Protein Synthesis

Review…  DNA:  Found in the nucleus  Double stranded  Contains the instructions for controlling the cell (including instructions for making proteins)  Has the bases A, T, C, G  RNA:  Can go outside the nucleus  Single stranded  Has the bases A, U, C, G  Ribosomes:  Make proteins

Steps of Protein Synthesis:  Transcription  Translation

Transcription  DNA is “unzipped” by RNA polymerase  RNA polymerase breaks the Hydrogen bonds between the DNA bases to separate the two strands  RNA polymerase makes a copy of RNA from the DNA that has been separated  The strand of RNA that is made is called mRNA (messenger RNA)

Transcription Transcription Animation

Translation  mRNA leaves the nucleus and enters the cytoplasm  Ribosomes attach to the mRNA strand and “reads” the information on the mRNA strand  Ribosomes also have RNA, called rRNA (ribosomal RNA), that does the “reading”  The information that is being “read” is called codons  Codons – a set of 3 bases

Translation  When the RNA is “read”, tRNA (transfer RNA) attaches to the mRNA strand  tRNA will have complementary bases that will match up with the mRNA  These complementary bases on the tRNA are called anticodons  Anticodons match up with the correct codons  tRNA also has an amino acid attached to the bottom of it

Translation  As more tRNAs attach to the mRNA, a bond will form between the amino acids on the tRNA  These bonds are called polypeptide bonds  As bonds form, tRNA detaches from the amino acids and mRNA Translation Animation

Proteins!!!  When all the amino acids have bonded together, they are in a chain  This chain is a protein  Amino acids are the building blocks of proteins  The protein chain will fold in to itself so that it is more compact to travel within and outside the cell