DNA to RNA One of the first steps in making proteins Transcription RNA DNA RNA polymerase Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only) DNA to RNA One of the first steps in making proteins

DNA vs. RNA Double-stranded Deoxyribose A, T, G, C Stays in nucleus Only one type Serves as a template for RNA Single-stranded Ribose A, U, G, C Goes out into cytoplasm 3 types (mRNA, tRNA, rRNA) Serves as a template for tRNA & proteins

Where are they at?  DNA stays in nucleus to minimize the risk of being damaged by digestive enzymes, bacteria, etc.  RNA is used as a messenger (carries a message from DNA in order to make proteins)

3 types of RNA Messenger RNA Copied from DNA goes from nucleus to ribosomes in the cytoplasm Ribosomal RNA -Structural component of the Ribosome. (Ribosomes are made of rRNA and proteins) Transfer RNA Brings Amino Acids to the Ribosomes that match the mRNA codons.

Transfer RNA - tRNA

Transcription Step 1 RNA polymerase binds to the promoter in DNA DNA is untwists & unzipped (like when it replicates)

Step 2 As DNA unzips, free RNA nucleotides (A, U, G, C) pair with complementary DNA nucleotides on one of the DNA strands For example: 5’ – AGC TAA CCG (DNA template strand) 5’ – UCG AUU GGC (new messenger RNA [mRNA] molecule)

Step 3 When the process of base pairing is complete, the mRNA molecule breaks away from DNA. DNA strands re-zip and twist.

TRANSLATION: mRNA  proteins (amino acid chains) The ribosome “reads” the mRNA 3 letters at a time. These 3- letter “words” are called codons. Each Amino acid has corresponding 3 letter codon The “start” codon (AUG) tells the ribosome to start making Amino Acid chains tRNA brings a methionine

mRNA leaves the nucleus and enters cytoplasm, in search of ribosomes.

There Are 20 Different Amino Acids

Each three letter codon in mRNA corresponds to a specific Amino Acid

tRNA… Floating around the cytoplasm are molecules of transfer RNA (tRNA), which have an “anticodon,” (complement of the codon) and carry an amino acid to the Ribosome EXAMPLE: mRNA - AUG GCA UAC (codons) tRNA - UAC CGU AUG (anticodons) Amino acid - (met) (ala) (tyr)

mRNA leaves the nucleus and enters cytoplasm, in search of ribosomes.

In the Ribosome There are room for two tRNA molecules in the ribosome. When two tRNA molecules are in the ribosome next to each other with amino acids attached, the two amino acids form a peptide bond. The first tRNA leaves, the second one moves over, and the next tRNA comes in with another amino acid.

Amino acids & Peptide Bonds Alanine Dipeptide

Protein Structure

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