Chapter 1 overview
1.1
DNA is the molecule of heredity
•“discovered” by Miesher (1869)
Slide of Friedrich Miescher.
Chapter 1 overview
1.1
DNA is the molecule of heredity
•“discovered” by Miesher (1869)
•the “stuff” of transformation is DNA
(R to S S. pneumoniae; Griffith 1920’s)
Fig. 1.2 The Griffith's experiment demonstrating bacterial transformation
© 2006 Jones & Bartlett Publishers
Chapter 1 overview
1.1
DNA is the molecule of heredity
•“discovered” by Miesher (1869)
•the “stuff” of transformation is DNA
(R to S S. pneumoniae; Griffith 1920’s)
(Avery MacLeod and McCarty, 1944)
Fig. 1.3 Diagram of the experiment demonstrating that DNA is the
active material in bacterial transformation
© 2006 Jones & Bartlett Publishers
Chapter 1 overview
1.1
DNA is the molecule of heredity
•“discovered” by Miesher (1869)
•the “stuff” of transformation is DNA
(R to S Streptococcus pneumoniae)
(Avery MacLeod and McCarty, 1944)
•infection of E. coli by T2 phage uses DNA
(Hershey and Chase, 1952)
Fig. 1.4 The Hershey-Chase ("blender") experiment,
© 2006 Jones & Bartlett Publishers
Chapter 1 overview
1.2
DNA is a double helix
•described by Watson and Crick (1953)
Fig. 1.6. Space filling model and
diagram showing helical
backbones of a DNA double helix
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pictures of Watson and Crick
Chapter 1 overview
1.2
DNA is a double helix
•described by Watson and Crick (1953)
•two long chains of nucleotides A, C, G, T
•complementary base pairing AT and CG
•strands have polarity (5’ to 3’)
•strands are antiparallel
Chapter 1 overview
1.3
DNA replication
•two identical molecules made from one
•semiconservative
•original strands
•separate
•act as templates
Fig. 1.7. Replication of DNA originally
proposed by Watson and Crick
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Chapter 1 overview
1.4
(Most) Genes code for proteins
•Genes have information for making proteins
Fig. 1.13. DNA Sequence coding for the first seven
amino acids in a polypeptide chain
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Chapter 1 overview
1.4
(Most) Genes code for proteins
•Genes have information for making proteins
•Several types of RNA are needed
Fig. 1.14. The "central dogma" of molecular genetics
© 2006 Jones & Bartlett Publishers
Chapter 1 overview
1.4
(Most) Genes code for proteins
•Genes have information for making proteins
•Several types of RNA are needed
•usually single-stranded
•ACGU
•bases are complementary AU CG
Chapter 1 overview
1.4
(Most) Genes code for proteins
•transcription
•in nucleus
•make mRNA from one strand
•RNA polymerase
Fig. 1.15. Transcription
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Chapter 1 overview
1.4
(Most) Genes code for proteins
•translation
•in cytoplasm
•at ribosomes
•nucleotides “read” in 3’s as codon
•codon compliments anticodon on tRNA
•tRNA carries particular amino acid
•ribosome attaches adjacent amino acids
•genetic code table
Fig. 1.16. The role of messenger RNA in translation
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Table 1.1. The standard genetic code.
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Chapter 1 overview
1.5
Genes change by mutation
•alteration of codon can change amino acid
•change in aa can inactivate enzyme
Fig. 1.17. The central dogma in action
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Fig. 1.18. The M1V mutant in the PAH gene
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Fig. 1.19. The R408W mutant in the PAH gene
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Chapter 1 overview
1.5
Genes change by mutation
•alteration of codon can change amino acid
•change in aa can inactivate enzyme
•examples of diseases
•PKU
•alkaptonuria
Fig. 1.10. Inborn errors of
metabolism
© 2006 Jones & Bartlett Publishers
Chapter 1 overview
1.6
Traits affected by genes and by environment
•genes may affect many traits
•traits may be affected by many genes
•some traits also affected by environment
PKU warning on Diet Coke
Chapter 1 overview
1.7
molecular unity of life
•organisms share similarities, e.g.,
•genetic apparatus
•gene similarities
•gene families
RNA from the small
subunit of the ribosome
Fig. 1.21. Evolutionary relationships among the major life forms as
inferred from similarities in DNA sequence
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Table 1.2. Comparisons of genomes and proteomes.
© 2006 Jones & Bartlett Publishers