Download 8.2 All Genetic Information Is Encoded in the Structure of DNA

Benjamin A. Pierce
•GENETICS ESSENTIALS
•Concepts and Connections
• SECOND EDITION
CHAPTER 8
DNA: The Chemical Nature of the Gene
© 2013 W. H. Freeman and Company
CHAPTER 8 OUTLINE
• 8.1 Genetic Material Possesses Several Key
Characteristics, 208
• 8.2 All Genetic Information Is Encoded in the Structure of
DNA, 208
• 8.3 DNA Consists of Two Complementary and Antiparallel
Nucleotide Strands That Form a Double Helix, 214
• 8.4 Large Amounts of DNA Are Packed into a Cell
• 8.5 Eukaryotic Chromosomes Possess Centromeres and
Telomeres
• 8.6 Eukaryotic DNA Contains Several Classes of
Sequence Variation
THE CASE OF NEANDERTHAL AN US
• Analyses showed that
Neanderthals and
Humans interbred.
• On average today
humans have 1-4% of
Neanderthal DNA
8.1 Genetic Material Possesses Several Key
Characteristics
• Genetic material has to contain complex information.
• Store large amounts of information
• Be stable
• And yet vary
• Genetic material must replicate faithfully.
• To be able to transfer correct information to descendents
• Genetic material must encode the phenotype.
• The genotype must determine the phenotype
8.2 ALL GENETIC INFORMATION IS ENCODED
IN THE STRUCTURE OF DNA
• Early Studies of DNA
• DNA As the Source of Genetic
Information
• The discovery of the transforming
principle:
8.2 All Genetic Information Is Encoded in the
Structure of DNA or RNA
• DNA As the Source of Genetic Information
• Identification of the transforming principle:
• Avery, Macleod, and McCarty’s experiment
• Fig. 8.2
• The Hershey–Chase Experiment
• Fig. 8.3
8.2 ALL GENETIC INFORMATION IS ENCODED IN
THE STRUCTURE OF DNA OR RNA
• DNA As the Source of Genetic Information
• Watson and Crick’s discovery of the three-dimensional
structure of DNA
• X-ray diffraction image of DNA
8.3 DNA CONSISTS OF TWO COMPLEMENTARY AND
ANTIPARALLEL NUCLEOTIDE STRANDS THAT
FORM A DOUBLE HELIX
• The primary structure of DNA
• Nucleotides
• Secondary structures of DNA
• The double helix
• Hydrogen bond and base pairing
• Antiparallel complementary DNA strands
8.3 DNA Consists of Two Complementary and
Antiparallel Nucleotide Strands That Form a
Double Helix
• Secondary structure of DNA
• Different secondary structures:
8.4 Large Amounts of DNA Are Packed into a Cell
• Supercoiling
• Positive supercoiling Fig. 8.16b
• Negative supercoiling Fig. 8.16c
• Topoisomerase: The enzyme responsible for adding and
removing turns in the coil.
8.4 Large Amounts of DNA Are Packed into a
Cell
• Chromatin Structure
• Euchromatin
• Heterochromatin
• Histone proteins
8.4 Large Amounts of DNA Are Packed into a
Cell
• Chromatin Structure
• The nucleosome
• Chromatosome
• Linker DNA
• High-order chromatin structure
• Epigenetic changes
8.5 Eukaryotic Chromosomes Possess
Centromeres and Telomeres
• Chromatin Structure
• Centromere structure
• Telomere structure
8.6 EUKARYOTIC DNA CONTAINS SEVERAL
CLASSES OF SEQUENCE VARIATION
• Types of DNA Sequences in Eukaryotes:
• Unique sequence DNA
• Gene family: Similar but not identical copies of unique DNA
sequences that arose through duplication of an existing gene.
8.6 Eukaryotic DNA Contains Several Classes
of Sequence Variation
• Types of DNA sequences in Eukaryotes:
• Repetitive DNA
• Moderately repetitive DNA: 150 ~ 300 bp long.
• Tandem repeat sequences
• Interspersed repeat sequences
• Short interspersed elements: SINEs : Alu element
• Long interspersed elements: LINEs.
• Highly repetitive DNA: less than 10 bp long.