1. 13.2 - The Genetic Code and Translation

2. The Genetic Code
mRNA carries the information for a specific protein written as a series of 3 bases called codons

3. a codon “codes for” the amino acid
an amino acid may have more than one codon because there are 64 possible codons
are different codon charts used to find the appropriate amino acid

4. one codon - AUG (Methionine) - is called the “start codon”
this tells the ribosome to begin making a protein
Three other codons are called “stop codons”
these tell the ribosome to stop adding amino acids to the chain because the protein is complete

5. use the code by reading from the center to the outside
example: AUG codes for Methionine (start codon)

6. use the code by reading letters from left to right
example: AUG codes for Methionine (start codon)

7. Name the Amino Acids
GGG?
UCA?
CAU?
GCA?
AAA?

8. Translation
process of decoding the mRNA into a protein
takes place in the cytoplasm at the ribosomes
ribosomes are site of protein synthesis

9. ribosomal RNA (rRNA), along with protein, makes up the ribosomes
rRNA is a globular shape

10. transfer RNA (tRNA) transfers amino acids to the ribosomes where proteins are synthesized (made)
transfer RNA (tRNA) is clover-leaf shape

11. each tRNA molecule has an attachment site at one end for a specific amino acid
opposite end has three nucleotide bases called the anticodon
anticodon in a tRNA is complementary to the 3 bases of a specific codon

12. Transfer RNA
amino acid
attachment site U A C
anticodon

13. Remember the Complementary Bases
for DNA:
C-G
A-T
for RNA:
A-U 13

14. example: codon (mRNA) = ACU amino acid coded for = threonine
anticodon (tRNA) =
UGA
threonine
U G A
A C U

15. mRNA attaches itself to one end of a ribosome
ribosome then moves along mRNA strand to “read” the code brought from the DNA
ribosome will put together the amino acids into a polypeptide chain that makes up the protein

17. Once it reaches the “stop codon” the ribosome will release the protein into the cell.