RNA and Protein Synthesis

1. RNA and Protein Synthesis BIOLOGY Chapter 10-2 and 10-3 (pgs 190-197)

2. Do Now • What is the function of DNA? • What are the 4 nitrogen bases in DNA nucleotides and how do they pair up (complimentary base pairing)? • What are the two main enzymes involved in DNA replication?

3. Review of DNA: DNA? • Organic molecule (nucleic acid) that is composed of repeating subunits - nucleotides • Stores and transmits the genetic information • Controls the production of protein

4. FYI… Each ‘gene’, or section of DNA, consists of a sequence of nucleotides arranged in a specific order according to our genetic ancestry. The order of these base units makes up the genetic information or “code” for specific characteristics (proteins) in the body.

5. Review of Proteins Proteins are also made up of a sequence of subunits called amino acids. And, in all cells, except for bacteria, DNA is stored in the nucleus and protein synthesis takes place in the ribosome in the cytoplasm… Ribosome

6. ? Question ? So, how do cells use the genetic information, or ‘code’ stored in DNA to make millions of different characteristics and proteins the body needs?

7. This is how we do it…. • The DNA (deoxyribonucleic acid) that contains the genetic code to make all of your proteins is trapped in the nucleus of the cell • The ribosomes, enzymes, and amino acid building blocks of protein are out in the cytoplasm • RNA (ribonucleic acid) is responsible for getting the ‘code’ from the nucleus to the cytoplasm • RNA Copies DNA and then moves outside the nucleus to synthesize proteins in the ribosome

8. RNA – Ribonucleic Acid Like DNA , RNA is a nucleic acid made up of repeating nucleotides Differs in structure: 1. Sugar (ribose) 2. Phosphate 3. 1 of four different Nitrogenous Bases (A, G, C, U) 4. Single strand

9. FYI - RNA RNA differs from DNA in several ways. • An RNA molecule has only one side of the ladder shape. • RNA has the bases A, G, and C. However, it has a base U or Uracil, instead of base T or thyamine. • So when forming base pairs, base A pairs with base U.

10. Comparison of DNA and RNA:

11. 3 Types of RNA: RNA: ribonucleic acid. Use information from DNA to make proteins. 1. mRNA – messenger RNA 2. tRNA– Transfer RNA 3. rRNA – Ribosomal RNA

12. Messenger RNA (mRNA) • Single, uncoiled chain of RNA that transcribes DNA’sinformation from nucleus to cytoplasm

13. Transfer RNA (tRNA) • Single chain of about 80 RNAnucleotides folded into a hairpin shape that bind to specific amino acids • There are 45 different varieties

14. Ribosomal RNA (rRNA) • Consists of RNA nucleotides in globular form – most abundant RNA type • Along with proteins, rRNA makes up the ribosomes where proteins are made

15. So, exactly how does RNA carry genetic information from DNA to the cytosol where it can assemble proteins? PROTEIN SYNTHESIS TRANSCRITION & TRANSLATION http://glencoe.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::550::400::/sites/dl/free/0078802849/383936/Vis_transcription_translation.swf::Visualizing%20Transcription%20and%20Translation

16. 2 Parts of Protein Synthesis • 1. TRANSCRIPTION-mRNA is produced from DNA in the nucleus. • 2. TRANSLATION-Takes place in the ribosome. mRNA is ‘read’ and amino acids are transferred into the growing chain of the protein by tRNA.

17. Transcription • Part 1 of protein synthesis • Process by which genetic information is copied from DNA to mRNA • An enzyme, RNA polymerase initiates transcription by binding to promoter regions on DNA • DNA molecule separates • Only one of the DNA strands acts as a template

18. Transcription • RNA polymerase connects RNA bases to the growing RNA strand • The same as when DNA is replicated but uracil is used instead of thymine • It continues until it reaches a termination signal

19. Transcription • PROMOTER-beginning of the gene being transcribed. • TERMINATION SEQUENCE-end of the gene being transcribed. Tells the RNA polymerase “let go”.

20. Do Now • How is RNA different from DNA? • What are the three types of RNA? • What is the purpose of Transcription?

21. Translation Part 2 of Protein Synthesis • WHAT ARE PROTEINS? • Proteins are polymers of amino acids • There are 20 different amino acids • The sequence of amino acids determines the structure of the protein • The function of the protein depends on its structure

22. Proteins:

23. Translation Part 2 of Protein Synthesis • The sequence of nucleotides in an mRNA strand is translated into a sequence of amino acids to make a protein • A series of 3 nucleotides (bases) on mRNA make a codon. Acodoncodes for one amino acid.

24. Codons

25. Translation Part 2 of Protein Synthesis • There are 64 codons and only 20 amino acids, so several codons can code for the same amino acid • There are also a startcodon (AUG) and stopcodons (UAA, UAG, UGA

26. Check for Understanding: • 3 mRNA bases = code for 1 amino acid • If you have 450 mRNA bases, how many amino acids would you code for? • How many codons would you have?

27. TranslationPart 2 of Protein Synthesis • mRNA goes to ribosome and begins translation from start codon • As the ribosome reads each codon, the corresponding tRNA will come and match its anticodon to the correct codon. • The anticodon is complementary to and pairs up with a corresponding mRNA codon.

28. TranslationPart 2 of Protein Synthesis • The amino acid carried by the tRNA will be linked to the prior amino acid in the chain. Ribosome reads the stop codonand the process stops.

29. TranslationPart 2 of Protein Synthesis

31. Summary: • Let’s watch protein synthesis in ACTION! • Or here… • Now Play “Drag and Drop Protein Syntheisis”