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VII RNA and Protein Synthesis. Genes, segment of DNA, are coded DNA instructions that control the production of proteins. Genetic messages can be decoded and used in protein synthesis by copying part of the nucleotide sequence from DNA into mRNA.
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Genes, segment of DNA, are coded DNA instructions that control the production of proteins. Genetic messages can be decoded and used in protein synthesis by copying part of the nucleotide sequence from DNA into mRNA. mRNA contains coded information for making proteins.
The Structure of RNA There are three main differences between RNA and DNA: The sugar in RNA is ribose instead of deoxyribose. RNA is generally single-stranded. RNA contains uracil in place of thymine.
Types of RNA There are three main types of RNA: messenger RNA ribosomal RNA transfer RNA
Types of RNA Messenger RNA (mRNA) carries copies of instructions for assembling amino acids into proteins.
Ribosomes are made up of proteins and ribosomal RNA (rRNA). Ribosome Ribosomal RNA
During protein construction, transfer RNA (tRNA) transfers each amino acid to the ribosome. Amino acid Transfer RNA
Protein Synthesis DNA molecule 5¢ 3¢ DNA strand (template) TRANSCRIPTION 5¢ 3¢ mRNA Codon TRANSLATION Protein Amino acid
Transcription DNA is copied in the form of RNA This first process is called transcription. The process begins at a section of DNA called a promoter.
RNA RNA polymerase DNA
RNA Editing Some DNA within a gene is not needed to produce a protein. These areas are called introns. The DNA sequences that code for proteins are called exons.
The introns are cut out of RNA molecules. The exons are the spliced together to form mRNA. Exon Intron DNA Pre-mRNA mRNA Cap Tail
The Genetic Code The genetic code is the “language” of mRNA instructions. The code is written using four “letters” (the bases: A, U, C, and G).
A codon consists of three consecutive nucleotides on mRNA that specify a particular amino acid.
Translation Translation is the decoding of an mRNA message into a polypeptide chain (protein) on ribosomes. During translation, the cell uses information from messenger RNA to produce proteins. Nucleus mRNA
The ribosome binds new tRNA molecules and amino acids as it moves along the mRNA and the anticodons of tRNA match the mRNA codons. Lysine Phenylalanine tRNA Methionine Ribosome mRNA Start codon
Protein Synthesis Lysine tRNA Translation direction mRNA Ribosome
The process continues until the ribosome reaches a stop codon. Polypeptide Ribosome tRNA mRNA
DNA mRNA Protein Codon Codon Codon Single strand of DNA Codon Codon Codon mRNA Alanine Leucine Arginine Amino acids within a polypeptide