#Question id: 24653
#Unit 2. Cellular Organization
Which of the following membrane protein form channel, in the form of gap junctions between cells?
#Question id: 3777
#Unit 3. Fundamental Processes
Which of the following types of cells are affected most by telomere shortening?
#Question id: 28469
#Unit 5. Developmental Biology
Which function is involved to the first differentiation event in mammalian development?
#Question id: 8692
#Unit 9. Diversity of Life Forms
Which of the following statements is accurate with regard to a phylogeny, as represented by a phylogenetic tree?
#Question id: 2899
#Unit 2. Cellular Organization
The H3.H4 tetramers and H2A.H2B dimers each interact with a particular region of the DNA within the nucleosome.
I. Histone H3.H4 tetramers occupy a key position in the nucleosome by binding the middle and both ends of the DNA.
II. The amino-terminal region of H3 most proximal to the histone-fold region forms a fourth a-helix that interacts with the final 13 bp at each end of the bound DNA.
III. The relatively short length of DNA bound by H2A.H2B dimers is sufficient to prepare the DNA for H3.H4 tetramer binding.
IV. The H3.H4 tetramer forms the bottom part of the histone octamer located across the disc from the DNA ends whereas two H2A.H2B dimer occupies the top part.
Which of the following represents the correct binding of the histones with the DNA?