The number and shape of chromosomes . A visual image of a chromosomal defect. A karyotype specifically shows the chromosomes of a person, while a pedigree just shows the movement of the disorder throughout generations
72 chromatids were present in the present in the primary oocyte during prophase 1 of meiosis.
The primary oocyte contains 72 chromatids during prophase 1 of meiosis as the mature ovum has 18 chromosomes.
The primary oocyte contains 72 chromatids , that means it contains 144 chromosomes. During the first meiotic division, it produces one secondary oocyte and one polar body.
The secondary oocyte has 72 chromatids, which again undergoes second meiotic division and produces mature ovum and second polar body . The mature ovum contains contains 36 chromatids which means it has 18 chromosomes.
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Chinese hamster ovary cell production of recombinant tissue‐type plasminogen activator (t‐PA) was increased by amplification of cotransfected dihydrofolate reeducates cDNA using stepwise adaptation to increasing methotrexate (MTX) concentrations. The highest producing clones were isolated at 5 μM MTX and yielded 26,000 U/106 cells/day t‐PA (43 μg/106 cells/day). Above 25 μM MTX, cell specific t‐PA production rates became increasingly variable and the cDNA copynumbers decreased. No apparent correlation between the cell specific t‐PA production rate and the growth rate was observed upon sub cloning of the amplified cells. When MTX selection was removed, the t‐PA production rate decreased up to tenfold within 40 days; this was accompanied by an up to 60% drop in cDNA copynumber. Subclones isolated after 108 days of culture in the absence of MTX were, on average, sixfold more stable than their parental cells. In culture without MTX, the maximum stable t‐PA production rate obtained (over 250 days) was 7000 ± 750 U/106cells/day (∼12 μg/106 cells/day), approximately threefold lower than the maximum unstable levels of production reached under selective pressure. Taken together, these results define a wide range of the highest t‐PA expression rates obtained under MTX selection, for which stable expression without selection has not been reported
Answer:
Embryological evidence
Explanation:
Deuterostomes is a group that includes echinoderms, hemichordates, and chordates. Although these animals exhibit a wide variety of body plans, they share a mouth secondarily formed during embryo development, which it is believed to be an evolutionarily derived character present between a common ancestor and all its descendants (i.e., a synapomorphy). This oral cavity is formed by the invagination of the ectoderm layer opposite to the blastopore of the gastrula.
