BELLRINGER: Draw the following box and fill in the squares, THIRD box on the last bell-ringer page: REPLICATIONTRANSCRIPTION Where in the cell does this take place? What is created in this process? When does this take place?WHY does this take place?

THE THREE TYPES OF RNA

Section 11.2 Summary – pages There are three types of RNA that help build proteins. # 1 Messenger RNA (mRNA) brings instructions from DNA in the nucleus to the cytoplasm. Then mRNA binds to ribosomes.

Section 11.2 Summary – pages # 2 Transfer RNA (tRNA) is the supplier. Transfer RNA delivers amino acids (the building blocks of proteins) to the ribosome to be assembled into a protein. Amino Acid How it binds with mRNA

Section 11.2 Summary – pages # 3 Ribosomes are made of Ribosomal RNA (rRNA). rRNA uses the instructions from mRNA and the supplies from tRNA to assemble the amino acids in the correct order.

mRNA brings the instructions. tRNA supplies the amino acid parts. rRNA builds the proteins using the instructions and amino acids. RIBOSOME

THE PROCESS OF TRANSLATION

During Transcription, mRNA is made. The copy of instructions for making proteins on an mRNA strand is in the form of a code.

Section 11.2 Summary – pages Every three letters on a mRNA strand, called a codon, is a code for a specific amino acid (a building block to make protein) The Genetic Code

There are thirty different kinds of amino acids. Different types of proteins are made with amino acids in different sequences

The codons on a mRNA strand need to be converted into amino acids. mRNA codons Amino Acids The process of converting the codons on mRNA into a sequence of amino acids to make a protein is known as translation.

Each codon codes for a specific amino acid. CODON CHART Every three letters on an mRNA strand is a codon.

Section 11.2 Summary – pages Sometimes there are several codons that code for the same amino acid….for instance, What two codons code for the amino acid “Arg” (Arginine)? The Genetic Code

T A C C C G T A T T C G A A G G C T Below is a DNA strand…. During Transcription, what mRNA strand would be made from this DNA? A U G G G C A U A A G C U U C C G A Using this mRNA strand, translate the codons into amino acids using your codon chart. MethionineGlycineIsoleucineSerine Phenylalanine Arginine

THIS IS WHAT TRANSLATION LOOKS LIKE

Section 11.2 Summary – pages Why does mRNA have to be made? (Why can’t DNA deliver it’s own instructions) Nucleus

Section 11.2 Summary – pages Translation takes place at the ribosomes (rRNA) of a cell. Where does mRNA take the instructions so that proteins can be made?

Section 11.2 Summary – pages mRNA brings the codons (message) from DNA to the ribosome (rRNA) Translation from mRNA to Protein RIBOSOME mRNA Coming from Nucleus

Section 11.2 Summary – pages As translation begins, one end of mRNA strand attaches to a ribosome. mRNA strand Ribosome Step 1

Section 11.2 Summary – pages tRNAs bring amino acids to the ribosomes. Translation from mRNA to Protein RIBOSOME mRNA Coming from Nucleus

Each tRNA only carries one amino acid. Amino acid

Section 11.2 Summary – pages There are also three nucleotides on the bottom of the tRNA called an anti-codon. Anti-codons complementary base pair with the codons on mRNA. (this is to make sure they are bringing the correct amino acid- If the anti-codon doesn’t base pair with the codon, then the wrong amino acid was brought) Anti-codon

Section 11.2 Summary – pages AUG is usually the first codon on the mRNA strand. This signals the ribosome to START making a protein. A tRNA with anticodon UAC comes and binds with this codon and drops off it’s amino acid “Methionine”. Methionine

Section 11.2 Summary – pages After the first tRNA binds with its codon, the mRNA slides down so that the ribosome can read the next codon.

Section 11.2 Summary – pages A new tRNA molecule carrying an amino acid pairs with the second mRNA codon. Alanine

Section 11.2 Summary – pages The amino acids then bond together. Once the first tRNA lets go of it’s amino acid, it is released from the ribosome. AlanineMethionine bond

Section 11.2 Summary – pages A chain of amino acids is formed until the stop codon is reached on the mRNA strand. Stop codon The end result is a protein