Answer the following attachment
LA#17: Central Dogma of Biology (DNA → RNA → Protein) – Transcription & Translation
DNA is often referred to as a genetic blueprint. In the same way that blueprints contain the instructions for construction of a building, the DNA found inside the nuclei of cells contains the instructions for assembling a living organism. The DNA blueprint carries its instructions in the form of genes. In most cases the genes direct the production of a polypeptide, from which other more complex proteins, such as enzymes or hormones, may be constructed. These polypeptides and other molecules run the organism’s metabolism and, in multicellular organisms, dictate what each cell’s job is. So, what is the language of these instructions and how are they read and decoded by the cellular organelles? This activity will focus on the decoding of genes in eukaryotes.
1. What molecule does DNA store the instructions for building?
2. Where is DNA located in a eukaryotic cell? Prokaryotic cell?
3. Where in the eukaryotic cell are proteins made?
4. How do you think the information stored in DNA gets to the ribosomes in the cytoplasm?
The flow of information in Eukaryotic Cells 
Figure 1: This figure shows the flow of information in cells from the DNA in the nucleus to a molecule called RNA to the creation of proteins in the cytoplasm. It was discovered that RNA, which is similar but not identical to DNA, moves from the nucleus to the cytoplasm. RNA is a nucleic acid polymer composed of nucleotides like DNA. However, RNA uses the sugar ribose and the nitrogen base uracil, instead of DNA’s deoxyribose and thymine. Also RNA is a much smaller molecule than DNA.
5. Fill in the blank: DNA Protein 
6. What are at least 3 differences between DNA and RNA?
Figure 2: This figure shows the flow of information in a little more detail.
7. What is the process of going from DNA to RNA called?
8. Look at how the DNA and RNA pair. What does the U in RNA pair with? How is this different from the base pairing rules in DNA?
9. What is the process of going from RNA to protein called?
10. How many letters of RNA are needed to code for one amino acid? What is this group called?
11. What is the purpose of transcription? (What does it make?) Where does this process occur?
12. Transcribe the following DNA template: ATC GGA TAC
Model 1: Transcription Details
In eukaryotes the enzyme RNA polymerase joins with several transcription factor proteins at the promoter, which is a special sequence of base pairs on the DNA template strand that signals the beginning of a gene. The transcription factor proteins, along with the RNA polymerase, is called the transcription initiation complex. This moves along the DNA template strand at about 40 base pairs per second producing pre-mRNA. When the RNA polymerase reaches the terminator sequence of base pairs on the DNA template strand, it completes the production of pre-mRNA and releases it into the nucleoplasm.
13. What monomers are used to construct this polymer and where are they found? 
14. What enzyme is required for transcription?
15. Which strand of the DNA contains the “blueprint” for the pre-mRNA?
16. In which direction is the DNA molecule read?
17. The DNA strand and pre-mRNA strand are anti-parallel. With this in mind label the 3ʹ and 5ʹ ends of the pre-mRNA strand in Model 1.
18. In which direction is the pre-mRNA molecule constructed?
19. What parts make up the transcription initiation complex?
20. Where on the DNA strand does the transcription initiation complex form?
21. Nearly all cells in an organism contain identical DNA, and each DNA strand may contain hundreds or thousands of individual genes. Is it likely that a cell would transcribe all the genes within its nucleus simultaneously? Justify your answer using complete sentences.
22. Considering the many types of cells in a multicellular organism, and their different functions, is it likely that all cells transcribe all their genes at some point in their lifetime? Justify your answer using complete sentences.
Figure 3: This diagram shows the processes of transcription and translation where they occur in a eukaryotic cell.
23. What is the process of translation? (What does it make?) 
Where does this process occur?
24. Examine Figure 3. What is each tRNA molecule carrying? What part of the tRNA binds with mRNA?
The 3 Types of RNA.
In any cell, only some of the genes are expressed, that is, transcribed into RNA. There are 3 major types of RNA, each encoded by its own type of gene:
• mRNA - Messenger RNA has the instructions for how to make the protein encoded within its sequence.
• tRNA - Transfer RNA attaches to amino acids and then transfers them to the ribosome during translation.
rRNA - Ribosomal RNA combines with ribosomal proteins to make up the actual ribosome. 
