(Solved): Exercise15: DNA, Genes, Chromosomes and Cancer Skill Check Worksheet NAME: Section: Activity 1: ...

Expert Answer

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1) The extraction of DNA from cells requires the breakdown of the cell membrane and the nuclear membrane to release the genetic material. The steps involved in the extraction process are designed to facilitate this breakdown and separate the DNA from other cellular components.

a) Blending the mixture of peas, salt, and water in the blender breaks down the cell walls, which are composed of cellulose. Cellulose is a complex carbohydrate that provides structural support to the plant cell. By blending the mixture, the cell walls are disrupted, and the cellular contents, including the DNA, are released into the solution. This makes it easier to extract DNA as it reduces the physical barriers that protect the genetic material.

b) Adding detergent to the mixture helps dissolve the lipids in the cell membrane, which is composed of a phospholipid bilayer. The phospholipid bilayer is a semi-permeable membrane that regulates the flow of molecules in and out of the cell. Detergents, which have both hydrophilic and hydrophobic regions, are amphipathic molecules. When added to the mixture, the detergent molecules insert themselves into the cell membrane, disrupting the lipid bilayer and releasing the cellular contents, including the DNA.

c) Adding meat tenderizer contains enzymes that break down the proteins, which helps release the DNA from the histones. The meat tenderizer helps to uncoil the DNA, which makes it easier to extract. The enzymes in meat tenderizers, such as papain and bromelain, break down the peptide bonds in the histone proteins, disrupting their ability to bind to the DNA. This allows the DNA to unwind and separate from the histones.

Histones are a group of proteins that are involved in the packaging of DNA in eukaryotic cells. The DNA molecule is incredibly long and must be packaged into a compact structure in order to fit inside the nucleus of the cell. Histones help accomplish this by forming complexes with the DNA to form a structure called chromatin. The histone proteins are positively charged and can bind to the negatively charged DNA molecule through ionic bonds. The histones form an octamer structure around which the DNA is wrapped, forming a nucleosome. Histones can also play a role in gene expression regulation. The packaging of DNA into chromatin can make certain regions of the DNA more or less accessible to transcription factors and other regulatory proteins.