Transcript Power Point 3 - G. Holmes Braddock

Benchmark 16.1
 By:
Danny Ramirez and Alex Esteva
Mendel's Law of Segregation
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Mendel's Law of Segregation states that allele pairs separate or
segregate during gamete formation, and randomly unite at
fertilization.
Mendel's law of independent
assortment
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Mendel's law of independent assortment states that the laws of
chance govern which particular characteristics of the parental pairs
will occur in each individual offspring.
Vocabulary
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Autosomal: the gene responsible for the
phenotype is located on one of the 22 pairs
of autosomes.
X-linked: the gene that encodes for the trait
is located on the X chromosome.
Dominant: conditions that are manifest in
heterozygotes.
Recessive: conditions are only manifest in
individuals who have two copies of the
mutant allele.
Mendelian Inheritance Patterns
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Mendel found the Mendelian Inheritance patterns. The four type of
patterns referred to single gene inheritance.
Autosomal Dominant
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Dominant conditions are expressed in individuals who have just one
copy of the mutant allele. Affected individual's have one normal
copy of the gene and one mutant copy of the gene. So their
offspring has a 50% chance of inheriting the mutant allele.
Autosomal Recessive
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Recessive conditions are clinically manifest only when
an individual has two copies of the mutant allele. When
just one copy of the mutant allele is present, an
individual is a carrier of the mutation, but does not
develop the condition. Females and males are affected
equally by traits transmitted by autosomal recessive
inheritance. When two carriers mate, each child has a
25% chance of being homozygous wild-type{not affected
; a 25% chance of being homozygous mutant ; or a 50%
chance of being heterozygous .
X-linked Recessive
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All X-linked recessive traits are fully evident in males because they only
have one copy of the X chromosome, thus do not have a normal copy of
the gene to compensate for the mutant copy. So women are rarely
affected by X-linked recessive diseases. Because the gene is on the X
chromosome there is no father to son transmission.
X-linked Dominant
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Because the gene is located on the X chromosome, there is no
transmission from father to son, but there can be transmission from
father to daughter. Children of an affected woman have a 50% chance of
inheriting the X chromosome with the mutant allele.
Dominant Inheritance
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One parent has a single, damaged dominant gene, who
overpowers its normal counterpart , affecting that
parent. When the affected parent has sex with an
unaffected and non-carrier partner, so the other noncarrier is homozygous recessive, the offspring are either
affected or not affected, but they are not carriers
Recessive inheritance
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Both parents carry a normal dominant gene and a faulty,
recessive, gene. The parents, although carriers, are
unaffected by the faulty gene, since their dominant
gene overpowers the faulty gene, however when they
mate. Their offspring are affected, not affected, or
carriers.
codominance
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Codominance is when two organisms share a
dominant allele, meaning they HAVE to be
dominant, they cannot be recessive.
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Some examples are: Blood type-- type AB is
codominant because both the antigen A and
antigen B show up in the genotype.
Another example is in cats. If a black cat and tan
cat mate, the kitten would have both black fur
and tan fur.
A dog with white fur and a dog with black fur mate
and produce a dog with both white and black fur.
Incomplete dominance
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Incomplete dominance is here the Dominant traits of
two heterozygotes are are not dominant to the other.
An example of this phenomenon is pink snapdragons.
If you cross red and white snapdragons, you get pink
snapdragons.
Multiple Alleles
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Multiple alleles means that there are three or more
forms of a gene for a trait. That doesn't mean that a
person can have all three of them. The person still only
gets two.
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(I got this example from the internet) an example
of multiple alleles is : it's like having three trays of
cookies, each tray having a different kind of
cookie. Your instructions are that you may have
any two cookies that you want. Can you have two
from the same tray? Yes. Can you have two
different kinds? Yes, you can have one of one kind
and one of a second kind. Can you have one from
each of the three trays? No, you can only have two
cookies.
Sex linkage
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The condition in which a gene responsible for a
specific trait is located on a sex chromosome,
resulting in sexually dependent inheritance of the
trait.
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Hemophilia, certain types of baldness, the placement
of sweat glands, and color blindness are all different
types of sex-linked traits in humans
Polygenic Inheritance
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Polygenic inheritance is when a single trait is
controlled by 2 or more alleles.
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Most human traits are polygenically inherited.
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Examples would be skin and eye color.
THE
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