Protein Synthesis Transcription and Translation DNA Transcription RNA Translation Protein

RNA Structure: nucleic acid made up of repeating nucleotides similar to DNA Consists of ribose sugar, nitrogenous base, and a phosphate group

TYPES OF RNA –Messenger RNA (mRNA): single uncoiled chain; mRNA carries genetic information from the nucleus to the cytosol –Transfer RNA (tRNA): about 80 RNA nucleotides folded into a hairpin shape; binds to specific amino acids –Ribosomal RNA (rRNA): RNA nucleotides in a globular form; rRNA makes up the ribosomes where proteins are made

TRANSCRIPTION Process in which genetic information is copied from DNA to RNA and is called mRNA RNA carries the genetic information from the DNA in the nucleus to the cytosol This way the information can be used to make proteins

TRANSCRIPTION RNA polymerase synthesizes RNA copies of specific sequences of DNA –RNA polymerase: the primary transcription enzyme RNA polymerase initiates transcription by binding to specific regions of DNA (promoters) Promoters: specific regions of DNA that mark the beginning of transcription in the chain, RNA polymerase binds to these promoters DNA molecule in the region separates when RNA polymerase binds Template: separated DNA chain used for transcription RNA polymerase adds complementary RNA nucleotides to the newly forming RNA molecule (uses complementary base pairing)

TRANSCRIPTION Transcription continues until the termination signal: a specific sequence of nucleotides that signifies the end of a gene RNA polymerase releases both the DNA molecule and newly formed RNA molecule All three types of RNA are involved in protein synthesis mRNA leaves the nucleus and moves into the cytosol to direct protein synthesis

TRANSLATION Process of assembling polypeptides from information encoded in mRNA by codons Codon: a combination of three mRNA nucleotides that code for a specific amino acid –Some codons code for translation to start and stop Start codon (AUG) codes for methionine Stop codon (UAA, UAG, UGA) causes translation to stop

TRANSLATION When mRNA leaves the nucleus, it migrates to a ribosome in the cytosol (this is the site of protein synthesis) tRNA transports amino acids to the ribosomes tRNA has a region that bonds to a specific amino acid and on the opposite end, it has an anticodon Anticodon: three nucleotides that is complimentary to and pairs with its mRNA codon Ribosomes are composed of rRNA and proteins

PROTEINS Proteins: polymers, made up of one or more polypeptides Polypeptides: amino acids linked by peptide bonds Sequence of amino acids determines the shape of the protein The shape (3-D structure) determines the function of the protein

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