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