Mitosis and Meiosis

Biology II

Warm-up (10-31-14)

• What are mitosis and meiosis?

• Why are there two processes? What is the difference?

Outline for the day

• Objectives• Cell Introduction

Objectives

• To introduce the topic of mitosis and meiosis and begin the description of cell division.

Warm up (11-3-14)

• Why is cell division important to the cell?• What has to happen in order for a cell to

divide?

Outline

• Objectives• Cell Cycle Notes

Objectives

• To determine what the cell cycle is and what its purpose is.

The Cell Cycle

• What is it?• What are the parts?• What is cell division?• Why is cell division important?

Cell Division

• Rudolf Virchow– German Physician– All cells must come from a previously existing cell– 1855– Part of cell theory

• In order to have cells reproducing, they have to go through cell division (reproduction of cells)

Cell Division

• Can either produce an entire organism or just a small portion of one.– Give an example of a situation where cell division

produces an entire organism…• Think of the differences between cells… we have both

unicellular and multicellular organisms

• Why is it important?– Renew and repair damaged cells– Growth of an organism (think of how babies begin…

how many cells are they at first?)

Cell Cycle

• Life of a cell from first formation through cell division

• What is produced at the end of the cell cycle?– Identical daughter cells with identical genetic

material– What is an evolutionary significance of having

identical genetic information?– What might an evolutionary disadvantage be of

having identical genetic information?

Cellular Organization

• Genome: cell’s DNA or genetic information– Prokaryote: a single long DNA molecule– Eukaryote: a number of DNA molecules

• Overall length of DNA is very long in eukaryotes

• Chromosomes: package of DNA molecules– Each eukaryote has a unique number of

chromosomes…. How many do humans have?• Somatic cells: have 46 chromosomes or 23 pairs of

chromosomes• Gametes: only have 23 chromosomes…. Why is this

important??

Distribution of Chromosomes

• Chromatin: makes up chromosomes in eukaryotes, DNA and its associated proteins

• Sister chromatids: compose a duplicated chromosome– Each contain identical DNA– In condensed form, it has a center region where

the sister chromatids are most closely attached called the centromere

– After separation, they are individual chromosomes

Mitosis vs. Cytokinesis vs. Meiosis

• Mitosis: division of the nucleus, production of somatic cells

• Cytokinesis: division of the cytoplasm• Meiosis: production of gametes, daughter

cells are not identical to parent, they only have one set of chromosomes

Is a cell always dividing?

• Phases of the cell cycle– Mitotic (M) phase• Mitosis and cytokinesis• Typically the shortest part of the cell cycle

– Interphase• 90% of cell cycle

– Cell grows, replicates DNA, prepares for cell division1. G1 phase (first gap)2. S phase (synthesis)3. G2 phase (second gap)– Cell grows, produces proteins, produces organelles4. finally, comes the Mitotic phase (not part of interphase)

Stages of Mitosis

1. Prophase2. Prometaphase3. Metaphase4. Anaphase5. Telophase

1. Cytokinesis overlaps with the later stages of mitosis

Look at the pictures!!

• Check out the diagram and discuss what you notice. What are some of the interesting defining characteristics during each of the phases?

• Now look at the worksheet. It will help walk you through the different stages of mitosis

Regulation of Mitosis

• There is a checkpoint system built into the cell cycle.– Molecular control– G2 checkpoint– M phase checkpoint

• Separation of sister chromatids cannot begin until lined up at metaphase plate and attached to spindle fibers

• Why is it evolutionarily beneficial to have the regulation of mitosis?– What does having checkpoints help prevent?

Haploid vs. Diploid

Haploid• The daughter cell has half of

the number of chromosomes as the parent cell

Diploid• The daughter cell has the

same number of chromosomes as the parent cell

Meiosis

• Meiosis I– Looks similar to mitosis

• Meiosis II– Creates a haploid cell

Warm up (11-4-14)

• What are the stages of the Cell Cycle?

• What is the advantage of the cell cycle?

Outline

• Objectives• Cell Cycle and Cell Division Notes

Objectives

• To determine how cell division occurs and the steps that must happen during cell division.

Warm up (11-5-14)

• Do you think all cells go through the cell cycle at the same rate? Give an example of cells that you think reproduce quickly

Outline

• Objectives

Objectives

• To determine how cell division occurs and the steps that must happen during cell division.

