Lecture 15 Flashcards
In what state is DNA more compact?
When it’s supercoiled
What is underwound and overwound DNA called?
negatively and positively supercoiled
What enzyme changes the level of supercoiling in DNA? What does Type I and II do?
topoisomerases
Type I: creates a break in one strand
Type II: makes a break in both strands, tie DNA into knots or untie knots
What is Denaturation? How is it monitored? What can increase the melting temperature?
Separating DNA into its separate components
monitored by following increase in UV light absorbance
melting temperature increases at higher G and C DNA content
What is renaturation / reannealing?
A single strand of DNA molecule associates
What are the 3 classes of DNA sequences?
Highly repeated
moderately repeated
non-repeated
What type of DNA sequence makes about 1-10% of total DNA?
Highly repeated
What are the 3 types of highly repeated DNA sequences?
Satellite - short and evolve rapidly
mini-satellite - unstable, basis of DNA fingerprinting
micro-satellite - shortest, small clusters, often genetic disorders
What is FISH and what is it used for?
Fluorescence in situ hybridization
generate towards specific DNA sequences
What DNA type often makes up 20 - 80% of total DNA? How often is it typically repeated?
Moderately repeated DNA
repeats a few times to 10,000s of times
some for gene products, most lack coding function
What DNA type exhibits Mendelian patterns of inheritance & localize to a site on the chromosome? What can they code for
Non-repeated DNA sequences
Code for polypeptides
When does Gene duplication occur?
unequal crossing of misaligned chromosomes
What are Transposons? What does it require?
certain DNA sequence than can be removed and randomly inserted into target sites
requires a transposase
What are Retro-Transposons? What intermediate does it use?
Same as transposon where DNA is inserted into another DNA but the donor instead makes an RNA copy, made into DNA then inserts
what may have given rise to genes?
Transposable DNA
