Ans.
Chromatin molecules are made up of DNA and histone proteins. Modification of chromatin structure include covalent, post-translational changes in histone proteins, present in chromation. Acetylation and methylation are two important histone modifications that affect structure of chromatin molecules.
Acetylation involves addition of an acetyl group to histones that increases transcription of DNA by loosen the association between DNA and nucleosome.
Methylation involves addition of a methyl group to histones that results in condensation of chromatin molecule and thus, decreases transcription of DNA.
Both acetylation and methylation are reversible processes.
Many chromatin modifications are genetic, means they can pass from one generation to another generation, called epigenetic modifications.
Thus, options B), C), D), E), and F).
A. similar animals fossils found in South America and Africa
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Answer:
The correct answer is option A.
Explanation:
White matter is the component of CNS which consist neuron cell bodies or myelinated cell axons or nerve fiber collectively known as fiber tracts mainly. Glial cells also one of the component of white matter, made up of few sulci and gyri. White matter makes superficial regions of the spinal cord and deep parts of the cerebrum.
The neuron cell bodies of white matter sends signals to neurons and each other. White matter regulates the action potentials function as coordinators in between brain parts.
Thus, the correct answer is option A.
Receptors which provide animals with information from the external environment are located in ears, tongue, eyes, and the nose. These are all receptors that can be found in our sensory organs and provide us with feedback from our nearby environment and the stimuli on which we should be alerted towards.
