21. Drawings and Short Answer a. Draw a DNA molecule with the following order of bases; CGA TTA GTG (template strand) b. Draw the order of bases in a mRNA molecule which would be transcribed from the DNA template strand in question #21a. C. Draw the tRNA's with the complementary anticodons from mRNA in question #21b. d. Draw the chain of amino acids that would be made from the mRNA codons. e. Name the chemical parts that make up a nucleotide. f. Compare DNA and RNA. g. Explain the purpose of mRNA, tRNA, and rRNA. h. What are the major functions of DNA?

**21. Drawings and Short Answer**<br /><br />**a. DNA Molecule**<br /><br />[Image: A DNA molecule should be drawn as a double helix. The template strand should have the bases CGA TTA GTG, and the complementary strand should have the bases GCT AAT CAC, connected by hydrogen bonds (represented by dashed lines). Label the 5' and 3' ends of each strand. Remember, the two strands run antiparallel.]<br /><br />**b. mRNA Molecule**<br /><br />[Image: A single-stranded mRNA molecule should be drawn. The sequence should be GCU AAU CAC (read 5' to 3'). This is complementary to the DNA template strand.]<br /><br />**c. tRNA Molecules**<br /><br />[Image: Three tRNA molecules should be drawn. Each tRNA should have an anticodon loop with the following anticodons (read 3' to 5'): CGA, UUA, GUG. Each tRNA should also have an amino acid attachment site. The corresponding amino acids (based on the mRNA codons) should be indicated but not attached in this drawing as the attachment occurs during translation within the ribosome.]<br /><br />**d. Amino Acid Chain**<br /><br />[Image: Three amino acids should be drawn connected by peptide bonds. The amino acids, from left to right (N-terminus to C-terminus), should correspond to the mRNA codons: Alanine (Ala) - Asparagine (Asn) - Histidine (His).]<br /><br />**e. Components of a Nucleotide**<br /><br />A nucleotide is composed of three parts:<br /><br />* A five-carbon sugar (deoxyribose in DNA and ribose in RNA)<br />* A phosphate group<br />* A nitrogenous base (adenine, guanine, cytosine, thymine in DNA; adenine, guanine, cytosine, uracil in RNA)<br /><br />**f. Comparison of DNA and RNA**<br /><br />| Feature | DNA | RNA |<br />|----------------|------------------------------------|-----------------------------------|<br />| Sugar | Deoxyribose | Ribose |<br />| Bases | Adenine, Guanine, Cytosine, Thymine | Adenine, Guanine, Cytosine, Uracil |<br />| Structure | Double-stranded helix | Single-stranded |<br />| Location | Primarily in the nucleus | Nucleus and cytoplasm |<br />| Function | Stores genetic information | Carries genetic information, protein synthesis |<br /><br /><br />**g. Purpose of mRNA, tRNA, and rRNA**<br /><br />* **mRNA (messenger RNA):** Carries the genetic code from DNA in the nucleus to the ribosomes in the cytoplasm, where protein synthesis occurs. It acts as a template for protein synthesis.<br />* **tRNA (transfer RNA):** Transports specific amino acids to the ribosome during protein synthesis. Each tRNA molecule has an anticodon that is complementary to a specific mRNA codon.<br />* **rRNA (ribosomal RNA):** A structural component of ribosomes. It plays a catalytic role in peptide bond formation during protein synthesis.<br /><br />**h. Major Functions of DNA**<br /><br />* **Storing genetic information:** DNA contains the instructions for building and maintaining an organism.<br />* **Replication:** DNA can make copies of itself to pass genetic information on to new cells.<br />* **Gene expression:** DNA directs the synthesis of proteins, which carry out various functions in the body. This occurs through transcription (making mRNA) and translation (making proteins).<br /><br /><br />