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Word - The Open University
Word - The Open University

... 1.1 Meiosis and the life cycle 1.1.1 Chromosomes and the life cycle The type of nuclear division called meiosis is intimately linked to the life cycle of organisms that reproduce sexually. Chromosomes are present in the cells of all eukaryotes. Their number varies enormously and is characteristic fo ...
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... females receive the dominant, red-eyed allele from their fathers and the recessive, white-eyed allele ...
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... when antibiotics are present (Novak, 1999). For example, there is concern that vancomycin tolerant strains are now appearing, with documented cases in Streptococcus pneumoniae (Novak, 1999). Because tolerance is often a direct precursor to resistance, this observation is of serious concern. Resistan ...
13.3 Mutations
13.3 Mutations

... or no effect; and some produce beneficial variations. Some negatively disrupt gene function. • Whether a mutation is negative or beneficial depends on how its DNA changes relative to the organism’s situation. • Mutations are often thought of as negative because they disrupt the ...
DNA ppt notes 2015
DNA ppt notes 2015

... mother chromosomes inherited  each cell contains from both parents hundreds to thousands of  each cell contains only mitochondria one nuclei  can be found in skeletal remains  Advantage: can use old, degraded samples ...
Exploitation of genes affecting meiotic non
Exploitation of genes affecting meiotic non

... Despite its occurrence in over 400 species of Angiosperms, apomixis is found in few species of agricultural importance: some forages, Citrus, apple, mango and orchids. Sexual hybridisation has been performed between pearl millet and its apomictic relatives to transfer apomixis. Apomictic plants disp ...
Local Similarity in Evolutionary Rates Extends over Whole
Local Similarity in Evolutionary Rates Extends over Whole

... cluster increases quadratically with cluster size, this protocol gives more weight to genes within larger clusters. A few large clusters of genes can thus dominate the test function, reducing the effective sample size and obscuring weak local similarities. Williams and Hurst (2000) circumvented this ...
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SCOOTER OER Fact Sheet: Dr V Rolfe, December 2010
SCOOTER OER Fact Sheet: Dr V Rolfe, December 2010

... The coding sequence is the region of the mRNA actually translated into protein. When calculating the length of the coding sequence, which of the following is the correct approach? The total length of the gene cluster is used The number of base pairs forming the untranslated regions is subtracted The ...
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... • Explain why sex-linked disorders occur in one sex more often than in the other. • Interpret a pedigree. ...
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Common Long Human Inversion Polymorphism on Chromosome 8p
Common Long Human Inversion Polymorphism on Chromosome 8p

... The inversion is likely mediated by two clusters of olfactory receptor genes that flank the inverted segment at both ends [9]. Olfactory receptor genes are found on nearly every human chromosome [11]. The flanking repeated sequences are apparently in inverted orientation (Matsumoto et al., in prepar ...
Patterns of Heredity
Patterns of Heredity

... Occurs because other genes besides the alleles for sex are also located on the sex chromosomes. recessive to the normal are ___________ condition and the Y chromosomes appear to lack genes for these traits. ...
Methylation Dynamics in the Early Mammalian Embryo: Implications
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... In light of growing concerns about epigenetic disturbances resulting from superovulation and embryo culture, there is clearly a need for both basic research on reproductive epigenetic events and long-term follow up studies of children born of ART. Similar to ART, somatic cell nuclear transfer techno ...
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... In light of growing concerns about epigenetic disturbances resulting from superovulation and embryo culture, there is clearly a need for both basic research on reproductive epigenetic events and long-term follow up studies of children born of ART. Similar to ART, somatic cell nuclear transfer techno ...
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... were more common than expected when they had less than ca. 20% of RIP target sites mutated. Specifically, 46 of 79 sequences with two RIP target sites mutated had the changes only in the coding or only in the non-coding strands (binomial distribution probabilities, P = 0.110), as did 19 of 30 sequen ...
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Implications of DNA replication for eukaryotic gene expression
Implications of DNA replication for eukaryotic gene expression

