Term
| Outline the classification of living organisms into three domains. |
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Definition
- Three domains of living organisms
1. Archaea: very primitive; live in extreme habitats
2. Eubacteria: more advanced
3. Eukaryota: all life forms with eukaryotic cells (have a nucleus)
- Use of ribosomal RNA sequences for classification
- rRNA is found in all cells
- rRNA is easy to isolate
- analyzed to determine the exact sequence of nucleotide bases
- the bases are a complementary copy of DNA
- can be compared by the use of computers and statistics |
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Term
| Explain the reasons for the reclassification of living organisms into three domains. |
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Definition
- There were found to be several differences between the domains now known as Archaea and Eubacteria
- The major reason was due to differences in the genes that transcribe rRNA
- Other reasons include cell wall differences, lipid bonding and rRNA sequences |
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Term
| Distinguish between the characteristics of the three domains. |
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Definition
Domain: Archaea
Histones: Proteins similar to histones
Introns: No
Ribosome size: 70S
Cell wall made of peptidoglycan: Not present
Cell membrane: Ester-linked glycerides, chirality of glycerol, saturated, branched, L-form of glycerol
Domain: Eubacteria
Histones: No
Introns: No
Ribosome size: 70S
Cell wall made of peptidoglycan: Present
Cell membrane: Ester-linked glycerides, unbranched, saturated or monounsaturated, D-form of glycerol
Domain: Eukaryota
Histones: Yes
Introns: Yes (most)
Ribosome size: 80S
Cell wall made of peptidoglycan: Cell wall not always present; not made of peptidoglycan
Cell membrane: Ester-linked glycerides, unbranched polyunsaturated, fluid, embeded with proteins and glycoproteins, D-form of glycerol |
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Term
Outline the wide diversity of habitat in the Archaea as exemplified by methanogens, thermophiles and halophiles.
Methanogens |
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Definition
- Obligate anerobes (must be without oxygen)
- Produce methane as waste product
- Found in the guts of cows, termite guts, waste landfills and marshes |
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Term
Outline the wide diversity of habitat in the Archaea as exemplified by methanogens, thermophiles and halophiles.
Thermophiles |
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Definition
-Live at temperatures close to boiling
- Tend to be extreme thermophiles (60 degrees C to 100 degrees C)
- Found in deep sea vents and hot springs |
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Term
Outline the wide diversity of habitat in the Archaea as exemplified by methanogens, thermophiles and halophiles.
Halophiles |
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Definition
- Live in saline habitats with high salt concentrations
- Tend to be extreme halophiles (very high concentrations)
- Found in the Great Salt Lake, The Dead Sea, and on Saltines |
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Term
| Outline the diversity of Eubacteria, including shape and cell wall structure. |
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Definition
Shapes of Eubacteria
- Coccus - round, spherical
- Bacillus - rod-shaped
- Spirilla - spiral
- Vibrio - comma shaped
Cell Wall Structure
- Gram Positive: 1 cell membrane, several layers peptidoglycan
- Gram Negative: 2 cell membranes, one single thin peptidoglycan, lipopolysaccharides outside of wall |
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Term
| State, with one example, that some bacteria form aggregates that show characteristics not seen in individual bacteria. |
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Definition
- Some bacteria form aggregates that show characteristics not seen in individual bacteria, eg. Vibrio fischeri
- Single individuals do not emit light unless they become part of a population with high density
- In dense populations, the concentration of the bacteria becomes high enough to trigger bioluminescence
- Happens when V. fischeri are living in mucus matrix in a squid
- Another example is Streptococcus mutans which forms biofilms on teeth, commonly known as plaque |
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Term
| Compare the structure of the cell walls of Gram-positive and Gram-negative Eubacteria. |
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Definition
Gram-positive:
- simple, one-cell membrane
- several layers of peptidoglycan
- no outer membrane
Gram-negative
- complex cell wall
- small amount of peptidoglycan
- thin peptidoglycan layer
- inner and outer membrane with peptidoglycan in between |
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Term
| Outline the diversity of microscopic eukaryotes, as illustrated by Saccharomyces, Amoeba, Plasmodium, Paramecium, Euglena and Chlorella. |
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Definition
Organism: Saccharomyces
Nutrition: Hetertroph (extracellular digestion)
Locomotion: Absent
Cell wall: Made of chitin
Chloroplasts: Absent
Cilia or Flagella: Absent
Organism: Amoeba
Nutrition: Heterotroph (intracellular digestion)
Locomotion: Slides using pseudopodia (amoeboid movements)
Cell wall: Absent
Chloroplasts: Absent
Cilia or flagella: absent
Organism: Plasmodium
Nutrition: Heterotroph (intracellular digestion)
Locomotion: Glides on substrate
Cell Wall: Absent
Chloroplasts: Absent
Cilia or flagella: Absent
Organism: Paramecium
Nutrition: Heterotroph (intracellular digestion)
Locomotion: swimming (cilia)
Cell wall: absent
Chloroplasts: absent
Cilia or flagella: cilia
Organism: Euglena
Nutrition: Autotroph and heterotroph
Locomotion: Swimming (flagella)
Cell wall: Absent
Chloroplasts: Present
Cilia or flagella: flagellum
Organism: Chlorella
Nutrition: Autotroph
Locomotion: none
Cell wall: made of cellulose
Chloroplasts: Present
Cilia or flagella: absent |
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