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Anatomy and Chemical Makeup of a Single Hair (Animation)
By: HWC, Views: 4938
The hair's outer cuticle surrounds hair cells filled with tough keratin macrofibrils. Each macrofibril consists of smaller microfibrils. A microfibril is made up of three keratin polypeptide chains. The chains are linked together by disulfide bonds. A hair consists of keratin chains held...
Functional zones in a mitochondrion
By: HWC, Views: 4646
A mitochondrion has a double membrane system. The outer membrane faces the cytoplasm. The inner membrane divides the organelles interior into two compartments. The enzymes that carry out the second stage reactions are in the semifluid matrix inside the inner compartment. Embedded in the ...
By: HWC, Views: 4648
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: 4726
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: 4546
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: 4599
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: 4409
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...
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