RNA Transcription

The Structure of RNA RNA consists of a long chain of nucleotides It is made of a 5-carbon sugar (ribose), phosphate group and nitrogen base RNA contains the four bases A, C, G, and U (uracil)

Comparing DNA and RNA There are four main differences between DNA and RNA The sugar in RNA is ribose instead of deoxyribose RNA is generally single-stranded RNA contains uracil instead of thymine There are three types of RNA and only 1 type of DNA.

There are three main types of RNA Messenger RNA – (mRNA) carries copies of instructions for the assembly of amino acids into proteins from DNA to the rest of the cell

2. Ribosomal RNA – (rRNA) makes up the major part of the ribosome 3. Transfer RNA – (tRNA) transfers amino acids to ribosomes during protein synthesis

The assembly of amino acids into proteins is done by RNA RNA’s Functions RNA can have many functions, but most RNA is involved in protein synthesis The assembly of amino acids into proteins is done by RNA

Transcription Transcription is the process where RNA molecules are produced by copying a sequence of DNA into a strand of RNA

Transcription requires an enzyme called RNA polymerase to bind to the DNA and separate the strands One strand of DNA is used as a template to assemble nucleotides into a strand of RNA

Transcription Steps 1. RNA polymerase binds to the DNA in the promoter regions and cause the DNA to unzip and unwind. Promoter regions have specific base sequences that tell where transcription should begin. Start and Stop 2. The enzyme directs the formation of H bonds between the bases on DNA and the complementary bases of RNA nucleotides.

3. RNA polymerase moves along the section of DNA and forms the sugar-to phosphate bonds between the RNA nucleotides. 4. The polymerase reaches a sequence of bases on DNA that signals transcription to stop.

5. The RNA strand detaches from the DNA and goes out into the cytoplasm. 6. The DNA reforms its H bonds and coils into the double helix. ALL THREE types of RNA are transcribed in this manner.

Transcription Needs to go to Ribosome for Translation Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only) RNA polymerase DNA RNA

Translation

Beginning of Translation The code is read three letters at a time Each group of three letters is called a codon

Beginning of Translation A codon is 3 consecutive nucleotides that specify a single amino acid that is to be added to the polypeptide tRNA is responsible for bringing the amino acid and turning into a polypeptide chain.

Steps of Translation Step 1: mRNA is transcribed (copied) from DNA in the nucleus and released into the cytoplasm Step 2: mRNA attaches to a ribosome in the cytoplasm as each codon of mRNA is read in the ribosome, tRNA brings in the proper amino acid the amino acids are turned into a polypeptide chain (each tRNA carries only one amino acid) each tRNA has 3 unpaired bases called anticodons the bases are complementary to one mRNA codon YOU WILL NEED TO MAKE A tRNA and cut out to explain your last step.

Steps of Translation Step 3: The ribosomes form peptide bonds between the first and second amino acids the ribosome simultaneously breaks the bond between the tRNA and its amino acid causing the tRNA to be released Step 4: The polypeptide chain grows (elongation) until a stop codon is reached the polypeptide chain is released to complete its protein conformation.

Codon and Anti-codon Nucleus Messenger RNA mRNA Lysine Phenylalanine Messenger RNA is transcribed in the nucleus. mRNA Lysine Phenylalanine tRNA Transfer RNA The mRNA then enters the cytoplasm and attaches to a ribosome. Translation begins at AUG, the start codon. Each transfer RNA has an anticodon whose bases are complementary to a codon on the mRNA strand. The ribosome positions the start codon to attract its anticodon, which is part of the tRNA that binds methionine. The ribosome also binds the next codon and its anticodon. Methionine Ribosome Start codon

Reading The Genetic Code

Protein Synthesis Proteins are made by joining amino acids into long chains called polypeptides Each polypeptide contains a different combination of the 20 amino acids Amino acids are biologically important organic compounds. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen.

Final ACT PROTEIN!!!! When the Ribosome reaches the stop codon, the last polypeptide bond is formed and the protein chain is released. The mRNA is then released from the ribosome.

PRACTICE FROM BEGINNING Everyone write in comp book

CHECK YOUR WORK

Transcription

mRNA Strand should look like this!!!

Translation

Final Process to make a protein