Today’s Agenda
Journal Question : What is a
chromosome?
*1. Lecture: Introduction to
Chromosomes, Mitosis & Meiosis
(slide 47)
2. Packet for Unit (Bring to class every
period)
(Buy Color Pencils & Glue Stick)
3. Today’s Focus: DNA Characteristics &
Chromosome Structure
4. Color first picture in packet: DNA: The
Double Helix.
5. Video: Genetics
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Cellular
Division/Reproduction
Dr. Rick Woodward
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DNA Characteristics
A. Long thin molecule
(double helix) that
stores genetic
information (Unit of
Heredity) “Blueprint for
Life”
B. Location: Nucleus of
the Cell
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DNA Characteristics
C. Function: Controls & Directs
Activities of the Cell
D. In humans there are 6 billion
pairs of nucleotides
- If a cell were the size of a
basketball, the DNA would
stretch for 40 miles!
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Chromosome
Structure
A. DNA is coiled into very
compact structures called
chromosomes.
B. Chromosomes are rodshaped structures of DNA
& Protein.
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Chromosome Structure
C. A histone is a protein molecule
that DNA wraps around during
chromosome formation.
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Anatomy of a Chromosome
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Chromosome Number
A. Each species has a
specific number of
chromosomes in each cell.
B. For each chromosome there
are two copies or one pair
(total):
(1) one from the mother
(2) one from father
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Chromosome Number
C. Humans have 46
chromosomes (23 pairs)
D. Gorillas have 48
chromosomes (24 pairs)
E. Your neighbor’s cat has 32
chromosomes (16 pairs)
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Genetically Engineered Cats
1. Some day these cats
may rule the planet with
the assistance of militant
cows.
2. What you are about see is
classified top secret by
the federal government.
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Not Genetically Modified
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Genetically Modified Cats
Martial Arts Super Cats
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Extreme Kung Fu Cat
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Bi-Pedal Snow Cat
Dodging a Bullet
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Karaoke Cats
Transmitting Code
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Gaming Nintendo Wii Cat
Genetically superior gaming skills
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Laser Cats
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Diabolical Joker Cat
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Cat-Mountain Goat
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More Laser Cats
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What is a Chromatid?
A. It is one of two identical
parts of a chromosome
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What is a Centromere?
A. Each
chromosome has
a central
constricted
region called a
centromere that
serves as an
attachment
point.
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What is a telomere?
A. The telomeres protect the
tips of the chromosomes
from damage.
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Sex Chromosomes
A. Determines the sex
of an organism.
B. In humans:
XX = female
XY = male
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Autosomes
A. An autosome is a chromosome
that is not a sex chromosome.
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Karyotype: A Picture of an
Individual’s Chromosomes
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Homologous
Chromosomes
A. Every cell of an organism produced
by sexual reproduction has two
copies of each autosome.
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Homologous
Chromosomes
B. We get one copy of each
autosome from each
parent.
C. Two copies of each
chromosome are called
homologous pairs of
chromosomes.
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*Haploid (1n) vs. Diploid (2n) Cells
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A. Haploid Cells (1n)
(1) One set of chromosomes
(2) Sperm cells
(3) Egg cells
B. Diploid Cells (2n)
(1) Two sets of chromosomes
(2) All non-reproductive cells.
(3) Zygote/Fertilized Egg
C. Red blood cells do not have any
chromosomes because they are
missing a nucleus
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Prokaryote vs. Eukaryote
A. Prokaryotes lack membranebound organelles.
1. Bacteria
B. Eukaryotes have membranebound organelles
(mitochondria, nucleus, etc.)
1. Plants & Animals
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Cell Division in
Prokaryotes
BINARY FISSION is the
division of a prokaryotic
cell (bacteria) into two
identical cells!
1. DNA copied
2. Cell begins to divide
3. Two identical haploid
cells.
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CELL DIVISION IN EUKARYOTES
Both the cytoplasm and the
nucleus divide.
 Two types:
1. MITOSIS (clones)
A. Reproduction of unicellular
organisms
B. Addition of cells to a tissue or
organ.
2. MEIOSIS (gametes/sex cells)
A. 1/2 the chromosome number
B. Cells recombine in sexual
reproduction.

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DNA Replication
The DNA must be copied and then
divided exactly so that each cell gets an
identical copy.
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Cellular Reproduction
(Mitosis)
A. Growth is the result
of a cell’s ability to
reproduce itself.
