolecules, not themselves)
When we’re the oldest fossils of true eukaryotes found?
Science relate the emergence of eukaryotes to what?
2.1 Billion years ago first fossils of Eukaryotes
Scientists relate the emergence of Eukaryotes to oxygen revolution
How were eukaryotic cells able to get chloroplast, mitochondria, etc?
They had cytoskeleton and were able to engulf them, acting as predators.
Through symbiosis
They were formerly small prokaryotes
(They did not digest them)
What is an endosymbiont?
A cell that lives inside another cell called the host cell
What type of organisms were the anecestors of mitochondria and plastids?
Mitochondria weee aerobic heterotrophic prokaryotes
Plastids were photosynthetic prokaryotes
In what way was symbiosis beneficial?
The heterotrophic host cell were able to benefit from the nutrients released from a photosynthetic symbiont.
And an anaerobic cell also benefits form an aerobic symbiont in an increasing aerobic world (oxygen revolution)
What is the evidence that mitochondria and plastids were prokaryotic microorganisms that were engulfed and acted in a symbiotic manner?
- Inner membranes of both organelles (plastids and mitochondria)have enzymes and transport systems homologous to those found in the plasma membrane of living prokaryotes
- Mitochondria and plastids replicate by splitting process similar to binary fission
- Each organelle contains a single, circular DNA molecule, like the chromosomes of bacteria are NOT associated with histones
- Organelles contains tRNA, ribosomes, and other molecules needed to transcribe and translate DNA to protiens
- The ribosomes in these organelles are closer to prokaryotic than eukaryotes
Which bacteria are the closest relatives of mitochondria and plastids?
Alpha proteobacteria - mitochondria
Cyanobacteria- plastids
Which cells are considered chimera?
Eukaryotic cells
How did mono cellular Eukaryotes evolve?
Prokaryotes Infolded their plasma membrane around the Nucleoid, until it developed into a nuclear envelope
Then alpha proteobacteria were engulfed (mitochondria) and SOME engulfed Cyanobacteria (plastids)
What Were the oldest known fossils of Multicellular eukaryotes?
And how did they arise?
1.2 Billion years ago, which were small algae
A collection of autonomous unicellular organisms were replicating and dependent on each other—> multicellular organisms
Some of these cells became specialized for different functions-> differentiation
When was their colonization of land by organisms?
Cyanobacteria and other photosynthetic prokaryotes coated damp terrestrial surfaces well over a billion years ago
Plants colonized land accompanying what?
Fungi
Even today, many roots of plants are associate with fungi thst help them absorb water and minerals from the soil.
These root fungi in return obtain organic nutrients from the plants (Symbiosis)
What are the most widespread and diverse land animals?
2nd most diverse?
Arthopods, particularly insects and spiders.
The 2nd most diverse are Terrestial vertebrae called tetrapods (4 limbs); include humans
