Protists Flashcards
What is a protist?
A protist is a parapmpletic group of eukaryotes that are not fungi, land plants, or animals. They are diverse and can reproduce asexually or sexually.
Protists typically inhabit moist environments and impact human health and welfare.
Why study protists?
Studying protists is important due to their impact on agriculture and health, such as the Irish potato famine caused by the oomycete Phytophthora infestans, which leads to crop losses, and malaria caused by Plasmodium species.
Five different species of Plasmodium can infect humans.
What is the life cycle of malaria?
Malaria is caused by a complex lineage of Plasmodium that multiplies in red blood cells, causing fever and mitosis. The parasite can cause protein to stick to capillaries, leading to oxygen deprivation.
The Plasmodium is haploid, meaning it has one copy of each chromosome.
What are red tides?
Red tides are caused by blooms of algae that grow in high density, particularly dinoflagellates, which produce toxins that turn coastal water red.
These toxins can build up in shellfish, leading to paralytic shellfish poisoning.
What is the role of protists in ecosystems?
Protists play important roles in ecosystems as the foundation for aquatic ecosystems, including plankton and phytoplankton, such as diatoms, which are considered the grass of the ocean.
They also form symbiotic relationships, such as reef-building corals with zooxanthellae.
What is coral bleaching?
Coral bleaching occurs when corals release zooxanthellae, which can happen at a rate of 200 times.
This process negatively affects coral health and the ecosystems they support.
How do termites benefit from protists?
Termites host protists called Trichonymphs in their gut, which help digest cellulose through symbiotic relationships.
What type of organisms were the first eukaryotes?
unicellular
The first eukaryotes were single-celled organisms.
Did the first eukaryotes have a nucleus?
yes
The presence of a nucleus is a defining feature of eukaryotic cells.
What structures did the first eukaryotes possess?
Mitochondria, Cytoskeleton, Endomembrane system
These structures are important for cellular functions and organization.
Did the first eukaryotes have cell walls?
no
Unlike many prokaryotes, the first eukaryotes did not have cell walls.
How could the first eukaryotes move?
with flagellum-like structure
This allowed them to swim in their environment.
What is the nuclear envelope likely derived from?
infoldings of the plasma membrane
This infolding led to the formation of the nucleus and endoplasmic reticulum.
What does post-transcriptional processing allow?
enables alternate RNA splicing
This physical separation of transcription and translation is significant for gene regulation.
What is the theory of endosymbiosis regarding mitochondria?
mitochondria were small prokaryotes that began living inside another organism
This theory suggests a symbiotic relationship leading to the evolution of mitochondria.
What type of prokaryotes are believed to be the origin of mitochondria?
aerobic heterotrophic prokaryotes
These prokaryotes were capable of utilizing oxygen for energy.
What is the new hypothesis regarding the host of mitochondria?
archaean
This suggests that the host organism was a type of archaea.
What does the origin of chloroplasts involve?
endosymbiosis
Chloroplasts arose through a similar process as mitochondria.
When did chloroplasts acquire mitochondria?
after mitochondria
Chloroplasts evolved following the acquisition of mitochondria.
What is serial endosymbiosis?
occurs when endosymbiotic events happen repeatedly
This concept explains the acquisition of multiple organelles over time.
What is one characteristic of mitochondria that resembles bacteria?
Same size as average bacterium
Mitochondria are comparable in size to bacteria.
What replication method do mitochondria use?
similar to binary fission in prokaryotes
This method of replication is a characteristic of prokaryotic cells.
What type of DNA do mitochondria have?
single circular DNA not associated with histones
This structure is reminiscent of bacterial DNA.
Which gene sequences are related to mitochondria?
a-proteobacteria
The genetic material of mitochondria is closely related to that of a-proteobacteria.
What structures do mitochondria have?
Mitochondria have ribosomes and a double membrane bound structure.
What can poison ribosomes?
Ribosomes can be poisoned by antibiotics.