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Cellular Reproduction
(Mitosis)
(1) New body cells are
produced from other,
already existing cells; when
one cell becomes two.
(Recall “The Cell Theory”)
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Cellular Reproduction
(Mitosis)
(2) Examples: Skin
cells, intestinal tracts
cells are continuously
being replaced.
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Cellular Reproduction
(Mitosis)
B. New cells are produced
that contain the same
genetic information as
the cells from which they
came.
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Cellular Reproduction
C. Mitosis = The process that
produces and replaces body
cells; exact copies.
(i.e. skin cells)
1. Continuance of an individual’s
growth throughout life.
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Cellular Reproduction
D. Meiosis = The process that
produces reproductive cells
needed for the formation of new
individuals.
1. Continuance of the species.
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Cellular Reproduction
I. Life from Life = Cells from Cells
A. Disproving Spontaneous
Generation:
(1668, Francesco Redi’s
controlled experiment showed
that maggots do not
spontaneously generate from
decaying meat.)
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Cellular Reproduction
B. Louis Pasteur disproved the theory
that microorganisms are not
spontaneously generated from air.
1. Used a flask with a long S-shaped
neck, boiled broth.
2. Pasteurization is the partial
sterilization of a substance by
increasing the temperature of that
substance to destroy objectionable
organisms (i.e. bacteria).
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Cellular Reproduction
C. Reproduction of Body Cells (Mitosis)
1. Cell reproduction occurs when parent
cells divide.
A. Two new daughter cells arise from
each parent cell.
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Cellular Reproduction
B. After reaching full
development, an organism
needs new cells to:
(1) repair damaged tissue,
replace cells that are lost
from outer surfaces (skin
cells) and resist disease.
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Cellular Reproduction
C. It is estimated that 25 million
cell divisions occur every
second in the adult human body.
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Cellular Reproduction
D. Rapid cell division or cell
growth that is out of
control is called cancer.
1. Suffix: -oma
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Looking at Cancer Cells
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
Today’s Agenda:
Journal Questions:
a. What is the difference between mitosis
and meiosis?
*1. Lecture: Cellular Reproduction & The
Stages of Mitosis (Slide …..)
2. Film on Cell Division
3. Homework: Work on packet and study
4. Lab next class: Karyotype Activity &
Microscope lab – Identifying the stages of
cell division.
5. Study Guide given out next week. (Exam
will also cover the organelles of the cell)
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The Cell Cycle
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Cellular Reproduction
2. The Cell Cycle
(Interphase + Mitosis = The Cell
Cycle)
“Interphase”
(1) Interphase (nonreproducing stage that follows
when cell reproduction/replication
is complete)
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Cellular Reproduction
(2) DNA Synthesis & Duplication
occur during Interphase.
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Cellular Reproduction
2. The Cell Cycle continued…
A. The cell spends most of its
life in interphase.
B. Chromatin is present in the
nucleus during interphase.
C. Midway through interphase
each chromosome and the
DNA it contains replicates.
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Mitosis
Mitosis = Division of nuclear material
a. There are four stages
b. Mitosis occurs in most of the cells in
Eukaryotes.
 P.M.A.T.
Please make another taco.

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Prophase, Metaphase, Anaphase, Telophase
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Vocabulary
-Centromere = region where two
chromatids join
-Chromatid = Either of two strands
that together form a chromosome.
-Gamete = Sex Cell (Sperm or Egg)
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Anatomy of a Chromosome
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Anatomy of a Chromosome
Review: A. The telomeres
protect the tips of the
chromosomes from damage.
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Anatomy of a Chromosome
Review: A histone is a protein
molecule that DNA wraps around
during chromosome formation.
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Vocabulary
-Cell plate = forms the plasma
membrane between two new
plant cells.
-Spindle (shown in green) =
Structure located between the
centrioles of a cell.
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The Four Stages of
Mitosis
(1) Prophase (first stage of mitosis)
A. Chromosomes condense
and organize: nuclear
membranes and nucleoli
disappear; spindle apparatus
assemble and attach to
centromeres of duplicated
chromosomes.
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-Each strand is a replica of the
other and is called a chromatid. 64
The Four Stages of
Mitosis
(2) Metaphase (second stage of
mitosis)
A. Spindles line up duplicated
chromosomes along the equator
(middle) of the cell, one spindle to
each half or chromatid of the
duplicated chromosome.
