sex chromosome
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Transcript sex chromosome
Sex Cells (Also called gametes)
Egg Cell (or ovum)
Sperm Cell
Sex Chromosomes
23 chromosomes in each sex cell
23rd chromosome is the “sex
chromosome”
Egg cell always carries
the “X” sex
chromosome
Sperm cell can carry
the “X” or the “Y” sex
chromosome
Which sex cell determines the
sex of the baby?
Genes
found
pass
on chromosomes
genetic traits to offspring
will be expressed if one
of the parents has the
gene for that trait.
will be expressed only if
both parents carry the
trait.
Definition: the process of
becoming pregnant
including fertilization
Starts with two tiny cells
(sperm and egg) that
join together to grow
into a baby
Fertilization
The strongest, fastest healthiest sperm
have the best chance of fertilizing the egg
Or
maybe the
most charming…
Clip
How does a woman know if
she is pregnant?
Missed period
Breast tenderness or fullness
Nausea and sometimes vomiting
Changes in appetite
Urination
Tiredness
Pregnancy Tests
Urine
test – tests for
pregnancy
hormone, HCG
Pelvic
exam –
checks for
enlarged cervix
Single cell formed
at conception by
union of sperm
and egg
Contains genetic
material from
both parents
From Zygote to Embryo
Zygote divides into a multi-celled mass
called an embryo as it travels down the
fallopian tubes
Embryo searches for a place to implant in
the uterine lining, or endometrium
It actually burrows beneath the surface
Actual image of implantation
After about two months, the embryo takes
on a human appearance and is now
called a fetus.
EMBRYO
FETUS
Click the photo to see the first few
weeks of development.
Formation of Twins
Identical
One egg and one
sperm
Zygote divides and
separates into two
Each have the same
DNA
Fraternal
Two eggs and two
sperm
Each have different
DNA
Grows from the
outer edges of the
embryo
Connects embryo
to uterine wall
Filters nutrients and
waste between
mother and baby
Grows between
placenta and baby
Provides baby with
oxygen and nutrients
Amniotic Sac
Thin, but strong, membrane filled with
fluid that cushions and protects the
fetus and regulates its temperature
How can smoking during a
pregnancy affect the baby?
After birth:
In the womb:
Low birth weight
Stillborn baby
Increased risk of
birth defects
Premature birth
Asthma and
breathing
problems
Increased risk of
SIDS
Affects physical
and intellectual
growth
Behavioral
problems
Did You Know?
Pregnant women who use drugs such
as heroin, cocaine, marijuana, PCP,
methadone, and/or amphetamines
may give birth to drug-addicted
babies.
How does alcohol use affect
the baby?
Increased risk of miscarriage
Birth defects
Fetal Alcohol syndrome (FAS)
- facial abnormalities
- malformations of the heart
- growth retardation
- mental disorders
“Water breaks” - amniotic sac bursts, the
fluid is released through the vaginal canal
Contractions - uterine muscles give
cramping sensation as cervix starts to
dilate
Either one could happen first!
Birth
Natural
birth - Baby is pushed out
through birth canal (vagina)
Caesarian section – Baby is removed
from uterus via surgery
Click the photo to see how the baby
makes its way out of the womb.
First Breath
The hole in the heart will
close, changing the heart
from a one-pump heart to a
two-pump heart.
The linking passage outside the heart will close
off and force oxygenated blood to the lungs so
the baby can take its first breath.
Umbilical cord
ceases working and
is cut and clamped
Placenta detaches
from the side of the
uterus and is pushed
out