 Homework:  Work on PS 14  Do Now:  Take out your Mitosis worksheet  Get back your test and look it over  Today’s Goals:  Describe the purpose and steps of the cell cycle  Describe the anatomy of a chromosome and explain how it changes during the cell cycle  Agenda:  Review Test 8  Lecture/Discussion: Cell Cycle & Mitosis

AP Biology - 3/1/11

 One cell grows and divides into two new cells  Purpose:  Growth  Replace dead cells  Repair tissues after injury  Asexual reproduction (in single-celled organisms) Amoeba reproducing

Stages of Mitosis Video: Mitosis.mpgMitosis.mpg

 Interphase: growth; copying of chromosomes & organelles  G1 phase: Cell grows  S phase: DNA replicates  G2 phase: More growth; cell prepares to divide  Mitosis: Chromosomes separate to form two new nuclei  Cytokinesis: Cell splits to form two new identical cells

G1 Phase:  Chromosomes are un- replicated - each contains one copy of its DNA G2 Phase:  Chromosomes are replicated - each contains two exact copies of its DNA Un-Replicated Chromosome Centromere – a small spot in the center of a chromosome Replicated Chromosome Sister Chromatids – two halves of a replicated chromosome – exact copies of each other Centromere S Phase: DNA Replication creates replicated chromosomes

 So they can split during mitosis and separate into two new cells  Each cell gets an exact copy of each chromosome ! Objectives for Class: Describe the purpose and steps of mitosis and cytokinesis. Draw diagrams showing how mitosis/cytokinesis separate chromosomes into two new cells..

Mitosis Animation

Animal cell:Plant Cells:

Prophase Anaphase Telophase/Cytokinesis Metaphase

 Chromosomes condense (become thicker and visible under the microscope)  Nuclear membrane begins to distintegrate  Centrosomes/centrioles move towards poles, and spindle apparatus forms Objectives for Class: Explain how mitosis separates the cell’s DNA into two different nuclei to create two new cells.

 Spindle is fully assembled, with centrosomes at opposite poles  Chromosomes lined up along middle of cell Objectives for Class: Explain how mitosis separates the cell’s DNA into two different nuclei to create two new cells.

 Sister chromatids separate into two unreplicated chromosomes and begin to move to opposite ends of the cell Objectives for Class: Explain how mitosis separates the cell’s DNA into two different nuclei to create two new cells.

 Two new nuclei form (membranes re-form)  Chromosomes de-condense (become thinner & less visible) Objectives for Class: Explain how mitosis separates the cell’s DNA into two different nuclei to create two new cells.

 Homework:  Analysis Questions for Lab 3A due tomorrow  Transformation Lab Report due Friday  Do Now:  Take out your Mitosis lab packet and turn to page 2  Find the region of the root tip in which you think the cell cycle will be happening fastest  Today’s Goals:  Identify stages of the cell cycle under the microscope  Determine the length of time that onion root tip cells spend in each phase of the cell cycle  Agenda:  Lab!

 Which phase do you think takes the longest? Why?  How can we figure this out using prepared slides like the one in the Do Now?

Homework:  Completed Transformation Lab Report due tomorrow Do Now:  Take out your Mitosis lab packet and turn to your results  Be ready to read out your data for each stage Today’s Agenda and Goals: 1. Mitosis Wrap-up:  Confirm and explain the results of the lab  Explain cytokinesis and plant/animal cell differences 2. Introduction to Embryology:  Brainstorm  Video

Cell splits to create two daughter cells – each with its own nucleus with identical chromosomes  Animal cells: cell membrane pinches inward to separate the two cells  Plant cells: new cell wall built by cellulose- containing vesicles aligning and fusing along the middle of the cell Objectives for Class: Explain how mitosis separates the cell’s DNA into two different nuclei to create two new cells.

Animal Cell Mitosis under the Microscope: 12_06AnimalMitosis_SV.mpg 12_06AnimalMitosis_SV.mpg

Pass your Mitosis Lab forward… Brainstorm: What comes to mind when you think of embryonic development?  What do you know about this process?  What are some of the things that happen in this process?  What questions do you have?

 Starts w/ fertilized egg (zygote)  Zygote divides and divides (mitotic cell cycle)  Cell differentiation/specialization  Development of different organs  Growth

Goals for Today:  Describe and illustrate key terms relating to embryonic development  Describe the key stages in early embryonic development  Describe the origins and development of the three embryonic germ layers

Homework:  Problem Set 14 will be due next WEDNESDAY.  Over the weekend, you should:  Do Section A and Section B  Be ready to present on your assigned question from Section C Do Now: 1. Take out the Embryonic Development packet and spend a few minutes answering #4 on page Take out PS 14 and read questions 6-8. Choose one you want to work on.

Today’s Goals: You will be able to:  Describe the development from zygote to embryo to fetus, and  Identify key stages and processes in embryonic development Agenda: In groups: 1. Complete Part 2 of the Embryonic Development packet 2. Take notes on your assigned question from PS 14.

a) Interphase b) Cytokinesis c) S phase d) Anaphase e) G1 f) G2 g) Metaphase h) Prophase i) Telophase j) Prophase k) Mitosis