A Genetic Code Game
The DNA Part
You will be given a short DNA nucleotide sequence. This is one strand of the double helix DNA molecule. You will need to find the complement strand. Remember that an A nucleotide pairs with a T nucleotide (A-T) and the C nucleotide pairs with a G nucleotide (C-G). In your journal write down the original DNA sequence and its complement. Example :
Original strand = GGACTTTGC
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Complement strand = CCTGAAACG
The mRNA Part
In the cell nucleus, the DNA is unraveled with the help of many proteins. A messenger RNA molecule (mRNA) is then created. The DNA will stay in the nucleus, but the mRNA can travel out into the cell. The mRNA is assembled nucleotide by nucleotide from the original DNA strand. This means the nucleotide sequence is almost identical to the DNA complement strand with one exception; The mRNA substitutes the nucleotide Uracil (U) for Thymine (T). In your journal write down the original DNA strand and the mRNA strand created. Example:
Original strand = GGACTTTGC
mRNA strand = CCUGAAACG
The Protein Part
After the mRNA leaves the nucleus it can assemble proteins with the help of large protein and another type of RNA; these are the ribosome and transfer RNA (tRNA). The mRNA, a ribosome and many tRNA work together to make a protein. Remember a protein is a long sequence of smaller molecules stuck together. These smaller molecules are amino acids. There are over twenty amino acids so a single mRNA nucleotide (an U, C, G, or A) isn't enough to tell the ribosome and tRNA which amino acid to use. The ribosome and tRNAs look at three mRNA nucleotides at a time. Each group of three is called a codon.
To figure out which amino acid is specified by a codon (a group of three mRNA nucleotides) you will use the decoder table. Start with the first three mRNA nucleotides and find the name of the amino acid that will be the first part of the protein.
Example: CCU = proline
Repeat the process for the rest of the mRNA.
Example: GAA = glutamate ACG = threonine
For our example, the original DNA strand encodes for a very short protein = proline + glutamate + threonine. Most proteins are hundreds of amino acids long. Rather than write down the entire name of an amino acid, biochemists use single letter abbreviations. In the decoder table that is the single capital letter following the amino acid name. Example : The amino acid sequence that makes our very short protein would be abbreviated as PET.
The "Game" Part
When decoded properly your DNA strand spells a word. What is that word?
AMINO NAME ABR. mRNA DNA alanine Ala a GCU CGA cysteine Cys c UGC ACG aspartate Asp d GAC CTG glutamate Glu e GAG CTC phenylalanine Phe f UUU AAA glycine Gly g GGU CCA histidine His h CAC GTG isoleucine Ile i AUC TAG lysine Lys k AAA TTT leucine Leu l CUA GAT methionine Met m AUG TAC asparagine Asn n AAC TTG proline Pro p CCC GGG glutamine Gln q CAA GTT arginine Arg r CGC GCG serine Ser s AGC TCG threonine Thr t ACC TGG valine Val v GUG CAC tryptophan Trp w UGG ACC tyrosine Tyr y UAU ATA call ACGCGAGATGAT can ACGCGATTG cap ACGCGAGGG cat ACGCGATGG dad CTGCGACTG dead CTGCTCCGACTG deal CTGCTCCGAGAT deep CTGCTCCTCGGG define CTGCTCAAATAGTTGCTC dry CTGGCGATA eat CTCCGATGG file AAATAGGATCTC fine AAATAGTTGCTC get CCACTCTGG help GTGCTCGATGGG hi GTGTAG high GTGTAGCCAGTG in TAGTTG keep TTTCTCCTCGGG key TTTCTCATA lad GATCGACTG lane GATCGATTGCTC late GATCGATGGCTC lean GATCTCCGATTG length GATCTCTTGCCATGGGTG let GATCTCTGG lie GATTAGCTC like GATTAGTTTCTC live GATTAGCACCTC nail TTGCGATAGGAT nap TTGCGAGGG nay TTGCGAATA neat TTGCTCCGATGG net TTGCTCTGG nice TTGTAGACGCTC pain GGGCGATAGTTG past GGGCGATCGTGG pet GGGCTCTGG ran GCGCGATTG rat GCGCGATGG rate GCGCGATGGCTC read GCGCTCCGACTG real GCGCTCCGAGAT sad TCGCGACTG sail TCGCGATAGGAT says TCGCGAATATCG snake TCGTTGCGATTTCTC tea TGGCTCCGA the TGGGTGCTC vain CACCGATAGTTG valid CACCGAGATTAGCTG wacked ACCCGAACGTTTCTCCTG way ACCCGAATA wet ACCCTCTGG yawn ATACGAACCTTG yell ATACTCGATGAT yes ATACTCTCG