Cell Growth and Cell Cycle Cell Cycle n

Cell Cycle n The series of events that cells undergo as they grow and

Two Parts of Cell Cycle n n Interphase: Period when the cell is growing

Phases of the Cell Cycle n Five phases n n n First Growth (G

First Growth n All normal cell activities occur during this period n n n

Synthesis n n n DNA is replicated during this phase Part of interphase Chromosomes

Second Growth n n n Microtubules needed for cell division are formed. Part of

Mitosis n n n The process of dividing the nucleus into two nuclei. Part

Cytokinesis n n n The process of dividing the organelles into two cells Part

Limits to Cell Growth n Cells divide when they become too large to handle

Limits to Cell Growth n DNA overload n n n DNA makes the protein

Limits to Cell Growth n Material exchange n n n Many materials diffuse into

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Cell Growth and Cell Cycle

Cell Cycle n The series of events that cells undergo as they grow and divide.

Two Parts of Cell Cycle n n Interphase: Period when the cell is growing or preparing for division. Cell Division- The cell is actively dividing into two cells.

Phases of the Cell Cycle n Five phases n n n First Growth (G 1) Synthesis (S) Second Growth (G 2) Mitosis (M) Cytokinesis (C)

First Growth n All normal cell activities occur during this period n n n Photosynthesis Respiration Chromosomes have one chromatid. Part of interphase Some cells never leave this phase: nerve cells, muscle cells

Synthesis n n n DNA is replicated during this phase Part of interphase Chromosomes are in the form of 2 chromatids joined by a centromere

Second Growth n n n Microtubules needed for cell division are formed. Part of interphase Chromosomes are in the form of 2 chromatids per chromosome.

Mitosis n n n The process of dividing the nucleus into two nuclei. Part of cell division At the end, chromosomes have 1 chromatid per chromosome.

Cytokinesis n n n The process of dividing the organelles into two cells Part of cell division DNA is in the form of 1 chromatid per chromosome

Limits to Cell Growth n Cells divide when they become too large to handle certain activities. n n DNA overload Material Exchange

Limits to Cell Growth n DNA overload n n n DNA makes the protein used in a cell Large cells need more protein than small cells but have the same amount of DNA can’t make enough protein to keep a large cell running.

Limits to Cell Growth n Material exchange n n n Many materials diffuse into and out of cells. As cells become larger, it takes longer for materials to move throughout the cell. By dividing the cell, the amount of surface area to volume increases allowing faster movement of materials.