SCMA*1120 Study Guide - Midterm Guide: Chemical Synapse, G1 Phase, Dna Replication
Document Summary
Topoisomerases: conversion between relaxed and supercoiled state is catalyzed by this enzyme. Supercoils are removed by transiently cleaving one strand of the dna double helix and passing the unbroken strand through the break. Supercoils are removed by transient cleaving both strands of the dna double helix and passing an unbroken region of the dna double helix through the break. Cells can regulate the separation of dna. This can occur by: h-bonds, can be separated relatively easily, termed melting. Can be put back together with renaturing. Dna is associated with proteins (histones)= chromatin. Histones: proteins with a high concentration of lysine and arginine (positive charge, subtypes, h1, h2a, h2b, h3 & h4. What can happen with dna: undergo cell division, heterochromatin, facultative vs. constitutive heterochromatin, transcribe rna, euchromatin. Nuclear localization signals: amino acid sequences which enable a protein to be recognized and then transported. Comprised of: fibrils: contain dna, granules: rrna being packaged. How: tight control over membrane potential.
