Membrane-bound nucleus

Eukaryotic ceils possess a discrete, membrane-bounded nucleus, the repository of the cell s genetic material, which is distributed among a few or many chromosomes. During ceil division, equivalent copies of this genetic material must be passed to both daughter ceils through duplication and orderly partitioning of the chromosomes by the process known as mitosis. Like prokaryotic... 

There are two general kinds of cells those having a membrane-bounded nucleus called eukaryotic cells, and those without a nuclear envelope called prokaryotic cells. Humans have eukaryotic cells. All eukaryotic cells contain a nucleus that contains the genome, the complete set of genes. Unless noted otherwise, our discussion will be restricted to eukaryotic cells. 

As we will see, the evolutionary tree is bisected into a lower prokaryotic domain and an upper eukaryotic domain. The terms prokaryote and eukaryote refer to the most basic division between cell types. The fundamental difference is that eukaryotic cells contain a membrane-bounded nucleus, whereas prokaryotes do not. The cells of prokaryotes usually lack most of the other membrane-bounded organelles as well. Plants, fungi, and animals are eukaryotes, and bacteria are prokaryotes. The biochemical functions associated with organelles are frequently present in bacteria, but they are usually located on the inner plasma membrane. 

Eukaryote. A cell or organism that has a membrane-bound nucleus. 

Prokaryotes (bacteria and blue-green algae) are the most abundant organisms on earth. A prokaryotic cell does not contain a membrane-bound nucleus. Bacteria are either cocci, bacilli or spirilla in shape, and fall into two groups, the eubacteria and the archaebacteria. 

Eukaryotic cells have a membrane-bound nucleus and a number of other membrane-bound subcellular (internal) organelles, each of which has a specific function. 

A eukaryotic cell is surrounded by a plasma membrane, has a membrane-bound nucleus and contains a number of other distinct subcellular organelles (Fig. 1). These organelles are membrane-bounded structures, each having a unique role and each containing a specific complement of proteins and other molecules. Animal and plant cells have the same basic structure, although some organelles and structures are found in one and not the other (e.g. chloroplasts, vacuoles and cell wall in plant cells, lysosomes in animal cells). 

Eukaryote An organism having a membrane-bound nucleus and usually other organelles... 

DNA Single, circular, double-helical molecule densely coiled, not bound to histones not membrane bound Very long linear molecules with extensive noncoding regions complexed histones and other proteins organized into chromosomes in membrane-bounded nucleus... 

Membrane-bound nucleus absent absent present... 

We turn now to transcription in eukaryotes, a much more complex process than in prokaryotes. In eukaryotes, transcription and translation take place in different cellular compartments transcription takes place in the membrane-bounded nucleus, whereas translation takes place outside the nucleus in the cytoplasm. In prokaryotes, the two processes are closely coupled (Figure 28.15). Indeed, the translation of bacterial mRNA begins while the transcript is still being... 

Nucleoid - The nucleoid is a region of cytoplasm where the chromosomal DNA is located. It is not a membrane bound nucleus, but simply an area of the cytoplasm where the strands of DNA are found. Most bacteria have a single, circular chromosome that is responsible for replication, although a few species do have two or more. Smaller circular auxiliary DNA strands, called plasmids, are also found in the cytoplasm. 

Double-membrane bound nucleus containing linear chromosomes. 

Eukaryotic cells, unlike prokaryotic cells, contain a defined membrane-bound nucleus and extensive Internal mem-... 

Eukarya is a group of organisms with a membrane-bound nucleus. They are multicellular and diverse in species machinery. Some eukaryotes have sexual reproduction, and gene exchange can occur also by transduction and transformation. Genetic information is based on several complex RNA polymerases, and translation starts with methionine. Eukarya was long considered as the third major domain of the life tree. Current molecular results... 

Amoeba species), and archamoebas, such as the pelobionts (which lack mitochondria and many other features of eukaryotic cells apart from a membrane-bounded nucleus). 

Most smaU-molecule drugs are produced by direct cheanical synthesis. Multiple steps can be involved as various intermediate molecules are created on the pathway to eventually synthesizing the desired molecnle. In contrast, larger-scale manufacture of biopharmaceuticals involves the employment of host cells to produce proteins that are safe and effective (Ho and Gibaldi 2003). The choice to use prokaryote host cells (prokaryotes are microorganisms with no distinct membrane-bound nucleus), lower eukaryote cells, or higher eukaryote (mammalian) cells, which becomes progressively more expensive in the order just listed, is predicated on what kind of host cell is needed to carry out necessary posttranslational modifications. 

Eukaryote—a single-celled or multicellular organism whose cells contain a distinct membrane-bound nucleus. 

Prokaryote—an organism of the kingdom Monera (or Prokaryotae), comprising the bacteria and cyanobacteria, characterized by the absence of a distinct, membrane-bound nucleus or membrane-bound... 

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