Replication Transcription Translation

DNA 1. Double Stranded Helix 2. Hydrogen Bonds between Nitrogenous Base Pairs 3. Adenine-Thymine and Guanine-Cytosine

Replication The duplication of DNA which occurs during the S phase of Interphase. 1 Strand  2 Complementary Strands DNA Polymerase

thymine adenine cytosine guanine phosphate deoxyribose sugar DNA nucleotide Deoxyribose sugar phosphate Nitrogenous base (guanine) RNA nucleotide ribose sugar phosphate Nitrogenous base (uracil) Sugar / phosphate “ strand ” Nitrogenous base “ rung ” Hydrogen bond (H-bonds)

Step 1: Hydrogen bonds between complimentary bases break DNA “ unzips ”

Step 2: DNA strands pull apart from each other

Step 3: DNA nucleotides in the cell match up with each side of the “ unzipped ” DNA each “ unzipped ’ strands forms a template for a new strand

Step 4: Each “ old ’ strand forms a template for a “ new ” strand two identical DNA molecules form “ old ” (original) strand “ new ” strand, identical sequence to the original

Transcription The process by which a molecule of DNA is copied into a complementary strand of RNA. 1 Strand DNA  2 Strands RNA RNA Polymerase Semiconservative Difference between replication and transcription

DNA RNA

Step 1: Hydrogen bonds between complimentary bases break DNA “ unzips ”

Step 2: DNA strands pull apart from each other

Step 3: RNA nucleotides in the cell match up with only one side of the “ unzipped ” DNA each “ unzipped ’ strands forms a template for a mRNA strand RNA nucleotide

Step 4: RNA nucleotides continue to match up with “ unzipped ” DNA until the message is completely transcribed mRNA strand One side of DNA strand

Step 4: mRNA strand breaks off from the DNA strand mRNA strand One side of DNA strand

Step 5: mRNA strand leaves the nucleus for the ribosome

Step 6: Once the mRNA leaves, the DNA “ zips ” back together Where rep, transl, transc occur

Translation The process in which the information in the nucleotide base sequence of mRNA is used to dictate the amino acid sequence of a protein. 1 Strand RNA  Amino Acid Chain  Protein

The problem: How does a particular sequence of nucleotides specify a particular sequence of amino acids? nucleotides By means of transfer RNA molecules, each specific for one amino acid and for a particular triplet of nucleotides in mRNA called a codon. The family of tRNA molecules enables the codons in a mRNA molecule to be translated into the sequence of amino acids in the protein.

RNA and Protein Synthesis RNA is a Single Stranded Nucleic Acid RNA Acts as a Messenger between DNA and Ribosomes Process Takes Amino Acids and Forms Proteins

Why Is It Necessary? DNA / Nucleus Ribosomes / Cytoplasm Need a Messenger

Definitions Codon 1. Three-base segment of mRNA that specify amino acids. 2. Sense Codons 3. Nonsense Codons Anticodon 1. Three-base segment of tRNA that dock with a codon. 2. Docking results in deposition of amino acid.

Protein Synthesis Proteins are coded directly from the mRNA with 3 bases (one codon) for each amino acid. What ’ s up with that?

Mutation A change in the nitrogenous base sequence of DNA; that change causes a change in the product coded for by the mutated gene.

Mutations What happens when you get insertions or deletions of bases in the DNA sequence? Usually you end up with a mess. THE BIG FAT CAT ATE THE RAT AND GOT ILL Deletion of one base THE IGF ATC ATA TET HER ATA NDG OTI LL And its all pops and buzzes.

Sickle-Cell Anemia

Definitions Carcinogens Substances and preparations which, if they are inhaled or ingested or if they penetrate the skin; may induce cancer or increase its incidence and can affect any cells or tissues Mutagens may induce hereditary genetic defects or increase their incidence and effect the germ cells (gonads) Teratogens may induce non-hereditary congenital malformations or increase their incidence and effect the growing fetus

Mutagens Tobacco products Nitrous Acid Mold Toxins X-rays Gamma Rays UV Radiation Some Artificial Sweeteners