The DNA and Histone Proteins Relationship
To begin with, a nucleic acid is a macromolecule that is made of nucleotides units, in which each nucleotide is composed of a nitrogenous base, 5-carbon sugar, and a phosphate group. The nucleic acid can be in a DNA or RNA form and both contain all the genetic information an organism needs to function. On the other hand, a protein is a macromolecule composed of many amino acids joined together by peptide bonds. Even though both nucleic acids and protein are mostly composed of Carbon, Oxygen, Hydrogen and Nitrogen, they greatly differ in their functions. Nucleic acids basically give cells the instructions to make a protein, however; the opposite is impossible. This process is called the central dogma.
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Histones are proteins found in the nucleus of eukaryotic cell, and are positively charged. The positive charge is what allows them to bind tightly to DNA (that are negatively charged because of the phosphate group). DNA needs histones, during the initiation of DNA replication, to allow the DNA polymerase move along the DNA and replicate the right amount of genetic material required for a daughter cell. However, as all proteins, histones need DNA and has to go through the process of transcription and translation to be formed. Histones are responsible for the packaging of DNA and play an important role in the regulation of gene expression. As mentioned earlier, the opposite charges allow histones and DNA to bind tightly, therefore; reducing the positive charge makes DNA more open to the gene expression. Histones induce gene expression by altering chromatin structure. Each histone type has an N-terminal tail that emerges from the histone core and plays a significant role in determining the gene influence [2]. The tail allows different modifications that alter gene expression, such as methylation and acetylation. The methylation process, for example, regulates gene expression by reducing the chemical interaction between the tail and DNA, which increases the transcription of genes
The first major effects of epigenetics on genes can be seen in the role of DNA methylation in mammalian epigenetics. DNA methylation provides a method of gene control in an organism, where it assures proper gene expression, as well as silencing of genes within cells, it does this through the manipulation of chromosome architecture, where it affects the packaging of the DNA by the binding of a methyl group to cytosine (Kullis & Esteller, 2010). The effects of this can
histone – these are a type of protein that help to organize the DNA. There are 8 histones that make up one group. Each have tails that are covered with chemical tags and stick out of the protein grouping. The chemical tags on the tails affect how they interact with DNA.
Structure and function in Biology is a broad concept that can be explored within a diverse range of topics across the subject matter. The following essay will be focussed mainly on the subject of Deoxyribonucleic Acid, or more commonly DNA. DNA is a highly complex, intricate and extraordinary macromolecule found within all living cells. DNA is a "biochemical noun" and can be defined as "...a self-replicating material which is present in nearly all living organisms as the main constituent of chromosomes. It is the carrier of genetic information." [Oxford Dictionary, c2016] DNA is found in the nucleus of eukaryotic cells, enclosed within a double membrane. Eukaryotic cells are multifaceted and require a high level of regulation to ensure smooth functioning. The double membrane of the nucleus allows gene expression, a key function of DNA, to be efficiently regulated.
The EZH2 (enhance of zeste homolog2) is an enzyme that in humans is fixed by EZH2 and its supply the information’s about making of enzyme called a histone me-thyltransferase. The ploycomb group (PcG) is a protein with the catalytic subunit of the PRC2 (polycomb repressive complex) which the transcriptional involved in maintaining the repressive of genes cells and also the EZH2 mainly performs as a silence gene. The EZH2 performs the role by addition of methyl groups on the ly-sine 27 of histone H3, a modification leading chromatin
Epigenetics refers to external modifications to DNA that turn genes on or off. These alterations do not change the DNA sequence, but instead, they affect how cells read genes. One common example of an epigenetic change is DNA methylation. DNA methylation is the addition of a methyl group to part of the DNA molecule which prevents certain genes from being expressed. It should be noted that epigenetics is a fairly new subdivision in genetics and its importance in evolution and heritability is currently being developed and debated (Furrow 2011).
Epigenetics, essentially, affects how genes are read by cells, and subsequently how they produce proteins.
It can turn certain genes on or off by tightly wrapping the structure of the gene making it unreadable and inactive. If it is making a gene active, it simply relaxes the genes structure making them available to read. In further detail, the epigenome alters genetic coding by using the epigenetic tags, or chemical tags, which respond to signals transferred by proteins, ultimately taken to a gene regulatory protein which attaches itself to a certain gene. There are many types of epigenetic tags that make genes effective or not. An example of a tag that turns off genes are Methyl tags. They are attached to a CG base pair, cytosine and guanine, where they block transcription machinery, such as RNA Polymerase, from binding to the DNA. Another way of silencing a gene is by gathering proteins that can bind to DNA with the methyl tags, to then block the transcription machinery. Acetyl tags are an example of tag that turns a gene on. They loosen the Dna from the histone to allow easy access. The acetyl tags are added to lysine, an amino acid, on the tails of histones. Acetyl tgs are just one of the tags that form a histone code, others include methyl, phosphoryl, ubiquitin, SUMO, and
Ok let's break DNA down first. DNA stands for Deoxyribonucleic acid. Deoxyribose is referred to the absence of an O in the Carbon 2 of the ribose pentose. DNA is made up of six smaller molecules a five-carbon sugar called deoxyribose, a phosphate molecule and four different nitrogenous bases adenine, thymine, cytosine and guanine. The basic building block of DNA is called a NUCLEOTIDE. A nucleotide is made up of one sugar molecule, one phosphate molecule and one of the four bases. In other words, the sugar that makes DNA is ribose a pentose sugar in the case of this molecule DNA its lacking an Oxygen in its carbon 2. Nucleic is referred to its position, our DNA most anyways is located on the nucleus of our cells, the presence of this nucleus is what differs us from Prokaryotes us being Eukaryotes.
Epigenetics is a field where advances are being made daily. Epigenetics is defined as “heritable changes in gene expression that occur without a change in DNA sequence,” as stated by Dr. Alan Wolffe. A way in which we can understand this definition is by taking the analogy of a card game. The cards, the DNA sequence, have been dealt and will not change, however we need to understand how to play the cards, the rules, which is epigenetics. The guidelines can vary and completely change the way the card game is played and who comes out on top. The rules that are studied and understood through this research paper are those of DNA methylation and chromatin. These changes can produce
DNA is made up of genes, which are small portions of the DNA strand. Genes create cellular protein needed for the body to function. DNA not only creates cellular proteins, but also has the instructions for when and where they will be made. (Racenis 2)
Epigenetic factors are compounds that attach to, or "mark" DNA. These factors interact with genetic material, but do not change the underlying DNA sequence. Instead, they act as chemical tags, indicating what, where, and when genes should be "turned on" or expressed. Some epigenetic factors come from natural sources or are even encoded in the DNA, and are a normal part of gene regulation. That is, the epigenome helps control which genes are active in a particular cell, and therefore, which proteins are transcribed locally. For example, epigenetic factors tell brain cells to act like brain cells, and skin cells to behave like skin cells. In the absence of a normal epigenome, disease can occur. These factors are also increasingly implicated in social and behavioral traits.
Epigenetics is the study of heritable modifications of your genes being expressed that are not manipulated by mutations in the DNA but by environmental factors. The increasing of inhibiting of transcribing genes is caused by epigenetic changes. The cells in the DNA are packaged together by proteins which are known as histones. DNA is wrapped around the protein (histones). Histone proteins and DNA are tagged chemically which alter gene expression. To impede DNA, DNA methylation is when a methyl group is added consisting of hydrogen and carbon molecules, which are used to limit gene expression. DNA methylation and Histone modification is most commonly known as an epigenetic modification. Epigenetic modifications are a long-term change in, which
When chemical tags are labeled the modifications are called epigenetic modification. These can be classified as modifications that take place on or above the genes. Epigenetic modification permits lasting changes in gene expression. Epigenetics studies the changes in gene expression or development caused by mechanisms other than changes in the primary DNA sequence. Epigenetics demonstrates how DNA interacts with the multitude of smaller molecules found within cells which can activate and deactivate cells. Epigenetics can be highly based off of nature versus nurture. Epigenetic changes are a part of normal development. As genes are activated some are
ONE of biology’s hottest topics is epigenetics. The term itself covers a multitude of sins. Strictly speaking, it refers to the regulation of gene expression by the chemical modification of DNA, or of the histone proteins in which DNA is usually wrapped. This modification is either the addition of methyl groups (a carbon atom and three hydrogens) to the DNA or of acetyl groups (two carbons, three hydrogens and an oxygen) to the histones. Methylation switches genes off. Acetylation switches them on. Since, in a multicellular organism, different cells need different genes to be active, such regulation is vital.
Chromosome- Chromosomes are the microscopic structure within cells that carries the molecule deoxyribonucleic acid. DNA is the hereditary material that influences the development and characteristics of each organism. In bacteria and bacteria-like organisms called archaebacteria, chromosomes are simple circles of DNA that float around in the cell. In more complex cells, or Eukaryotes, chromosomes are stored within a well developed and defined nucleus. In eukaryotic cells, chromosomes are highly complex structures in which the shape of the DNA molecules is linear, rather than circular. Chromosomes consist chiefly of proteins and DNA. Tiny chemical subunits called nucleotide bases form the structure of DNA. A sequence of these bases that are along a DNA strand will create a code for the production of a special protein also known as a gene. Genes occupy precise locations on the chromosome. Each cell contains enough DNA to form a thread extending about 2 m (about 7 ft). Proteins called histones play a key role in packaging DNA within chromosomes. Sections of