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PDNA
A plasmid is a small, extrachromosomal DNA molecule within a cell that is physically separated from chromosomal DNA and can replicate independently. They are most commonly found as small circular, double-stranded DNA molecules in bacteria; however, plasmids are sometimes present in archaea and eukaryotic organisms. In nature, plasmids often carry genes that benefit the survival of the organism and confer selective advantage such as antibiotic resistance. While chromosomes are large and contain all the essential genetic information for living under normal conditions, plasmids are usually very small and contain only additional genes that may be useful in certain situations or conditions. Artificial plasmids are widely used as vectors in molecular cloning, serving to drive the replication of recombinant DNA sequences within host organisms. In the laboratory, plasmids may be introduced into a cell via transformation. Synthetic plasmids are available for procurement over the int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extrachromosomal DNA
Extrachromosomal DNA (abbreviated ecDNA) is any DNA that is found off the chromosomes, either inside or outside the nucleus of a cell. Most DNA in an individual genome is found in chromosomes contained in the nucleus. Multiple forms of extrachromosomal DNA exist, and, while some of these serve important biological functions, they can also play a role in diseases, such as ecDNA in cancer. In prokaryotes, nonviral extrachromosomal DNA is primarily found in plasmids, whereas, in eukaryotes extrachromosomal DNA is primarily found in organelles. Mitochondrial DNA is a main source of this extrachromosomal DNA in eukaryotes. The fact that this organelle contains its own DNA supports the hypothesis that mitochondria originated as bacterial cells engulfed by ancestral eukaryotic cells. Extrachromosomal DNA are often used in research of replication because they are easy to identify and isolate. Although extrachromosomal circular DNA (eccDNA) is found in normal eukaryotic cells, extrachrom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plasmid (english)
A plasmid is a small, extrachromosomal DNA molecule within a cell that is physically separated from chromosomal DNA and can replicate independently. They are most commonly found as small circular, double-stranded DNA molecules in bacteria; however, plasmids are sometimes present in archaea and eukaryotic organisms. In nature, plasmids often carry genes that benefit the survival of the organism and confer selective advantage such as antibiotic resistance. While chromosomes are large and contain all the essential genetic information for living under normal conditions, plasmids are usually very small and contain only additional genes that may be useful in certain situations or conditions. Artificial plasmids are widely used as vectors in molecular cloning, serving to drive the replication of recombinant DNA sequences within host organisms. In the laboratory, plasmids may be introduced into a cell via transformation. Synthetic plasmids are available for procurement over the intern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prokaryote
A prokaryote () is a single-celled organism that lacks a nucleus and other membrane-bound organelles. The word ''prokaryote'' comes from the Greek πρό (, 'before') and κάρυον (, 'nut' or 'kernel').Campbell, N. "Biology:Concepts & Connections". Pearson Education. San Francisco: 2003. In the two-empire system arising from the work of Édouard Chatton, prokaryotes were classified within the empire Prokaryota. But in the three-domain system, based upon molecular analysis, prokaryotes are divided into two domains: ''Bacteria'' (formerly Eubacteria) and ''Archaea'' (formerly Archaebacteria). Organisms with nuclei are placed in a third domain, Eukaryota. In the study of the origins of life, prokaryotes are thought to have arisen before eukaryotes. Besides the absence of a nucleus, prokaryotes also lack mitochondria, or most of the other membrane-bound organelles that characterize the eukaryotic cell. It was once thought that prokaryotic cellular components within the cytop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Episome
An episome is a special type of plasmid, which remains as a part of the eukaryotic genome without integration. Episomes manage this by replicating together with the rest of the genome and subsequently associating with metaphase chromosomes during mitosis. Episomes do not degrade, unlike standard plasmids, and can be designed so that they are not epigenetically silenced inside the eukaryotic cell nucleus. Episomes can be observed in nature in certain types of long-term infection by adeno-associated virus or Epstein-Barr virus. In 2004, it was proposed that non-viral episomes might be used in genetic therapy for long-term change in gene expression. As of 1999, there were many known sequences of DNA (deoxyribonucleic acid) that allow a standard plasmid to become episomally retained. One example is the S/MAR sequence. The length of episomal retention is fairly variable between different genetic constructs and there are many known features in the sequence of an episome which will aff ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DnaA
Introduction Based on the Replicon Model, a positively active initiator molecule contacts with a particular spot on a circular chromosome called the replicator to start DNA replication. DnaA is a protein that activates initiation of DNA replication in bacteria. It is a replication initiation factor which promotes the unwinding of DNA at oriC. The DnaA proteins found in all bacteria engage with the DnaA boxes to start chromosomal replication. In addition to the DnaA protein, its concentration, binding to DnaA-boxes, and binding of ATP or ADP, we will cover the regulation of the DnaA gene, the unique characteristics of the DnaA gene expression, promoter strength, and translation efficiency. The onset of the initiation phase of DNA replication is determined by the concentration of DnaA. DnaA accumulates during growth and then triggers the initiation of replication. Replication begins with active DnaA binding to 9-mer (9-bp) repeats upstream of oriC. Binding of DnaA leads to strand s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iteron
