Biology Exam1 chapter 13 part 2

Biology Exam1 chapter 13 part 2 - Chapter 13: Gene...

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Chapter 13: Gene Expression pg. 279 Discovery of the Gene Protein Relationship o Scientists did not really know that enzymes are proteins until early 20 th century o Beadle and Tatum proposed the one-gene, one-enzyme hypothesis Looked for mutations interfering with known metabolic reactions that produce essential molecules such as amino acids and vitamins Strains that contained mutations did not reproduce and grow properly Each mutant strain had a mutation in only one gene and that each gene affected only one enzyme This theory has now been changed to say that each gene affects one polypeptide chain Information Flow from DNA to Protein: An Overview pg. 282 o RNA is the link between DNA and protein o When a gene that codes for a protein is expressed, first an RNA copy is made of the information in the DNA o RNA is a polymer of nucleotides Usually single stranded (but it can have internal complementary pairing) Sugar is ribose (has hydroxyl group at 2’) Base uracil is substitutes for thymine o DNA is transcribed to form RNA pg. 282 Process in which RNA is synthesized resembles DNA replication in that the sequence of bases in the RNA strand is determined by complementary base pairing with one of the DNA strands ( template strand ) Transcription: (copying) process in which RNA synthesis takes information in one kind of nucleic acid (DNA) and copies it as another nucleic acid (RNA) Three main kinds of RNA molecules are transcribed: mRNA: messenger RNA, single strand of RNA that carries the information for making a protein tRNA: transfer RNA, single strand of RNA that folds back on itself to form a specific shape – each kind of tRNA bonds with only one kind of amino acid and carries it to the ribosome rRNA: ribosomal RNA. In a globular form, is an important part of the structure of ribosomes and has catalytic functions needed during protein synthesis o RNA is translated to form a polypeptide pg. 282 Translation: process in which transcribed information in the mRNA is used to specify the amino acid sequence of a polypeptide Codon: sequence of three consecutive bases in mRNA that specifies one amino acid Triplet code: code determined by the codon in mRNA Genetic code: assignments of codons for amino acids and for start and stop signals tRNA are crucial parts of the decoding machinery because they connect amino acids and nucleic acids tRNAs link with a specific amino acid tRNAs recognize the appropriate mRNA codon for that particular amino
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This note was uploaded on 01/18/2012 for the course BIO 101 taught by Professor Martin during the Fall '08 term at Rutgers.

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Biology Exam1 chapter 13 part 2 - Chapter 13: Gene...

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