molecular evolution
DESCRIPTION
Molecular Evolution. Lecture 1. Origins of variation: gene structure. Why this course. A Human Language Gene Changes the Sound of Mouse Squeaks Of Mice and Monologues The Origins of Lactase Persistence. II. What is DNA? A. DNA 1. Composition: polymer of nucleotides:. 1. Nitrogen base - PowerPoint PPT PresentationTRANSCRIPT
Molecular Evolution
Lecture 1. Origins of variation: gene structure
Why this course
• A Human Language Gene Changes the Sound of Mouse Squeaks
• Of Mice and Monologues
• The Origins of Lactase Persistence
II. What is DNA? A. DNA1. Composition: polymer of nucleotides:
1. Nitrogen base
2. Deoxyribose [ribose for RNA]
3. Phosphate
Types of nitrogen bases
DNA nucleotides are attached to each other 5’ to 3’
Bases can form hydrogen bonds with a complimentary antiparallel DNA strand
Specific pairing between the nitrogen bases
The complete DNA alphabet (fyi)Symbol Meaning Origin of designationG G GuanineA A AdenineT T ThymineC C CytosineR G or A puRineY T or C pYrimidineM A or C aMinoK G or T KetoS G or C Strong interaction (3 H bonds)W A or T Weak interaction (2 H bonds)H A or C or T not-G, H follows G in the alphabetB G or T or C not-A, B follows AV G or C or A not-T (not-U), V follows UD G or A or T not-C, D follows CN G or A or T or C aNy
Some features of DNA
• Purines pair with pyrimidines
(e.g. # purines = # pyrimides)
• The # of A = # of T; #G = # of C• (% G + C content of 2 species’ DNA will vary)
• GC-rich DNA is more stable than AT-rich (more hydrogen bonding)
• Two strands of the duplex lie antiparallel
DNA replication
leading strand 5’ to 3’ continuous replication
lagging strand discontinuous replication
http://upload.wikimedia.org/wikipedia/commons/a/ac/GeneticCode21.svg
The genetic code: redundancy compensating for mutation
Redundancy and the Wobble position
5’ 5’3’3’
Functional redundancy in the amino acid code
• http://www.russell.embl-heidelberg.de/aas/general.html
5’3’ 3’5’
Transcription
Translation
CCAA BB
gene Bgene Bgene Agene A gene Cgene C
5’
Transcription/translation Differences between prokaryotic and eukaryotic mRNAs
EukaryoticEukaryoticMonocistronic
Poly A tails
Transported from nucleus to cytoplasm
Half-life: minutes - hours
5’ methylated G cap
PolycistronicProkaryoticProkaryotic
No tails
Transcription/Translation coupled
Half-life: seconds - minutes
No cap
Transcription/Translation