Ch8

Front 1

osmosis

Back 1

the tendency of a fluid, usually water, to pass through a semipermeable membrane into a solution where the solvent concentration is higher, thus equalizing the concentrations of materials on either side of the membrane.

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isotonic solution

Back 2

a solution having the same osmotic pressure as blood

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hypertonic solution

Back 3

any solution with a higher salt concentration than normal body cells so that the water is drawn out of the cells by osmosis; any solution with a higher osmotic pressure than another solution

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passive transport

Back 4

transport of a substance across a cell membrane by diffusion; expenditure of energy is not required

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facilitated diffusion

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in cell biology, a process by which substances are transported across cell membranes by means of protein carrier molecules

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active transport

Back 6

the movement of ions or molecules across a cellular membrane from a lower to a higher concentration, requiring the consumption of energy.

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endocytosis

Back 7

the transport of solid matter or liquid into a cell by means of a coated vacuole or vesicle

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exocytosis

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the transport of material out of a cell by means of a sac or vesicle that first engulfs the material and then is extruded through an opening in the cell membrane

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chromosome

Back 9

any of several threadlike bodies, consisting of chromatin, that carry the genes in a linear order: the human species has 23 pairs, designated 1 to 22 in order of decreasing size and X and Y for the female and male sex chromosomes respectively.

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chromatin

Back 10

the readily stainable substance of a cell nucleus, consisting of dna, RNA, and various proteins, that forms chromosomes during cell division.

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cell cycle

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the cycle of growth and asexual reproduction of a cell, consisting of interphase followed in actively dividing cells by prophase, metaphase, anaphase, and telophase.

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interphase

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the period of the cell cycle during which the nucleus is not undergoing division, typically occurring between mitotic or meiotic divisions. Also called interkinesis. Compare G1 phase, S phase, G2 phase.

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mitosis

Back 13

the usual method of cell division, characterized typically by the resolving of the chromatin of the nucleus into a threadlike form, which condenses into chromosomes, each of which separates longitudinally into two parts, one part of each chromosome being retained in each of two new cells resulting from the original cell

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prophase

Back 14

Cell Biology . the first stage of mitosis or meiosis in eukaryotic cell division, during which the nuclear envelope breaks down and strands of chromatin form into chromosomes.

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sister chromatid

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any of the chromatids formed by replication of one chromosome during interphase of the cell cycle especially while they are still joined by a centromere

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centromere

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a specialized structure on the chromosome, appearing during cell division as the constricted central region where the two chromatids are held together and form an X shape

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centriole

Back 17

a small, cylindrical cell organelle, seen near the nucleus in the cytoplasm of most eukaryotic cells, that divides in perpendicular fashion during mitosis, the new pair of centrioles moving ahead of the spindle to opposite poles of the cell as the cell divides: identical in internal structure to a basal body.

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spindle

Back 18

a spindle-shaped structure, composed of microtubules, that forms near the cell nucleus during mitosis or meiosis and, as it divides, draws the chromosomes to opposite poles of the cell.

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metaphase

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the stage in mitosis or meiosis in which the duplicated chromosomes line up along the equatorial plate of the spindle

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anaphase

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the stage in mitosis or meiosis following metaphase in which the daughter chromosomes move away from each other to opposite ends of the cell.

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telophase

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the final stage of meiosis or mitosis, in which the separated chromosomes reach the opposite poles of the dividing cell and the nuclei of the daughter cells form around the two sets of chromosomes.

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cytokinesis

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the division of the cell cytoplasm that usually follows mitotic or meiotic division of the nucleus.

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tissue

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an aggregate of similar cells and cell products forming a definite kind of structural material with a specific function, in a multicellular organism.

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organ

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a grouping of tissues into a distinct structure, as a heart or kidney in animals or a leaf or stamen in plants, that performs a specialized task