Term
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Definition
| The process of making a linear chain of amino acids (aka a polypeptide) in which the amino acids are joined by peptide bonds. |
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Term
| What is the sequence of amino acids in the polypeptide chain determined by? |
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Definition
| The sequence of nucleotides in the mRNA. |
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Term
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Definition
| Every 3 nucleotides in the mRNA that codes for an amino acid. |
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Term
| What are the 3 components of Protein Synthesis? |
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Definition
| mRNA, tRNA/aminoactyl-synthases, ribosoems. |
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Term
| tRNA's and aminoacetyl-synthases |
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Definition
| the components that actually perform the translation from nucleotide to amino acid language. |
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Term
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Definition
| has the sequence information (from the gene)that determines amino acid sequence of protein. |
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Term
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Definition
| The work benches where translation takes place and the source of enzymatic activity (peptidyl transferase) for peptide bond formation. |
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Term
| What is the structure of tRNA? |
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Definition
| Small RNA's with conserved clover-leaf structure. |
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Term
| How many different aminoacetyl-synthases are there? |
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Definition
| 20; one for each of the amino acids. |
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Term
| Charged tRNA/ Activated Amino Acid |
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Definition
| recognize unique sequence and structural features of the tRNA and attach appropriate amino acid to the tRNA. |
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Term
| Where is the energy derived from to create avtivated amino acids? |
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Definition
| High energy phosphate bonds in ATP. |
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Term
| What are ribosomes made of? |
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Definition
| Large complexes of protein and rRNA (composed of 2 subunits: large and small) |
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Term
| What do ribosomes do when they are not synthesizing proteins? |
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Definition
| The subunits are not connected-they float free in the cytoplasm. |
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Term
| What are the three sites for binding tRNA on ribosomes? |
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Definition
| (p) a peptidyl site, (a) an aminoacyl site, (e) an exit site |
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Term
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Definition
| recognizes different codons in mRNA by complementary base pairing |
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Term
| Initiation of Translation |
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Definition
1. the small subunit of the ribosome binds near the 5' end of mRNA
2. a special "initiator" tRNA charged with methionine then base pairs with the universal start codon AUG.
3. the large robosomal subunit then attaches. this attachment uses energy provided by the hydrolysis of GTP. In this "initiation complex" the charged tRNA is positioned in the P site of the ribosome. |
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Term
| Elongation of Translation |
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Definition
1. tRNA with anticodon complementary to next codon in mRNA binds to A site
2. amino acid in P site cleaved from tRNA and attached to amino acid in A site with new peptide bond.
3. peptide bond is catalyzed by "peptidyl transferase", an exnzyme that is really a ribozyme (rRNA)
4. mRNA and attached tRNAs threaded towards left (translocation)
5. Places growing polypeptide chain in P site and an uncharged tRNA in E site where it exits from the ribosome.
6. Now ready for another cycle of amino acid addition and peptide bond formation |
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Term
| Amino acids are joined by _______________________. |
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Definition
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Term
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Definition
| linear chain of amino acids |
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Term
| Polypeptides have __________ and ____________ ends. |
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Definition
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Term
| What do functional proteins consist of? |
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Definition
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Term
| Polypeptides chains have ___________. |
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Definition
| polarity- N and C terminus |
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Term
| When does elongation stop? |
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Definition
| when a stop codon is encountered |
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Term
| No tRNA has _________________. |
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Definition
| an anticodon that can bind to a stop codon. Insteaad special protein release factors bind to the A site and the protein is release and the robosome disssassociates into large and small subunit (requires two GTP) |
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Term
| How long does it take to synthesize an average sized protein? |
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Definition
| half a minute (200-500 amino acids) |
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Term
| How is the rate of protein production increased? |
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Definition
| Having multiple ribosomes attach and translate mRNA at the same time (polyribosomes). |
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Term
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Definition
| heritable changes in the base pair sequence of DNA (the DNA is not chemically damaged, it just has a different sequence of base pairs) |
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Term
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Definition
| changes in just one base pair of the DNA. The change of even a single nucleotide in a DNA template strand can lead to the production of an abnormal protein. |
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Term
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Definition
| replaces one nucleotide and its partner with another pair of nucleotides. |
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Term
| What are the 3 types of base-pair substitutions? |
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Definition
1. silent mutations
2. missense mutations
3. nonsense mutations |
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Term
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Definition
| no effect on the amino acid produced by a codon because of the redundancy in the genetic code. |
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Term
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Definition
| code for an amino acid, but the amino acid is different from that encoded in the original, unmutated gene |
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Term
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Definition
| change an amino acid codon in a stop codon, nearly always leading to a nonfunctional protein |
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Term
| What type of mutation leads to sickle cell anemia? |
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Definition
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Term
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Definition
| when they occur in protein coding region of a gene, they typically will have more severe effects on the encoded protein than more substitutions (frameshift effect). |
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