1. NOTES CHPT. 10

2. Flow of Genetic Information
Chapter 10
Section 4 Protein Synthesis
Flow of Genetic Information
The flow of genetic information can be symbolized as DNA RNA protein.

3. RNA (Ribonucleic Acid) Structure and Function
Section 4 Protein Synthesis
Chapter 10
RNA (Ribonucleic Acid) Structure and Function
RNA has the sugar ribose instead of deoxyribose and uracil in place of thymine.
RNA is single stranded and is shorter than DNA.

4. TRANSCRIPTION OF mRNA
THIS PROCESS STARTS AT THE PROMOTER REGION OF DNA. THIS REGION IS THE STARTING POINT OF A GENE.

5. TRANSCRIPTION INITIATION…
…IS THE COMING TOGETHER OF TRANSCRIPTION FACTORS (PROTEINS) AND RNA POLYMERASE AT THE PROMOTER.

6. TRANSCRIPTION ELONGATION…
…TAKES PLACE AS ENZYMES UNWIND THE DOUBLE HELIX OF DNA AND mRNA NUCLEOTIDES ARE MATCHED UP WITH THE TEMPLATE STRAND OF DNA.

7. THE CODING STRAND OF DNA…
…HAS THE CODE FOR THE TYPE OF PROTEIN TO BE BUILT ENCODED IN IT.

8. TRANSCRIPTION TERMINATION…
…TAKES PLACE WHEN A DNA TERMINATOR SEQUENCE IS REACHED BY RNA POLYMERASE.

9. RNA PROCESSING
A RNA CAP IS PUT ON THE 5′ END OF mRNA. ON THE 3′ END OF THE mRNA A “POLY A TAIL” IS ATTACHED.
THESE MODIFICATIONS AIDE IN PROTEIN SYNTHESIS.

10. RNA Processing…
mRNA INTRONS ARE EXCISED BY snRNP’s (RIBOZYMES & PROTEINS).
mRNA EXONS ARE SPLICED TOGETHER AND WILL LEAVE THE NUCLEUS TO BE TRANSLATED.

11. ALTERNATE SPLICING IS DONE TO MAKE SLIGHTLY DIFFERENT VERSIONS OF PROTEINS DURING TRANSLATION.

12. TRANSLATION OF mRNA TO MAKE A PROTEIN
THE GENETIC CODE IS THE CORRESPONDENCE BETWEEN THE CHEMICAL LANGUAGES OF mRNA AND PROTEIN.

13. TRANSLATION INITIATION IS THE STAGE WHEN THE INITIATION COMPLEX FORMS.
THE INITIATION COMPLEX CONSISTS OF mRNA, INITIATOR tRNA, THE AMINO ACID METHIONINE, AND A SMALL RIBOSOMAL SUBUNIT.

14. ELONGATION BEGINS WHEN A LARGE RIBOSOMAL SUBUNIT ATTACHES TO THE INITIATION COMPLEX.

15. A POLYPEPTIDE (AMINO ACID CHAIN WHICH IS A PROTEIN) STARTS TO FORM AS tRNA’s CARRY THEIR CORRESPONDING AMINO ACIDS TO THEIR COMPLEMENTARY mRNA’s. tRNA’s ARE RECYCLED AFTER DROPPING OFF THEIR AMINO ACIDS.

16. THE P site ON A RIBOSOME HOLDS THE GROWING AMINO ACID CHAIN.

17. THE A site HOLDS THE NEXT AMINO ACID TO BE ADDED TO THE AMINO ACID CHAIN.

18. THE RIBOSOME MOVES DOWN THE mRNA ONE CODON AT A TIME AS TRANSLATION PROGRESSES.

19. TRANSLATION ENDS WHEN A STOP CODON IS REACHED.

20. A RELEASE FACTOR ATTACHES TO THE STOP CODON AND CAUSES THE PROTEIN TO BE RELEASED. THE TRANSLATION COMPLEX IS BROKEN DOWN AND RECYCLED.

21. PROTEIN FOLDING
THE PRIMARY (1◦) STRUCTURE OF A PROTEIN IS ITS AMINO ACID SEQUENCE.

22. THE SECONDARY (2◦) STRUCTURE OF A PROTEIN IS FORMED BY HYDROGEN BONDS BETWEEN NONADJACENT CARBOXYL GROUPS AND AMINO GROUPS.
LOOPS, COILS, SHEETS, BARRELS, AND HELICES ARE SOME OF THE SHAPES FORMED AT THIS STAGE.

23. THE TERTIARY (3◦) STRUCTURE OF A PROTEIN FORMS AS R GROUPS INTERACT WITH WATER.

24. PROTEINS THAT CONSIST OF MORE THAN ONE POLYPEPTIDE FORM A QUATERNARY (4◦) STRUCTURE.

25. CHAPERONE PROTEINS HELP TO DIRECT PROTEIN FOLDING.

26. UBIQUITIN IS AN ENZYME THAT HELPS STRAIGHTEN OUT MISFOLDED PROTEINS.
A MISFOLDED PROTEIN WITH MORE THAN ONE UBIQUITIN TAG ATTACHED TO IT WILL BE RECYCLED IN AN ORGANELLE CALLED A PROTEASOME.

27. THE FOLDED SHAPE OF A PROTEIN DETERMINES ITS FUNCTION IN A CELL.

28. MISFOLDED PROTEINS CAUSE GENETIC DISEASES.

29. PRIONS (MISFOLDED DISEASE CAUSING PROTEINS) MAKE NORMAL PROTEINS FOLD INTO DISEASE CAUSING ONES.

30. SCRAPIE & MAD COW DISEASE (TRANSMISSABLE SPONGIFORM ENCEPHALOPATHIES)