Chapter 9 1

Chapter 9.1 –Cellular Reproduction NWRC – BIO 30 Nancie martin

Section 9.1 Page 244-247 • Do large cells perform tasks more efficiently than small cells? Bigger isn’t bigger at the cellular level Small cells transport substances more efficiently than large cells . Diffusion is a slow process, the larger the cell the less efficient transport within it becomes

Cell Size • Calculate a cells surface area and it’s volume to determine ratio of area to volume – the larger the ratio the more efficient the cell is. Smaller cells have higher ratios.

Cell Size • To calculate the surface area of a cell multiple the LXWX # of sides • To calculate the volume multiply LXWXH • You will note that the ratio increases as the size of the cell decreases making smaller cells more efficient

The Cell Cycle • Cells reproduce by a cycle of growing and dividing in 2 – this is called the cell cycle • There are 3 main stages of the cell cycle • Interphase • Mitosis • Cytokinesis

You need a piece of paper and some coloured pencils to follow along with this demo on the cell cycle

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• Video on mitosis • Mitosis demo

This happens here!!

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G1 phase: The period prior to the synthesis of DNA. In this phase, the cell increases in mass in preparation for cell division. Note that G1 the G in G1 represents gap and the 1 represents first, so the G1 phase is the first gap phase

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S phase: The period during which DNA is synthesized. In most cells, there is a narrow window of time during which DNA is synthesized. Note that the S represents synthesis.

G2 phase: The period after DNA synthesis has occurred but prior to the start of prophase. The cell synthesizes proteins and continues to G2 increase in size. Note that the G in G2 represents gap and the 2 represents second, so the G2 phase is the second gap phase.

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The Cell Cycle • The cell cycle is an ordered set of events, culminating in cell growth and division into two daughter cells. Non-dividing cells not considered to be in the cell cycle. The stages, pictured on previous slide, are G1-S-G2-M. The G1 stage stands for "GAP 1". The S stage stands for "Synthesis". This is the stage when DNA replication occurs. The G2 stage stands for "GAP 2". The M stage stands for "mitosis", and is when nuclear (chromosomes separate) and cytoplasmic (cytokinesis) division occur.(your book adds C as a separate stage) Mitosis is further divided into 4 phases

Assessment • 1. When the cell increases in size transport of nutrients and wastes across the plasma membrane and control of cell contents by the nucleus becomes increasingly difficult

Assessment • 2. Interphase Mitosis and Cytokinesis

Assessment • 3. DNA is replicated during the S phase

Assessment • 4.