1. Section 12.3 – RNA & Gene Expression I.Gene Expression A.Gene Expression – the display of genes into specific traits 1.Gene expression produces proteins by transcription and translation. 2.Both processes require RNA.

2. B.Transcription: DNA to RNA 1.Copying DNA into RNA to move the genetic information from the nucleus to the cytoplasm. C.Translation: RNA to proteins 1.Using RNA to make a specific protein. ***The central dogma is the concept that all cells are governed by a cellular chain of command: DNA  RNA  protein

3. II.Ribonucleic Acid – RNA *moves genetic information from DNA (in nucleus) to the cytoplasm to make proteins.

4. A.DNAvs.RNA PhosphatePhosphate Sugar is DeoxyriboseSugar is Ribose Nitrogen Bases: C,G,A,TNitrogen Bases: C,G,A,U (uracil replaces thymine in RNA; A-U, C-G) Double HelixSingle Strand

6. B.Types of RNA 1.Messenger RNA (mRNA) – one, uncoiled chain carries genetic information from DNA (nucleus) to the cytoplasm 2.Transfer RNA (tRNA) – single chain of about 80 nucleotides, binds to amino acids 3.Ribosomal RNA (rRNA) – RNA in globs, these join with proteins to make ribosomes

7. III.Transcription: genetic information is copied from DNA to make RNA (in the nucleus) 1.An enzyme called RNA Polymerase binds to DNA at a specific spot called the promotor. a)Promotor – special sequence of nitrogen bases that marks the beginning of a gene or section of DNA to be copied.

8. 2.The double helix of DNA separates at the promotor. 3.RNA Polymerase begins binding RNA nucleotides together as it “reads” the DNA strand a)RNA uses uracil (U) instead of thymine (T). Ex: DNA: CCTGCTAGA mRNA: GGACGUCU

10. 4.Transcription continues until RNA Polymerase reaches another specific section of DNA called the termination signal. a)The newly formed mRNA is released into the cytoplasm. b)The RNA Polymerase releases and the double helix reforms (thus DNA is unchanged in the this process!)