Download Lecture Notes with Key Figures PowerPoint - HMartin

PowerPoint® Lecture Presentation for
Concepts of Genetics
Ninth Edition
Klug, Cummings, Spencer, Palladino
Chapter 10
DNA Structure and Analysis
Lectures by David Kass with contributions from
John C. Osterman.
Copyright
© 2009©Pearson
Education,
Inc.
Copyright
2009 Pearson
Education,
Inc.
10.1The Genetic Material Must Exhibit
Four Characteristics
• It must be able to:
• replicate
• store information
• express information
• The Cenral Dogma
• allow variation by mutation
Copyright © 2009 Pearson Education, Inc.
Section 10.2
• Until 1944, Observations Favored Protein
as the Genetic Material
• Known that genetic material is physically
transmitted from parent to offspring.
• Proteins and nucleic acids were the major
candidates for the genetic material.
Copyright © 2009 Pearson Education, Inc.
10.3 Evidence Favoring DNA as the
Genetic Material Was First Obtained
during the Study of Bacteria and
Bacteriophages
Copyright © 2009 Pearson Education, Inc.
Section 10.3
• Griffith showed that
avirulent strains of
Diplococcus
pneumoniae could
be transformed to
virulence.
Copyright © 2009 Pearson Education, Inc.
Section 10.3
• Avery, MacLeod, and McCarty (1944)
demonstrated that the transforming
principle was DNA and not protein.
Copyright © 2009 Pearson Education, Inc.
Copyright © 2009 Pearson Education, Inc.
Figure 10.4
Section 10.3
• Hershey and Chase (1952) demonstrated
that DNA, and not protein, enters the
bacterial cell during bacteriophage
infection and directs viral reproduction.
Copyright © 2009 Pearson Education, Inc.
Copyright © 2009 Pearson Education, Inc.
Figure 10.5
Copyright © 2009 Pearson Education, Inc.
Figure 10.6
Section 10.4
• Indirect and Direct Evidence Supports the
Concept that DNA Is the Genetic Material
in Eukaryotes
• DNA is found only where the primary genetic
function occurs.
• Whereas protein is found throughout the cell.
• This provides indirect evidence for DNA as
the genetic material.
Copyright © 2009 Pearson Education, Inc.
Section 10.4
• UV light is capable
of inducing
mutations in the
genetic material
and is most
mutagenic at a
wavelength of 260
nm.
Copyright © 2009 Pearson Education, Inc.
Section 10.4
• Strongest direct evidence for DNA =
recombinant DNA technology.
Copyright © 2009 Pearson Education, Inc.
Section 10.6
• Knowledge of Nucleic Acid Chemistry Is
Essential to the Understanding of DNA
Structure
• Nucleotides are the building blocks of
DNA.
• They consist of:
• a nitrogenous base
• a pentose sugar
• a phosphate group
Copyright © 2009 Pearson Education, Inc.
Section 10.6
• Nitrogenous bases can be purines or
pyrimidines.
• Purines
• adenine (A) and guanine (G)
• Pyrimidines
• cytosine (C), thymine (T), and uracil (U)
Copyright © 2009 Pearson Education, Inc.
Section 10.6
• DNA and RNA both contain A, C, and G.
• Only DNA contains T.
• Only RNA contains U.
• RNA contains ribose as its sugar.
• DNA contains deoxyribose (Figure 10.9).
Copyright © 2009 Pearson Education, Inc.
Copyright © 2009 Pearson Education, Inc.
Figure 10.9
Section 10.6
• A nucleoside contains the nitrogenous
base and the pentose sugar.
• A nucleotide is a nucleoside with a
phosphate group added.
Copyright © 2009 Pearson Education, Inc.
Section 10.6
• The C-5' position is the location of the
phosphate group on a nucleotide.
Copyright © 2009 Pearson Education, Inc.
Section 10.6
• Nucleotides can have one, two, or three
phosphate groups and are called NMPs,
NDPs, and NTPs, respectively.
Copyright © 2009 Pearson Education, Inc.
Section 10.6
• Nucleotides are
linked by a
phosphodiester
bond between
the phosphate
group at the C-5'
position and the
OH group on the
C-3' position.
Copyright © 2009 Pearson Education, Inc.
Section 10.7
• Chargaff showed that the amount of A is
proportional to T and the amount of C is
proportional to G, but the percentage of
C + G does not necessarily equal the
percentage of A + T (Table 10.3).
Copyright © 2009 Pearson Education, Inc.
Early DNA Studies
•
•
Rosalind Franklin and Maurice Wilkins studied DNA
structure using X-ray scattering
From X-ray diffraction patterns they deduced that DNA
– Is long and thin
– Has a uniform diameter of 2 nanometers
– Is helical, and is twisted like a corkscrew
– Consists of repeating subunits
Copyright © 2009 Pearson Education, Inc.
Section 10.7
• Watson and Crick proposed:
• DNA is a right-handed double helix
• Two strands are antiparallel and the bases
are stacked on one another.
• Two strands are connected by A-T and G-C
base pairing
• There are 10 base pairs per helix turn (Figure
10.14).
Copyright © 2009 Pearson Education, Inc.
Copyright © 2009 Pearson Education, Inc.
Figure 10.14
Copyright © 2009 Pearson Education, Inc.
Figure 10.15
Section 10.7
• A-T & G-C base
pairing provides
complementarity of
the 2 strands &
chemical stability to
the helix.
• A-T base pairs form
2 hydrogen bonds &
G-C base pairs form
3 hydrogen bonds.
Copyright © 2009 Pearson Education, Inc.
Section 10.7
• Arrangement of
sugars and bases
along the axis
provides another
stabilizing factor.
Copyright © 2009 Pearson Education, Inc.
Alternative Forms of DNA Exist
• Watson-Crick DNA model is of
B-DNA, which is believed to be the
biologically significant form.
• A-DNA is slightly more compact than
B-DNA.
• C-DNA, D-DNA, and E-DNA are also
right-handed forms of DNA that are less
compact than B-DNA.
• Z-DNA forms a left-handed double helix
Copyright © 2009 Pearson Education, Inc.
Copyright © 2009 Pearson Education, Inc.
Figure 10.17
Section 10.9
• The Structure of RNA Is Chemically Similar
to DNA, but Single Stranded
• In RNA:
• the sugar ribose replaces deoxyribose of DNA
• and uracil replaces thymine of DNA
• Usually single-stranded
Copyright © 2009 Pearson Education, Inc.
Section 10.9
• There are 3 classes of cellular RNAs:
• messenger RNA (mRNA)
• the template for protein synthesis
• ribosomal RNA (rRNA)
• components of ribosomes for protein synthesis
• transfer RNA (tRNA)
• carry amino acids for protein synthesis
Copyright © 2009 Pearson Education, Inc.
The End
Copyright © 2009 Pearson Education, Inc.
http://www.molecularstation.com/molecular-biology-images/data/502/DNA_animation.gif