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Questions and Answers
What is the characteristic that unites protists as a group?
What is the characteristic that unites protists as a group?
Which of the following is NOT a characteristic of protist cell surfaces?
Which of the following is NOT a characteristic of protist cell surfaces?
What is a key difference between eukaryotic cells and prokaryotes?
What is a key difference between eukaryotic cells and prokaryotes?
According to the endosymbiotic theory, what is the origin of chloroplasts?
According to the endosymbiotic theory, what is the origin of chloroplasts?
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What is the primary function of pseudopodia in protists?
What is the primary function of pseudopodia in protists?
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What is the term for protists that can obtain energy through both photosynthesis and ingestion of food particles?
What is the term for protists that can obtain energy through both photosynthesis and ingestion of food particles?
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What is evidence for the endosymbiotic theory?
What is evidence for the endosymbiotic theory?
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What is a characteristic of mitochondrial and chloroplast DNA?
What is a characteristic of mitochondrial and chloroplast DNA?
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What is the advantage of meiosis in protist sexual reproduction?
What is the advantage of meiosis in protist sexual reproduction?
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What is a key difference between prokaryotic and eukaryotic cell division?
What is a key difference between prokaryotic and eukaryotic cell division?
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Study Notes
Eukaryotic Origins
- Eukaryotic cells differ from prokaryotes in having a cytoskeleton and compartmentalization (nucleus and organelles).
- Eukaryotes appeared in microfossils about 1.5 billion years ago.
Evolution of Nucleus and Organelles
- The nucleus and endoplasmic reticulum arose from infoldings of the prokaryotic cell membrane.
- Many organelles evolved via endosymbiosis between an ancestral eukaryote and a bacterial cell.
Endosymbiosis
- Mitochondria evolved from aerobic bacteria engulfed by larger bacteria.
- Chloroplasts evolved from photosynthetic bacteria engulfed by larger bacteria.
- Chloroplasts originated from a single line of cyanobacteria.
- Hosts are not monophyletic, and brown algae engulfed red algae that already had chloroplasts, resulting in secondary endosymbiosis.
Evidence for Endosymbiosis
- DNA inside mitochondria and chloroplasts is similar to bacterial DNA in size and character.
- Ribosomes inside mitochondria are similar to bacterial ribosomes.
- Chloroplasts and mitochondria replicate by binary fission, not mitosis.
- Mitosis evolved in eukaryotes.
Mitosis
- Prokaryotes carry genes on a single DNA molecule, while eukaryotes have multiple chromosomes.
- Mitosis and cytokinesis developed to separate chromosomes and other cell contents during cell division.
- Mitosis evolved over thousands of years.
Overview of Protists
- Protists are the most diverse of the four eukaryotic kingdoms.
- They are united by not being fungi, plants, or animals, but vary considerably in other aspects.
- Protists can be unicellular, colonial, or multicellular, and have all types of nutrition and symmetries.
Classification of Protists
- Protists are not monophyletic, but are present in all six eukaryotic supergroups: Excavata, Chromalveolata, Archaeplastida, Rhizaria, Amoebozoa, and Ophisthokonta.
Cell Surface in Protists
- Protists have a varied array of cell surfaces, including plasma membrane, extracellular matrix (ECM), and diatoms with silica shells.
- Cysts are dormant cells with resistant outer coverings used for disease transmission.
Locomotion in Protists
- There are three primary means of locomotion: flagella, cilia, and pseudopodia ("false feet").
Nutrition in Protists
- Autotrophs can be photosynthetic or chemoautotrophic.
- Heterotrophs include phagotrophs that ingest particulate food matter, and mixotrophs that are both phototrophic and heterotrophic.
Reproduction in Protists
- Asexual reproduction is typical, and includes mitosis, budding, and schizogony.
- Sexual reproduction involves meiosis, producing haploid gametes that unite to form a zygote, allowing for genetic recombination.
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Description
This quiz covers the characteristics of eukaryotic cells, their origins, and the development of cellular structures such as the nucleus and endoplasmic reticulum.
