Lecture 1/22/25 Flashcards
What charge does DNA have?
DNA has a negative charge due to its phosphate backbone.
How does DNA move in gel electrophoresis?
DNA moves toward the positive electrode; smaller fragments travel faster.
What do the bands in gel electrophoresis represent?
They represent DNA fragments of different sizes.
What is a nuclease?
An enzyme that cleaves DNA or RNA by breaking phosphodiester bonds.
What is the difference between exonucleases and endonucleases?
Exonucleases remove nucleotides from the ends; endonucleases cut within the sequence.
Why are restriction endonucleases special?
They recognize specific DNA sequences and cut at defined sites.
What is a ligand?
A molecule that binds to a protein.
When is a ligand a substrate?
When it undergoes a chemical reaction after binding.
How do proteins read and bind to a DNA sequence?
Through specific interactions with bases in the major and minor grooves.
What is the function of DNA ligase?
It joins DNA fragments by forming phosphodiester bonds.
What do cofactors do in relation to enzymes?
They assist enzymes in catalyzing reactions.
Give examples of cofactors.
Metal ions (Mg²⁺, Zn²⁺) and coenzymes (NAD⁺, FAD).
What is the difference between cofactors and coenzymes?
Cofactors can be metal ions or organic molecules; coenzymes are organic molecules that participate in enzyme function.
