RNA and Protein Synthesis Honors Biology

RNA Ribonucleic acid – Made of nucleotides, similar to DNA Consist of 5 carbon sugar—Ribose Phosphate group Nitrogenous base – Cytosine – Guanine – Adenine – Uracil

RNA Different from DNA— – Single stranded – Contains different sugar (ribose instead of deoxyribose) – Has a different nitrogenous base

RNA Three types of RNA – mRNA- (messanger)-disposable copy of the information on DNA molecule that is able to leave nucleus – rRNA- (ribosomal)-the material that a ribosome is made of – tRNA- (transfer)-brings amino acids to the ribosome for translation

mRNA Language of mRNA is read in 3 letter sections called codons. Codons specify a specific amino acid A sequence of amino acids is the instructions for what polypeptide (protein) chain to build Some amino acids are specified by more than one codon AUG is a start codon-tells when a protein is about to be built UAA, UAG, and UGA are all stop codons-tells the end of the amino acid chain.

Transcription Process by which information from DNA molecule in the nucleus is copied onto an mRNA molecule so that information can be delivered to the ribosomes to make proteins. Occurs in the nucleus

Transcription RNA polymerase binds to a promoter region on a DNA molecule. – A promoter region is a sequence of nucleotides that tells an enzyme where transcription should start (at the start of a gene)

Transcription RNA polymerase splits apart the DNA molecule and uses one side of the DNA as a template and assembles a strand of complementary mRNA.

Transcription The mRNA molecule is edited inside the nucleus. Non-coding regions called introns are spliced out by splicesomes. The remaining coding regions, called exons, are spliced back together to produce the final mRNA molecule

Transcription The mRNA molecule receives a “cap” and a “tail” to prevent degradation by enzymes as it enter the cytoplasm and for easy recognition by a ribosome.

Transcription The finished mRNA molecule leaves the nucleus through a nuclear pore and enter the cytoplasm.

Translation The process by which information from an mRNA molecule is used by a ribosome and tRNA molecule to make sequence of amino acids that codes for a finished protein. Happens in the ribosomes

Translation Ribosome attaches to mRNA molecule. mRNA is read in 3 letter sections called codons. tRNA molecule with corresponding amino acid enters ribosome and attaches to corresponding mRNA codon in A site of ribosome. mRNA and tRNA move to P site of ribosome. Amino acid attaches to next amino acid in chain.

Translation tRNA moves to E site in ribosome and exits It will go out into cytoplasm and bind to another corresponding amino acid The amino acid chain grows until all the codons on the mRNA are read. The mRNA is thn dismantled and nucleotides are used again.

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Mutations Changes in a DNA sequence that subsequently affects the amino acid chain that is produced. – Gene mutation Point mutation – AUG CCC GUA GGC – AUG GCC GUA GGC

Mutations Gene mutations – Frameshift mutations-insertion or deletion of a nucleotide AUG CCC GUA GGC AUG GCC CGU AGG C

Mutations Chromosomal Mutations – Changes in number or structure of chromosomes Deletion Duplication Inversion Translocation