Chp 9 - DNA Technologies Flashcards
What is the structure of DNA in eukaryotes?
Long, linear dsDNA in chromosomes bound by proteins to form chromatin; circular dsDNA in mitochondria and plant chloroplasts.
What is the structure of DNA in prokaryotes?
Single circular dsDNA supercoiled to form a nucleoid; may also contain plasmids.
What is the B form of DNA?
Right-handed helix with 10 base pairs per turn; the major form of chromosomal DNA.
What is DNA supercoiling?
The process of adding/removing turns in DNA to achieve the target twist ratio. Positive supercoils are overwound; negative supercoils are underwound.
What role do topoisomerases play?
Enzymes that add/remove supercoils in DNA.
What is histone acetylation?
Modification of histone proteins by acetylation of lysine residues, loosening chromatin structure to increase gene expression.
What are restriction endonucleases?
Bacterial enzymes that cleave DNA at specific sequences, used to cut foreign DNA.
How do bacteria protect their DNA from restriction endonucleases?
By methylating recognized DNA sequences using methylase enzymes.
What is a restriction map?
A map showing locations where restriction enzymes act on DNA, determined using electrophoresis.
What is recombinant DNA?
Hybrid DNA created by splicing DNA sequences from different sources, often using sticky ends and DNA ligase.
What is the Holliday model for recombination?
A model where single-stranded breaks in DNA allow strand invasion, forming a Holliday junction that is cleaved to restore chromosomes.
