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Homogeneously Staining Region
Homogeneously staining regions (HSRs) are chromosomal segments with various lengths and uniform staining intensity after G banding. This type of aberration is also known as Copy Number Gains or Amplification. An HSR is one type of change in a chromosome's structure which is frequently observed in the nucleus of human cancer cells. In the region of a chromosome where an HSR occurs, a segment of the chromosome, which presumably contains a gene In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ... or genes that give selective advantage to the progression of the cancer, is amplified or duplicated many times. As a result of the duplication this chromosomal segment is greatly lengthened and expanded such that when it is stained with a fluorescent probe specific to the region ( Fluorescent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
G Banding
G-banding, G banding or Giemsa banding is a technique used in cytogenetics to produce a visible karyotype by staining condensed chromosomes. It is the most common chromosome banding method. It is useful for identifying genetic diseases through the photographic representation of the entire chromosome complement.Speicher, Michael R. and Nigel P. Carter. "The New Cytogenetics: Blurring the Boundaries with Molecular Biology." ''Nature'' Reviews Genetics, Vol 6. Oct 2005. The metaphase chromosomes are treated with trypsin (to partially digest the chromosome) and stained with Giemsa stain. Heterochromatic regions, which tend to be rich with adenine and thymine (AT-rich) DNA and relatively gene-poor, stain more darkly in G-banding. In contrast, less condensed chromatin (Euchromatin)—which tends to be rich with guanine and cytosine ( GC-rich) and more transcriptionally active—incorporates less Giemsa stain, and these regions appear as light bands in G-banding. The pattern of bands are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosome Abnormality
A chromosomal abnormality, chromosomal anomaly, chromosomal aberration, chromosomal mutation, or chromosomal disorder, is a missing, extra, or irregular portion of chromosomal DNA. These can occur in the form of numerical abnormalities, where there is an atypical number of chromosomes, or as structural abnormalities, where one or more individual chromosomes are altered. Chromosome mutation was formerly used in a strict sense to mean a change in a chromosomal segment, involving more than one gene. Chromosome anomalies usually occur when there is an error in cell division following meiosis or mitosis. Chromosome abnormalities may be detected or confirmed by comparing an individual's karyotype, or full set of chromosomes, to a typical karyotype for the species via genetic testing. Numerical abnormality An abnormal number of chromosomes is called aneuploidy, and occurs when an individual is either missing a chromosome from a pair (resulting in monosomy) or has more than two chromosome ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosome
A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are the histones. These proteins, aided by chaperone proteins, bind to and condense the DNA molecule to maintain its integrity. These chromosomes display a complex three-dimensional structure, which plays a significant role in transcriptional regulation. Chromosomes are normally visible under a light microscope only during the metaphase of cell division (where all chromosomes are aligned in the center of the cell in their condensed form). Before this happens, each chromosome is duplicated ( S phase), and both copies are joined by a centromere, resulting either in an X-shaped structure (pictured above), if the centromere is located equatorially, or a two-arm structure, if the centromere is located distally. The joined copies are now called si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Nucleus
The cell nucleus (pl. nuclei; from Latin or , meaning ''kernel'' or ''seed'') is a membrane-bound organelle found in eukaryotic cells. Eukaryotic cells usually have a single nucleus, but a few cell types, such as mammalian red blood cells, have no nuclei, and a few others including osteoclasts have many. The main structures making up the nucleus are the nuclear envelope, a double membrane that encloses the entire organelle and isolates its contents from the cellular cytoplasm; and the nuclear matrix, a network within the nucleus that adds mechanical support. The cell nucleus contains nearly all of the cell's genome. Nuclear DNA is often organized into multiple chromosomes – long stands of DNA dotted with various proteins, such as histones, that protect and organize the DNA. The genes within these chromosomes are structured in such a way to promote cell function. The nucleus maintains the integrity of genes and controls the activities of the cell by regulating gene expres ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cancer
Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal bleeding, prolonged cough, unexplained weight loss, and a change in bowel movements. While these symptoms may indicate cancer, they can also have other causes. Over 100 types of cancers affect humans. Tobacco use is the cause of about 22% of cancer deaths. Another 10% are due to obesity, poor diet, lack of physical activity or excessive drinking of alcohol. Other factors include certain infections, exposure to ionizing radiation, and environmental pollutants. In the developing world, 15% of cancers are due to infections such as ''Helicobacter pylori'', hepatitis B, hepatitis C, human papillomavirus infection, Epstein–Barr virus and human immunodeficiency virus (HIV). These factors act, at least partly, by changing the genes of ... [...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] |
Gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a basic unit of heredity and the molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protein-coding genes and noncoding genes. During gene expression, the DNA is first copied into RNA. The RNA can be directly functional or be the intermediate template for a protein that performs a function. The transmission of genes to an organism's offspring is the basis of the inheritance of phenotypic traits. These genes make up different DNA sequences called genotypes. Genotypes along with environmental and developmental factors determine what the phenotypes will be. Most biological traits are under the influence of polygenes (many different genes) as well as gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fitness (biology)
Fitness (often denoted w or ω in population genetics models) is the quantitative representation of individual reproductive success. It is also equal to the average contribution to the gene pool of the next generation, made by the same individuals of the specified genotype or phenotype. Fitness can be defined either with respect to a genotype or to a phenotype in a given environment or time. The fitness of a genotype is manifested through its phenotype, which is also affected by the developmental environment. The fitness of a given phenotype can also be different in different selective environments. With asexual reproduction, it is sufficient to assign fitnesses to genotypes. With sexual reproduction, recombination scrambles alleles into different genotypes every generation; in this case, fitness values can be assigned to alleles by averaging over possible genetic backgrounds. Natural selection tends to make alleles with higher fitness more common over time, resulting in Darwin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hybridization Probe
In molecular biology, a hybridization probe (HP) is a fragment of DNA or RNA of usually 15–10000 nucleotide long which can be radioactively or fluorescently labeled. HP can be used to detect the presence of nucleotide sequences in analyzed RNA or DNA that are complementary to the sequence in the probe. The labeled probe is first denatured (by heating or under alkaline conditions such as exposure to sodium hydroxide) into single stranded DNA (ssDNA) and then hybridized to the target ssDNA ( Southern blotting) or RNA (northern blotting) immobilized on a membrane or in situ. To detect hybridization of the probe to its target sequence, the probe is tagged (or "labeled") with a molecular marker of either radioactive or (more recently) fluorescent molecules. Commonly used markers are 32P (a radioactive isotope of phosphorus incorporated into the phosphodiester bond in the probe DNA), digoxigenin, a non-radioactive, antibody-based marker, biotin or fluorescein. DNA sequences o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluorescent In Situ Hybridization
Fluorescence ''in situ'' hybridization (FISH) is a molecular cytogenetic technique that uses fluorescent probes that bind to only particular parts of a nucleic acid sequence with a high degree of sequence complementarity. It was developed by biomedical researchers in the early 1980s to detect and localize the presence or absence of specific DNA sequences on chromosomes. Fluorescence microscopy can be used to find out where the fluorescent probe is bound to the chromosomes. FISH is often used for finding specific features in DNA for use in genetic counseling, medicine, and species identification. FISH can also be used to detect and localize specific RNA targets (mRNA, lncRNA and miRNA) in cells, circulating tumor cells, and tissue samples. In this context, it can help define the spatial-temporal patterns of gene expression within cells and tissues. Probes – RNA and DNA In biology, a probe is a single strand of DNA or RNA that is complementary to a nucleotide sequence ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
June Biedler
June Biedler (June 24, 1925 – April 16, 2012) was an American scientist primarily known for her discovery of proteins that lead to resistance of cancer cells to chemotherapy. Her work has been crucial for an understanding of both the development of drug resistance and also for strategies to circumvent such resistance. In addition, Biedler made important contributions to an understanding of the molecular mechanisms of neuroblastoma development, particularly of the role of the N-myc oncogene in the genesis of neuroblastoma Early life and education Biedler was born June 24, 1925 in New York City. She grew up in Rye, Westchester County NY. She was the daughter of Ashby Lee Biedler, an insurance executive and the former Betty Holloway. She was also the step-daughter of Percy M. Stewart, an investment banker. As a teenager, she was a neighbor and friend of Barbara Bush. She made her social debut at the Westchester Cotillion in 1943. Biedler was a graduate of the Madeira S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DHFR
Dihydrofolate reductase, or DHFR, is an enzyme that reduces dihydrofolic acid to tetrahydrofolic acid, using NADPH as an electron donor, which can be converted to the kinds of tetrahydrofolate cofactors used in 1-carbon transfer chemistry. In humans, the DHFR enzyme is encoded by the ''DHFR'' gene. It is found in the q11→q22 region of chromosome 5. Bacterial species possess distinct DHFR enzymes (based on their pattern of binding diaminoheterocyclic molecules), but mammalian DHFRs are highly similar. Structure A central eight-stranded beta-pleated sheet makes up the main feature of the polypeptide backbone folding of DHFR. Seven of these strands are parallel and the eighth runs antiparallel. Four alpha helices connect successive beta strands. Residues 9 – 24 are termed "Met20" or "loop 1" and, along with other loops, are part of the major subdomain that surround the active site. The active site is situated in the N-terminal half of the sequence, which includes a conser ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
