Protists Flashcards

Questions and Answers

What is the difference between protists and prokaryotes?

The major difference is that protists are eukaryotes while bacteria and archaea are both prokaryotes. This means that prokaryotes do not have a nucleus and contain circular DNA, while eukaryotes have a nucleus and contain linear DNA.

What is the species diversity of protists in Eukarya? Why is it so low?

10% because it is extremely abundant and found in all ecosystems, and also plants, animals, and fungi are not included in protista.

Protists are paraphyletic. What does that mean?

A group of taxa that consists of all descendants of a hypothetical common ancestor minus one or more monophyletic groups of descendants. They don't share derived characteristics separating them from other groups.

What are red tides caused by? What are the effects of a red tide?

Red tides are caused by dinoflagellates, which are toxin-producing protists. They can lead to shellfish poisoning in humans. Signup and view all the answers

How much of the world's carbon do protists fix? What does it mean to fix carbon?

Protists fix half of the world's carbon. Carbon fixation is the conversion of inorganic carbon to organic compounds for organisms. Signup and view all the answers

What is the base of the aquatic food chain?

Phytoplankton. Signup and view all the answers

What is meant by the global carbon cycle?

The movement of carbon atoms. Signup and view all the answers

How are phytoplankton a key carbon sink?

They convert carbon dioxide into sugar molecules during photosynthesis. Signup and view all the answers

How do phytoplankton help mediate global warming?

They are a repository for carbon. Signup and view all the answers

The earliest eukaryotic organisms must have had ________.

unicellular, nucleus, mitochondria, and no cell wall. Signup and view all the answers

Be able to describe the life cycle of malaria.

Mosquitos are vectors. A mosquito bite transfers protists to liver cells, where they reproduce by mitosis. New cells then explode from the liver, infecting the human. The mosquito becomes infected after biting the human, reproduces during meiosis, and passes it on to baby mosquitos. Signup and view all the answers

Describe the leading hypothesis of the origin of the nuclear envelope. What evidence supports it? What is the advantage of having a nucleus?

<ol> <li>A cell membrane folded in on itself, creating the endoplasmic reticulum. 2) Infoldings are present in some bacteria, and the nuclear envelope is continuous with the ER. 3) Separation of transcription and translation.</li> </ol> Signup and view all the answers

Describe the leading hypothesis of the origin of the mitochondrion. What evidence supports this? What did the mitochondrion provide the eukaryote? What did the eukaryote provide the mitochondrion?

<ol> <li>The eukaryote engulfs bacteria but doesn't consume it. 2) Mitochondria are the same size as bacteria, have their own genomes, manufacture their own proteins, and have double membranes. 3) The mitochondrion provided ATP. 4) The eukaryote provided protection.</li> </ol> Signup and view all the answers

Describe the leading hypothesis of the origin of the chloroplast. What evidence supports this? What did the chloroplast provide the eukaryote? What did the eukaryote provide the chloroplast?

Photosynthesis originated in bacteria. A protist engulfed cyanobacteria, and then another protist engulfed that protist. Chloroplasts have four membranes. Signup and view all the answers

What is the endosymbiosis hypothesis?

The mitochondrion took up residence in a eukaryotic cell 2 billion years ago. Signup and view all the answers

What is meant by secondary endosymbiosis?

When a eukaryotic cell engulfs another eukaryotic cell that has undergone primary endosymbiosis. Signup and view all the answers

What is the difference between phagocytosis and absorptive feeding?

Phagocytosis: ingest packets of food, eat bacteria, archaea, and other protists. Absorptive: nutrient taken directly from the environment. Signup and view all the answers

Absorptive feeding is common in what kind of protists?

Decomposers and parasites. Signup and view all the answers

What are the three ways protists move?

<ol> <li>Amoeboid motion (pseudopodia). 2) Swimming with flagella. 3) Swimming with cilia.</li> </ol> Signup and view all the answers

Of the 7 major lineages of Eukarya, how many contain protists?

6 contain protists. Signup and view all the answers

Study Notes

Differences Between Protists and Prokaryotes

Protists are eukaryotes; prokaryotes include bacteria and archaea.
Eukaryotes possess a nucleus and linear DNA; prokaryotes have no nucleus and contain circular DNA.

Species Diversity of Protists

Protists represent 10% of species diversity within Eukarya.
Diversity is low due to abundance in ecosystems, with plants, animals, and fungi excluded from the protist kingdom.

Paraphyletic Nature of Protists

Protists form a group excluding one or more monophyletic groups of descendants.
They lack shared derived characteristics that set them apart from other groups.

Red Tides

Caused by toxin-producing dinoflagellates, a type of protist.
Result in shellfish poisoning in humans.

Carbon Fixation by Protists

Protists are responsible for fixing half of the world's carbon.
Carbon fixation involves converting inorganic carbon into organic compounds.

Aquatic Food Chain

Phytoplankton serves as the foundational base of the aquatic food chain.

Global Carbon Cycle

Describes the movement of carbon atoms through various forms in the environment.

Phytoplankton as a Carbon Sink

During photosynthesis, phytoplankton convert carbon dioxide into sugar molecules.

Role of Phytoplankton in Global Warming

Function as a reservoir for carbon, mitigating global warming effects.

Earliest Eukaryotic Organisms

Must have been unicellular, contained a nucleus, had mitochondria, and lacked a cell wall.

Life Cycle of Malaria

Mosquitoes act as vectors; they transfer protists to human liver cells via bites.
Protists reproduce within liver cells, then infect more human cells.
Infected humans pass on the protist to mosquitoes, allowing reproduction during meiosis.

Origin of the Nuclear Envelope

Hypothesis suggests the cell membrane folded inward, forming the endoplasmic reticulum (ER).
Evidence includes infoldings in some bacteria and the nuclear envelope's continuity with the ER.
Benefits include separation of transcription and translation processes.

Origin of Mitochondria

Eukaryotic cells engulf bacteria, which become mitochondria.
Mitochondria share size and genome similarities with bacteria and have double membranes.
Mitochondria provide ATP; eukaryotes protect them in return.

Origin of Chloroplasts

Photosynthesis originates in bacteria; protists engulf cyanobacteria through secondary endosymbiosis.
Chloroplasts are characterized by four membranes.

Endosymbiosis Hypothesis

Proposes that mitochondria became integrated into eukaryotic cells around 2 billion years ago.

Secondary Endosymbiosis

Occurs when a eukaryotic cell engulfs another eukaryotic cell that has already undergone primary endosymbiosis.

Feeding Mechanisms in Protists

Phagocytosis involves ingesting food packets, including bacteria and other protists.
Absorptive feeding takes nutrients directly from the environment.

Absorptive Feeding in Protists

Common among decomposer and parasitic protists.

Movement Types in Protists

Movement methods include amoeboid motion via pseudopodia, swimming with flagella, and ciliary swimming.

Protists Within Eukarya

Out of seven major lineages in Eukarya, six contain protists.

Unique Features of Protist Groups

Amoebozoa, Rhizaria, Excavata, and others exhibit distinct morphologies, feeding strategies, and movement types.
Specific examples include Euglenida in Excavata and Oomycota, along with diatoms and brown algae.

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Description

Test your knowledge on protists and their characteristics with these flashcards. This quiz covers the differences between protists and prokaryotes, as well as the species diversity of protists in Eukarya. Perfect for students studying biology or life sciences.