Download Complex Patterns of inheritance

Genetics continued…
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1. What is the difference between a genotype
and a phenotype?
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2. What are Punnett Squares used for?
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3. What is probability?
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4. What did you notice from the horned
monster activity from yesterday?
5. What is a monohybrid?
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Sometimes genetic traits aren’t as simple as
fur color, seed color, or flower color. In
circumstances- there are COMPLEX
PATTERNS OF INHERITANCE.
Ex. The blended traits from inherited traits
lab like nose, eye size, hair texture, etc….
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These are traits that are carried on one of the
sex chromosomes.
Traits are usually more common in males than
females. This is because if carried on an X
chromosome- a male only has to have one
allele to contain the trait when a female must
have both X chromosomes with the trait.
Females can be carriers and not have the trait.
Males cannot be carriers.
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XXX Syndrome
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Klinefelter’s syndrome
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Females
XXY- males
Turner Syndrome
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X- females with only 1 X
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JACOB’S SYNDROME: In males- have an
extra Y Chromosome (XYY)
Mostly normal
 Excessively tall
 Occasionally excessive acne
 Possible excessive aggression
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More
Examples 
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The alleles are on the X chromosome. More
common in males
XB
Distinguishes color
Xb
Color Blind
XBXB
Normal female able to distinguish color
XBXb
Normal Female carrying color blind trait
XbXb
Color Blind female
XBY
Normal male able to distinguish color
XbY
Color Blind Male
XH
Ability to clot blood
Xh
hemophilia
XHXH
Normal Female that can clot blood
XHXh
Normal female carrying hemophilia trait
XhXh
Female with hemophilia (can’t clot blood)
XHY
Normal Male that can clot blood
XhY
Male with hemophilia
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This is where no allele is considered dominant
over the other.
Example: Red flower X White flower = red and
white flower.
Example: Roan cattle
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Example: BLOOD TYPES
There are four different phenotypes:
A, B, AB, and O
3 alleles are used to produce 6 genotypes:
A,B,O
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Written with I as dominant allele. The
superscript A and B represents the actual blood
type.
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IA= Type A blood
IB= Type B blood
i = Type O blood
IAIA
Type A
IAi
Type A
IBIB
Type B
IBi
Type B
IAIB
Type AB due to codominance
ii
Type O
Give to
Get from
Type AB
AB
AB, A, B, O
Type A
A, AB
A, O
Type B
B, AB
B, O
Type O
O, A, B, AB
O
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When a phenotype of F1 generation is in between
that of the parents.
Ex. Cross of Red flower (4 o’clocks) with white
flowers: All F1 are pink.
Neither allele is completely dominant over the
other.
When pink F1 are self pollinated, the results are
strange:
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With incomplete dominance, a cross between
organisms with two different phenotypes
produces offspring with a third phenotype that
is a blending of the parental traits.
It's like mixing paints, red + white will make
pink. Red doesn't totally block (dominate) the
white, instead there is incomplete dominance,
and we end up with something in-between.
GENETICS
Continued…
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1. What is an example of a sex-linked trait?
2. Why is it more common for males to have a
sex-linked trait than females?
3. Predict the possible offspring of a colorblind
male and a normal female.
4. Predict the possible offspring of a mom with
blood type IAi and a dad with Ibi.
5. What is a possible explanation for a
chromosomal disorder?
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Refers to a record of an organism’s ancestry.
A pedigree is a diagram which are constructed
to show biological relationships.
Can be used to show how traits are passed
from one generation to another.
Circles represent females, Squares represent males. Colored circles
represent those that have the trait that is being traced. Horizontal
lines represent parents and vertical lines show offspring.
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Caused by dominant allele, H on chromosome #4.
Disease causes debilitating nerve damage but
disease doesn’t usually show until age 40. Usually
by this time- person has started career and family.
The trait may have already been passed on to
offspring.
Symptoms: Difficulty walking, speaking, holding
objects. Within a few years- lose total control of
muscles. Usually die at early age.
Since it is dominant- it only takes one H to have
disease.
H
H
h
Hh
Hh
h
Hh
Hh
If mom was heterozygousshe’d have 50% chance of
having a child afflicted. 
 If mom was homo dom- all
children would have
Huntington’s
H
h
h
Hh
hh
h
Hh
hh
Recessive genetic disorder on chromosome #15
(autosomal)
It is caused by the lack of enzyme involved in lipid
metabolism.
The missing enzyme causes lipids to build up in the
Central Nervous System.
Remember that lysosomes
have enzymes
that break down Lipids in
cells.
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As fat builds up in cells there is deterioration of
mental and physical abilities.
The child becomes blind, deaf, and unable to
swallow.
Muscles begin to atrophy and paralysis sets in.
Other neurological symptoms include
dementia, seizures, and an increased startle
reflex to noise. Children usually do not live to
age 4.
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Cystic fibrosis is a common recessive genetic
disease which affects the entire body, causing
progressive disability and often early death.
It affects chromosome #7.
CF is caused by a mutation in the gene for the
protein cystic fibrosis transmembrane
conductance regulator (CFTR).
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This gene is required to regulate the
components of sweat, digestive juices, and
mucus.
Although most people without CF have two
working copies of the CFTR gene, only one is
needed to prevent cystic fibrosis.
CF develops when neither gene works
normally. Therefore, CF is considered an
autosomal recessive disease.
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Dominant genetic disorder characterized as
having extra fingers and toes.
Occurs in 1 in every 500 live births.
The extra finger (s) or toe (s) tend to be poorly
developed and are sometimes just tissue without any
bone being present.
Although, some extra digits can be functional. Errors
occur during fetal development and they are caused
by one of several mutations on a gene that is located
on the short arm of chromosome 7 (autosomal)