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Chapter 7

chapter 7 bio 1225 notes.docx

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Biology 1225
Michael Butler

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Chapter 7 Gene Expression and Control 1. Information encoded within the nucleotide sequence of DNA occurs is subsets called Genes 2. Converting the information in a gene to RNA or protein product is called gene expression 3. RNA is produced during transcription 4. Ribosomal RNA (rRNA) and transfer RNA (tRNA) interact during translation of a messenger RNA (mRNA) into a protein product. DNA-----transcription-----mRNA----translation----Protein (polypeptide chain of amino acids) rRNA and tRNA interact during translation of mRNA to make protein 1 RNA - Ribose is found in RNA - RNA is a nucleic acid ie. Ribonucleic acid - occurs in a single stranded form that is similar to a single strand of DNA - Contains uracil (nucleotide) instead of thymine. Therefore Uracil pairs with Adenine (U-A) and Guanine pairs with cytosine (G-C) - There are different kinds of RNA – a cell transcribes several kinds of RNA and each has a specific function – each has a role in protein synthesis: a. rRNA – main component in ribosomes which assembles amino acids into polypeptide chains (proteins) b. tRNA – delivers RNA to ribosomes during translation one by one in the order specified by the mRNA. ****it carries an amino acid – is a ferry molecule it carries a specific amino acid to a ribosome c. mRNA – encodes information for synthesis of a polypeptide ie. protein building message – Messenger between DNA and protein – transfers information from the nucleus to the cytoplasm – RNA polymerase synthesises a mRNA chain during transcription DNA - the only role is to store a cell’s heritable information 2 Transcription – process by which enzymes assemble an RNA – using the nucleotide sequence of a gene as a template – ie DNA to RNA – is the synthesis of RNA from DNA – can produce all 3 different kinds of RNA – begins at a promoter Translation – Process by which a polypeptide chain is assembled from amino acids in the order specified by an mRNA – ***proteins are made by translation – by the process of translation the protein building information in an mRNA is translated into a sequence of amino acids. The results is a polypeptide chain that twists and folds into a Protein – when the information of mRNA is converted to a polypeptide Gene – DNA sequence that encodes an RNA or protein – Specifies a given polypeptide – DNA has a structure that allows it to replicate prior to each cell division so that the daughter cells have the same chromosomes and Genes as the original zygote had – Bases/nucleotides A-T and C-G – sequences of these 4 bases along the length of the chromosomes forms genes 3 Beadle and Tatum won the Nobel prize for developing the first clear definition of a gene: One gene – One enzyme – in other words a gene is a section of a DNA molecule that codes for an enzyme in one of the chemical processes of a cell. – Remember enzymes are catalysts at each stage of biochemical pathways – Enzymes bring the reactants together in the right way so that the reactions occur quickly – It is believed that given the 1.) correct enzymes in the correct order and 2.) the raw materials or substrates – all of the chemical reactions of the cell occur and therefore all of the characteristics of the organism are possible. – ***What we actually inherit from our parents is the information to make enzymes and the other proteins of the cell – the textbook says one gene – on protein to encompass proteins other than enzymes like hormones, membrane proteins etc. 4 How Proteins are Made - DNA contain the information for all of the proteins that the cell can possibly make over its li
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