Protein Synthesis Transcription and Translation DNA Transcription RNA

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

TRANSCRIPTION • Process in which genetic information is copied from DNA to RNA and is called m. RNA • 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 • m. RNA leaves the nucleus and moves into the cytosol to direct protein synthesis

TRANSLATION • Process of assembling polypeptides from information encoded in m. RNA by codons • Codon: a combination of three m. RNA 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 m. RNA leaves the nucleus, it migrates to a ribosome in the cytosol (this is the site of protein synthesis) • t. RNA transports amino acids to the ribosomes • t. RNA 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 m. RNA codon • Ribosomes are composed of r. RNA 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

Protein Assembly • http: //nobelprize. org/educational_games/m edicine/dna/b/translation_ani. ht ml • http: //highered. mcgrawhill. com/sites/0072437316/student_view 0/ chapter 15/animations. html# • http: //learn. genetics. utah. edu/content/begi n/dna/transcribe/