Iterons are directly repeated DNA sequences which play an important role in regulation of plasmid copy number in bacterial cells. It is one among the three negative regulatory elements found in plasmids which control its copy number. The others include antisense RNAs and ctRNAs. Iterons complex with cognate replication (Rep) initiator proteins to achieve the required regulatory effect. Regulation of Replication Iterons have an important role in plasmid replication. An iteron-containing plasmid origin of replication can be found containing about five iterons about 20 base pairs in length total. These iterons provide a saturation site for initiator receptor proteins and promote replication thus increasing plasmid copy number in a given cell. Limiting Factors of Initiation There are 4 main limiting factors leading to no initiation of replication in iterons: *Transcriptional autorepression *Initiator dimerization *Initiator titration *Handcuffing Transcriptional auto-repress ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Replicon (genetics)
A replicon is the entire region of DNA that is independently replicated from a single origin of replication. A bacterial chromosome contains a single origin, and therefore the whole bacterial chromosome is a replicon. The chromosomes of archaea and eukaryotes can have multiple origins of replication, and so their chromosomes may consist of several replicons. The concept of the replicon was formulated in 1963 by François Jacob, Sydney Brenner, and Jacques Cuzin as a part of their replicon model for replication initiation. According to the replicon model, two components control replication initiation: the replicator and the initiator. The replicator is the entire DNA sequence (including, but not limited to the origin of replication) required to direct the initiation of DNA replication. The initiator is the protein that recognizes the replicator and activates replication initiation. Sometimes in bacteriology, the term "replicon" is only used to refer to chromosomes containing a single ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Origin Of Replication
The origin of replication (also called the replication origin) is a particular sequence in a genome at which replication is initiated. Propagation of the genetic material between generations requires timely and accurate duplication of DNA by semiconservative replication prior to cell division to ensure each daughter cell receives the full complement of chromosomes. Material was copied from this source, which is available under Creative Commons Attribution 4.0 International License This can either involve the replication of DNA in living organisms such as prokaryotes and eukaryotes, or that of DNA or RNA in viruses, such as double-stranded RNA viruses. Synthesis of daughter strands starts at discrete sites, termed replication origins, and proceeds in a bidirectional manner until all genomic DNA is replicated. Despite the fundamental nature of these events, organisms have evolved surprisingly divergent strategies that control replication onset. Although the specific replication o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plasmid Replication (english)
A plasmid is a small, extrachromosomal DNA molecule within a cell that is physically separated from chromosomal DNA and can replicate independently. They are most commonly found as small circular, double-stranded DNA molecules in bacteria; however, plasmids are sometimes present in archaea and eukaryotic organisms. In nature, plasmids often carry genes that benefit the survival of the organism and confer selective advantage such as antibiotic resistance. While chromosomes are large and contain all the essential genetic information for living under normal conditions, plasmids are usually very small and contain only additional genes that may be useful in certain situations or conditions. Artificial plasmids are widely used as vectors in molecular cloning, serving to drive the replication of recombinant DNA sequences within host organisms. In the laboratory, plasmids may be introduced into a cell via transformation. Synthetic plasmids are available for procurement over the intern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Joshua Lederberg
Joshua () or Yehoshua ( ''Yəhōšuaʿ'', Tiberian: ''Yŏhōšuaʿ,'' lit. 'Yahweh is salvation') ''Yēšūaʿ''; syr, ܝܫܘܥ ܒܪ ܢܘܢ ''Yəšūʿ bar Nōn''; el, Ἰησοῦς, ar , يُوشَعُ ٱبْنُ نُونٍ '' Yūšaʿ ibn Nūn''; la, Iosue functioned as Moses' assistant in the books of Exodus and Numbers, and later succeeded Moses as leader of the Israelite tribes in the Hebrew Bible's Book of Joshua. His name was Hoshea ( ''Hōšēaʿ'', lit. 'Save') the son of Nun, of the tribe of Ephraim, but Moses called him "Yehoshua" (translated as "Joshua" in English),''Bible'' the name by which he is commonly known in English. According to the Bible, he was born in Egypt prior to the Exodus. The Hebrew Bible identifies Joshua as one of the twelve spies of Israel sent by Moses to explore the land of Canaan. In Numbers 13:1, and after the death of Moses, he led the Israelite tribes in the conquest of Canaan, and allocated lands to the tribes. According to bibl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecular Biology
Molecular biology is the branch of biology that seeks to understand the molecular basis of biological activity in and between cells, including biomolecular synthesis, modification, mechanisms, and interactions. The study of chemical and physical structure of biological macromolecules is known as molecular biology. Molecular biology was first described as an approach focused on the underpinnings of biological phenomena - uncovering the structures of biological molecules as well as their interactions, and how these interactions explain observations of classical biology. In 1945 the term molecular biology was used by physicist William Astbury. In 1953 Francis Crick, James Watson, Rosalind Franklin, and colleagues, working at Medical Research Council unit, Cavendish laboratory, Cambridge (now the MRC Laboratory of Molecular Biology), made a double helix model of DNA which changed the entire research scenario. They proposed the DNA structure based on previous research done by Ro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell (biology)
The cell is the basic structural and functional unit of life forms. Every cell consists of a cytoplasm enclosed within a membrane, and contains many biomolecules such as proteins, DNA and RNA, as well as many small molecules of nutrients and metabolites.Cell Movements and the Shaping of the Vertebrate Body in Chapter 21 of Molecular Biology of the Cell '' fourth edition, edited by Bruce Alberts (2002) published by Garland Science. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos. It is also common to describe small molecules such as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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