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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
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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.
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? 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
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 homologous chromosome?
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!