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Chromosomal in Biological Definition

Chromosome

... 5 Karyotype 6 Human chromosome 7 chromosomal aberrations 8 See also 9 External links ... It seems to serve structural purposes during the chromosomal stages. Heterochromatin can be further ... a small number of unclonable gaps. [1] chromosomal aberrations Some chromosome abnormalities do ...

Genetic recombination

... genes. One mechanism leading to recombination is chromosomal crossing over . In analog fashion exchange of ... Crossing over Main article: chromosomal crossover Crossing over of two chromosomes occurs during meiosis . After chromosomal replication , the four available chromatids ...

Plasmid

... of a bacterium with plasmids enclosed. (1) chromosomal DNA . (2) Plasmids Plasmids are ... DNA molecules that are separate from the chromosomal DNA (Fig. 1). They usually occur in bacteria , ... DNA to be duplicated independently from the chromosomal DNA (Fig. 2). Figure 2 : Schematic ...

Y chromosome

... 1 Function 2 chromosomal conditions related to chromosome Y 3 Repair ... male sexual determination and development. chromosomal conditions related to chromosome Y The ... learning problems in some boys and men. Other chromosomal conditions exist as well. Such conditions often ...

Down syndrome

... Down syndrome is estimated at 1 per 660 births, making it the most common chromosomal abnormality. Maternal age influences the risk of conceiving a baby with ... at age 40 it is 1/106 and at age 49 it is 1/11. (Source: Hook EB. Rates of chromosomal abnormalities at different maternal ages. Obstet Gynecol 1981;58:282.) ...

Polymerase chain reaction

... can copy fragments up to 40 kb in size, which is still much less than the chromosomal DNA of a eukaryotic cell --for example, a human cell contains about ... chromatography . Figure 5 : Cloning a gene using a plasmid. (1) chromosomal DNA of organism A. (2) PCR. (3) Multiple copies of a single gene from ...

X chromosome

... rather than completely missing. Some women with Turner syndrome have a chromosomal change in only some of their cells. These cases are called Turner syndrome mosaics (45,X/46,XX). chromosomal conditions involving the sex chromosomes often affect sex determination ...

Bacterial conjugation

... is integrated, the transferred DNA consists of the F-plasmid sequence plus an amount of chomosomal DNA from the donor bacterium. The amount of chromosomal DNA that is transferred depends on how long the bacteria hold contact; the transfer of the whole bacterial chromosome would take about 100 minutes. ...

Brain

... disorders are congenital . Tay-Sachs disease , Fragile X syndrome , Down syndrome , and Tourette syndrome are all linked to genetic or chromosomal errors. Malfunctions in the embryonic development of the brain can be caused by genetic factors or by drug use or disease in the mother. ...

Cancer

... . Oncogenes promote cancer when "switched on" by a mutation, whereas tumor suppressor genes prevent cancer unless "switched off" by a mutation. chromosomal translocation , such as the Philadelphia chromosome , is a special type of mutation and may involve oncogenes or tumor suppressor genes. In general, ...

Chromosomal crossover

... chromosomal crossover is the process by which two chromosomes , paired up during Prophase I of meiosis , exchange some distal portion of their DNA . ...

Developmental biology

... of organismal form in an evolutionary context. The findings of developmental biology can help to understand developmental malfunctions such as chromosomal aberrations , for example, Down syndrome . An understanding of the specialization of cells during embryogenesis may shield information on how to ...

Gene

... chromosomes . He later showed that genes occupy specific locations on the chromosome. With this knowledge, Morgan and his students began the first chromosomal map of the fruit fly Drosophila . In 1928 , Frederick Griffith showed that genes could be transferred. In what is now known as Griffith's ...

Karyotype

... chromosomes are arranged and displayed (often on a photo) in a standard format: in pairs, ordered by size. Karyotypes are examined in searches for chromosomal aberrations , and may be used to determine other macroscopically visible aspects of an individual's genotype , such as sex (XX vs. XY pair). The ...

Meiosis

... if any, are due to the alternation of densely stained chromomeres in comparison with non-staining areas. Chromomeres are regions where the chromosomal material is tightly coiled. Homologous chromosomes derived from maternal and paternal gamete nuclei come together and pair up. They have same ...

Mitosis

... this point, each new nucleus contains one copy of each chromosome. Mitosis is complete. Endomitosis Endomitosis is a process that occurs when chromosomal replication takes place without nuclear or cellular division, resulting in cells with many copies of the same chromosome. This process may also be ...

Oncogene

... protein structure, caused by an increase in protein ( enzyme )activity a loss of regulation the creation of a hybrid protein , through a chromosomal aberration during cell division . A distinct aberration in a dividing stem cell in the bone marrow leads to adult leukemia An increase ...

Patau syndrome

... Patau syndrome , also known as Trisomy 13 , is a chromosomal aberration, a disease in which a patient has an additional chromosome 13 . Patau syndrome is associated with severe mental retardation , small ...

Phage

... away. ) Some phages (so-called temperate phages ) can instead enter a relatively harmless state, either integrating their genetic material into the chromosomal DNA of the host bacterium (much like endogenous retroviruses in animals) or establishing themselves as plasmids . These endogenous phages, ...

Sperm

... cells contain half of the genetic information needed to create life. Generally, the sex of the offspring is determined by the sperm, through the chromosomal pair "XX" (for a female ) or "XY" (for a male ). Sperm cells were first observed by Antoni van Leeuwenhoek in 1679 . Contents ...

Mitosis

... this point, each new nucleus contains one copy of each chromosome. Mitosis is complete. Endomitosis Endomitosis is a process that occurs when chromosomal replication takes place without nuclear or cellular division, resulting in cells with many copies of the same chromosome. This process may also be ...

Trait

... point along this string is the centromere ; the distance from a gene to the centromere is referred to as the gene's locus or map location. A chromosomal region known to control a trait while the responsible gene within not being identified is referred to as a quantitative trait locus . The nucleus ...
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