Unit 7 Notes

1. Unit 7 Notes RNA, Protein Synthesis, Mutations, & Gene Expression Unit 7 Quiz: December 2, 2015 (Friday) Unit 7 Test: December 10, 2015 (Friday)

2. The Central Dogma • The reading & expressing genes from DNA to RNA to proteins occurs in all living things from bacteria to humans and is refer to by scientists as the central dogma of biology.

3. Three types of RNA-page 3 of foldable • Messenger RNA (mRNA) • Carries genetic information from DNA in the nucleus to direct protein synthesis in the cytoplasm • Ribosomal RNA (rRNA) • Associates with protein to form the ribosome • Transfer RNA (tRNA) • Transports amino acids to the ribosome

4. RNA • I. RNA – Venn (pp. 336) Your Foldable DNA contains specific sequences of nucleotides known as ___________. The instructions they contain are carried out through the making of _______________(Protein synthesis or gene expression). • DNA can’t leave the nucleus because of its double helix structure • RNA is used to take the genetic code from the nucleus to the cytoplasm genes proteins

6. II. PROTEIN SYNTHESIS (pp. 337-341) • In protein synthesis, the instructions contained in _______ are carried out through the making of a protein. Protein synthesis takes place in two steps: DNA

7. Transcription nucleus instructions • A. Transcription takes place in the _____________ and allows the _______________ of DNA to be carried out to the ________________. 1. First, the enzyme ___________________________, unzips part of the DNA molecule. 2. RNA nucleotides are moved in according to base pairing rules and ________________ is synthesized. There are 3 important ways that transcription differs from replication: a. Only _______________ of the DNA molecule is copied in transcription. b. In RNA, the nucleotide that pairs with adenine is ______. The nitrogen base, _______, is not found in RNA. c. Only the portion of __________________________________________ is “unzipped” and transcribed. ribosome RNA Polymerase mRNA one side uracil thymine DNA representing a gene

8. Transcription • 3. When the mRNA is first transcribed, there are long sequences of _____________ that are not required for the synthesis of the protein called _________. The DNA sequences that code for the protein are known as _____________. Introns are edited out (cut out) of the mRNA before it leaves the nucleus and the remaining _____________ are spliced together to form the final mRNA. nucleotides introns exons exons

9. protective 4. Before mRNA is ready to leave the nucleus a ____________ cap is added to the 5’ end called the ________________ and a long string of ___________ nucleotides called the ____________ to the 3’ end. So far scientist have determined the GTP cap helps in ________________ recognition but have yet to learn the significance of the poly A tail. 5’ GTP Cap adenine poly A tail ribosome

11. Transcription nucleus 5. mRNA leaves the ___________ through the _______________ and travels to the _________________, the site of protein synthesis. When mRNA arrives at the ribosome, the two parts of the ribosome, (small and large ribosomal subunits) come together and form a functioning ribosome. nuclear pores ribosomes

14. Translation ribosome tRNA mRNA amino acid B. Translation takes place at the ______________. The message in ________ is read by the ribosome, _______ brings the corresponding ____________ to make the final product – a polypeptide chain ____________. • Ribosomes • Synthesized in the _____________________ of eukaryotic cells • Composed of _______________ and ___________________ • Composed of two _________________ that come together when translation begins • Two locations for eukaryotic ribosomes • Bound Attached to ___________________ Synthesize proteins _________________________________________ • Free • Found in ________________ • Synthesize Proteins _______________________ protein nucleolus rRNA protein subunits rough ER Destined for export out of cell cytosol Remain in the cell

15. Codons monomers amino acids 1. Codons – A Mechanism to “Read” mRNA The ______________ of proteins are _______________. There are ____ amino acids used in building the proteins essential for life. The mRNA message is read by the ribosome in groups of three __________________ called __________. Each codon codes for a specific amino acid. A codon can be made up of any combination of the 4 nucleotides; in other words, there are 4 X 4 X 4, or ____ possibilities for codons. Since there are only 20 amino acids, many different codons represent the same amino acid. There are codons that are _________( AUG_) and ________ signals for the amino acid chain. The genetic code is ___________; that is, the same ____________ codes for the same____________ in all organisms. 20 nucleotides codons 64 start stop universal codon amino acid

16. Codon Charts • Ex: CCC

17. Using Codons • For the following codons, identify the corresponding amino acid: • a. UAC - ______________________________ • b. AGA - ______________________________ • c. GCA - ______________________________ • d. CCU - ______________________________ • For the following amino acids, give all possible codons: • a. arginine - ______________________________________________ • b. glycine - _______________________________________________ Tyrosine Arginine Alanine Proline CGU, CGC, CGA, CGG, AGA, AGG GGU, GGC, GGA, GGG

18. tRNA amino acid 2. tRNA –transfer RNA • The function of tRNA is to transfer the _____________ specified by the _____________ to the ____________ for protein synthesis. The __________ of the cell is stocked with all 20 amino acids required for protein synthesis. ThetRNAmolecule carries an __________ at one end and at the other end, it has a group of ___ nucleotides known as an _______________. The anticodon binds to the mRNA codon according to basepairing rulesand insures that the proper amino acid is brought to the ribosome. ribosome mRNA codon cytosol amino acid 3 anticodon

19. t RNA firsttRNA (initiator RNA) • When the__________________________________ comes to the ribosome to begin initiation, its anticodon attaches to the codon of the mRNA that is located in the _________ of the ribosome. • The next t RNA enters and its anticodon attaches to the mRNA codon in the ___________ of the ribosome. The two amino acids form a ______________________ (with the aid of the enzyme peptidyl transferase & rRNA). • The initiator tRNA is bumped off, but it leaves its amino acid behind as a part of the growing polypeptide chain P site A site peptide bond

20. 3. Building a Protein mRNA • The ________ slides through the ribosome (translocates) so that the next codon is in the A site. As the codon is read, the t RNA with the corresponding _anticodon_ (according to base-pairing rules) comes to the ribosome carrying its amino acid. That amino acid forms a peptide bond to the last amino acid in the polypeptide chain. This whole process is known as elongation, and will continue until a stop codon on the mRNA is reached. This begins termination. Then the ribosome releases the amino acid chain, which coils & folds to form a _protein; the t RNA, mRNA, and ribosomal subunits disassemble.

21. Building a Protein