25. What does Figure 4 show?
Model 2 – mRNA Processing
Introns are sections of pre-mRNA that are noncoding. That is, they don’t provide useful information for the production of the polypeptide being synthesized. There is evidence that suggests these introns allow certain sections of DNA to code for different polypeptides when different sections are removed. The removal of specific sections is triggered by a signal response in the cell. The portions of the pre-mRNA that remain are called exons. The methyl cap (sometimes called the GTP cap or 5ʹ cap) helps the mRNA molecule move through the nuclear pore and attach to a ribosome, its final destination. mRNA is a short-lived molecule. Once in the cytoplasm the mRNA will be subject to exonucleases that immediately start removing individual nucleotides from the 3ʹ end of a nucleic acid. The individual mRNA nucleotides will then be free to be used again during the process of transcription.
26. Compare the pre-mRNA in Model 1 to the mRNA leaving the nucleus in Model 2.
a. What has been removed from the pre-mRNA to make it into mRNA?
b. What has been added to the mRNA that was not present in the pre-mRNA, and where on the mRNA strand are the additional items located?
27. Identify the structure through which the mRNA leaves the nucleus. 
28. The nucleotides on the mRNA will be “read” in the next step to producing a polypeptide. What sequence of bases indicates the starting point for the polypeptide “blueprint”?
29. The “m” in mRNA is short for “messenger.” Why is this molecule called messenger RNA?
30. The human genome contains about 25,000 genes and yet produces about 100,000 different polypeptides. Propose an explanation of how this is possible.
31. Form a hypothesis about the advantage of the poly-A tail added to the 3ʹ end of the mRNA.
32. Different mRNA molecules can have poly-A tails of different lengths. Considering the purpose of adding the poly-A
tail (from the previous question), why are some tails longer than others? Justify your answer using complete sentences.
33. Summarize the steps of transcription.
34. The message in your DNA of who you are and how your body works is carried out by cells through gene expression. In most cases this means synthesizing a specific protein to do a specific job. First, mRNA is transcribed from the DNA code. Then, the mRNA sequence is translated into a polypeptide sequence. Only some genes are expressed in a particular cell. Why do you think that this is true? Why would you express a gene? Why wouldn’t you?
Model 3 – Codons
35. Model 3 defines the code scientists have discovered that relates the nucleotide sequence of mRNA to the amino acid sequence of polypeptides.
a. What do the letters U, C, A, and G represent?
b. What do the abbreviations such as Phe, Ile, Ala, and Gly represent?
c. The language of mRNA is often described as a “triplet code.” Explain the significance of this reference.
36. If an mRNA molecule had 300 nucleotides in the coding region of the strand, how many amino acids would be in the polypeptide that was synthesized? Show mathematical work to support your answer.
37. How many different codons (triplets) code for the amino acid Proline (Pro)?
Compare all of the codons for Proline. What are the similarities and differences?
Considering that mistakes can occur during transcription and DNA replication, what advantage is there for an organism to have multiple mRNA sequences code for the same amino acid?
38. Using the mRNA codon chart, complete the following:
DNA → TAC CTT CGG ATG GTC ACT
mRNA →
polypeptide sequence →
39. According to the table, what amino acid is at the beginning of every polypeptide?
40. The codons shown are used in all species on Earth with very little variation. What might scientists conclude from this?
Model 4 – Translation
41. What are the three stages of translation?
42. According to Model 4, when the mRNA leaves the nucleus, to which cellular organelle does it attach?
43. The mRNA attaches to the organelle at the sequence AUG. What is the significance of this sequence of nucleotides?
44. Describe the movement of the ribosome as translation occurs.
The ribosome is a large complex of ribosomal RNA (rRNA) and proteins. It consists of two subunits. The smaller subunit binds to the mRNA strand and the larger subunit holds the tRNA molecules in place while the covalent peptide bond is formed between the amino acids. Several ribosomes can attach to an mRNA molecule simultaneously. This allows for many polypeptide chains to be synthesized at once.
45. The tRNA molecules in a cell are short sequences of nucleotides (about 80 bases) that contain an anticodon and
carry a specific amino acid. Find the tRNA in Model 2 that is carrying the Histidine (His). What sequence of nucleotides
makes the anticodon on this tRNA molecule?
What codon on mRNA would match this anticodon?
46. During elongation, how many tRNA molecules are held in the ribosome at the same time?
47. What will happen to the unattached tRNA once it has delivered its amino acid?
48. Describe two things that occur during termination as illustrated in Model 4.
