Biological Diversity (taxonomy) Flashcards
What is a photoautotroph?
An organism that uses light as energy (as in photosynthesis)
What are the taxonomy categories, in order from largest to smallest?
Domain, kingdom, phylum, class, order, family, genus, specie
What is phylogeny?
Evolutionary relationships
What is systematics?
The study of evolutionary relationships among organisms.
What are saprobes/saprophytes?
Organisms that consume dead, decaying matter. They are called decomposers because they contribute to the decay of organic matter.
What are the domains?
Archaea, bacteria, eukarya
What are 2 major groups of archaea?
Methanogens and extremophiles
What are methanogens?
Obligate anaerobes that produce methane as a by-product of obtaining energy from H2 to fix CO2.
Where do methanogens live?
Mud, swamps, and guts of cows, humans, termites, and other animals
What are halophiles?
Organisms that live in environments with high salt concentrations. Most are aerobic and heterotrophic, while others are anaerobic and photosynthetic with the pigment bacteriorhodopsin.
What are thermophiles?
Organisms that live in hot (60-80C) environments such as hot springs and geysers. Most are sulfur-based chemoautotrophs.
What are characteristics of eukaryotic cells?
- chromosomes are long, linear DNA w/histone proteins
- chromosomes enclosed in nucleus
- organelles
- flagella and cilia are made of the protein tubulin in “9+2” microtubule arrays
What are characteristics of prokaryotic cells?
- single chromosome is short, circular DNA, and may or may not have histones
- some have plasmids, small circular DNA molecules
- no nucleus
- no organelles, although membranes might serve similar functions
- flagella are made of the globular protein flagellin
What are chemoautotrophs?
organisms that obtain energy from inorganic substances (as in chemosynthesis). Examples of substances: hydrogen sulfide (H2S), ammonia, nitrite, nitrate
What is a parasite?
organism that obtains energy from living tissues of a host
What characteristics distinguish Archaea from other prokaryotes and eukaryotes?
1) Cell walls contain polysaccharides, but not peptidoglycan (as in bacteria), cellulose (in plants), or chitin (in fungi)
2) Plasma membranes contain different phospholipids. Glycerol is an isomer of that in bacteria and eukaryotes. Hydrocarbon chains are branched and attached with ether-linkages.
What are similarities between Archaea and eukaryotes?
1) DNA are associated w/ histone proteins.
2) Ribosome activity is not inhibited by antibiotics streptomycin and chloramphenicol.
What characteristics distinguish bacteria from archaea and eukaryotes?
1) Cell walls are made with peptidoglycan, a monosaccharide with amino acids.
2) DNA is not associated w/ histones.
3) Ribosome activity is inhibited by the antibiotics streptomycin and chloramphenicol.
How many kingdoms are used to categorize all organisms?
5
What features have been traditionally used to categorize bacteria?
1) mode of nutrition/how they metabolize resources
2) production of endospores
3) means of motility (flagella–apical/posterior/covering the cell, corkscrew motion, gliding through slime secretions)
4) shape: cocci (spherical), bacilli (rod shaped), spirilla (spirals)
5) Gram-positive vs Gram-negative
What is the difference between Gram-positive and Gram-negative bacteria?
Gram-positive bacteria have a thick peptidoglycan cell wall, while Gram-negative bacteria have a thin peptidoglycan wall covered with a layer of lipopolysaccharides.
What is an endospore?
A resistant body that contains genetic material and a small amount of cytoplasm within a durable wall.
What are some common groups of bacteria?
1) Cyanobacteria
2) Chemosynthetic bacteria
3) Nitrogen-fixing bacteria
4) Spirochetes
What are cyanobacteria?
- Photosynthetic bacteria that use chlorophyll a, split H20, and release 02, like in plants.
- They contain accessory pigments called phycobilins.
- Some have heterocysts that produce nitrogen-fixing enzymes.
What is a heterocyst?
A specialized cell that produces nitrogen-fixing enzymes.
What happens when nitrogen is fixed?
Inorganic, unreactive nitrogen gas is converted to ammonia, which can be used for nitrogen-containing amino acids and nucleotides.
What are chemosynthetic bacteria?
Autotrophic bacteria that use inorganic materials. Some are called nitrifying bacteria because they convert nitrite to nitrate.
What are nitrogen-fixing bacteria?
Heterotrophs that fix nitrogen. Many establish mutualistic relationships with plants (both benefit from interdependent relationship). The bacteria live in nodules in plant roots.
What is a mutualistic relationship?
When both parties benefit from an interdependent relationship.
What is a spirochete?
Coiled bacteria that moves with a corkscrew motion. They have internal flagella that is position within layers of the cell wall.
What are the kingdoms in the domain Eukarya?
1) Protista
2) Fungi
3) Plantae
4) Animalia
What is convergent evolution?
When features shared by two or more groups arose independently.
What are characteristics of organisms in the kingdom protista? What domain does this belong in?
Organisms may be algaelike, animallike, fungus like, unicellular, or multicellular. This kingdom is artificial and used mainly for convenience because in many cases, the evolutionary relationships are weak and/or poorly understood. Many features represent convergent evolution. Belongs to the domain Eukarya.
What are characteristics of algaelike (or plant-like) members of the Protista?
- All are photosynthetic.
- All have chlorophyll a, but may have others in addition.
- Different accessory pigments
- Categorized by: chlorophylls and accessory pigments, form of carb used for energy storage, # of flagella, makeup of cell walls
What are important algaelike taxa?
1) Euglenoids
2) Dinoflagellates
3) Diatoms
4) Brown algae
5) Rhodophyta (red algae)
6) Chlorophyta (green algae)
What are euglenoids?
Algaelike protist that have:
- 1-3 flagella at apical (leading) end
- thin protein strips called pellicles wrapped over cell membranes instead of cellulose cell wall
- can become heterotrophic in absence of light
- some have eyespot that permits phototaxis (the ability to move in response to light)
What is phototaxis?
The ability to move in response to light.
What are dinoflagellates?
Algaelike protists that have:
- 2 flagella (1 posterior, 1 transverse and rests in encircling midgroove perpendicular to 1st)
- some are bioluminescent
- others produce nerve toxins that concentrate in filter-feeding shellfish, which causes illness in humans when eaten
What are diatoms?
Algaelike protists that have tests (shells) consisting of silica (SiO2) that fit together like a box with lid.
What are brown algae?
Algaelike protists that are multicellular and have flagellated sperm cells. Some are giant seaweeds (kelps).
What are rhodophyta?
AKA red algae Algaelike protists that: -contain red accessory pigments called phycobilins -are multicellular -gametes do not have flagella
What are chlorophyta?
AKA green algae
Algaelike protists that:
-have both chlorophyll a and b
-cellulose cell walls
-store carbs as starch
-gametes can be isogamous, anisogamous, or oogamous
Trends towards multicellularity:
-unicellular (Chlamydomonas)
-colonies of 4-32 cells (Gonium and Pandorina)
-colonies of 100s cells (Volvox)
Charophytes (a lineage of Chlorophytes) are believed to be the ancestors of plants.