Reproduction and
Development
The Cycle of Life
You
Cancer
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Disorder caused when cells lose the
ability to control the cell cycle
Damaged cells replicate without
control or fail to self-destruct when
needed
Damaged cells form a tumor that
invade healthy functioning tissue
Cells can metastasize (move to new
areas of the body)
The Cell Cycle
Interphase
Interphase (cont)
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Time of growth, normal activity,
and preparation for division
___- some cells enter this stage
after birth; they perform normal
processes but do not prepare for
division; some cell enter for awhile,
some for life
___- time of growth and normal
activities
Interphase (cont)
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___- replication of DNA, two copies
of the same chromosome are now
held together at a centromere; cell
will prepare the protein that will
form the spindle and prepare the
centrioles
___- time for growth and normal
activities; extra cellular components
are also made
Cell Division
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Occurs in two stages
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Mitosis- division of the ________
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Cytokinesis- division of ____________
Mitosis
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Division in ________ cell
Divides one cell into two _________
__________ cells
Cells start ______ and end ______
DNA Review
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Chromatin
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Form of DNA
during ________
Chromosome
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Form of DNA
during cell division
__________center point
holding two sister
chromatids
together
Sister _________two copies of a
chromosome held
together by a
centromere
Prophase
Prometaphase
Metaphase
Anaphase
Telophase
Cytokinesis
Controlling the Cell Cycle
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Factors affecting mitotic rate
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___________- cells stop growing as they
crowd (outside)
_________ and growth factors- chemical
signals from outside cell (outside)
Cyclins and kinases- chemical signal
from inside cell (________)
Controlling the Cell Cycle (cont)
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__________- tips of chromosomes
with repeating DNA sequence (inside)
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Shortens every time mitosis occurs
Cells only divide about 50 times before
stopping division
Some cells can divide more because
telomerase repairs the telomeres
Controlling the Cell Cycle (cont)
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Checkpoints (inside)
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DNA Damage Checkpoint (___)- halts
division until damage can be repaired
Apoptosis Checkpoint (___)- enough
survivins must accumulate to push cell
into division
Spindle Assembly Checkpoint
(_________)- halts mitosis if
chromosomes are not properly
attached to spindle
Cell Death- Apoptosis
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Cell receives signal
Caspases destroy cell creating small
pieces that can be phagocytized
Mitosis and apoptosis are used
together to create structures and
keep them healthy
Down Syndrome
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Disorder caused by
gametes that were
made improperly
during meiosis
Individuals receive
an extra
chromosome 21
The extra genetic
material leads to
the symptoms
Meiosis
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Division to form __________
Creates four ______ cells
Cells start ______ but end _______
Occurs in ____ divisions
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Reduction division- cuts chromosome
number in ______
Equational division- very similar to
mitosis
Prophase I
Prometaphase I
Metaphase I
Anaphase I
Telophase I
Cytokinesis I
Meiosis II
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Similar to _______
Two haploid cells created by Meiosis
I both divide
Creates four haploid cells
Spermatogenesis
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Spermatogomium stem cell divides
(mitosis) to form one spermatogonium
and one primary spermatocyte
Primary spermatocyte divided (meiosis I)
to form two secondary spermatocytes
Both secondary spermatocytes divide
(meiosis II) to form four spermatids
Spermatids mature into sperm
Oogenesis
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Oogonium stem cell develops into
primary oocyte
Primary oocyte divides (meiosis I)
to form one large secondary oocyte
and one small polar body
After fertilization, both divide
(meiosis II) to form one zygote and
three polar bodies
Sirenomelia
Pregnancy
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Begins at fertilization in the
________________
Divided into trimesters
Gestation length- ___ weeks
First 8 weeks- ______
Remaining time- ____
Embryonic Development
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Zygote goes through cleavage (rapid
division) to form a morula and then a
blastocyst
Blastocyst implants in uterus forming
structures like placenta to
communicate with mother
Neural tube develops
Organogenesis begins forming
primitive organs
Fetal Development
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Growth and maturation of
structures formed during embryonic
period
Usually ultrasound preformed at 20
weeks to look for abnormalities; sex
can be determined at this time
Multiples
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Dizygotic (________) twins- two
eggs, two sperm, alike as siblings
but share uterine environment
Monozygotic (_______) twins- one
egg, one sperm, same DNA
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Different types depending on what
supporting structures they share
If separate late, twins may become
conjoined
Birth Defects
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Can be _________ or __________
controlled
Genetic birth defects can be passed
to other generations
Teratogens (chemicals causing birth
defects) are environmental
Some birth defects are apparent
some are subtle
Teratogens
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Thalidomide
Illegal drugs
Alcohol
Cigarettes
Vitamins (overdose)
Some drugs
Some viruses
The Critical Period
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Structures are affected if the toxin
or the gene is around during that
structure’s critical period
The brain’s critical period lasts
throughout pregnancy so many
birth defects have an effect here
Cell Specialization
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≈ ____ different cell specializations
Beginning cells of embryo are
totipotent (can give rise to ____
other cell types)
Later in development these early
cells create stem cells which are
pluripotent (may give rise to ____,
but not all, cell types)
Stem Cells
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Stem Cell Divisions
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Can divide into two ____________
Can divide to form one stem and one
__________ cell
Progenitor cells go to divide and
specialize into mature cell types
Sources of Stem Cells
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Embryonic Stem Cells (ES cells)
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Obtained from 5-day old embryos
Create an embryo clone using somatic
cell nuclear transfer
Somatic Stem Cells
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Collect stem cells from umbilical cord
blood
Collect or stimulate stem cell in organs
throughout the body
Aging
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Systems seem to peak at about ___
Many dominant genetic disorders
will occur
Other multifactorial disorders will
occur as environmental factors
accumulate