The Cell Cycle Chapter 2, Lesson 1

Big questions for something so small! You start life as a single cell!! You will have a trillion cells!! SO . . . How are all these cells made? How long does a cell live?

The Cell cycle Cell cycle = the life cycle of a cell Just like all living things, our CELLS have a cycle of life.

Draw Figure 1 from page 88 in your notebook. Use Color Left Side Draw Figure 1 from page 88 in your notebook. Use Color Predict: How long does it take to make a new cell? Explain.

Length of Cell Cycle Different for different cells. Humans may have as many as 500 different types of cells in your bodies. Skin cells = new cells every 24 hours Liver cells = 1 year or more Brain = never makes new cells, you get one chance. Most our cells are like skin and take 24 hours

Left Length of Cell Cycle Other organisms have cycles that are shorter Zebra Fish: From 1 cell to hatching in 48 hours. Sea Urchin From 1 cell to 4 in 2 hours. http://www.exploratorium.edu/imaging_station/gallery.php?Category=Mitosis&Section=Introduction

Left Side Length of cell cycle Describe: Describe the zebra fish or the sea urchin. Predict: Why do different kinds of organisms’ cells have different cell lengths? Talk with your partner and compare your answers.

We will know begin the Cell Cycle Main Phases of cell cycle Interphase Birth/Childhood Mitosis Teenager Cytokinesis Leaving your parents

Beginning the Cell Cycle Interphase

First is Interphase When a cell is getting ready to reproduce The longest phase. The chromosomes in the nucleus look like a bunch of thin spaghetti because they are getting ready to be copied.

The Phases of Interphase To summarize look at TB pg 91 Now what do you think Interphase does? Talk with a partner. Answer Growth and regular cell functions. NUCLEUS makes chromatids Organelles make copies of themselves.

The Phases of Interphase Do ALL cells go finish interphase? Answer: Muscles, nerve, brain. Injuries to these can be permanent. The cells don’t leave interphase. Drugs literally kill brain cells. . . You can’t get them back once they have been damaged.

Time for a Vocabulary lesson

DNA vs. Chromosomes What is DNA? What is a chromosome? A macro molecule that makes proteins. What is a chromosome? DNA tightly coiled around some proteins into a smaller package. Humans have 46 chromosomes. http://learn.genetics.utah.edu/content/begin/tour

What is a homologous chromosome? From mom Homologous chromosomes are the matched set. From dad You get one from mom and one from dad. So we have 23 pairs of homologous chromosomes. /

What is a chromatid? Chromatid: copy of chromosome Centromere: a region near middle of each chromatid that holds together each sister chromatid

Left Predict: Why do we need chromatids? Predict: Why do we need centromeres? Talk with your partner. Answer: The cell needs to make copies of EVERY chromosome so the new cell has EVERY chromosome. Centromeres hold the copy to the original for a while.

For tomorrow More about this later. But what are some things you notice?

Now we move on the to . . . Mitosis

Different cells at different times Four main phases Prophase Metaphase Anaphase Telephase 1 What phase is this? Anaphase How do we know? The chromosomes are not lined up in the center or all the way at the ends.

Name the Phase and defend 3 1 2 4 1 = Metaphase 4 = Interphase 2 = Telophase 3 = Prophase

Now to the end of the cycle Cytokinesis

Cytokinesis The final stage Cytoplasm divides Organelles divide up Occurs very quickly – like you “splitting” off this campus on a Friday.

The results of cell division NO parent cell exists anymore! The TWO daughter cells are identical!