The Cell CycleChapter 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.e

du/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?

http://learn.genetics.utah.edu/content/begin/tour

A macro molecule that makes proteins.

DNA tightly coiled around some proteins into a smaller package. Humans have 46 chromosomes.

What is a homologous chromosome?

/

Homologous chromosomes are the matched set.

From momFrom mom

From dadFrom 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

2

3

14

1 = Metaphase

2 = Telophase

3 = Prophase

4 = Interphase

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!