AUA Med 1-- Biochemistry – DNA – Questions With Complete Solutions

Describe the structure of a prokaryotic (bacterial) genome correct answer: 1. Circular in bacterial cells, 2. attached to the plasma membrane, 3. Can include a separate DNA fragment (plasmid DNA) What shape are plasmids? correct answer: Also circular What are 2 properties of plasmids? correct answer: 1. Can carry antiobiotic resistance, 2. Can be transferred between bacteria How many DNA molecules are in a human chromosome/genome? correct answer: 1 single DNA molecule What is chromatin? correct answer: String of nucelosomes connected by the linker DNA into a "beads on a string" arrangement. What is chromatin composed of? correct answer: DNA + Histones + Non-Histone What are the types of histones in chromatin? correct answer: Linker H1, Core H2A, H2B, H3, H4 What are the non-histone proteins in chromatin? correct answer: HMGs, transcription factors, etc. What is a nucleosome? correct answer: Basic unit of organization of DNA around a histone octamer (two each of the core histones H2A,H2B, H3, & H4. Which histone bounds a nucleome bead in place? correct answer: H1 (the "linker"). H1 binding is required for higher order folding of chromatin What is the difference between "mitotic chromosome" and "interphase chromosome"? correct answer: In mitotic chromosome, the chromatin fibers are further folded into the higly condensed mitotic chromosome for cell division. In interphase chromosome, nucleosomes are arranged into chromatin (string) for transcription, replication, repair, etc.