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The Four Stages of
Mitosis
(3) Anaphase (third stage of mitosis)
A. The centromere of each
duplicated chromosome is
separated and paired chromatids
are pulled apart.
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The Four Stages of
Mitosis
(4) Telophase (Forth stage of mitosis)
A. Chromosomes uncoil: nucleoli
reappear, cytokinesis
(Cyto = cell, Kine = movement)
occurs and genetically identical
daughter cells are produced.
-(In animal cells, the plasma
membrane pinches in.)
-(In most plants, a cell plate begins
to appear.)
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Cytokinesis
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Mitosis Animation
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Summary of Mitosis

Prophase:
 Chromosomes condense
 Nuclear envelope disappears
 centrosomes move to opposite sides of the cell
 Spindle forms and attaches to centromeres on
the chromosomes

Metaphase
 Chromosomes lined up on equator of spindle
 centrosomes at opposite ends of cell
Anaphase
 Centromeres divide: each 2-chromatid
chromosome becomes two 1-chromatid
chromosomes
 Chromosomes pulled to opposite poles by the
spindle
Telophase
 Chromosomes de-condense
 Nuclear envelope reappears
 Cytokinesis: the cytoplasm is divided into 2 cells


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Mitosis Review
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Control of the Cell Cycle
A. Rate of Cell Division
1. Different types of cells divide
at different rates.
2. Bone marrow cells
reproduce rapidly to form new
red blood cells.
-Red Blood Cells are replaced
every 120 days.
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Control of the Cell Cycle
3. Nerve and muscle cells
never reproduce once
they mature.
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Control of the Cell Cycle
4. If one kind of cell begins
to reproduce too rapidly,
cancer develops.
(a) Malignant Cancers are
deadly.
(b) Benign Cancers are
not usually deadly.
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Regulation of the Cell Cycle
A. Most normal cells will divide
repeatedly until they come in
contact with another cell.
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Regulation of the Cell Cycle
B. When cells stop dividing, they
always stop at the same point in
the cell cycle –just before DNA
replication begins in interphase.
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Regulation of the Cell Cycle
C. Control proteins have
been discovered that
can activate mitosis.
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Meiosis (Sexual Reproduction)
A. Meiosis – Reduces the
chromosome number by
half and results in new
genetic combinations in
the gametes.
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Meiosis (Sexual Reproduction)
B. This process of cell division is involved
in sexual reproduction.
(1) Recall: Mitosis is for cellular
reproduction
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Meiosis (Sexual Reproduction)
C. In animals meiosis often results in two
gametes: haploid egg (1n) cells and
haploid sperm cells (1n).
(1) Sperm (n) + Egg (n) =
Zygote/Fertilized Egg (diploid/2n)
(2) Zygote develops into a new organism.
(3) Meiosis and fertilization are important
processes because they result in genetic
variation.
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Meiosis (Sexual Reproduction)
D. In meiosis two nuclear divisions
take place (Meiosis I, Meiosis II)
instead of one as in mitosis.
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Meiosis (Sexual Reproduction)
E. Meiosis I, like mitosis,
follows a period of interphase.
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Meiosis (Sexual Reproduction)
F. Meiosis II occurs in each cell
formed during Meiosis I.
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Production of Reproductive Cells
Chromosome Numbers & Characters
A. Diploid Cells
1. Animal Cells – Chromosomes
come in pairs.
2. Simple Plant Cells – Do not
have paired chromosomes (i.e.
moss, fungi)
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Production of Reproductive Cells
(Meiosis)
Chromosome Numbers & Characters
3. Complex Plants have paired
chromosomes.
(i.e. carrots, cabbages, oak trees)
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Production of Reproductive Cells
(Meiosis)
Chromosome Numbers & Characters
4. Human Cells have 23 pairs of
chromosomes; a fruit fly cell’s
contain four pairs of chromosomes.
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Cell Reproduction in
Prokaryotes
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A. Cell reproduction in
prokaryotes (bacteria) is
through binary fission.
B. Each new cell receives a
copy of the single
chromosome.
C. Prokaryotes have a single
chromosome (no protein
spools)
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Steps of Binary Fission in Bacteria
See Packet (p.39)
1. The single chromosome is attached
to the inside of the cell membrane.
2. A duplicate chromosome is formed.
3. The new chromosome attaches to
the cell membrane.
4. Growth of new cell membrane and
cell wall material separates the two
copies of the chromosome and
elongates the cell.
