Replication Transcription Translation

DNA 1.Its structure is a Double Helix 2. Made up of nucleotides which consist of a phosphate group, a sugar, and a nitrogenous base 3. Hydrogen Bonds hold the Nitrogenous Base Pairs 4. Complimentary bases pairs bond Adenine-Thymine and Guanine-Cytosine

Gene A gene is a segment of DNA A gene is a sequence of nucleotides that codes for a functional product (usually a protein) 1 gene = 1000’s of base pairs possibilities of combinations

A Gene is a Segment of DNA When a gene is expressed, DNA is transcribed to produce RNA and RNA is then translated to produce proteins.

Genotype and Phenotype Genotype- the letters 1. Genetic Composition of an Organism 2. Represents the Potential Properties Phenotype- the actual organism 1. The Expression of the Genes 2. What You See

Replication Replication occurs before a cell divides so that each new cell formed can have a copy of the DNA Occurs in the nucleus of the cell 1 Strand  2 Complementary Strands The primary enzyme in this process is DNA Polymerase

One More Time!

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 of DNA making a complimentary strand of RNA. Occurs in the nucleus of the cell 1 Strand DNA  2 Strands RNA The primary enzyme involved in this process is RNA Polymerase

DNA RNA

Label the Following

One More Time!

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

Translation The process in which an amino acid chain is made from mRNA template 1 Strand RNA  Amino Acid Chain  Protein This occurs in the cytoplasm with the help of ribosomes

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 and has Uracil instead of thymine RNA Acts as a Messenger between DNA and Ribosomes Process Takes Amino Acids and Forms Proteins

Why Is It Necessary? DNA is in the Nucleus Ribosomes are in the Cytoplasm This requires a Messenger to go between the nucleus and the cytoplasm

Definitions Codon 1. Three-base segment of mRNA that specify amino acids. Anticodon 1. Three-base segment of tRNA that dock with a codon. 2. Docking results in depositing of amino acid which is added to a chain.

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 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