Lectures: Intro to Eukarya Flashcards
What traits do (mostly) all Eukarya have, suggesting they were
present in common ancestor (*found in other domains)?
- Cell walls*
- Flagella and/or cilia*
- Cells with nuclei surrounded by nuclear membrane
- Mitochondria organelles
- Cytoskeleton with microtubules and microfilaments
- Linear chromosomes
- Mitosis
- Sexual reproduction
True or False. Eukarya is the only domain with multicellularity.
True
What are the 4 main derived traits in of Eukarya?
6: main derived traits in of Eukarya
* Nuclei with nuclear envelope
* Linear chromosomes
* Membrane-bound organelles
* Sexual reproduction
Nuclear envelope:
- Hypothesized to have arisen by
infoldings of the plasma membrane - Occurs in some bacteria
- Also created endoplasmic reticulum (ER)
- Modern Eukarya have continuous nuclear envelopes and ER
Advantage: separates
- Transcription (DNA –> RNA)
- Translation (RNA –> proteins)
Endosymbiotic theory
theory that states that eukaryotes may have been a product of one cell engulfing another, one living within another, and evolving over time until the separate cells were no longer recognizable as such
(proposed by Lynn Margulis as the origin of mitochondria)
Mitochondria:
- generate ATP, also clusters of iron and sulfur that are important cofactors of many enzymes
Evidence that original mitochondria were α-proteobacterium:
- Size
- Mitochondrial genomes
- Gene sequences related to bacteria rather than Eukarya nuclear genome - Double membranes
- Foldings of inner membrane (cristae) resembles outer surface of α-proteobacterium - Replicate by fission
Do some or all Eukarya have plastids?
some
Plastids
one of a group of related organelles in plant cells that are involved in the storage of starches, fats, proteins, and pigments
(appears to have endosymbiotic origins)
True or False. Photosynthetic Eukarya have cells with plastids rich in pigments that capture light energy.
True, most commonly chlorophyll, but other pigments can be used
Secondary endosymbiosis
Endosymbiosis also applied to origin of eukaryotic chloroplasts
– Organelle used for photosynthesis
What 4 pieces of evidence supports the hypothesize that protist
engulfed a cyanobacterium?
- Size
- Four membranes
- Circular DNA genome with similar
genes - Some protists have chloroplasts with
peptidoglycan outer layer
What is one of the most significant changes to life on Earth?
Multicellularity
What is hypothesized to have started with cells sticking together after cell division?
Multicellularity
True or False. “Colonies” of cells could have higher fitness due to specialization.
True, different cells express different genes
