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12–3 RNA and Protein Synthesis __________ are coded DNA instructions that control the production of proteins. Genetic messages can be decoded by copying part of the ____________ sequence from DNA into RNA. o RNA contains coded information for making ____________. The Structure of RNA _______ consists of a long chain of nucleotides. Each nucleotide is made up of a __- ________ ________, a ____________ group, and a _____________ ________. There are three main differences between RNA and DNA: __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ What are the three main types of RNA? Types of RNA There are three main types of RNA: o _________________________ o _________________________ o _________________________ Messenger RNA (________) carries copies of ______________ for assembling amino acids into proteins. Ribosomes are made up of proteins and ____________ ______ (rRNA). During protein construction, __________ ________ (tRNA) transfers each amino acid to the ribosome. What is transcription? Transcription RNA molecules are produced by copying part of a _____________ __________ of DNA into a _______________ _____________ in RNA. This process is called ___________________. o Transcription requires the enzyme _______ _______________. During transcription, RNA polymerase binds to DNA and separates the DNA strands. RNA polymerase then uses one strand of DNA as a template from which nucleotides are assembled into a strand of RNA. RNA polymerase binds only to regions of DNA known as ___________. o Promoters are signals in DNA that indicate to the enzyme where to bind to make RNA. RNA Editing The DNA of eukaryotic genes contains sequences of nucleotides, called ___________, that are not involved in coding for proteins. The DNA sequences that code for proteins are called ______________. o When RNA molecules are formed, introns and exons are copied from DNA. The introns are ______ _____ of RNA molecules. The exons are then __________ together to form _______. The Genetic Code The genetic code is the “___________” of mRNA instructions. The code is written using four “_________” (the bases: A, ________, C, and G). A __________ consists of ________ consecutive nucleotides on mRNA that specify a particular amino acid. Each codon specifies a particular _______ ______ that is to be placed on the polypeptide chain. Some amino acids can be specified by more than one codon. There is ____ codon _______ that can either specify the amino acid methionine or serve as a “______” codon for protein synthesis. There are ______ “______” codons that do not code for any amino acid. These “stop” codons signify the end of a ________________. What is translation? Translation ________________ is the decoding of an mRNA message into a polypeptide chain (protein). o Translation takes place on _____________. During translation, the cell uses information from messenger RNA to produce proteins. Messenger RNA is transcribed in the ______________, and then enters the ______________ where it attaches to a ________________. Translation begins when an ___________ molecule attaches to a ribosome. As each codon of the mRNA molecule moves through the ribosome, the proper _________ ______ is brought into the ribosome by tRNA. o In the ribosome, the amino acid is transferred to the growing polypeptide chain. The ribosome binds new _________ molecules and amino acids as it moves along the mRNA. Protein Synthesis The process continues until the ribosome reaches a stop codon. The Roles of RNA and DNA The cell uses the DNA “________ _____” to prepare RNA “_____________.” The DNA stays in the _____________. The RNA molecules go to the protein building sites in the cytoplasm—the _______________. Genes and Proteins _____________ contain instructions for assembling proteins. Many proteins are ____________, which catalyze and regulate chemical reactions. Proteins are each specifically designed to build or operate a component of a living cell. The sequence of bases in DNA is used as a _______________ for mRNA. The codons of mRNA specify the sequence of amino acids in a protein.
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