Placed on the same page as your notes Warm-up pg. 48 Complete the complementary strand of DNA A T G A C G A C T Diagram 1 A T G A C G A C T T A A C T G C T G

RNA and Transcription

Genes Genes are coded DNA instructions that control the production of proteins within the cell To decode the genetic message, you must copy part of the nucleotide sequence from DNA into RNA, ribonucleic acid RNA contain coded information for making proteins

Structure of RNA RNA, like DNA, consists of a long chain of nucleotides. There are three main differences between DNA and RNA: 1.) the sugar in RNA is ribose instead of deoxyribose 2.) RNA is generally single stranded 3.) RNA contains uracil in place of Thymine Think of RNA as a disposable copy of a segment of DNA. RNA is a working copy of a single gene.

Three Types of RNA Messenger RNA (mRNA): carry instructions for the assembling of amino acids into proteins Ribosomal RNA (rRNA): type of RNA that makes up the major part of ribosomes Transfer RNA (tRNA): transfers each amino acid to the ribosome as it is specified by coded messages in mRNA

Transcription Transcription: Creates an RNA molecule by copying part of a DNA sequence Transcription requires an enzyme known as RNA polymerase RNA polymerase separates the DNA strands and then uses one strand of DNA as a template from which nucleotides are assembled into a strand of RNA

Transcription RNA polymerase knows where to join because of a region of DNA known as promoters

Code the mRNA The following sequence is found on DNA: ATTCGATGC What would be the sequence on mRNA? UAAGCUACG One more example: DNA strand: AATGC RNA strand: UUACG Remember!!!!! Uracil replaces Thymine in RNA

RNA Editing The DNA contains sequences of nucleotides, called introns, that are NOT involved in coding for proteins The DNA sequences that code for proteins are called exons When RNA molecules are formed both the introns and the exons are copied from the DNA. The introns are cut from RNA molecules while in the nucleus

The Genetic Code Remember! RNA has four different bases: U, A, G, C Proteins are made by joining amino acids into long chains called polypeptides. A codon is a three-nucleotide sequence on messenger RNA that codes for a single amino acid

For example, consider the following RNA sequence: This sequence would be read three bases at a time as: The codons represent the different amino acids: Codons can also signify for protein synthesis to start or stop

On Left Hand Page: Analysis Questions (Write Questions): 1._________ acts as a template to make the RNA molecule. 2.Describe 3 ways RNA and DNA differ. 1.__________________________ 2.__________________________ 3.__________________________ 3.If the DNA molecule has the base adenine, the RNA molecule will have the base _______________. 4.If the DNA molecule has the base thymine, the RNA molecule will have the base _______________. 5.If the DNA molecule has the base cytosine, the RNA molecule will have the base _______________. 6.If the DNA molecule has the base guanine, the RNA molecule will have the base _______________. 7.Transcription occurs in the _______________of cells. The diagram below represents a section of DNA that has been unwound for transcription. Create the strand of messenger RNA that would be made from this strand of DNA. A T G A C G A C T