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 division
1. G1 phase (first gap)
2. S phase (synthesis)
3. G2 phase (second gap)
– Cell grows, produces proteins, produces organelles
4. finally, comes the Mitotic phase (not part of interphase)
Stages of Mitosis
1.
2.
3.
4.
5.
Prophase
Prometaphase
Metaphase
Anaphase
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/ani
mations/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_ce
ll_division.html
• Mitosis vs. Meiosis
• http://www.youtube.com/watch?v=zGVBAHA
sjJM
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_pl
ace/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.