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California Genetics Standard 2E
# 9 Half of all our genetic
information comes from
each parent.
Sperms
EGG
Sperms Magnified
Genetics Standard 2E
Know why
approximately half of
an individual’s DNA
sequence comes from
each parent.
It is because when our parent
got together they both shared
their genetic make-up. This
genetic sharing is designed to
make a person better then each
parent because we are a
combination of both.
This genetic sharing
occurs at the instance
of fertilization (2N).
When sperm (1N) and
egg (1N) unite. Egg
and sperm cells are
also called gametes.
The formation of stronger &
smarter offspring, however,
begins during the formation of
eggs in a female’s ovaries and
during the formation of sperm
in the male’s testes.The process
of making sperms (testes) and
eggs (ovaries) is called meiosis.
During meiosis the cells
in the ovaries and the
testes use whole body
cells that have two set of
genetic information that
we get from each of our
parents.
Because the whole body cells
get one set of genetic info from
the sperm and the other from
the egg they are considered to
be Diploid 2N. During meiosis
the whole body cells undergo
a reduction division in which
the number of chromosomes is
cut in half 1N (haploid). This
means gametes only have one allele for each trait.
A multicellular organism develops
from a single zygote or fertilized
egg, and its phenotype depends on
its genotype, which is established
at fertilization (Standard 2D).
Haploid 1N
Egg
Haploid 1N
Sperm
Diploid 2N
+
=
Body Cell
1. What is the process that
allows for genetic sharing?
A.Meiosis
B. Mitosis
C. Fertilization
D. Transformation
2. What is the process that
makes sperm and eggs
called?
A.Meiosis
B. Mitosis
C. Fertilization
D. Transformation
3. Where are sperms made?
A. Ovaries
B. Testes
C. Urinary bladder
D. Fallopian Tubes
4. Where are eggs made?
A. Ovaries
B. Testes
C. Urinary bladder
D. Fallopian Tubes
5. During meiosis the diploid
2N body cell undergoes a
reduction to become?
A. 4N
B. 1N
C. Haploid
D. B & C