Question

6. What are the 3 types of RNAs discussed in this unit and what is the unique role that each of them has in protein synthesis? Type of RNA Role in Protein Synthesis MBNA ARNA ARNA 7. Why must a codon consist of three bases instead of two? (Hint: think about the number of amino acids that must be coded for) 8 Transcribe and translate the following template DNA sequence: 3-TAC GGGAATCGGTCTGITCAGATT-5' 9. Put the following steps of DNA Isolation in their proper order adding detergent, adding isopropanol, adding salt, using blender, adding meat tenderizer. (Think about WHY they are used in order to correctly answer the question.) 10. On YouTube, there are lots of videos showing how to do this at home. However, most of them leave out the use of the meat tenderizer. At the end of their isolation experiment, they are left with lots of snot-like goo, which they call "DNA". Is this truly just DNA they have? What is it most likely to actually be? Unit 8, page 18

Answer 1

6.

Type of RNA	Role in protein synthesis
mRNA	Triplet base sequences available on mRNA provide the sequence in which amino acids are arranged in polypeptide chain formed from protein synthesis.
rRNA	rRNA forms small and large subunits of ribosome. During protein synthesis, rRNA in small subunit of ribosome reads triplet base sequences available on mRNA. rRNA in large subunit of ribosome connects amino acids during protein synthesis.
tRNA	tRNA brings amino acids to the site of protein synthesis.

7. Codons must code for 20 commonly found amino acids. If a codon will consist of two bases instead of three, number of codons would be sufficient to code for only 16 amino acids. A codon consists of three bases rather than two because codons containing three bases each are sufficient to coding for 20 commonly found amino acids.

8. The question gives template DNA strand. The polarity of template DNA strand is 3' to 5'. Transcription takes place on template strand of DNA. The base sequence on RNA molecule formed as a result of transcription of DNA is complementary to base sequence on template strand of DNA molecule. So, template DNA sequence will be transcribed as follows.

Template DNA sequence: 3'- T A C G G G A A T C G G T C T G T T C A G A T T -5'

Coding DNA sequence: 5'- A T G C C C T T A G C C A G A C A A G T C T A A -3'

Transcribed sequence- 5'- A U G C C C U U A G C C A G A C A A G U C U A A -3'

In order to transcribe template DNA sequence, please refer to following table. ​​​

Template DNA sequence codon	Transcribed sequence codon	Translated amino acid
T A C	A U G	Methionine
G G G	C C C	Proline
A A T	U U A	Leucine
C G G	G C C	Alanine
T C T	A G A	Arginine
G T T	C A A	Glutamine
C A G	G U C	Valine
A T T	U A A	Stop codon

The template DNA sequence will be translated as follows.

Methionine-Proline-Leucine-Alanine-Arginine-Glutamine-Valine

9. Proper order of steps of DNA isolation is using blender, adding detergent, adding salt, adding meat tenderizer and adding isopropanol. Use of blender during DNA isolation separates cells from each other. Detergent is added to destroy cell membranes and cause cell lysis. Salts are used to separate DNA from other contents of cell. Meat tenderizer is added to separate proteins that are bound to DNA. Isopropanol is added to precipitate out DNA from aqueous solution obtained during DNA isolation.   

10. The videos that leave out the use of meat tenderizer and call snoot-like goo as DNA do not have just DNA. It is most likely to actually be DNA and proteins bound to it because meat tenderizer is required to separate proteins that are bound to DNA during its isolation.