H3 and H4 histones first form heterodimers that then come together to form a tetramer with two molecules each of H3 and H4. While H2A and H2B form heterodimers in solution but not tetramers. This assembly without DNA called Histone-only Intermediates 

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#Id: 4025

#Unit 7. System Physiology – Animal

Large quantities of positive potassium ions diffuse out of the SA node.

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#Id: 8225

#Unit 2. Cellular Organization

Hurler’s disease- mutation in a structural gene that codes for an individual lysosomal hydrolase.

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#Id: 8769

#Unit 1. Molecules and their Interaction Relevant to Biology

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#Id: 4911

#Unit 13. Methods in Biology

Variance always has squared units. For example, the variance of a set of weights estimated in kilograms will be given in kg squared.

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#Id: 7096

#Unit 3. Fundamental Processes

Formylation is not strictly necessary because nonformylated Met-tRNAf can function as an initiator.