The correct answer is: 2.5%
The vast majority of the human genome (97.5%) is comprised of non-coding DNA with different functions. Non-coding DNA includes telomeres, introns, non-coding RNA genes and gene regulatory sequences.
• Telomeres-ends of DNA with protective role (prevents shortening of DNA),
• Non-coding RNA genes-e.g. genes for tRNA,
• Gene regulatory sequences such as promoter, enhancers and silencers.
The structure of a typical antibody molecule
Antibodies are the secreted form of the B-cell receptor. An antibody is identical to the B-cell receptor of the cell that secretes it except for a small portion of the C-terminus of the heavy-chain constant region. In the case of the B-cell receptor the C-terminus is a hydrophobic membrane-anchoring sequence, and in the case of antibody it is a hydrophilic sequence that allows secretion. Since they are soluble, and secreted in large quantities, antibodies are easily obtainable and easily studied. For this reason, most of what we know about the B-cell receptor comes from the study of antibodies.
Antibody molecules are roughly Y-shaped molecules consisting of three equal-sized portions, loosely connected by a flexible tether. Three schematic representations of antibody structure, which has been determined by X-ray crystallography, are shown in Fig. 3.1. The aim of this part of the chapter is to explain how this structure is formed and how it allows antibody molecules to carry out their dual tasks—binding on the one hand to a wide variety of antigens, and on the other hand to a limited number of effector molecules and cells. As we will see, each of these tasks is carried out by separable parts of the molecule. The two arms of the Y end in regions that vary between different antibody molecules, the V regions. These are involved in antigen binding, whereas the stem of the Y, or the C region, is far less variable and is the part that interacts with effector cells and molecules.
Blood flows to the brain through the internal carotid and vertebral arteries and away from the brain through the internal jugular vein. The internal carotid artery supplies the brain, while the external carotid nourishes other portions of the head, such as the face, skull, scalp and the meninges. The vertebral arteries provide supply to the upper spinal cord, brainstem, cerebellum, and the posterior part of the brain.
It seems that you have missed the given options for this question, but anyway, here is the answer. We are constantly bombarded by a variety of stimuli inside and outside of our bodies but we are not overwhelmed by sensory information because a<span> very tiny percentage of incoming sensory information is received by the cerebral cortex. Hope this helps.</span>
1.) The cell wall protects the cell by providing support and maintaining the cells shape.
