Grade/Subject Liberty Middle School – EDI 2013

1

LO:Students will be able to explain and diagram the phases1 of the cell cycle.

1 Phases - The steps in a process.

Concept Development: The cell cycle describes the growth, development, and reproduction of a cell.

Skill Development/Guided Practice: The Cell Cycle: You’ll spend most of your life growing and developing. Only a small portion of a human’s life cycle is spent in the reproductive phase1. The same is true for cells. The cell cycle describes the growth, development, and reproduction of a cell. The phases1 of the cell cycle are: interphase, mitosis, and cytokinesis.

Interphase: A cell performs specific functions during interphase. During interphase, the chromosomes in the nucleus are like a bunch of thin spaghetti noodles. Each chromosome is so thin that it cannnot be observed with a light microscope. The three phases1 of interphase are G1, S and G2. During G1 phase, a cell grows and carries out its usual cellular functions. For example muscle cells are using oxygen and glucose to produce ATP necessary for your body to move. Growth continues into S phase1. During S, the chromosomes inside a cell’s nucleus replicate2. The copies of a chromosome made during S phase1 are called sister chromatids. Sister chromatids are held together at a region near the middle of each chromatid called the centromere. The replication2 of chromosomes during S phase1 ensures that the two new cells formed by cell division are identical. A cell continues to grow and carry out cellular functions during the final G2 phase1. It also replicates2 organelles during this phase1 of interphase.

2Replicate – make an identical copy

Grade/Subject Liberty Middle School – EDI 2013

2

Skill Development/Guided Practice:

Phases of Mitosis

Prophase: The first phase1 of mitosis is prophase. Two major events happen during prophase. First, the DNA that makes up a replicated2 chromosome twists into tight coils. The other major event during prophase is that the membrane around the nucleus breaks apart.

Metaphase: During the second phase1 of mitosis, metaphase, the replicated2 chromosomes move to the middle of the cell . The pairs of sister chromatids line up end to end across the center of the cell. Hair-like spindle fibers pull and push the chromosomes to the middle of the cell.

Anaphase: In the third phase1, anaphase, the sister chromatids of each replicated2

chromosome begin to separate. The spindle fibers pull the centromere apart and chromatids move away from each other, toward opposite ends of the cell. Now the chromatids are called chromosomes.

Telophase: The final phase1 of mitosis is telophase. During telophase, a new membrane forms around each set of chromosomes. The chromosomes become less tightly coiled. At the end of telophase, there are two new nuclei that are identical to each other and the original nucleus. However the cell has not divided.

2Replicate - make an identical copy

Cytokinesis:Cytokinesis is the final phase1 of cell division. During cytokinesis, the cytoplasm and its components divide to form two identical cells called daughter cells. During cytokinesis the cell membrane squeezes inward similar to squeezing the middle of a balloon.

Relevance:

1Phases – The steps in a process

1- Understanding mitosis provides us with a mechanism (the how) behind organisms evolving from unicellular to multicellular organisms.2- Understanding mitosis provides a foundation for meiosis (next lesson).3- Science jokes are awesome!

Grade/Subject Liberty Middle School – EDI 2013

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1) Use the guide below to draw each phase of cellular reproduction. Draw a box around and label the steps that together make up mitosis.

2) What are the 3 phases of the cell cycle?

3) Why is it important that the DNA replicates during interphase?

4) Explain what happens during each phase of cellular reproduction. Interphase:

Prophase:

Metaphase:

Anaphase:

Telophase:

Cytokinesis:

5) How is mitosis different from cytokinesis? If cytokinesis failed to happen what would be the outcome for the cell?

Grade/Subject Liberty Middle School – EDI 2013

4

Closure / Exit Ticket:

In your own words, explain why cellular reproduction is important to organisms.

In your own words, explain why cellular reproduction is important to organisms.

In your own words, explain why cellular reproduction is important to organisms.

In your own words, explain why cellular reproduction is important to organisms.

In your own words, explain why cellular reproduction is important to organisms.

In your own words, explain why cellular reproduction is important to organisms.

Grade/Subject Liberty Middle School – EDI 2013

5

Word Transfer

Ex. “When I say determine, you say figure out. When I say figure out, you say determine”

T Teacher pre-readsS Students read

T/S Teacher and Students readPS Pair Share on a higher order question

NV<3> Non-volunteer, about 3 studentsV Take a Volunteer

PS<SF> Pair Share on a higher order question and give them a sentence frameCFU Ask a higher order question to check for understandingCFU (in the Skill Development) Asking a process question may not be necessaryWB Students use a whiteboard for short response

Delivery Strategies Legend – Consider putting these symbols as reminders to use the strategies at first. You can delete them as you get used to the pattern of the delivery.

Do Not Print For Students