Meiosis Animation

• http://www.sumanasinc.com/webcontent/animations/content/meiosis.html

Warm up (11-6-14)

• What are the four phases of mitosis and what happens during each phase?

Outline

• Objectives

Objectives

• To determine how cell division occurs and the steps that must happen during cell division.

Twizzler Mitosis and Meiosis

Warm up (11-7-14)

• Think of why each of the phases in mitosis is evolutionarily significant. In other words, how are each of these phases an adaptation that allows a cell to be better suited for its environment?

Outline

• Objectives• Mitosis and Meiosis lab prep

Objectives

• To determine how cell division occurs and the steps that must happen during cell division.

• To prepare for the mitosis and meiosis Lab by gaining background information from the lab manual

Warm up (11-10-14)

• Judging by what you know about mitosis and meiosis, what is an evolutionary advantage to having haploid cells?

• Think of a situation where having haploid cells might not be advantageous.

Outline

• Objectives• Mitosis and Meiosis lab prep

Objectives

• To prepare for the mitosis and meiosis Lab by gaining background information from the lab manual

Cell Cycle and Cell Division

• http://www.biologycorner.com/bio1/notes_cell_division.html

• Mitosis vs. Meiosis• http://

www.youtube.com/watch?v=zGVBAHAsjJM

Lab Notebook Set Up

Warm up (11-11-14)

• What is the purpose of the mitosis and meiosis lab?

• In your lab notebooks, write a hypothesis about what you think will occur in this experiment

Outline

• Objectives• Mitosis and Meiosis lab demo

Objectives

• To demonstrate the mitosis and meiosis Lab by showing the students exactly what they will be doing in the lab for the rest of the week

Virtual Lab!!

• http://www.phschool.com/science/biology_place/labbench/

Warm up (11-12-14)

• What is one thing that is really important to remember while doing the mitosis and meiosis lab?

• What do you think, just by reading the procedure and the background information is something we, as practicing scientists, could do to assist with experimental design?

Outline

• Objectives• Mitosis and Meiosis lab

Objectives

• To begin the meiosis and mitosis lab, to gain a deeper understanding of the individual phases of mitosis and meiosis by looking at onion root cells.

Warm up (11-13-14)

• As practicing scientists, what are some suggestions we can make to improve our personal experimental design to reduce the number of errors?

• For example, think about our methods and procedures

Outline

• Objectives• Mitosis and Meiosis lab

Objectives

• To begin the meiosis and mitosis lab, to gain a deeper understanding of the individual phases of mitosis and meiosis by looking at onion root cells.

Warm up (11-14-14)

• As practicing scientists, what are some suggestions we can make to improve our personal experimental design to reduce the number of errors?

• For example, think about our methods and procedures

Outline

• Objectives• Mitosis and Meiosis lab

Objectives

• To begin the meiosis and mitosis lab, to gain a deeper understanding of the individual phases of mitosis and meiosis by looking at onion root cells.

Warm up (11-17-14)

Outline

• Objectives• Mitosis and Meiosis lab

Objectives

• To begin the meiosis and mitosis lab, to gain a deeper understanding of the individual phases of mitosis and meiosis by looking at onion root cells.

Warm up (11-18-14)

Outline

• Objectives• Mitosis and Meiosis lab

Objectives

• To begin the meiosis and mitosis lab, to gain a deeper understanding of the individual phases of mitosis and meiosis by looking at onion root cells.

Warm up (11-19-14)

Outline

• Objectives• Mitosis and Meiosis lab

Objectives

• To begin the meiosis and mitosis lab, to gain a deeper understanding of the individual phases of mitosis and meiosis by looking at onion root cells.

Warm up (11-20-14)

Outline

• Objectives• Mitosis and Meiosis lab

Objectives

• To begin the meiosis and mitosis lab, to gain a deeper understanding of the individual phases of mitosis and meiosis by looking at onion root cells.

Warm up (11-21-14)

Outline

• Objectives• Mitosis and Meiosis lab

Objectives

• To begin the meiosis and mitosis lab, to gain a deeper understanding of the individual phases of mitosis and meiosis by looking at onion root cells.