What is the second membrane of mitochondria?
The second membrane functions as a food vacuole.
What structures provide support and protection in cells?
Cytoskeletons provide structures for support and protection.
What are diatoms made of?
Diatoms have glass-like silicon-oxide shells.
What type of cell wall do green algae have?
Green algae have cellulose cell walls.
What do euglenids have under their plasma membrane?
Euglenids have flexible protein strips called pellicle.
What is the growth form of Volvox?
Volvox is large and complex, consisting of many cells.
What happens to the adult colony of Volvox when it becomes too big?
The adult colony dies when it becomes too big.
What type of organism is Kelp?
Kelp is multicellular.
What defines multicellularity?
- Cells are differentiated to perform different functions and express different genes.
- Cells cannot survive individually.
What is fragmentation in the context of reproduction?
Fragmentation is a form of asexual reproduction.
What types of organisms are tunicates related to?
Tunicates are related to sponges, anemones, and jellyfish.
How many times has multicellularity evolved?
Multicellularity has evolved many times independently or once.
What is mixotrophic nutrition?
Mixotrophic nutrition involves both absorptive feeding and photosynthesis.
What is absorptive feeding?
Absorptive feeding is when fungi secrete digestive enzymes to decompose dead matter.
What do decomposers eat?
Decomposers eat dead matter.
What is parasitic feeding?
Parasitic feeding occurs when organisms live inside other organisms.
What is a shared derived characteristic of chloroplasts?
Chloroplasts are bound by a double membrane.
This characteristic indicates they are part of a monophyletic group.
What is secondary endosymbiosis?
It occurs when the original host becomes a second endosymbiont.
What are the main photosynthetic pigments?
Chlorophyll a and b, along with other pigments.
What is the advantage of having a unique combination of pigments?
It allows the absorption of different wavelengths of light, reducing competition.
What is ingestive feeding?
It involves taking in packs of food.
Examples include phagocytosis and filter feeding.
What is phagocytosis?
It is the process of engulfing food.
What is filter feeding?
It uses cilia to create currents that sweep food into the gullet.
How do amoebas utilize ingestive feeding?
They have more membrane to change shape and engulf food.
How do amoebas move?
Amoebas use pseudopodia for motility.
How do Volvox move?
Volvox use flagella for motility.
How do paramecium swim?
Paramecium swim using cilia.
What is rolling in motility?
It is a form of movement observed in some organisms.
What is gliding in motility?
It is muscle propulsion by micrasterias, which are some diatoms that secrete mucus.
What is asexual reproduction?
Asexual reproduction involves a single parent producing offspring that are clones, requiring less energy.
What is sexual reproduction?
Sexual reproduction involves two parents producing genetically different offspring, which can mutate and develop resistance.
What is meiosis?
Meiosis is the process that reduces the chromosome number by half, occurring after fertilization.
Why did sex evolve?
Sex evolved for crossover, independent assortment, and unique combinations of alleles.
What is the advantage of sexual reproduction?
The advantage is increased diversity and genetic variability, which enhances survival and reproduction in changing environments.
What is the life cycle of bacteria and archaea?
Bacteria and archaea undergo cell division, feeding, and dividing again, and are always haploid.
What does meiosis introduce in sexual reproduction?
Meiosis introduces distinct haploid and diploid phases in the life cycle.
What is the alteration of generations?
It alternates between multicellular haploid and multicellular diploid phases.
What is a sporophyte?
A sporophyte is a diploid multicellular phase that reproduces spores, which are single cells that do not fuse.
How are gametes produced?
Gametes are made from mitosis, with fertilization leading to the formation of a zygote, which undergoes mitosis.
What are the major lineages of Eukaryotes?
There are 7 major monophyletic groups in Eukaryotes.
What is a slime mold?
Slime molds are unicellular organisms without a brain that find the shortest route to spread genes.
What are the two types of slime molds?
The two types of slime molds are cellular and plasmodial.
