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By: HWC, Views: 4645
Prophase is the first step in the mitotic process. During prophase, the chromosomes condense. The centrosomes begin to form a spindle and move into position on opposite sides of the cell. Sister chromatids are held together by a protein called cohesin at the centromere. Prometaphase is the sec...
Sister chromatids of a metaphase chromosome animation
By: HWC, Views: 4724
At metaphase, the chromosomes are duplicated and are at their most condensed. In each chromosome. two identical sister chromatids are held together at a constricted region called the centromere. When a chromosome is condensed, interactions among chromosomal proteins keep loops of DNA tightly ...
Homologous chromosomes during prophase I - Animation
By: HWC, Views: 4545
The chromosomes were duplicated during interphase and the sister chromatids are now in thin threadlike form. Each chromosome becomes zippered to its homologue, so that all four chromatids are closely aligned. The chromosomes are tightly aligned, but we will show them as separate so that y...
By: HWC, Views: 4596
During interphase, the chromosomes will be duplicated in preparation for mitosis, which divides the chromosomes, and cytokinesis, which divides the cell's cytoplasm. In early prophase, the duplicated chromosomes begin to condense. Each chromosome consists of two sister chromatids joined at the...
By: HWC, Views: 4407
Osmosis is when a solvent, such as water, moves from a low-solute concentration solution to a higher-solute concentration solution through a semipermeable. Osmosis is an example of diffusion (a special case of diffusion) in which the molecules are water, and the concentration gradient occurs a...
By: HWC, Views: 4668
This is a cell during metaphase I. For each pair of chromosomes, any gamete produced by this cell could contain either the maternal chromosome or the paternal chromosome. How many different combinations of maternal and paternal chromosomes are possible in the gametes produced by a cell with th...
By: HWC, Views: 4621
Spermatogenesis takes place inside the seminiferous tubules. Diploid spermatogonia located near the outer edge of the tubule divide mitotically to form primary spermatocytes. The first meiotic division produces secondary spermatocytes with a haploid number of duplicated chromosomes. T...
Mendel's pea plant, Pisum sativum experimental
By: HWC, Views: 4530
Mendel chose the garden pea plant, Pisum sativum, for experimental tests of his ideas about inheritance. Under normal circumstances, the garden pea plant is self-fertilizing. This cross-section shows the gamete-forming structures. Sperm-producing pollen grains form in the stamens. Eggs deve...
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