RNA & PROTEIN SYNTHESIS RNA & PROTEIN SYNTHESISRNA & PROTEIN SYNTHESISRNA & PROTEIN SYNTHESIS THE PROCESS OF MAKING PROTEINS MURTAUGH 1B LIVING ENVIRONMENT

ESSENTIAL QUESTIONS How are RNA and DNA alike and different? How are RNA and DNA alike and different? How are proteins created? How are proteins created? What is the difference between transcription and translation? What is the difference between transcription and translation? Where in the cell do transcription and translation occur? Where in the cell do transcription and translation occur?

VOCABULARY RNA- Ribonucleic Acid, the only other nucleic acid besides DNA, a macromolecule necessary for RNA- Ribonucleic Acid, the only other nucleic acid besides DNA, a macromolecule necessary for coding, decoding, regulation, and expression of genes. Messenger RNA- Messenger RNA-RNA molecules that carries copies of instructions. Ribosomal RNA- Ribosomal RNA-Type of RNA that makes up the major part of the ribosome. Transfer RNA- Transfer RNA- Type of RNA molecule that transfers amino acids to the ribosome. Polypeptide- macromolecule, amino acids linked together to form proteins, another name for protein

VOCABULARY Transcription- Transcription-Process in which part of the nucleotide sequence of DNA is copied into a complementary sequence of RNA. Translation- Translation-Decoding of mRNA message into a polypeptide chain. Codon- Codon- Three nucleotide sequences on messenger RNA that codes for single amino acid. Anticodon- Anticodon-Group of three bases on a tRNA molecules that are complementary to an mRNA codon. Mutation- Mutation-A change in DNA sequence that affects the genetic code.

RNA RNA The only other Nucleic Acid besides DNA The only other Nucleic Acid besides DNA Made of long chains of nucleotides: Made of long chains of nucleotides: = Ribose A Sugar = Ribose A Phosphate group A Phosphate group A Nitrogen base: Guanine, Cytosine, Adenine or Uracil A Nitrogen base: Guanine, Cytosine, Adenine or Uracil  GC/AU Single stranded Single stranded

3 TYPES OF RNA 3 TYPES OF RNA Messenger RNA (mRNA) – carries copies of instructions from the DNA (serve as messengers from the DNA to rest of cell). Messenger RNA (mRNA) – carries copies of instructions from the DNA (serve as messengers from the DNA to rest of cell). Ribosomal RNA (rRNA)– proteins that make up ribosomes. Ribosomal RNA (rRNA)– proteins that make up ribosomes. Transfer RNA (tRNA)– transfers amino acids to the ribosome. Transfer RNA (tRNA)– transfers amino acids to the ribosome.

TRANSCRIPTION TRANSCRIPTION First step in protein synthesis (the making of proteins) First step in protein synthesis (the making of proteins) Transcription – RNA molecules are produced by copying part of the nucleotide sequence of DNA into a complementary strand. Transcription – RNA molecules are produced by copying part of the nucleotide sequence of DNA into a complementary strand. An enzyme (RNA polymerase) helps unwind the DNA strand. An enzyme (RNA polymerase) helps unwind the DNA strand. Transcription occurs in the nucleus of eukaryotic cells. Transcription occurs in the nucleus of eukaryotic cells.

RNA DNA RNA polymerase TRANSCRIPTION Section 12-3 Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only) Go to Section:

HOW DOES RNA POLYMERASE KNOW WHEN TO START & STOP? There are certain nucleotide sequences on the DNA that the enzyme will bind to which tell it to start. These are called promoters. There are certain nucleotide sequences on the DNA that the enzyme will bind to which tell it to start. These are called promoters. The same sequences tells the enzymes to stop transcription. The same sequences tells the enzymes to stop transcription.

THE GENETIC CODE THE GENETIC CODE Polypeptides – long chains of amino acids that will form proteins. Polypeptides – long chains of amino acids that will form proteins. Amino acids- the building blocks or subunits of proteins Amino acids- the building blocks or subunits of proteins There are 20 different amino acids. There are 20 different amino acids. The code for making proteins comes in 4 “letters”. G-C-A-T The code for making proteins comes in 4 “letters”. G-C-A-T The code is read in 3 “letters” at a time, called codons. The code is read in 3 “letters” at a time, called codons.

CODONS CODONS Codon – 3 consecutive nucleotides that specify a single amino acid that is added to a polypeptide chain. Codon – 3 consecutive nucleotides that specify a single amino acid that is added to a polypeptide chain. UCGCACGGU = UCGCACGGU =UCG-CAC-GGU Serine – Histidine – Glycine This is how DNA is read in order to transcribe it to RNA This is how DNA is read in order to transcribe it to RNA

64 POSSIBLE CODONS 64 POSSIBLE CODONS

TRANSLATION TRANSLATIONTRANSLATION Translation – decoding a mRNA message into a polypeptide chain Translation – decoding a mRNA message into a polypeptide chain Takes place in the ribosomes. Takes place in the ribosomes. The ribosome reads the message. The ribosome reads the message.

1 ST & 2 ND STEPS 1 ST & 2 ND STEPS Messenger RNA must be transcribed from DNA in the nucleus and released into the cytoplasm. Messenger RNA must be transcribed from DNA in the nucleus and released into the cytoplasm. mRNA attaches to a ribosome. mRNA attaches to a ribosome. tRNA brings amino acids to mRNA. tRNA brings amino acids to mRNA. 3 bases on the tRNA = anticodon. 3 bases on the tRNA = anticodon. Anticodons match up with codons. Anticodons match up with codons. ACC (codon) matches with UGG (anticodon). ACC (codon) matches with UGG (anticodon).

Messenger RNA Messenger RNA is transcribed in the nucleus. Transfer RNA The mRNA then enters the cytoplasm and attaches to a ribosome. Translation begins at AUG, the start codon. Each transfer RNA has an anticodon whose bases are complementary to a codon on the mRNA strand. The ribosome positions the start codon to attract its anticodon, which is part of the tRNA that binds methionine. The ribosome also binds the next codon and its anticodon. mRNA Start codon Ribosome Methionine Phenylalanine tRNA Lysine Nucleus TRANSLATION: MRNA AND TRNA mRNA Go to Section:

3 RD & 4 TH STEPS 3 RD & 4 TH STEPS The ribosome forms peptide bonds between the amino acids. The ribosome forms peptide bonds between the amino acids. The ribosome continues to grow the amino acid chain until it reaches a stop codon on the mRNA. The ribosome continues to grow the amino acid chain until it reaches a stop codon on the mRNA. It then releases the polypeptide chain. It then releases the polypeptide chain. h5mJbP23Buo

The Polypeptide “Assembly Line” The ribosome joins the two amino acids— methionine and phenylalanine—and breaks the bond between methionine and its tRNA. The tRNA floats away, allowing the ribosome to bind to another tRNA. The ribosome moves along the mRNA, binding new tRNA molecules and amino acids. mRNA Ribosome Translation direction Lysine tRNA Ribosome Growing polypeptide chain mRNA Completing the Polypeptide The process continues until the ribosome reaches one of the three stop codons. The result is a growing polypeptide chain. TRANSLATION CONTINUED: FORMING THE POLYPEPTIDE CHAIN Go to Section: tsb2SqR-R0

fromtoto make up CONCEPT MAP also calledwhich functions toalso called which functions to can be RNA Messenger RNA Ribosomal RNA Transfer RNA mRNACarry instructions rRNA Combine with proteins tRNA Bring amino acids to ribosome DNARibosomeRibosomes Go to Section: