Where Is Most of the Dna Found in the Eukaryotic Cell? Coursehero

Organelles found in eukaryotes and prokaryotes have specific cell tasks. For example, the nucleus in eukaryotes contains information in the form of DNA.

Eukaryotic cells are characterized by the presence of membrane-bound organelles. Eukaryotic cells contain organelles with either a single membrane or two membranes, as well as organelles not bound by a membrane, which are known as non-membrane bound. Every eukaryotic cell contains a nucleus that is a membrane-bound organelle that contains most of the genetic material (DNA). This structure directs a cell's growth, division, and death. This genetic material is classified as deoxyribonucleic acid (DNA), which is an organic molecule containing coded instructions for the life processes of an organism. DNA consists of nucleotides bonded together in the form of a double helix. The nuclear envelope, a double membrane that is semipermeable and surrounds a nucleus. The DNA inside the nucleus contains genetic information of the organism, except in the case of a gamete. A gamete is the sex cell of a sexually reproducing organism, with a haploid set of chromosomes. This means they contain half the genetic information of the organism. The role of the nucleus is to maintain and preserve the cell's DNA as well as provide a site for genetic transcription. This process of transcription involves transferring the genetic information in DNA to ribonucleic acid (RNA). Ribonucleic acid (RNA) is a organic molecule that carries genetic messages out of the nucleus; consists of a single strand of nucleic acids. In most organisms, RNA is involved in protein synthesis, gene regulation, and post-transcriptional modification.There are many classes of RNA. The most common are mRNA, tRNA, and rRNA. Messenger RNA (mRNA) is a molecule made from a DNA template from which a protein is translated; mRNA determines the amino acid sequence in proteins. Transfer RNA (tRNA) is the molecule that carries each amino acid to the strand of mRNA during translation of protein synthesis. Ribosomal RNA (rRNA) is a component of ribosomes that catalyzes peptide bond formation. Once the genetic message in mRNA is created, it can leave the nucleus and be sent to the cytoplasm, composed of cytosol, an aqueous fluid that fills the fluid part of the cytoplasm in the cell, and organelles that fills the spaces around the internal cell structures and organelles.

The nucleus, an organelle enclosed by a double-layer membrane called the nuclear envelope, is found in all eukaryotic cells.

Another type of organelle enclosed in a membrane is the mitochondrion (plural, mitochondria), the organelle responsible for generating energy for the cell. The outer membrane of the mitochondrion gives the organelle its shape and structure, while the inner membrane folds back and forth within the organelle, forming an intermembrane space where the respiratory reactions of the citric acid cycle and oxidative phosphorylation take place. These reactions harness the energy from the oxidation (loss of electrons) of food molecules, usually sugars, to produce adenosine triphosphate (ATP), the chemical unit of energy for the cell. This ATP is then released for use by other cellular structures.

Remarkably, mitochondria have unique DNA and enzymes when compared to the nucleus. They reproduce by dividing, just as cells do. For this reason, they are suspected to have derived from symbiotic organisms in the early evolution of eukaryotes. It is likely that an organism similar to the modern mitochondrion was engulfed by an early eukaryote. The mitochondrion provided energy for the eukaryote, which in turn provided most of the materials necessary for the mitochondrion to survive. Over time, the mitochondrion lost all functions other than providing energy but retained its own DNA. Mitochondrial DNA remains unique, separate from nuclear DNA.

The mitochondrion is the energy center of the cell, where sugars and other nutrients are oxidized, producing adenosine triphosphate (ATP), the chemical unit of energy.

Some eukaryotic cells, such as those in plants, also contain chloroplasts. The chloroplast is a membrane-bound organelle found in plants and some other organisms that captures energy from light and converts it into chemical energy. Chloroplasts contain stacks of disklike structures called thylakoids, which are home to light-harvesting complexes. Both chloroplasts and mitochondria are found in photosynthetic eukaryotic cells. Thus, scientists concluded both organelles to be separate structures with similar origins. Chloroplasts are thought to have been bacteria engulfed by eukaryotic cells early in evolution through a process known as endosymbiosis. During this process, bacteria and early eukaryotic cells lived in a mutually beneficial relationship. Similar to the way mitochondria were incorporated into the cell, chloroplasts lost all functions other than converting light energy into chemical energy, relying on the cell for other needs.

Chloroplasts are membrane-bound organelles found in photosynthetic eukaryotic cells. They are responsible for capturing light energy and converting it to chemical energy.

Where Is Most of the Dna Found in the Eukaryotic Cell? Coursehero

Source: https://www.coursehero.com/sg/cell-biology/eukaryotic-structures/

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