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).
<h2>Answer:</h2>
Following are the four combinations of active or inactive regulatory proteins that could be present anytime in the cell:
- Active repressor , Active activator
- Active repressor, Inactive activator
- Inactive repressor, Active activator
- Inactive repressor, Inactive activator
The answer is B mesoderm because the embrionery orgin of the kidney is in the mesoderm
Answer;
B) all levels of organization within an organism are interdependent.
Explanation;
-The biological levels of organization of living things arranged from the simplest to most complex are: organelle, cells, tissues, organs, organ systems, organisms, populations, communities, ecosystem, and biosphere.
The levels of organization are dependent on each other, for example, the organ systems rely on each other for many different things and cannot function without the other. e.g. The nervous and endocrine systems control the activities of the digestive, excretory, circulatory and respiratory systems. Organ systems need to work together to maintain homeostasis in the body.
