1. 12-3 RNA and Protein Synthesis
A ribosome; where proteins are made

2. I. The Structure of RNA

3. RNA is a nucleic acid
RNA is made of:
long chains of nucleotides
Ribose sugar
Single-stranded
Has a nucleotide called Uracil instead of Thymine
The nucleotides are Adenine, Uracil, Guanine, & Cytosine
Guanine bonds w/ cytosine, & adenine bonds w/ uracil

4. An RNA molecule is a working copy of a single gene
Genes- coded DNA instructions that control the making of proteins w/i the cell

5. Discussion Review Questions:
What is a protein?
List the protein you ate today and/or yesterday
What role do proteins play in your body functions?

6. Answers:
What is a protein? A macromolecule that is formed by many amino acids that are linked together
List the protein you ate today and/or yesterday Chicken, Beef, Fish, Lamb, dairy products, beans, and nuts
What role do proteins play in your body functions? Needed by the body for growth, repair, movement, immune response, to make up enzymes, etc.

7. II. Types of RNA

8. There are 3 main types of RNA:
Messenger RNA (mRNA)– carries copies of instructions from genes (DNA) for putting together amino acids into proteins.
Carries “messages” from DNA to the rest of the cell.
Is transcribed from genes that encode proteins

9. Ribosomal RNA (rRNA)- makes up a major part of the ribosome
proteins are put together here
Binds to other proteins in the cytoplasm before it is activated
Has a way to decode mRNA into amino acids and interacts with tRNA during translation

10. Transfer RNA (tRNA)- transfers each amino acid to the ribosome as it is determined by the coded messages in mRNA.
Binds to other proteins in the cell before it is activated

11. Discussion w/ Partner:
Page figure 12-14
Where is DNA located in the eukaryotic cell?
Where does transcription take place?
Where does protein synthesis take place?

12. Where does transcription take place? In the nucleus
Answers:
Where is DNA located in the eukaryotic cell? In the nucleus of the cell
Where does transcription take place? In the nucleus
Where does protein synthesis take place? In the cytoplasm of the cell

13. What are the two main regions of a ribosome?
In Your Notebook
Page 301 figure 12-13
What are the two main regions of a ribosome?
Each letter on the ribosome represents a different protein; how many proteins are on a ribosome?

14. Answers:
What are the two main regions of a ribosome? 30S and 50S, mRNA brings codons b/w these two regions during translation
Each letter on the ribosome represents a different protein; how many proteins are on a ribosome? 6

15. III. Transcription

16. RNA Polymerase- an enzyme that binds to DNA & separates the DNA strands during transcription
Promoters- A specific DNA nucleotide sequence where mRNA starts transcription
RNA polymerase only connects to the “promoter” region of DNA

17. Transcription happens when:
Transcription- RNA molecules are made by copying a part of the nucleotides from a DNA sequence
Transcription happens when:
RNA polymerase connects to DNA & separates the DNA strands.
RNA polymerase then uses one strand of DNA as a template to put together nucleotides into a strand of RNA.

18. Transcription

19. Transcribe the following from dna to mrna
DNA strand: AAT GCT GCG GAT

20. Results of Transcription from dna to mrna:
DNA codon: AAT GCT GCG GAT mRNA codon: UUA CGA CGC CUA

21. IV. RNA Editing

22. Introns- DNA sequences of nucleotides that do not code for a protein
Exons- sequences that does code for a protein
The introns are cut out of RNA molecules.
The exons are then spliced together to form mRNA.
They are expressed in the production or synthesis of proteins

23. Contrast introns and exons.
Discuss w/ partner:
Contrast introns and exons.

24. Answer: Contrast introns and exons.
Exons code for proteins and introns do not code for proteins

25. V. The Genetic Code

26. Is universal in all organisms
Proteins are made by putting together a lot of polypeptides.
Polypeptides -a combination of any or all 20 amino acid molecules.
The order of the amino acid determines the characteristic of the protein

27. mRNA’s language is called the genetic code which is 3 “letters” transcribed from DNA.
The code is written using four “letters” (the bases: A, U, C, and G

28. Codon -three nucleotides that are next to each other on mRNA that determine a particular amino acid

29. The Genetic Code

30. 1. For what amino acid does the mRNA codon ACA code?
In your notebook:
1. For what amino acid does the mRNA codon ACA code?

31. Answer:
For what amino acid does the mRNA codon ACA code? Threonine

32. VI. Translation

33. Takes place on the ribosomes
Takes place after transcription (DNA to mRNA)
The cell uses info from mRNA to produce proteins.
Translation- the decoding of an mRNA message into a polypeptide chain (protein)
A ribosome and tRNA molecules work together to translate a mRNA molecule. The growing amino acid chain will become a protein.
Credit: National Human Genome Research Institute

34. Translation begins when an mRNA molecule attaches to a ribosome.
The ribosome binds new tRNA molecules and amino acids as it moves along the mRNA
A. Messenger RNA
Ribosome
start codon
mRNA

35. As each codon of the mRNA molecule moves through the ribosome, the proper amino acid is brought into the ribosome by tRNA.
In the ribosome, the amino acid is transferred to the growing polypeptide chain
B. Transfer RNA

36. In the process anticodons are formed
Anticodon- 3 unpaired bases of tRNA that are complementary to mRNA
The DNA codon is what gets transcribed and translated into an amino acid.

37. The ribosome forms a peptide bond b/w the amino acids.
The ribosome also breaks the bond b/w tRNA & it’s amino acid; the tRNA molecule is released
C. The Polypeptide “Assembly Line”

38. The polypeptide chain grows until a “stop” codon on mRNA is reached
D. Completing the Polypeptide
The polypeptide chain grows until a “stop” codon on mRNA is reached
Both the mRNA & the new polypeptide chain are released, ending the translation process.
The polypeptide will form a protein.
Stop Codon

39. The sequence of bases in DNA is used as a template for mRNA.
The codons of mRNA specify the sequence of amino acids in a protein.

40. Transcribe & translate the following mRNA codon to amino acids
DNA codon: AAT GCT GCG GAT mRNA codon: UUA CGA CGC CUA

41. The protein is made from mRNA’s codon
Answers
DNA codon AAT GCT GCG GAT
mRNA codon UUA CGA CGC CUA
tRNA anticodon: AAU GCU GCG GAU
Amino Acid s : Leucine Arginine Arginine Aspartic Acid
The protein is made from mRNA’s codon

42. VII. The roles of dna & Rna

43. DNA stays safely inside the nucleus
RNA molecules go to the ribosomes which are the protein building cites inside the cytoplasm

44. VIII. Genes & Proteins

45. Genes are tools which are each specifically designed to build or operate a part of a living cell.
A gene the codes for an enzyme to produce a certain pigment determines the color of a flower
A gene produces an enzyme that produced red blood cell surface antigen; this determines your blood type.