Chapters 12&13 Notes: DNA, RNA & Protein Synthesis Name Period Words to Know: nucleotides, DNA, complementary base pairing, replication, genes, proteins, mrna, rrna, trna, transcription, translation, codon, anticodon, gene expression, mutation, chromosomal mutation, point mutation, frameshift mutation, differentiation, mutagen The Structure of DNA In prokaryotes (no nucleus), DNA is. In eukaryotes, DNA is on the in the nucleus. Nucleotide Parts Double-stranded Linked nucleotides 1) Sugar - 2) Phosphate group (has element phosphorous) 3) Nitrogenous Sugar and phosphate make the sides. Bases make the rungs. Nucleotide Types 1) Adenine (A) 2) Thymine (T) 3) Cytosine ( C ) 4) Guanine (G) bonds with bonds with Called complementary basepairing. 1
DNA Replication When does it happen? cell division (mitosis or meiosis) Where does it happen? In the Step 1: Enzyme (DNA Polymerase) DNA Step 2: Enzyme attaches free to the original strands until both strands are copied. Step 3: Replication occurs in spots along the DNA until all parts are copied. Two strands are made. Now cell division can occur! Replication in Different Cells In prokaryotes: Starts at a point and proceeds in two directions until the entire chromosome is copied. In eukaryotes: Begins at places and proceeds in two directions until the entire chromosome is copied. RNA Genes: Section of DNA with the instructions to make 1. Found in the. Proteins: Many amino acids together. Proteins are made in the cytoplasm by, but the instructions for doing this (the DNA) can t leave the nucleus. How can this work??? RNA: A single-stranded of DNA. 2
DNA vs. RNA RNA Chain of nucleotides. Sugar is. - stranded. Bases are A,U,G,C. (U = uracil.) DNA Chain of nucleotides. Sugar is. - stranded. Bases are A,T,G,C. Types of RNA Messenger RNA (mrna): Copies in the nucleus. Transfer RNA (trna): Brings amino acid to the for protein assembly. Ribosomal RNA (rrna): Inside ribosome. Helps with. To go from DNA to a Protein, there are two steps: 1) Transcription- mrna makes of DNA 2) Translation- is made from mrna Transcription: mrna copies DNA Step 1: enzyme (RNA Polymerase) DNA promoter: regions of DNA where the binds Step 2: mrna bases make a of DNA Step 3: (bad bases) are removed, (good bases) are spliced together Step 4: cap and tail are Step 5: mrna leaves the for the cytoplasm. Ribosomes & Protein Synthesis Codons: A section of three mrna bases in a row that for one amino acid. Anticodons: The corresponding trna that the amino acid. 3
Translation: the mrna is translated into a 1.) Ribosome finds the start, AUG, on mrna. 2.) The corresponding on the trna binds into place. 3.) The ribosome reads the next codon & its corresponding anticodon. 4.) The ribosome the two amino acids on the trna together. The trna lets go. 5.) This continues until a codon is reached. Then the last trna & ribosome fall off. 6.) The amino acid chain into its proper structure. The central dogma of molecular biology= -> RNA-> protein gene expression: process by which a gene its product, which carries out its 4
Mutations Mutations: Changes in the DNA sequence that changes the it codes for. Two Types: 1.) Chromosomal Mutations 2.) Gene Mutations Chromosomal Mutations: Result from changes in a whole. 1.) gene deletions: Parts of a chromosome break and, with a gene missing. Ex: Cris-du-chat Syndrome 2.) gene duplications: Most duplications have no consequences. 3.) gene inversions: Part of a chromosome becomes oriented in the of its usual direction. Usually no phenotypic consequences. 4.) translocations: Part of a chromosome breaks off and attaches to a chromosome. Can lead to zygotes. Point mutations: Occur at a single in the DNA. Usually one nucleotide is for another, changing an amino acid. Ex: Sickle Cell Anemia Frameshift mutations: A type of point mutation where an nucleotide is added or deleted, shifting the reading of codons, resulting in changes to ALL of the amino acids. Ex: Huntingdon s Disease Mutagen: An agent that causes a in DNA. Ex: smoke, high energy radiation (X rays, UV light, nuclear radiation), chemicals (dioxins, asbestos, benzene, cyanide, formaldehyde), and high temperatures. 5
Note: In some cases, a gene mutation may have effects leading to evolution. Gene Regulation & Expression Proteins bind to sections of DNA that control. More in eukaryotes because cells are specialized. Differentiation: When new cells become in structure & function during embryonic development. 6