Chapter 9 – Cellular Reproduction Section 1- Cellular Growth

Section 1 Cellular Reproduction Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide.

Section 1 - Cellular Growth Cellular Reproduction Cell Size Limitations The ratio of a cell’s surface area (area covered by plasma membrane) to its volume (space taken up by the inner contents) is the major factor that limits the size of the cell. As a cell grows, its volume increases much more rapidly than the surface area. When cells get too large they cannot get enough nutrients into and out of the cell.

Section 1 - Cellular Growth Cellular Reproduction Cell Size Limitations Small cells also maintain more efficient transport systems. Cell size also affects the ability of a cell to communicate instructions for cellular function.

Section 1 – Cellular Growth Cellular Reproduction The Cell Cycle Cell division prevents the cell from becoming too large. Cell division is the way the cell reproduces so that you grow and heal certain injuries. Cell division is asexual reproduction, meaning the offspring are clones/identical to the parent. Cells reproduce by a cycle of growing and dividing called the cell cycle and become two cells.

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The cell cycle has 3 main stages: Section 1 – Cellular Growth Cellular Reproduction The Cell Cycle The cell cycle has 3 main stages: 1. Interphase - the stage during which the cell grows, carries out cellular functions, and replicates (makes copies of the DNA). - G1 (1st growth phase) - S (Synthesis phase) - G2 (2nd growth phase) 2. Mitosis – the cell’s nucleus and nuclear material divide. 3. Cytokinesis – the cell’s cytoplasm divides, creating a new cell.

The Stages of Interphase Section 1 – Cellular Growth Cellular Reproduction The Stages of Interphase The first stage of interphase, G1 The cell is growing, carrying out normal cell functions, and preparing to replicate DNA.

The Stages of Interphase The Second Stage of Interphase, S Section 1 – Cellular Growth Cellular Reproduction The Stages of Interphase The Second Stage of Interphase, S - The cell copies its DNA in preparation for cell division.

The Stages of Interphase The Third Stage of Interphase, G2 Section 1 – Cellular Growth Cellular Reproduction The Stages of Interphase The Third Stage of Interphase, G2 The cell prepares for the division of its nucleus.

- Visible only during cell division. Section 1 – Cellular Growth Cellular Reproduction Chromosomes – rod-shaped structures that contain the genetic material that is passed from one generation to the next. - Visible only during cell division. Chromatin – relaxed form of DNA in the cell’s nucleus; loose network of bumpy threads.