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Steps of Binary Fission in Bacteria
5. More new membrane and cell
wall form and push inward at
the midpoint of the length of
the cell.
6. The two chromosomes
become separated.
7. Two separate daughter cells
are produced.
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Cellular Reproduction
“Answers to first page of packet” p.37
Many early scientists performed
faulty experiments that convinced
them that (1) nonliving things
could give rise to living things.
This idea is called (2)
spontaneous generation.
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Cellular Reproduction
In 1668, (3) Francisco Redi
disproved this theory. However, in
1675, the world of (4)
microorganisms was discovered,
reopening the split between
scientists over spontaneous
generation.
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Cellular Reproduction
An experiment performed by (5)
Louis Pasteur in 1864 ended the
debate. At the time, (6) air was
believed to be necessary for
spontaneous generation. Pasteur
proved that microorganisms are
not spontaneously generated.
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Cellular Reproduction
This work led to the theory of (7)
biogenesis, which stated that all
organisms are produced from other
(8) organisms. This tied in with
the (9) cell theory, formulated
about the same time. By the late
19th century, scientists worked with
these two theories that indicated
that all life must come from (10)
life.
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Cellular Reproduction
11. Early in the organism’s
development, the cells contribute
to overall growth. Later, new cells
are needed to repair damaged
tissues, replace lost cells, and
resist disease.
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Cellular Reproduction
12. What would happen to a cell if it
continued to grow unchecked?
The surface area of the plasma
membrane would not be large
enough to meet the cell’s needs.
The cell would stare or become
poisoned.
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Cellular Reproduction
13. Replication is the process of
making an exact copy. It provides
the cell with a second set of
chromosomes for reproduction.
14. Interphase and mitosis make up
the cell cycle.
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Work on the Karyotype in your packet
1. Cut out chromosomes.
2. Arrange into homologous pairs.
3. Tall to Small, Number 1-23 pairs:
(Recall 1-22 = Autosomes)
(23 = Sex Chromosomes)
4. Glue into your composition book.
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Today’s Agenda
Journal Question: What is a
karyotype?
1. Study guide for Exam – Answer
questions 1-42.
2. Finish your karyotype.
3. Finish your packet.
4. Micro-slide viewer lab
5. Homework: Study, Complete all of
your work.
6. Everything is due on Exam day.
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Pay Attention!
1. Micro-slide viewer activity first!
a. Plant Mitosis Slide
b. Meiosis Slide
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Today’s Lab Questions:
Write down questions 1-8 in
your composition book
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1. What is the difference between mitosis, meiosis, and
binary fission?
2. What do homologous pairs of chromosomes refer to?
3. Label the parts of a chromosome: Chromatid,
Centromere, Gene
4. How many pairs of chromosomes do human’s have?
5. What does XX = ________ and XY = __________
6. What is a karyotype?
7. What is the function of a spindle fiber? What is a
tetrad?
8. Diagram a picture of the Cell Cycle. Include: G1, S,
101
G2, M
Today’ s Cell Cycle Lab
1. Carefully read all instructions on
today’s laboratory handout (which is
in your unit packet).
2. Diagram/Draw all phases on the cell
cycle in your composition book.
3. List two facts for each phase.
4. Answer questions 1-8 from the
laboratory handout in your
composition book.
5. Start studying tonight for your exam.
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Different Stages of the Cell Cycle
(Onion Root Tip): Today’s Lab
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Today’s Agenda:
*1.Brief Lecture: Reviewing
Mitosis & Meiosis
2. Answer Study Guide
Questions 1-42.
3. Complete Unit Packet
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Exchanging Genetic
Information: Crossing Over
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Crossing Over
Exchanging genetic information
and producing genetic variation.
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Crossing Over
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*Gametes are genetically
different from the parent cell
because….
*1. Independent assortment/Crossing Over
*2. Meiosis is important to make gametes.
*3. Meisosis and fertilization are important
because the end result is genetic variation.
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Tetrads
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Tetrad
When the two homologous pairs are aligned
(side by side) we call the pair a tetrad.
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Mitosis
Somatic Cells = Body Cells
ie. Skin Cells
Cells that make up your toe….mitosis.
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Meiosis
Gametes: Reproduction
A. ____ Determines the gender of the child.
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Meiosis
Gametes (Sex Cells)
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Haploid (1n) Diploid (2)
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Work on your Study Guide!
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Get Started….
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