Term
| knock-out mutants/null mutants/loss-of-function mutants |
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Definition
| alleles that do not function at all |
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Term
| one-gene, one-enzyme hypothesis |
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Definition
| genes contain the information needed to make proteins, many of which function as enzymes |
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Definition
| technique for picking certain types of mutants out of many thousands of randomly generated mutants |
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Term
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Definition
| short-lived molecules of RNA; one of several distinct types of RNA |
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Definition
| enzyme that catalyzes synthesis of RNA; polymerizes ribonucleotides into strands of RNA according to the information provided by the sequence of bases in a particular stretch of DNA |
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Term
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Definition
DNA codes for RNA, which codes for proteins (DNA transcribed to mRNA, mRNA translated to proteins)
o according to central dogma, organism’s genotype determined by sequence of bases in DNA while its phenotype is a product of the proteins it produces |
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Term
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Definition
| a strand of DNA is used as a template for the manufacture of a strand of pre-mRNA; DNA acts as a permanent record, which is copied via transcription to mRNA; making a copy of information |
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Definition
| information encoded in a strand of mRNA is used to construct a protein; also often referred to as protein synthesis |
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Term
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Definition
| rules that specify the relationship between a sequence of nucleotides in DNA or RNA and sequence of amino acids in a protein |
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Definition
| the three-base sequence of mRNA that specifies the addition of a specific amino acid |
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Term
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Definition
| sequence of codons divided into three |
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Term
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Definition
| AUG; codes for amino acid methionine; same for prokaryotes and eukaryotes |
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Term
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Definition
| UAA, UAG, UGA; also known as terminal codons; signal that protein is complete and end of translation process |
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Term
| most genes contain ______ |
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Definition
| instructions for making proteins |
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Term
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Definition
| worked with Neurospora; knock out a gene and infer what it does by studying mutant phenotype |
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Term
| what radiation does to DNA |
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Definition
| damages it, often in a way that makes affect gene nonfunctional |
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Term
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Definition
| tested and confirmed one-gene, one-enzyme hypothesis; normal cells can grow without arginine b/c can make their own. organisms synthesize arginine via metabolic pathway. if could only grow on medium w/ arginine, b/c can't make its own. documented a specific genetic defeat and a defect at a specific point in metabolic pathway |
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Term
| reasons it seemed unlikely that DNA directly catalyzed protein synthesis |
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Definition
| shape too irregular - can't mind to a variety of substrates |
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Definition
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Term
| ribosomes (site of protein synthesis) |
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Definition
- outside of nucleus, in cytoplasm
- b/c not in same place as DNA, first clue that info doesn't flow directly from DNA to proteins |
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Term
| hereditary material is ______ |
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Definition
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Term
| sequence of bases in DNA specifies ________, which specifies ________ |
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Definition
| sequence of bases in RNA; sequence of amino acids in protein |
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Term
| according to central dogma, organism's genotype determined by ____ while its phenotype is a product of _______ |
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Definition
| sequence of bases in DNA; product of the proteins it produces |
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Term
| many proteins function as ______ |
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Definition
| enzymes that catalyze chemical reactions |
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Term
| alleles of the same gene differ in ______. this causes _____ |
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Definition
| their DNA sequence; proteins produced by different alleles of the same gene to frequently differ in amino acid sequence |
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Term
| central dogma suggests info flows only _______ |
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Definition
| DNA -> RNA -> proteins; in some cases info flows from RNA back to DNA |
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Term
| Gamow - how many bases in a codon? |
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Definition
| 20 amino acids used, two-base code would give 16 (4x4) amino acids, three-base code would give 64 (4x4x4) amino acids [triplet code] |
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Term
| because it is a three-base code, _____ |
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Definition
| genetic code is redundant - more than one triple of bases specify same amino acid |
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Term
| although redundant, code is _________ |
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Definition
| unambiguous b/c one codon never codes for more than one amino acid |
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Term
| ___ codons specify the same amino acids in all organisms |
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Definition
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Term
| Crick & Brenner - confirmation of three-base code |
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Definition
| when added or deleted one base, loss of function - b/c reading frame out of register - protein produced from altered DNA has a completely different sequence of amino acids |
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Term
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Definition
| predicted mRNA carry info from DNA to site of protein synthesis |
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Term
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Definition
| created method for synthesizing RNAs of known sequence - based on enzyme called polynucleotide phosphorylase, which catalyzes formation of phosphodiester bonds between any ribonucleotides available, in random order |
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Definition
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Term
| polypeptides are assembled from ______ |
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Definition
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| what discovery violated the central dogma |
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Definition
| the discovery of RNA viruses that synthesize DNA using reverse transcriptase |
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