DNA To RNA To Proteins

1. DNA To RNA To Proteins Transcription, Translation → ProteinsWhich is The Central Dogma of Biology

2. The Structure of RNA • Long Chains of Nucleotides • 5 Carbon Sugar ( Ribose ) • Phosphate Group • Nitrogenous Base • A, G, C, U ( no T ) • Single Stranded

3. Types of RNA RNA Mostly For Protein Synthesis Three Types of RNA Messenger RNA, mRNA Ribosomal RNA, rRNA Transfer RNA, tRNA

4. Types of RNA mRNA A Copy of the Recipe in the DNA. Transports the Recipe to the Ribosome. rRNA Part of ribosome. It Reads the Recipe in the mRNA Puts the ingredients together tRNA Transports Amino Acids (the ingredients) from cytoplasm to the Ribosomes in the Order Needed to make the Protein (the Cookies)

5. Transcription (mRNA) The process of copying the DNA nucleotide sequence into a complementary sequence of RNA ( copying the recipe) Requires a special enzyme:RNA Polymerase(Transcription Rate= ~60 nucleotides/second)

6. RNA Polymerase DNA DNA RNAPolymerase

7. Transcription Key Concept: During transcription, RNA polymerase binds to DNA and separates the DNA strands. RNA Polymerase then uses one strand of DNA as a template to assemble nucleotides into RNA

8. Transcription Promoters • Regions on DNA that show where RNA Polymerasemust bind to begin the Transcription of RNA • Specific base sequences act as signals • Other base sequences indicate stopping points

9. TranscriptionThe Devil is in the Details RNA Splicing After the DNA is transcribed into mRNA: Editing must be done to the mRNA chain to make the mRNA functional

10. TranscriptionThe Devil is in the Details Intronsneed to be removed • These are non-functional segments of the mRNA strand copied from the DNA • Snipped out of the chain in the nucleus Exonsneed to be glued back together • These segments contain the real recipe and need to be reconnected to make the real, functional mRNA This Process is called: mRNA Splicing

11. mRNA Splicing

12. The Genetic Code Proteins are: • long chains of amino acids. • There are 20 different amino acids • The order of amino acids in the protein determine its shape and function

13. The Genetic Code There are 20 amino acidsbut only 4 bases in RNA.So, How Can You Design A Code? Adenine A Cytosine C Guanine G Uracil U RNABases

14. The Genetic Code The genetic code consists of “words” three bases long Each “word” is called aCodon: A codon is three consecutive nucleotides that code for a single amino acid

15. The Genetic Code For Example: UCGCACGGU= RNA Sequence UCG - CAC -GGU= Codons UCGcodes for Serine CACcodes for Histidine GGUcodes for Glycine

16. The Genetic Code If you have 4 Bases and…. Codonsare defined with 3 Bases….. How many combinations of 3 can you make? There Are 64 Possible 3-base codons Since there are only 20 amino acids,some amino acids are represented by multiple codons

17. Code Wheel Table On Page 303

18. Code Table

19. 8 Essential Amino Acids Essential AA = An Amino Acid That Can NOT Be Made, It Must Be Eaten

20. Translation Translationis the process of decoding the mRNA and chaining Amino Acids together into the polypeptide chain(making the protein) (See pages 245-247) • Ribosomes • Read mRNA and construct the proteins

21. Translation Step A

22. Translation Step B

23. Translation Step C Step C • Ribosome connects the amino acids together as they come into the ribosome • Ribosome disconnects the the 3rd amino acid from the ribosome to float into the cytoplasm

24. Translation Step D • Step D • Polypeptide chain grows until the mRNA STOP Codon is reached • The ribosome then releases the polypeptide chain into the cytoplasm

25. The Roles of DNA & RNA DNA= The Cookbook mRNA= A copy of the recipe from “The Cookbook”

26. Genes & Proteins • Genes are instructions for assembling proteins (recipes in a cookbook) • Proteins (the cookies from the recipe)are enzymes that catalyze and regulate chemical reactions • Pigments, antigens, regulators • Proteins are the keys to biological function