UCONN MCB 2410 #1 – Flashcards

First stage of cell cylce. The period between cell divisions, in which teh cell grows, develops, and functions. In interphase, critical events necessary for cell division take place.

DNA is being synthesized, RNA and proteins are being produced, and hundreds of biochemical reactions necessary for cellular functions are taking place. Interphase includes several checkpoints. These checkpoints insure that all cellular components are present and in good working order before the cell proceeds to the next stage.

1. G₁

2. S Phase

3. G₂

The Mitotic Phase. The period of active cell division. Includes mitosis and Cytokinesis, or cytoplasmic division.

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Stagese include: Prophase, Metaphase, Anaphase, Telophase (cytokinesis)

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Production of gametes in a male animal, this takes place in the testes. Their diploid primordial germ cells divide mitotically to produce diploid cells called spermatogenia. Each spermatogenium can undergo repeated rounds of mitosis, giving rise to numerous additional spermatogonia. Alternatively, a spermatogonium can initiate meiosis and enter into prophase I. Now called a Primary Spermatocyte, each Primary spermatocyte completes meiosis I, giving rise to two haploid secondary spermatocytes that then undergo meiosis II with each producing two haploid spermatids. Thus, each primary spermatocyte produces a total of four haploid spermatids, which mature and develop into sperm.

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The production of gametes in a female animal. Within the ovaries, diploid primordial germ cells divide mitotically to produce oogonia. Like spermatogonia, oogonia can undergo repeated round so f mitosis or they can enter into meiosis. When they enter prophase I, these still-diploid cells are called primary oocytes. Each primary oocyte completes meiosis I and divides. In oogenesis cytokinesis is unequal: most of the cytoplasm is allocated to one of the two haploid cells, the secondary oocyte. The smaller cell, which contains half of the chromosomes but only a small part of the cytoplasm is called the first polar body; it may or may not divide further. The secondary oocyte completes meiosis II, and, again, cytokinesis is unequal;most of the cytoplasm passes into on the cells. The larger cell , which acquires most of the cytoplasm is the ovum, the mature female gamete. The smaller cell is the second polar body. Only the ovum is capable of being fertilized, and the polar bodies usually disintegrate. Oogenesis, then, produces a single mature games from each primary oocyte.

1. Metacentric: Centromere is essentially midway between the sister chromatids. The p and q arms are basically equal in length.

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2. Submetacentric: The centromere is slightly higher than on a metacetric chromosome. The p arm is slightly shorter than the q arm.

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3. Acrocentric: The centromere is almost at the very top of the chromosome. The p arm is very short and the q arm is very long.

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4. Telocentric: The centromere is at the very top of the chromosome, at the telomere. The p arm is basically nonexistent and the q arm is very long.

Process in which chromosomes of a eukaryotic cell divide to give rise to haploid reproductive cells. Consists of two division: meiosis I and meiosis II.

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Meiosis I: First phase of meiosis. In meiosis I, chromosome number is reduced by half.

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Meiosis II: Second phase of meiosis. Events in meiosis II are essentially those in mitosis.

rearrangement in which a segment of a chromosome has been inverted 180 degrees.

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Pericentric- Includes the centromere

Paracentric- Excludes the centromere

Presence of an additional copy of a chromosome (2n+1).

One additional member of a homologous pair. Almost always lethal.

Trisomy 21

Characterized by variable degrees of mental retardation, characteristic facial features, some retardation of growth and development, and an increased incidence of heart defects, leukemia, and other abnormalities; caused by teh duplication of all or part of chromosome 21