RNA and Protein Synthesis
RNA RNA is a molecule that helps makes proteins. It’s similar to DNA and is used to make a temporary copy of DNA.
Components of RNA RNA is single stranded and it consists of : a. Sugar: Ribose b. Phosphate c. 4 nitrogen bases Adenine and uracil (base pairs) Cytosine and guanine (base pairs)
Compare RNA to DNA DNA RNA Sugar Deoxyribose Ribose # strands Double stranded Single Stranded nitrogen bases Adenine, Thymine Adenine, Uracil Cytosine, Guanine Cytosine, Guanine
Types of RNA There are 3 types of RNA mRNA (messenger RNA) RNA that carries genetic information from the cell nucleus to the ribosomes in the cytoplasm
Types of RNA tRNA (Transfer RNA) RNA that delivers the amino acids necessary for protein synthesis to the ribosomes. AMINO ACID: Compounds that contain carbon, oxygen, hydrogen and nitrogen. They join together to form proteins. There are 20 essentail amino acids.
Types of RNA rRNA (ribosomal RNA) RNA that forms part of the ribosomes where proteins are built
Proteins Proteins are made of amino acids Amino acids are made of three nitrogen bases bonded together
Steps in Protein Synthesis Protein Synthesis is the making of proteins DNA unwinds and separates. Each side becomes a pattern on which a new side forms. Because DNA can not leave the nucleus, mRNA mades a copy of the instructions in the DNA for making a particular protein. This takes place in the nucleus.
Steps in Protein Synthesis EXAMPLE: If the DNA strand were as follows: C A T A G C G G A A C T T T C A G C the mRNA strand would be: G U A U C G C C U U G A A A G U C G There is no thymine in RNA. Uracil takes it place so everywhere you have adenine on the DNA strand, uracil will bond to it on the RNA strand.
Steps in Protein Synthesis Once mRNA makes a copy of the instructions in the DNA for a particlar protein, it leaves the nucleus and carries these instructions to the ribosomes in the cytoplasm. 5. tRNA translates the instructions from mRNA.
Steps in Protein Synthesis Example: If the instructions from mRNA are as follows: G U A U C G C C U U G A A A G U C G The tRNA translates this to be C A U A G C G G A A C U U U C A G C (Remember, when there is adenine, the complimentary base is uracil. If the base is uracil, the complemenatry base would be adenine.
Steps in Protein Synthesis Each set of 3 mRNAs is referred to as a “codon” for a specific amino acid. tRNA encodes “anticodons” to recognize the codons from mRNA. Each set of 3 tRNAs is an anticodon. Anticodons enable tRNA to bring the correct amino acid to the ribosome, where they bond together in a long chain called a polypeptide. The polypeptide will eventually become the protein.
Steps in Protein Synthesis 6. As the tRNA translates the mRNA codons for a particular amino acid, its anticodons circle around in the cytoplasm and pick up the correct amino acid . It takes the amino acids over to the ribosome where the acids bond together in a long polypetide chain. The tRNA is then released back to the cytoplasm.
Steps in Protein Synthesis 7. When the mRNA has been comletely translated, the polypeptide chain becomes the protein.
EXAMPLE DNA C A T A G C mRNA G U A U C G tRNA C A U A G C
Review Questions Which base is in RNA but not DNA? What are the components of RNA? List 3 ways in which RNA is different from DNA. What are the three types of RNA and what is the function of each? What is an amino acid? Where are proteins assembled in the cell?
Review Questions What are amino acids made of? What are proteins made of? Why is it necessary for RNA to make a copy of the DNA? What is the difference between a codon and an anitcodon? What is a polypeptide chain?
Review Questions Suppose you have the following DNA strand. C T G A C What would be the complimentary mRNA strand that would be synthesized from it? 13. What would be the tRNA strand that would be created from the mRNA strand in #12?
Review Questions Suppose you had the tRNA strand C A U G C A U G C What would the mRNA strand have looked like? What would the DNA strand have looked like?