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Biology B
Inquiry-Protein Synthesis
Protein synthesis is the process your body goes through to make a protein. Protein synthesis is a two part process that involves a second type of nucleic acid along with DNA. This second type of nucleic acid is RNA, which stands for ribonucleic acid.
1. There are three things that make DNA and RNA different. One is that DNA contains the sugar deoxyribose and RNA contains the sugar ribose. Look at the picture above-what are the other two things that are different between DNA and RNA?
There are actually three types of RNA: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). Here are the roles of the three types of RNA:
-mRNA: carries the code to make the protein
-tRNA: brings the correct amino acid to the ribosome for translation
-rRNA: makes up ribosomal structure
Transcription
In the first part of protein synthesis, the DNA will unwind and the two DNA strands will unzip from each other. Similar to the way DNA replicates itself, a single strand of messenger RNA (mRNA) is then made by pairing up mRNA nucleotides with the exposed DNA nucleotide bases.
§ The Process
Transcription occurs in the nucleus, and it uses the leading strand of the DNA molecule.
2. Which nitrogen base of RNA base pairs to the adenine on the DNA?
3. Which nitrogen base of RNA base pairs to thymine on the DNA?
4. Which nitrogen base of RNA base pairs to guanine on the DNA?
5. Which nitrogen base of RNA base pairs to cytosine on the DNA?
6. You are given the following DNA sequence: ATTGCGATTCGATAC-what would the mRNA sequence be?
7. A codon is a sequence of three nitrogen bases on the mRNA. How many codons are in the strand that you sequenced above?
Translation
After the mRNA is made, it leaves the nucleus and travels to the ribosome. In the ribosome, the mRNA code is translated into a protein sequence. In this process, each set of three mRNA bases (the codon) will pair with a complimentary tRNA base triplet (called an anticodon). Each tRNA is specific to an amino acid, as tRNA's are added to the sequence, amino acids are linked together by peptide bonds, eventually forming a protein that is later released by the tRNA. We will learn more about this in class.