... terminally differentiated non-dividing cell, they do not explain why either transcription complexes or nucleosomes are assembled onto DNA in the first place. Clearly, as both nucleoprotein structures can incorporate the same DNA molecule, the possibility exists of a competition occurring between the ...
Evolutionary Computing A Practical Introduction
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... Usually less able to to survive and so reproduce Occasionally more able to survive and so reproduce More reproduction leads to more of the “new improved” genetic “Good” sets of genes get reproduced more “Bad” sets of genes get reproduce less Organisms as a whole get better and better at surviving in ...
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... highly polygenic traits, and that the additive variation explained  by a part of the genome is approximately proportional to the total length of DNA contained within genes therein. Genome-wide association studies (GWAS) have led to the discovery of hundreds of marker loci that are associated with co ...
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Genetics of male subfertility: consequences for the clinical work-up

... Azoospermia factor (AZF) and deletions of the Y chromosome Recently, there have been several studies devoted to defining key regions on the Y chromosome which are suspected to contain important genes responsible for spermatogenesis. These regions are located on the long arm of the Y chromosome (Yqll ...
P57: Beckwith-Wiedemann Syndrome
P57: Beckwith-Wiedemann Syndrome

... Tests for BWS Bone X-ray Blood tests for low sugar Ultrasound of the abdomen X-ray of the abdomen MRI of the abdomen Chromosome studies ...
Restriction enzymes
Restriction enzymes

... enzyme will cut it up into small pieces. They cut up only certain base pair sequences and thus are handy in genetics • The bacterial cell protects its own DNA from restriction by adding methyl groups (--CH3) to adenines or cytosines within the sequences that would otherwise be recognized by the rest ...
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Chromosome



A chromosome (chromo- + -some) is a packaged and organized structure containing most of the DNA of a living organism. It is not usually found on its own, but rather is complexed with many structural proteins called histones as well as associated transcription (copying of genetic sequences) factors and several other macromolecules. Two ""sister"" chromatids (half a chromosome) join together at a protein junction called a centromere. Chromosomes are normally visible under a light microscope only when the cell is undergoing mitosis. Even then, the full chromosome containing both joined sister chromatids becomes visible only during a sequence of mitosis known as metaphase (when chromosomes align together, attached to the mitotic spindle and prepare to divide). This DNA and its associated proteins and macromolecules is collectively known as chromatin, which is further packaged along with its associated molecules into a discrete structure called a nucleosome. Chromatin is present in most cells, with a few exceptions - erythrocytes for example. Occurring only in the nucleus of eukaryotic cells, chromatin composes the vast majority of all DNA, except for a small amount inherited maternally which is found in mitochondria. In prokaryotic cells, chromatin occurs free-floating in cytoplasm, as these cells lack organelles and a defined nucleus. The main information-carrying macromolecule is a single piece of coiled double-stranded DNA, containing many genes, regulatory elements and other noncoding DNA. The DNA-bound macromolecules are proteins, which serve to package the DNA and control its functions. Chromosomes vary widely between different organisms. Some species such as certain bacteria also contain plasmids or other extrachromosomal DNA. These are circular structures in the cytoplasm which contain cellular DNA and play a role in horizontal gene transfer.Compaction of the duplicated chromosomes during cell division (mitosis or meiosis) results either in a four-arm structure (pictured to the right) if the centromere is located in the middle of the chromosome or a two-arm structure if the centromere is located near one of the ends. Chromosomal recombination during meiosis and subsequent sexual reproduction plays a vital role in genetic diversity. If these structures are manipulated incorrectly, through processes known as chromosomal instability and translocation, the cell may undergo mitotic catastrophe and die, or it may unexpectedly evade apoptosis leading to the progression of cancer.In prokaryotes (see nucleoids) and viruses, the DNA is often densely packed and organized. In the case of archaea by homologs to eukaryotic histones, in the case of bacteria by histone-like proteins. Small circular genomes called plasmids are often found in bacteria and also in mitochondria and chloroplasts, reflecting their bacterial origins.
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