Chapter 3: Nucleic Acids and Transcription (3.1: Major Biological…
Chapter 3: Nucleic Acids and Transcription
3.1: Major Biological Functions of DNA
Transformation: "The conversion of cells from one state to another, as from nonvirulent to virulent, when DNA released to the environment by cell breakdown is taken up by recipient cells"
Replication: The process of copying DNA
Mutation: An error in replication
Central Dogma: information transfer goes from DNA to RNA to protein
Steps in Replication
Transcription: Synthesis of RNA from a DNA template.
Translation: synthesis of polypeptide chain corresponding to coding sequence present in mRNA.
Replication does not occur consistently: Genes are "expressed", or turned on, at certain times/ in certain places
In prokaryotes, transcription and translation take place in the cytoplasm
In Eukaryotes, Transcription occurs in nucleus, translation in cytoplasm.
3.2: Chemical Composition and Structure of DNA
Nucleotides make up DNA
3' End: Free Hydroxyl
Strands are Antiparallel
Major groove and minor groove make up asymetrical helix
10 Base pairs per complete turn
5' End: Free phosphate
Topoisomerase: causes Supercoiling
Chromosome: Structure of one DNA molecule
Evolutionarily Conserved Characteristics: Persist relatively unchanged through diversification of organisms
Chromatin: DNA, RNA, and histones (proteins)
Adenine bonds with Thymine: 2 H bonds
Guanine and Cytosine: 3 H Bonds
Base Stacking: Stabilizing hydrophobic interactions between bases in the same strand of DNA
DNA vs RNA:
Complex base pairing, can have 3D shape, Reactive molecule (2' hydroxyl), assist in chemical reactions (ribosome)
Long double stranded structures, stable molecule, simple duplication