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Zygotene

... do so across the synaptonemal complex , which is over 100 nm thick, is unknown. 3. Pachytene ... Full article >>> The zygotene stage sees the completion of synapsis . The combined homologous chromosomes are said to be bivalent , a reference to the two homologous chromosomes . The...

Zoology

... and descent of species , as well as their change over time, i.e. their evolution . Full article >>> But the confocal microscope came up in the 1960's for botany and zoology and microbiologists never used it. Because after all if you're in a single cell , you don't need a fancy micr...

Zygote

...e >>> Hetero zygote advantage (or over dominant selection ) is an example in which an allele selected against in the homozygous state is retained because of the superiority of hetero zygote s. Full article >>> The human zygote is a totipotent cell . It basicall...

Yellow fever

...er United. Yellow fever in Mississippi Valley - over 13.000 dead US arbitration rejects Argentinean claims to Paraguay's part of Chaco region West Bromwich Albion F.C. play their first match. Full article >>>...

Xenopus

...nt, J. Morph.136:153. A "Citation Class ic" cited over 1130 times. (ORNL). Full article >>> Ectopic expression of Gli2 in Xenopus embryo s has been reported to lead to a repression of Gli1-mediated floor plate induction, also consistent with Gli2 playing a repressive role (Ruiz i ...

VLSI

VLSI : Very large- scale integration allowing over 100,000 trans istors on a chip. Full article >>> BISP: VLSI Solutions to Sequence -Comparison Problems Tim Hunkapiller, Leroy Hood, Ed Chen, and Michael Waterman Physical Map ping of DNA Molecule s Richard M. Karp ... Full a...

Vestigial organ

...le >>> vestigial organ any organ over the course of evolution had become reduced in function and usually in size. vibrissa (plural, vibrissae) Any of the stiff sensitive hairs found around the mouth s of mammals ; whiskers. Full article >>> appendix Blind sac at the ...

Vaccine

...accine derive from the work of Edward Jenner who, over 200 years ago, ... Full article >>> Vaccine A vaccine is an antigen ic preparation used to produce active immunity to a disease, in order to prevent or ameliorate the effects of infection by any natural or 'wild' strain of the...

Uterus

...ugh successive stages inside the female's uterus over a period of 38 weeks, it is called an embryo , then a fetus . Full article >>> The os is each end of the cervix , internal (to the uterus ) and external (to the vagina ) A municipality of the county Hedmark in Norway, see Os, Hed...

Urinary bladder

.... This tissue type also forms a protective layer over muscle , nerves , and blood vessels . Full article >>> Each pyramid together with the associated overlying cortex forms a renal lobe. The tip of each pyramid (called a papilla) empties into a calyx , and the calyces empty into ...

Unlinked

...>>> The frequency at which crossing over occurs between two chromosomal loci ; the proba...linked during meiosis . Related Terms: Crossing over ... Full article >>> : In genetic epidemiology, an epistatic effect is the modifi...

Unicellular

...ea that geological processes have remained uniform over time and that slight changes over long periods can have large- scale consequences; proposed by James Hutton in 1795 and re? Full a...

Umbilical cord

... the placenta and umbilical cord that are left over after birth is one source of adult stem cell s. Full article >>> In birds and reptiles, it fuses with the chorion to form the chorioallantoic membrane which assists in respiration , and in addition it is the site of storage of nitr...

Turgor

...ng cells by pressing against a membrane. turning over The mixing of thermal zones in a standing body of freshwater due to cold, more dense water "sinking" from the top through the other layers. Full article >>> (Redirected from Turgor ) Jump to: navigation, search Osmotic pressure or tu...

Tumor suppressor

...hat encodes it, p53, can result in loss of control over cell division and thus cancer . Full article >>> The process involves both oncogene s and tumor suppressor genes. Oncogene s promote cancer when "switched on" by a mutation , whereas tumor suppressor genes prevent cancer ...

Tube feet

...Full article >>> It positions itself over a bivalve and attaches tube feet to each side of the shell . By working tube feet in an alternating fashion, it opens the shell open. Only a small crack is needed to insert its cardiac stomach into the prey. Full article >>> ...

Trisomy

...e >>> Advanced maternal age -- women over age 34 (age 35 at delivery) at increased risk for nondisjunction trisomy in fetus . Alcoholism -- a chronic and progressive condition character ized by the inability to control the consumption of alcohol. Full article >>> Three o...

Transversion

...rather than changes in the DNA sequence enduring over generations being a result of the latter; for example, silent transition - transversion combinations would alter the melting point ... Full article >>>...

Transition

...d it happen subsequent to that time? Did it happen over a broad front? Did it happen to one group of individuals or one small tribe, who then became modern human s? Full article >>> An antibody selected for its ability to catalyze a chemical re action by binding to and stabilizing the ...

