1. To be successful today…
Set up Cornell Notes for Protein Synthesis
New Semester & Expectations
3) New Spiral Notebook (8.5 x 11 in)
by TUES 1/16
To be successful today…
BYOD Color of the day is Phones are in put away in backpacks

2. Essential Question: How is a protein made using the code of nucleotides from DNA?

3. G1: Normal Cell Function

4. Recall…
Where does protein synthesis occur?
Where is DNA located?

5. RNA : Ribonucleic Acid

6. Turn to a Partner
List all the similarities and differences with DNA and RNA

7. RNA Single- stranded Ribose sugar Uracil replaces thymine
Can leave nucleus with DNA’s instructions
3 types ~ mRNA, rRNA, tRNA

8. Function of RNA
Carries out DNA instructions by building proteins

9. 3 Types of RNA Messenger RNA (mRNA)
Carry copies of instructions for building a protein from nucleus to ribosome

10. 2. Ribosomal RNA (rRNA)
Structural component of ribosomes

11. 3. Transfer RNA (tRNA)
Transfers an amino acid to the ribosome to be added to the protein.

12. Talk to a Partner
List the 3 types of RNA & their functions

13. Central Dogma of Biology

14. Protein synthesis occurs in two steps:
Transcription
Translation

15. Protein Synthesis in Prokaryotes
Replication, transcription & translation occur in the cytoplasm at the same time

16. Protein Synthesis in Eukaryotes
Replication, transcription & translation are separated by time and location

17. Transcription
Process of copying a specific portion of DNA (gene), producing a complimentary strand of mRNA
mRNA acts like an intermediate link between DNA in the nucleus and protein synthesis in the cytoplasm
Think of mRNA as a temporary copy of DNA that is used and then destroyed

18. Steps of Transcription
1. RNA polymerase attaches to a promoter site, part of the DNA strand that codes for a gene, and separates that section of the DNA strand

19. Steps of Transcription
2. RNA polymerase uses one DNA strand as a template to assemble nucleotides into a complementary strand of mRNA.
This follows the base pairing rules for DNA replication except that in RNA, uracil rather than thymine, pairs with adenine.

21. Talk to a Partner…

22. Steps of Transcription continued
Once polymerase reaches the terminator site (end of the gene), mRNA separates from the DNA strand & leaves the nucleus. DNA strands rejoin or zip closed.

23. Transcription Animation

24. Explain the process of transcription
Talk to a Partner
Explain the process of transcription

26. Translation
RNA to PROTEIN

27. Translation into a Protein
Proteins are made by joining amino acids with a peptide bond into long chains called polypeptides.
Each polypeptide contains a combination of any or all of the 20 different amino acids.

28. The genetic code is read three letters at a time, so that each “word” of the coded message is three mRNA bases long.
This 3-letter “word” is known as a codon.
Each codon corresponds to a particular amino acid (the anti-codon on tRNA).

29. Translation Animation

30. Steps to Translation

31. mRNA leaves the nucleus and attaches to a ribosome
2. The tRNA molecule with the correct anticodon attaches to the mRNA codon.

32. 3.The AA is released from
the tRNA. Peptide bond is formed between AA.
4.The mRNA slides through
the ribosome.The next tRNA attaches to the
mRNA codon.
5. This process continues until a STOP codon is reached.

33. Translation: RNA to PROTEIN
Talk to a Partner
Translation: RNA to PROTEIN

34. Because there are 4 different bases, there are 64 possible 3-base codons.
61 of them code for amino acids and 3 of them are “stop codons” that signal the end of the protein.
There is also one codon that specifies methionine which serves as the “start” codon for protein synthesis.

35. Decoding codons into amino acids

36. Decoding codons into amino acids

37. DNA: TAC TGG CCT TCG ACT
mRNA:
tRNA:
Amino Acids:
AUG ACC GGA AGC UGA
UAC UGG CCU UCG ACU
Met-Thr-Gly-Ser

38. Talk to a partner…
Which amino acids do the following mRNA codons code for?
UCU UCC UCA UCG AGU AGC
This is known as redundancy in the genetic code….

40. Proteins Code for Traits
The properties of proteins are determined by the number, order, and arrangement of amino acids joined together.
Proteins provide the shape, structure, and pigment within your cells that you see as your physical traits
Each mRNA codes for a different protein & different proteins mean different traits

41. Proteins Code for Traits

43. To sum it all up:

44. mRNA requires EDITING before use
Pre-mRNA transcribed in nucleus – not all bases will be translated into a protein
Exons – DNA bases that are transcribed into mRNA and eventually code for amino acids in proteins (=expressed genes)
Introns – DNA basesthat are found btwn exons & are not translated into a protein (=interrupted genes)

45. mRNA EDITING
Image by Riedell

46. RNA editing continued
Exons are spliced together by enzymes to create mature mRNA that will become a protein
Animation – no sound google chrome

47. Cornell Summary

48. Protein Synthesis

49. How does RNA POLYMERASE know where a gene starts and stops?
Enzyme binds to places with specific DNA sequences called _______________.
PROMOTERS tell _________________
where to start.
Signals at the end of the gene code cause transcription to _____ .
PROMOTERS
RNA POLYMERASE
stop