Questions and Answers
What do protists, archaea, and bacteria make up together?
What is a common ancestor?
What is the main difference between eukaryotes and prokaryotes?
What does the name 'archaea' suggest?
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What type of environment did archaea likely live in when they first appeared on Earth?
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What is a characteristic of thermophiles?
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What do methanogens produce?
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Why are archaea considered extremophiles?
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What is the main difference between a nucleoid and a nucleus?
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What is the shape of bacterial chromosomes?
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What is the function of plasmids in bacteria?
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What is the purpose of inclusion bodies in bacteria?
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Why do bacteria need to store nutrients in inclusion bodies?
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What is the purpose of chemotaxis in bacteria?
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What is the main difference between prokaryotes and eukaryotes?
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What is the function of flagella in bacteria?
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What is a characteristic that distinguishes archaea from bacteria and protists?
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What is the term used to describe protists that are related to plants?
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What is the primary environment in which protists are found?
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What is the term used to describe the movement of bacteria towards or away from chemicals?
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What is the outermost structure of a bacterium that can be washed off?
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What is the protein that makes up the prokaryotic flagella?
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What are the small, yellow projections found on the surface of some bacteria?
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Where can bacteria be found?
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What is the term used to describe the structure that surrounds the cell wall of a bacterium?
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What is the primary function of flagella in bacteria?
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Study Notes
Unicellular Organisms
- Unicellular organisms, including protists, archaea, and bacteria, make up most of the living things on Earth.
- All living things come from a common ancestor.
Eukaryotes and Prokaryotes
- The main evolutionary difference is between the kingdoms of eukaryotes and prokaryotes.
- Eukaryotes have a nucleus, whereas prokaryotes do not (meaning they came before the nucleus).
Archaea
- Archaea are the oldest organisms, and their name sounds like "archaic", meaning really old.
- They were the first to appear on Earth and are used to extreme environments, such as high temperatures, weird weather conditions, and little oxygen.
- They are extremophiles, meaning they like extreme environments.
- There are three types of archaea:
- Thermophiles (like extreme temperatures)
- Halophiles (like extremely salty environments)
- Methanogens (make methane gas)
- Archaea have different cell walls and cell membranes than bacteria or protists.
Protista
- Protista is a "grab bag" for unicellular organisms, including some multicellular ones.
- Protists are eukaryotes that are not plants, fungi, or animals.
- They mostly live in moist or aquatic environments.
- Protists can be categorized into:
- Photosynthesizing protists (related to plants, called Algae)
- Non-photosynthesizing protists (related to fungi and animals, with subgroups like Protozoa, including amoebas, and fungal-like, including slime molds)
- Protists have evolved unique ways of getting nutrients, such as photosynthesis, and unique movement structures, like cilia, flagella, and amoeba-like movements.
Bacteria
- Bacteria can be found in diverse environments, including all around us and inside of us.
- Because of this, they can both help and hurt us.
- Bacteria have a general structure, including:
- Capsule (or slime layer)
- Cell wall
- Plasma membrane
- Prokaryotic flagella (made of protein flagellin, used for movement and chemotaxis)
- Fimbriae (or pili, small yellow projections)
- Inside the cell, bacteria have:
- Cytoplasm
- Ribosomes
- No nucleus, but a nucleoid area for the chromosome
- Chromosome is not membrane-bound and is circular, double-stranded DNA
- Some bacteria have plasmids (extra pieces of DNA)
- Inclusion bodies (store nutrients for the bacteria)
- Prokaryotes have no membrane-bound organelles, so they need to get their nutrients straight from the environment and store them in inclusion bodies.
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Description
Learn about the different types of unicellular organisms, including protists, archaea, and bacteria, and their evolutionary differences.