Transgenic

... Full article >>> Transgenic s and over expression Mapping , cloning , and sequencing... Full article >>> transgenic s and over expression mapping , cloning , and sequencing gene expression measuring spatial and tempor...

Trans-

...> He actually wrote an amazing book a little over a hundred years ago, where he just catalogued what he called "homeotic mutants" or " trans- formants," where one part of the body was trans formed into another. Full article >>>...

Trans

...ere the primitive streak forms. It lies directly over the subgerminal cavity and so appears trans parent. Full article >>> Nutrient cycling. The pattern of trans fer of nutrients between the components of a food web Nutrients. Those constituents required by organ isms for maintenance...

Trait

...otypic expression of polygenic trait s varies over a wide range. Human polygenic trait s include...mdash; at least until one's reproductive years are over — increases fitness . Such trait s are adaptation s. Sexual Selection ... Full article...

Tobacco mosaic virus

...). The capsid may be a single protein repeated over and over, as in tobacco mosaic virus (TMV). Full article >>>...

Tetrad

...aphase of meiosis and are involved in crossing over . A tetrad is also the four haploid cell s produced by one complete meiotic division . Full article >>> Bivalent s ( tetrad s) become aligned in the center of the cell and are attached to spindle fibers . The chromosome align...

Synapton

...o so across the synapton emal complex , which is over 100 nm thick, is unknown. 3. Pachytene ... Full article >>> Leptotene : chromosomes condense, the axial element of the synapton emal complex (a protein lattice that keeps homologous chromosomes toghether) is formed. Full a...

Synaptonemal complex

... do so across the synaptonemal complex , which is over 100 nm thick, is unknown. 3. Pachytene ... Full article >>> Related Terms: Synaptonemal complex This expression was introduced by Moses (1958) for the structure which he discovered in electron micrographs of paired chromosomes ...

Synapsis

...y exchange fragments by a process called crossing over . Full article >>> Synapsis . The ... do so across the synaptonemal complex , which is over 100 nm thick, is unknown. 3. Pachytene ... Full article >>> Synapsis The pairing...

Sympatric

... the same habitat . Observation of many species over the years has failed to establish even a single instance of two diagnostically different population s that exist in sympatry and have then merged ... Full article >>> Convergent Evolution when sympatric species evolve similar ch...

Suppressor

...hat encodes it, p53, can result in loss of control over cell division and thus cancer . Full article >>> In class I mutants, no mutation was evident in trpA -- evidently a suppressor mutation occured (a mutation in another gene , usually t RNA , to compensate for another muta...

Survival

...iagnosed at stage one cancer have 90% survival over five to ten years. Whereas people who are diagnosed at stage four have 10% survival roughly. Full article >>> A trait that assists an organ ism in survival and reproduction in a certain environment is said to be adaptive. Wh...

Stroma

...ilurian reefs. Some stroma toporoid specimens are over 16 feet in diameter. Full article >>> stroma . A compact, usually spore -producing structure formed from fungal mycelium on the surface of a host . Full article >>> stroma thylakoid A thylakoid that does not o...

Spirochetes

...nfected with Lyme disease spirochetes every year over ... Full article >>>...

Spiracles

...;>> spiracles Minute pores distributed over the surface of an insect's body that serve as entrances to the trachea l system. Covered in Lab 12 Animal Diversity II ... Full article >>> Insects use trachea l respiration with openings on the sides of the thorax and abdomen...

Spinal cord

... together and bone and muscle are unable to grow over this open section. Full article >>>...

Spermatogonia

...duces 4 haploid spermatids . This process takes over three weeks to complete. Full article >>> spermatogonia : primitive cells within the seminiferous tubules that undergo a series of changes and then meiosis to yield sperm cells . sperm cells : haploid cell s within the male ...

Sperm cells

... of many higher animals , the acrosome develops over the anterior half of its head. It is a cap-like structure derived from the Golgi apparatus . In Eutherian mammals , acrosome formation is completed during testicular maturation. Full article >>> ~ 10-100 µm ( sperm cells , apart fr...

Somatic cell

...d rodent tumor cells are fused ( hybrid ized); over time, after the chromosomes mix, human chromosomes are preferentially lost from the hybrid cell until only one or a few remain. Full article >>> somatic cell Ordinary body cell ; pertaining to or character istic of a body...

Somatic

...d rodent tumor cells are fused ( hybrid ized); over time, after the chromosomes mix, human chromosomes are preferentially lost from the hybrid cell until only one or a few remain. Full article >>> somatic cell Ordinary body cell ; pertaining to or character istic of a bo...

Small intestine

...ion occur. The small intestine is a coiled tube over 3 meters long . Coils and folding plus villi give this 3m tube the surface area of a 500-600m long tube. Full article >>> small intestine : the site of chemical digestion ; includes the duodenum , jejunum , and ileum . smooth...

