Interphase (01:51)

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The cell cycle consists of the events in a cell's life from birth to division. Interphase consists of three growth stages: gap phase 1; S phase, when DNA replication occurs; gap phase 2, when the cell synthesizes proteins.

Cell Division (00:45)

In mitosis, the cell divides the nucleus; centromeres break off, and duplicated chromosomes separate. In cytokinesis, remaining cell materials, the organelles, divide.

Mitosis (01:21)

Histones help keep chromosomes, with long DNA strands in tight space, structurally stable. The cell makes spindle fibers to pull on opposite sides of chromosomes.

Prophase (01:43)

The nucleus gets the signal to begin chromosome separation and division and undergoes chromosome condensation. Centrosomes make spindle fibers. Loose DNA triggers lysosomes.

Metaphase, Anaphase and Telophase (01:34)

Metaphase attaches chromosomes to spindles and lines them up to the equator. Anaphase pulls chromosomes apart. In telophase, the nuclear envelope is reformed and spindle fibers are attached.

Cytokinesis (00:54)

Cytokinesis completes cell division by separating cell components. Spindle fibers squeeze the plasma membrane toward the equator. Technically, cytokinesis occurs throughout mitosis.

Meiosis (01:17)

Meiosis is the cell division in sexual reproduction. Male and female produce gametes, which fuse to form a new cell, while each losing half their chromosomes, creating genetic variability.

Meiosis One and Two (01:34)

Meiosis creates four new cells. Meiosis one in females creates a functional cell and a polar body. The functional cell produces a haploid gamete in meiosis two.

Definitions of Chromosome Types (00:57)

Diploid cells contain the normal number of chromosomes; haploid cells contain half the normal number. Homologous chromosomes come half from the mother, half from the father.

Meiosis One (02:04)

In Meiosis One, chromosome rearrangement creates genetic diversity in gametes. In prophase one, homologous chromosomes touch each other in genetically similar regions. Recombination can occur.

Metaphase One and Anaphase One (01:04)

In metaphase one, tetrads are lined up randomly -- independent assortment. In anaphase one, homologous chromosomes separate, creating new combinations of maternal and paternal cells.

Telophase One and Cytokinesis One (00:55)

In Telophase one, daughter cells enter interkinesis. In Cytokinesis one, each cell divides into haploids.

Meiosis Two (01:43)

In prophase two, similar genetic sequences are attracted and can form a break, allowing recombination. The narrator briefly describes metaphase two, anaphase two, and telophase two.

Gametes Fuse (00:42)

Cytokinesis two produces gametes, which have haploid chromosomes and fuse with a gamete of the opposite sex. Crossing over and independent assortment produces genetic variation.

Reason for Apoptosis (01:27)

Apoptosis is programmed cell death; death and regeneration is necessary due to exposure of cells to their environment. It is thought that particular proteins begin the process when activated.

Process of Apoptosis (01:52)

Nucleases destroy DNA and also serve a protective function. Chromosome shortening triggers apoptosis. Homeostatic imbalance kills the cell. Macrophages clean up remnants.

Apoptosis and Cancer (01:16)

Apoptosis prevents old or damaged cells from dividing. When apoptosis breaks down, cells from uncontrolled growth form a tumor.

Credits: Cell Division and Growth (00:44)

Credits: Cell Division and Growth