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25 Cards in this Set
- Front
- Back
Transcription
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Synthesis of RNA using a DNA template (DNA making copies of RNA).
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Translation
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Synthesis of a protein using genetic information encoded in a mRNA molecule (translating nucleic acids into amino acids).
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P site
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Holds the tRNA carrying the growing polypeptide chain (protein).
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A site
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Holds the tRNA carrying the next amino acid to be added to the growing chain.
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E site
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Site from which empty tRNA’s exit.
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Stage 1: Initiation
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The initiator tRNA waits in the P site for the next tRNA to occupy the A site.
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Stage 2: Elongation
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The tRNA in the P site is translocated to the E site and released while the tRNA in the A site is translocated to the P site.
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Stage 3: Termination
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Release factor promotes hydrolysis of the bond between tRNA in the P site and the last amino acid of the polypeptide.
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mRNA degradation in prokaryotes
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Bacterial mRNA molecules are degraded by enzymes within a few minutes of their synthesis.
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mRNA Degradation eukaryotes
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mRNA molecules in multicellular eukaryotes typically survive for hours, days, or even weeks.
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Protein Processing and Degradation
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i. Process proteins for functional protein molecules.
ii. Add phosphate groups to in/activate proteins. iii. Add sugars to in/activate cell surface proteins. iv. Transport proteins to target destinations in order to function. |
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proteasomes
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Giant protein complex that recognizes and destroys proteins tagged for elimination by the smaller protein ubiquitin.
i. Regulates the length of time each protein functions. ii. Example: cyclins during cell cycle = short-lived. |
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Multistep Model of Cancer Development
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1. Loss of tumor suppressor gene APC
2. Activation of the ras oncogene 3. Loss of tumor suppressor gene DCC 4. Loss of tumor suppressor gene p53 5. Additional mutations |
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Bacteriophages
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i. Most complex capsids.
ii. Elongated icosahedral heads with DNA. iii. Protein tailpiece with fibers for attachment to a bacterium. |
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Lytic cycle
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Replicative cycle resulting in the release of new phages by lysis (and death) of the host cell.
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Lysogenic cycle
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Replicative cycle in which the viral genome becomes incorporated into the bacterial host chromosome, replicating with the chromosome without killing the host.
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Pathways of Emerging Viruses
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Step #1: Mutation of existing viruses.
Step #2: Dissemination of viral diseases from small, isolated human populations. Step #3: Spread of existing viruses from other animals which become sources of new diseases in humans. |
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Basic structure of a bacterium
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1. Nucleoid
2. Cytoplasm and ribosomes 3. Cytoplasmic membrane 4. Cell wall 5. Capsule 6. Pili 7. Flagella |
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Gram Positive
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Structurally less complex cell walls with more
peptidoglycans (traps crystal violet); usually less toxic. Tend to be less resistant to antibiotics due to simpler cell wall (antibiotics inhibit cell wall function by interfering with its construction). |
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Gram Negative
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Structurally more complex cell walls with less
peptidoglycans (loses crystal violet); usually more toxic. Tend to be more resistant to antibiotics due to more complex cell wall (lipid portions tend to be toxic causing fever or shock). |
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Archaea
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Extremophiles
Thermophiles Halophiles Methanogens |
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Extremophiles
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Organisms that live in environmental conditions so extreme that few other spp can survive there.
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Thermophiles
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Organism that lives in hot environments (60 - 80°C or higher). DNA and proteins do not denature.
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Halophiles
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Organism that lives in a highly saline environment
Compensate for water loss by pumping K ions into the cell until an isotonic concentration is reached between the cell and its environment. |
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Methanogens
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Organisms that produce methane as a waste product of the way it obtains energy.
i. Found in swamps and marshes. ii. Found in guts of herbivores. iii. Poisoned by oxygen. |