RNA Another Nucleic Acid

RNA Structure RNA is the second type of nucleic acid found in a cell. There are 3 different types of RNA Structure of RNA: Long chain of nucleotides 5-carbon sugar called ribose Phosphate Nitrogen bases- Adenine, Guanine, Cytosine and Uracil (instead of Thymine) Just a single strand

Function of RNA The function of RNA is to carry the code from DNA in the nucleus to the ribosomes in the cytoplasm (where the code will be used to make proteins).

Quick Check Compare the details of DNA to RNA Feature DNA RNA # of strands 2 1 Type of sugar Deoxyribose Ribose Nitrogen bases A, T, G, C A, U, G, C Location in cell Nucleus Nucleus → Ribosome in cytoplasm Number of forms 3 Job description Carries genetic information Take info from DNA to the ribosomes to make proteins

Types of RNA Messenger RNA (mRNA)- this is the piece of RNA that takes the code (“message”) from the DNA to the ribosome. Transfer RNA (tRNA)- this RNA brings (“transfers”) amino acids from the cytoplasm to the ribosome/ mRNA. Ribosomal RNA (rRNA)- this is the structural part of a ribosome (a ribosome is only protein and RNA)

Types of RNA

Transcription Transcription is the process in which a part (gene) of the DNA is copied into mRNA. Players Piece of DNA Nucleotides Enzyme- RNA polymerase

Transcription What happens: RNA polymerase finds a sequence called the promoter, binds to the DNA and unzips the strands RNA polymerase “reads” one strand of the DNA and adds the appropriate complementary RNA nucleotides The product= a single strand of mRNA

Quick Check tRNA 1. The three types of RNA are _______ , _______ and ______ . 2. The process of making RNA from DNA is called ________________. 3. mRNA has to be made from DNA because the DNA cannot leave the _________ and the proteins coded for by the DNA are made by the ____________ which are found in the _____________. 4. If the sequence of DNA is AGTAGGTCA, what is the mRNA made from it? __________________ mRNA rRNA transcription nucleus ribosomes cytoplasm UCAUCCAGU

The Genetic Code Proteins are continuously made by linking together amino acids. There are 32 different amino acids. The sequence of nitrogen bases in DNA and mRNA determine the order of amino acids in protein. Codon= the sequence of 3 nucleotides that codes for a specific amino acid. Anti-codon= the complementary sequence to the codon; it is found on the tRNA

Codon Chart

Quick Check Use your amino acid chart to identify the amino acid that goes with each codon. 1. AUG ___________________ 2. UGA ___________________ 3. AAA ___________________ 4. GAG ___________________ 5. UCA ___________________ 6. UCC ___________________ Methionine (start) Stop Lysine Glutamate Serine Serine

Translation The sequence of nucleotides in mRNA provides the instructions to the ribosomes for putting together a protein. Translation- the decoding of an mRNA message into an amino acid chain (protein). Parts involved: mRNA Ribosome tRNA Amino acids

Translation How it’s done: mRNA attaches to a ribosome in the cytoplasm The codon on the mRNA is “read” by the ribosome. The ribosome brings in the correct anti-codon with an amino acid attached. The anti-codon of the tRNA matches up with the codon on the mRNA.

Translation The second codon is “read” and the ribosome brings in the next tRNA. A peptide bond forms between the amino acids on the 2 tRNA’s in the ribosome. The first tRNA loses its amino acid and it leaves the ribosome. The ribosome slides along continuing the process until a STOP codon is reached.

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