Denaturation of DNA
Hydrogen bonds among base pairs are disturbed
Hypo-chromic effect
stacked bases in DNA reduce absorption of UV light
UV absorption of DNA increases when back stacking is lost
denatured DNA can be detected by monitoring UV absoprtion
Renaturation of partially denatured DNA
Strands spontaneously anneal when temperature and pH returns to normal range
In DNA replication and transcription
catalyzed by enzymes
Renaturation of completely denatured DNA
Two step process
1st step (Slow step)
By random collisions strands find each other
2nd (fast step)
spontaneous annealing of unpaired bases
In DNA Replication and transcription
A-T base pairs in DNA are denatured while G-T remain intact to imitate strand separation
called bubbles
Catalyzed by enzymes
partial denatuation
Occurs at high temperatures and extreme changes in pH
temperature is characteristic to each species of DNA
DNA rich in Guanine - Cytosine base pairs
denatures at very high temperatures
DNA rich in Adenine - Thymine base pairs
denatures at lower temperatures
Viral and Bacterial DNA
Denature at slowing heating Temperatures