Site

...omatid s of paired chromosomes (during crossing over ) at the site of identical nucleotide sequence s. Homozygote . Full article >>> The mitochondria l permeability transition (PT) pore, also called the mitochondria l megachannel, is a multi protein complex formed at the conta...

Sister Chromatids

...ow do non sister chromatids ensure that crossing over between them will occur without the loss or gain ...fibers . Full article >>> crossing over between sister chromatids either on the same or on homologous chromosomes Source: Jenkins, John...

Sister chromatid

sister chromatid exchange crossing over between sister chromatid s either on the same ...all) ... Full article >>> crossing over the reciprocal exchange of genetic material between non- sister chromatid s during synapsis ...

Siphon

...iphon , circulates through the mantle cavity and over the gills , and leaves through the excurrent siphon . Full article >>> When the siphon of the sea slug Aplysia is gently touched, the animal withdraws its gill for a brief period. However, if preceded by an electrical shock to it...

Similarity

...nes came from the same origin al gene some time over evolution ary time. Full article >>> The degree of similarity in nucleotide sequence is a function of divergence time. If two population s had recently separated, few differences would have built up between them. Full article ...

Shell

..., a steel shell ed turtle might be an improvement over regular turtles. Full article >>> This `dark side' of oxygen relates directly to the fact that each oxygen atom has one unpaired electron in its outer valence shell , and molecular oxygen has two unpaired electrons. Full arti...

Sexual

... which the contents of the male gamete cell go over into and unite with the female cell (con = with together; juga = a yoke; -tion = process of action of) ... Full article >>> ascospores . A spore produced within the saclike cell of the sexual state of a fungus . auricle. A...

Sexual reproduction

... which the contents of the male gamete cell go over into and unite with the female cell (con = with together; juga = a yoke; -tion = process of action of) ... Full article >>> Definition: Haploid reproductive cells that unite during sexual reproduction to form a diploid zy...

Sequence homology

... Physalaemus frogs, and how the calls have evolved over time. You also will see how scientists use molecular information to develop an evolutionary tree based on sequence homology . Full article >>> These proteins have several regions with sequence homology , including a centrally loc...

Selection

...e in frequency relative to less well-adapted forms over a number of generations. selection coefficient ....#62; Selection . A change in allele frequency over time in a population Sequential hermaphrodite . An individual that sequentially produces male and...

Segment

...tain physical character istic, thereby dominating over a recessive gene present on another chromosome . Full article >>> Messenger RNA (m RNA ) The transcript of a segment of chromosomal DNA which is a template for protein synthesis. Methyl trans ferase Enzymes that cata...

Scale

... VLSI : Very large- scale integration allowing over 100,000 trans istors on a chip. Full article >>> Normalization is to scale data such that data from different microarray s can be compared. Related Microarray ... Full article >>> Lindinger proposed the emendatio...

Satellite DNA

...atellite DNA Very high repetitions (from 1,000 to over 100,000 copies) of a basic motif or repeat unit (commonly 100 - 300 base pair s) which occur at a few loci on the genome . Minisatellite ... Full article >>> There are few satellite DNA binding proteins isolated, none of the...

Rostrum

rostrum Dorsal part of capitulum projecting over chelicerae in acarines. Full article >>> rostrum Anterior point of Arthropod head. Covered in Lab 12 Animal Diversity II rough endoplasmic reticulum Endoplasmic reticulum when it is covered with ribosomes is referred to as r...

Root cap

...ts . Cells forming a protective series of layers over the root meristem . PICTURE ... Full article >>> root cap A cone of cells at the tip of a plant root that protects the apical meristem . root hair ... Full article >>> root cap A thimble-shaped group of cells ...

RNA interference

...A interference Gene knockout Transgenic s and over expression Mapping , cloning , and sequencing...A interference gene knockout transgenic s and over expression mapping , cloning , and sequencing gene expression ... Full article >>&...

Restriction enzyme

... and cuts DNA at those sites. Bacteria contain over 400 such enzymes that recognize and cut over 100 different DNA sequence s. Full article >>> DNA insert and vector molecule...

Reproduction

... which the contents of the male gamete cell go over into and unite with the female cell (con = with together; juga = a yoke; -tion = process of action of) ... Full article >>> Defective phage A phage that lacks one or more functions that are required for reproduction . Defined...

Replication

...o the duplication of a gene , which may diverge over time. Though the two sequence s may remain the same or be only slightly altered, they are typically regarded as separate genes (i.e. Full article >>> The replication of a cell to form two daughter cell s with identical sets of c...

Renal

...vering of the kidney . cortex : The outer layer over the internal medulla . It contains blood vessels , glomeruli (which are the kidney s' "filters") and urine tubes and is supported by a fibrous matrix. Full article >>> renal arteries : arteries in which blood enters the kidn...