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DNA and Translation• Gene: section of DNA that
creates a specific protein
– Approx 25,000 human genes
• Proteins are used to build cells and tissue
• Protein synthesis involves two processes:
1) Transcription
2) Translation
• Transcription takes place in the nucleus– 1) DNA double helix is broken apart– 2) mRNA nucleotides match up– 3) Finished mRNA detaches, and moves to a
ribosome
• Codon: Combination of 3 mRNA nucleotides
• Each mRNA codon matches with 1 of 20 amino acids
• Ribosome reads codons 1 at a time
• Codon AUG = Methionine (Start)
• Codon GUU = Valine• Codons UAA or UAG or UGA
= Stop
• Defined: Process of making proteins– Step 1: mRNA enters ribosome– Step 2: Ribosome reads one mRNA codon at a time– Step 3: tRNA delivers amino acids until a protein is
created
Translation Details• Translation begins
when the mRNA codon “AUG” is read by the ribosome
• Each mRNA codon matches with a specific amino acid
AUG = methionineGCU = alanine
• tRNA carries over the proper amino acid– tRNA anticodon
matches with the mRNA codon
– Ensures proper match• One by one, amino acids
are linked together• Translation ends when a
“stop” codon is read by the ribosome
• End result: Protein
Because the codon and anticodon don’t match, the wrong amino acid will not be delivered.
This is why the anticodon is important!
GAU AUG CCG AGU CCA GGA UCU UGA
tRNA
UACtRNA
GGCtRNA
UCAtRNA
GGUtRNA
CCUtRNA
AGA
Methionine Pro-line Serine Pro-line Gly-cine Serine
Practice Problem
DNA mRNA codon
tRNA anticodon
Amino Acid
Always use mRNA to find the amino acid
DNA mRNA codon
tRNA anticodon
Amino Acid
Practice ProblemAlways use mRNA to find the amino acid
DNA mRNA codon
tRNA anticodon
Amino Acid
Practice ProblemAlways use mRNA to find the amino acid
CCA
GGU
CCA
Kobe Kuiz1) Define transcription? Translation?2) What are genes and how are they different from
chromosomes?3) How many nucleotides make a codon?4) The anticodon can be found on which object?5) The anticodon must match the ______.6) Place the following steps in order from start to finish:
– Proteins are assembled– Ribosome reads a codon one at a time– mRNA arrives at the ribosome– tRNA delivers amino acids to the ribosome
7) Be able to solve practice problems similar to the three examples on slides #9-11.
mRNA codes
mRNA codes