2.4 2.4 Physical chemistry Physical chemistry of nucleic acidsof nucleic acids

A Variety of DNA Structures A Variety of DNA Structures A form A form

Separating the Two Strands of a DNA Double Helix Separating the Two Strands of a DNA Double Helix

Reuniting the Separated DNA Strands Reuniting the Separated DNA Strands

Hybridization of Two Different Polynucleotide Chains Hybridization of Two Different Polynucleotide Chains DNAs of Various Sizes and Shapes DNAs of Various Sizes and Shapes The Relationship between DNA Size and Genetic CaThe Relationship between DNA Size and Genetic Ca

pacity pacity

DNA Content and the C-Value ParadoxDNA Content and the C-Value Paradox

Nucleic acid can form several types of double helix

B-DNA A-DNA Z-DNA

Bp/turn 10.4 11 12

Rotation/bp +34.6º +34.7º -30.0º

Vertical rise/bp 3.38Å 2.56 Å 5.71Å

Helical diameiter 19 Å 23Å 18Å

A variety of DNA structure

Separating the two strands of

a DNA double helix

DNA denature;

DNA melting;

Tm (The temperature at which the DNA strands are half denatured.)

Hyperchromic shift

Reuniting the separated DNA strands

Annealing / renaturation

Three important factors:

Temperature : ~Tm-25°C

DNA concentration : the higher the concentration , the faster the annealing

Renaturation time: The longer the time,the more will occur.

C0t: DNA concentration and time

The more complex a DNA, the higher its C0t1/2

DN

A/R

NA

hybridization

DNAs of Various sizes and shapes

•The sizes are expressed three ways:

molecular weight,

number of base pairs and

length. 1 helical turn = 10.5 bp = 34Å; 1bp = 660 d.

•Measure DNA sizes

electron microscope

gel electrophoresis

Chapter 3

An Introduction to Gene Function

Color-enhanced scanning electron micrograph of DNA strands showing transcription detail

Three major activities of Three major activities of genegene

InformationInformation ReplicationReplication MutationMutation

3.1 Storing Information Overview of Gene Expression Protein Structure Protein Function The Relationship between Genes and Proteins Discovery of Messenger RNA Transcription Translation Ribosomes: Protein-Synthesizing Machines Transfer RNA: The Adapter Molecule Initiation of Protein Synthesis Translation Elongation Termination of Translation and mRNA Structure

3.1 Storing Information3.1 Storing Information

Overview of Gene Expression Overview of Gene Expression Protein Structure Protein Structure Protein FunctionProtein Function The Relationship between Genes and Proteins The Relationship between Genes and Proteins Discovery of Messenger RNA Discovery of Messenger RNA Transcription Transcription Translation Translation Ribosomes: Protein-Synthesizing Machines Ribosomes: Protein-Synthesizing Machines Transfer RNA: The Adapter Molecule Transfer RNA: The Adapter Molecule Initiation of Protein Synthesis Initiation of Protein Synthesis Translation Elongation Translation Elongation Termination of Translation and mRNA StructureTermination of Translation and mRNA Structure

Tertiary structure of myoglobin

Tertiary structure of the core region common to all protein kinase

The globular domains of an immunoglobin

Evidence for One gene-one enzyme

Pathway of pantothenate synthesis

3.2 Replication

Semi-conservative replication

3.3 Mutations

Sickle-Cell Disease