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Bio II Ch 27 Vocab
| Term | Definition |
|---|---|
| Prokaryotes are... | Unicellular; small |
| Key feature of nearly all prokaryotic cells | Cell wall |
| Most bacterial cell walls contain... | Peptidoglycan |
| Peptidoglycan | a polymer composed of modified sugars cross-linked by short polypeptides; found in bacterial cell walls |
| Gram stain | developed by Hans Christian Gram; used to categorize bacterial species according to differences in cell wall composition |
| Gram-positive bacteria | simple walls composed of a thick layer of peptidoglycan; purple |
| Gram-negative bacteria | less peptidoglycan, structurally more complex with outer membrane containing lipopolysaccharides |
| T or F: Lots of prokaryotes have a capsule around the cell wall | T |
| Capsule | sticky layer of polysaccharide or protein that surrounds the cell wall of many prokaryotes |
| Endospores | resistant cells that certain bacteria develop in order to withstand harsh conditions; happens when a bacteria lacks water or essential nutrients |
| Fimbriae | hairlike appendages on prokaryotes that are used to attach to surfaces or other cells |
| T or F: 100% of all prokaryotes are capable of taxis | F; only 50% |
| Taxis | a directed movement toward or away from a stimulus |
| Pili | appendages that pull two cells together prior to DNA transfer from one cell to the other |
| T or F: Cells of prokaryotes are simpler than eukaryotes | T |
| Most common structure that enables prokaryotes to move: | Flagella |
| Chemotaxis | where organisms change their movement pattern in response to a chemical; if they move TOWARD nutrients/O2, it is POSITIVE chemotaxis; if they move AWAY from nutrients/O2, it is NEGATIVE chemotaxis |
| T or F: Prokaryotic cells have compartementalization | F; they do not |
| Nucleoid | analogous to a nucleus; houses the prokaryotic chromosome; NOT enclosed in cytoplasm |
| Plasmids | extra-chromosomal DNA; there is a PROBLEM = it can cause RESISTANCE (R-plasmid = resistant plasmid) |
| Binary fission | how bacteria reproduce; a single prokaryotic cell divides into 2 cells |
| T or F: No mitosis OR meiosis for prokaryotes | T |
| What accounts for new mutations arising? | Genetic recombination |
| What 3 ways can prokaryotes utilize genetic recombination? | 1) Transformation 2) Transduction 3) Conjugation |
| Transformation | a change in genotype and phenotype due to the accumulation of external DNA by a cell |
| Horizontal gene transfer | this is what transformation results in when the external DNA is from a member of a different species |
| Transduction | a process in which bacteriophages carry bacterial DNA from 1 bacterial cell to another - also known as Horizontal Gene Transfer |
| Bacteriophage | a virus that lives in a bacteria |
| Conjugation | the direct transfer of DNA between 2 cells that are temporarily joined; if 2 DIFFERENT SPECIES = Horizontal Gene Transfer |
| F (fertility) factor | a particular piece of DNA that results in a prokaryote's ability to form pili and donate DNA during conjugation |
| F factor as a plasmid | F plasmid; cells containing the plasmid, called F+ cells, function as DNA donors during conjugation // cells lacking the plasmid, F- cells, function as DNA recipients during conjugation; F+ can convert F- to F+ if entire copy of plasmid is transferred |
| Hfr cell | a cell with the F factor built into its chromosome; functions as a donor during conjugation with an F- cell and exchanges DNA |
| R plasmids | can carry resistance genes that fight against certain antibiotics (R for resistance) |
| Phototrophs | organisms that obtain energy from light |
| Chemotrophs | organisms that obtain energy from chemicals |
| Autotrophs | organisms that need only CO2 or related compounds as a carbon source |
| Heterotrophs | organisms that require at least 1 organic nutrient (like glucose) to make organic compounds // ie HUMANS |
| Photoautotrophs | energy source = light carbon source = CO2, HCO3-, or related compounds |
| Chemoautotrophs | energy source = inorganic chemicals carbon source = CO2, HCO3- |
| Photoheterotrophs | energy source = light carbon source = organic compounds |
| Chemoheterotrophs | energy source = organic compounds carbon source = organic compounds ie HUMANS |
| Obligate aerobes | need O2 for cellular respiration |
| Obligate anaerobes | cannot grow in the presence of O2 |
| Anaerobic respiration | O2 is NOT the final electron acceptor; uses other molecules like nitrate and sulfate |
| Nitrogen fixation | the conversion of atmospheric nitrogen (N2) to ammonia (NH3); carried out by certain prokaryotes, some of them having mutualistic relationships with plants; can be done in plants like LEGUMES (beans) |
| Nitrogen is needed for what? | Amino acids AND nucleic acids |
| T or F: Eukaryotes can obtain nitrogen only from a limited group of nitrogen compounds | T |
| T or F: Prokaryotes are unable to metabolize nitrogen in various forms | F; they can |
| What domain are extremophiles a part of? | Archaea |
| Extremophiles | archaea that live in extreme environments/conditions (ie Yellow Stone hot spring) |
| Extreme halophiles | live in high-salinity environments |
| Extreme thermophiles | live in very hot environments |
| Methanogens | organisms that release methane as a by-product of how they obtain energy. Found in the aerobic guts of cattle, termites, and other herbivores. They are needed for their role in essential nutrition for these organisms |
| Decomposers | chemoheterotrophic prokaryotes that break down dead organisms and waste products. They provide carbon, nitrogen, and other elements |
| Symbiosis | 2 species living in close contact with each other |
| Mutualism | both species benefit |
| Commensalism | 1 species benefits, and the other is not harmed/hurt |
| Parasitism | the host is harmed |
| Exotoxins | proteins secreted by certain bacteria |
| Endotoxins | lipopolysaccharide components released only when the bacteria die |
| Mutualistic bacteria | 500-1,000 species living in our gut; aids human well-being |
| Pathogenic bacteria | cause about half of all human diseases; only 3-5% of bacteria make you sick |
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