2.  Genes are coded DNA instructions that will control the production of proteins  These messages have to change to RNA to be decoded.  RNA will give the information or codes to make proteins

3.  RNA still has a 5 carbon sugar ring, but instead of deoxyribose sugar it is ribose sugar  RNA still contains 4 nitrogen bases, but thymine is replaced by uracil and still pairs with adenine.  RNA is single stranded only  Hundreds or thousands of RNA molecules can be produced from a single DNA sequence that has changed to RNA

4.  3 Types of RNA 1. Messenger RNA (mRNA) – carries copies of instructions for assembling amino acids into proteins. 2. Ribosomal RNA (rRNA) contribute to the formations of ribosomes that serve to assemble proteins. 3. Transfer RNA (tRNA) transfers the coded mRNA message of each amino acid to the ribosome

5.  Copying a DNA sequence into RNA is known as transcription -Prokaryotes- takes place in cytoplasm -Eukaryotes – takes place in nucleus *Requires enzyme RNA polymerase to bind and separate DNA strand and begin copying from template -RNA polymerase binds to promotor regions on DNA to begin copying the sequence

6.  After RNA strand has been copied it is edited before being sent to the ribosome  Introns are intervening sequences whose function is still unknown, but will be spliced from the RNA strand  Exons are the expressed sequences that are pasted together and sent to ribosome as final mRNA product

7.  Codons – consist of 3 consecutive nucleotides or are 3 letter sequences -code for a specific amino acid - 64 possible codes from codons - 61 of 64 are functional amino acids, the other 3 are stop sequence codons - AUG has dual function as a start sequence codon and codes for methionine Ex: UC G – CAC – GGU serine-histidine-glycine

10.  Decoding mRNA messages into a polypeptide chain which will become a protein is known as translation  Steps in translation: 1. mRNA leaves the nucleus after transcription and a ribosome seeks out the strand in the cytoplasm 2. Ribosome attaches the mRNA strand and beginning scanning for the start sequence AUG 3. tRNA molecule contains an anticodon that is complementary to the mRNA sequence and attaches the appropriate amino acid 4. Assembly line of amino acids begins as one tRNA molecule brings the next match and the previous one breaks bonds with ribosome and is discarded to retrieve more animo acids 5. Polypeptide chain is formed until a stop codon in the sequence causes the chain to be released and ending translation

12.  DNA serves as the master plan  RNA is the disposable copy, that can be reproduced over and over again  Genes contain the instructions for coding proteins  Proteins are enzymes that catalyze and regulate chemical reactions and have significance in determine color, shape, blood type, sex of the offspring and many other traits

13.  Evolutionary reasons for RNA intermediate: 1. provides protection for DNA and its genetic information 2. allows more copies of a protein to be made simultaneously 3. each RNA transcript can be translated repeatedly.