Unit 6 Notes:RNA

&Protein Synthesis

(1) What is RNA?

• RNA = RiboNucleic Acid

• Structure:– RNA Nucleotide = Phosphate, Ribose Sugar, N.Base– Types of Nitrogenous Bases:

• Uracil (U) pairs with Adenine (A)• Guanine (G) pairs with Cytosine (C)• [U in RNA replaces the T in DNA.]

• Types of RNA:• Messenger RNA (mRNA)• Ribosomal RNA (rRNA)• Transfer RNA (tRNA)

(2) Protein Synthesis Basics

• Overall Goal: Use DNA to put together the correct sequence of amino acids, building a specific protein molecule.

• Steps:1- Transcription (DNA RNA)2- Translation (RNA Protein)

• Keep In Mind:Your genetic code IS the unique order of nitrogenous bases!

(3) Codons & Anticodons

• CODONS:– Codons are located on Messenger RNA (mRNA). – 1 Codon = 3 Nitrogenous Bases– 1 Codon = 1 Amino Acid

• ANTICODONS:– Anticodons are located on Transfer RNA (tRNA).– 1 Anticodon = 3 Nitrogenous Bases– 1 Anticodon = 1 Amino Acid

(4) Transcription: DNA RNA • Overall Goal: Take the code from DNA nitrogenous

bases and copy it onto an RNA molecule.

• Why??: DNA cannot leave the nucleus. DNA cannot be directly translated into protein.

• Steps:1. DNA strands unwound and separated by helicase.2. The enzyme RNA Polymerase binds to DNA.3. RNA Polymerase matches up RNA bases with DNA bases.4. END PRODUCT = 1 Strand of Messenger RNA (mRNA)5. mRNA leaves the nucleus.

• Keep In Mind:Only 1 strand of DNA needs to be transcribed since the bases are complimentary.

(5) Transcription Examples:

WHAT WOULD BE THE CORRESPONDING STRAND OF mRNA?

DNA Template: TAC—GCG—AAA—ACT

(6) Translation: RNA Amino Acids• Overall Goal: Take the code from RNA molecule and

translate it into an amino acid chain (protein).

• Why??: DNA and RNA are only instructions. Proteins are the molecules that actually do things inside cells.

• Steps:1. mRNA moves through Ribosomal RNA (rRNA) 5’ 3’.2. Begin with the Start Codon, and End with the Stop Codon.3. mRNA codons are matched up with tRNA anti-codons.4. Every 1 Codon = 1 Amino Acid brought by Transfer RNA5. END PRODUCT = 1 Specific Polypeptide (Protein).

• Keep In Mind:tRNA molecules are floating around waiting to match up their anticodons to mRNA codons during translation. They automatically have amino acids ready to go!

(7) Translation Examples:

WHAT WOULD BE THE CORRESPONDING AMINO ACID SEQUENCE?

mRNA Strand: AUG—CGC—UUU—UGA