Science Homework (On Genetics) Help!

[Puchiko]

Trar Wrote:2. How does a DNA molecule determine the structure of a specific protein?

The sequence of the different amino acids is called the primary structure of the peptide or protein. Counting of residues always starts at the N-terminal end (NH2-group), which is the end where the amino group is not involved in a peptide bond. The primary structure of a protein is determined by the gene corresponding to the protein. A specific sequence of nucleotides in DNA is transcribed into mRNA, which is read by the ribosome in a process called translation. The sequence of a protein is unique to that protein, and defines the structure and function of the protein. The sequence of a protein can be determined by methods such as Edman degradation or tandem mass spectrometry. Often however, it is read directly from the sequence of the gene using the genetic code. Post-transcriptional modifications such as disulfide formation, phosphorylations and glycosylations are usually also considered a part of the primary structure, and cannot be read from the gene.

Quote:4. List the sequence of events that happens during protein synthesis.

• Transcription - Protein synthesis starts in the nucleus, where the DNA is held. DNA structure is two chains of sugars and phosphates joined by pairs of nucleotides deoxyadenosine, deoxyguanosine, thymidine, and deoxycytidine. Similar to DNA replication, the DNA is "unzipped" by the enzyme helicase, leaving the single nucleotide chain open to be copied. RNA polymerase reads the DNA strand, and synthesizes a single strand of messenger RNA (mRNA). This single strand of mRNA leaves the nucleus through nuclear pores, and migrates into the cytoplasm where it joins with ribosomes.Where protein synthesis occurs by the formation of peptide bonds and polypeptide chains.
  Note: in the new RNA strand, the nucleotide uridine takes the place of thymidine.
• Translation - the process of converting the mRNA codon sequences into an amino acid polypeptide chain.
  
  1. Initiation - A ribosome attaches to the mRNA and starts to code at the FMet codon (usually AUG, sometimes GUG or UUG).
  
  2. Elongation - tRNA brings the corresponding amino acid to each codon as the ribosome moves down the mRNA strand.
  
  3. Termination - Reading of the final mRNA codon (aka the STOP codon), which ends the synthesis of the peptide chain and releases it.[/list:u]
  

  Quote:5. What is messenger RNA? Describe how it performs its function.

  Messenger ribonucleic acid (mRNA) is a molecule of RNA encoding a chemical "blueprint" for a protein product. mRNA is transcribed from a DNA template, and carries coding information to the sites of protein synthesis: the ribosomes. Here, the nucleic acid polymer is translated into a polymer of amino acids: a protein. In mRNA as in DNA, genetic information is encoded in the sequence of nucleotides arranged into codons consisting of three bases each. Each codon encodes for a specific amino acid, except the stop codons that terminate protein synthesis. This process requires two other types of RNA: transfer RNA (tRNA) mediates recognition of the codon and provides the corresponding amino acid, while ribosomal RNA (rRNA) is the central component of the ribosome's protein manufacturing machinery.
  

  Quote:6. Does transfer RNA perform its function in the nucleus or the cytoplasm? Explain your answer.

  CYTOPLASM, don't know why.
  
  So, yeah, I didn't help much with this one, but... I'm not paid for it or anything so...
  Good luck with the rest