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AP Bio Chapter 17
Ap Bio Chapter 17
| Word | Definition |
|---|---|
| auxotrophs | nutritional mutants ("increase" "nourishment") |
| Beatle & Tatum's one gene-one polypeptide (protein) hypothesis | Some proteins are composed of different polypeptide chains encoded by separate genes. Hypothesis-mutation in a gene encoding a specifc polypeptide can alter the ability of the encoded protein to function producing an altered phenotype. |
| Transcription | synthesis of RNA under the direction of DNA |
| mRNA | carries a genetic message from the DNA to the proetin-synthesizing machinery of the cell (Ribosome!) |
| Translation | the actual synthesis of a polypeptide which occurs under the direction of nRNA |
| RNA Processing | modification of RNA before it leaves the nucleus, a process unique to eukaryotes |
| Primary Transcript | a more general initial term for RNA transcript |
| triplet code | the genetic instructions for a polypeptide chain are written in the DNA as a series of three-nucleotide words |
| template strand | provides the template for ordering the sequence of nucleotides in an RNA transcript |
| codons | the mRNA base triplets |
| reading frame | a group of specific codes being read |
| RNA polymerase | an enzyme that pries the two strands of DNA apart and hooks togetherthe RNA nucleotides as the base-pair along the DNA template |
| transcription unit | the stretch of DNA that is transcribed into an RNA molecule |
| promoter | a region of DNA twhere RNA polymerase attaches and initiates transcription |
| transcription factors | mediate the binding of the RNA polymerase and the initiation of transcription |
| transcription initiation complex | the complete assembley of transcription factors and RNA polymerasebound to the promoter |
| TATA Box | a crucial promoter DNA sepquence in forming the initiation complex |
| terminator | functions as the actual termination signal` |
| 5' cap | protects the mRNA from degradation from enzymes & functions as an "attach here" signal to the ribosomes |
| poly(A)tail | a strand of 30 to 200 adenine nucleotides that prevents the degradation of the RNA |
| RNA splicing | the removal of a large portion of the RNA molecule that is initially synthesized |
| spliceososome | interacts with the splice sites at the ends of an intron. it cuts at specific points to release the intron, then immediately joins together the two exons that flanked the intron |
| ribozymes | RNA molecules that function as enzymes |
| domains | discrete structual and functional components of proteins, includes the active site and can attach the protein to the cell membrane, the exons of a "spit gene" code for different domains |
| tRNA (transfer) | transfer amino acids from the cytoplasm's amino acids pool to a ribosome |
| wobble | the relaxation of the base-pairing rules |
| aminoacytl-tRNA synthetase | a specific enzyme that that joins amino acids to the correct tRNA |
| rRNA (ribosomal) | the ribisomal subunits that are constraucted by proteins and RNA molecules |
| P site | holds the tRNA carrying the growing polypeptide chain |
| A site | holds the tRNA carrying the next amino acid to be added to the chain |
| E site | the exit site |
| Initiation | when mRNA and 2 subunits of the ribosome come together |
| Elongation | amino acids are added one by one to the first amino acid |
| Termination | the final stage of translation where elongation continues until the stop codon reaches an A |
| polyribosomes | strings of ribosomes |
| signal peptide | thich targets the protection of the ER |
| signal recognition (SRP) | functions as the adapter that brings the ribosome to a receptor protein built into the ER membrane |
| Mutations | changes in the genetic material of a cell (or virus) |
| point mutations | chemical changes in just one or a few base pairs in a single gene |
| base-pair substitutions | the replacement of one nucleotide and its partner in the complementary DNA strand with another pair of nucleotides |
| missence mutations | the altered codon still codes for an amino acid and thus makes sense, although not necesarily the right sense |
| nonsence mutaions | alterations that change an amino acid codon to a stop signal , lead to nonfunctional proteins |
| insertations and deletions | additions or losses of one or more nucleotide pairs in a gene |
| frameshift mutation | occurs when the number of nucleotides inserted or deleted is not a multiple of 3 |
| mutagens | interact with DNA to cause mutation |
| Ames test | uses easily grown bacteria to test organisms for mutagenic activity |