General Genetic

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General Genetic

• Bio 221 Lab 7

Exceptions to Simple Inheritance
(Non-Mendelian inheritance)
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• 1-Widow's Peak (W, w) front hairline Dominant
  allele in heterozygous or homozygous individuals
  results in a V-shaped
• 2-Ear lobes (A, a) Ear lobes may be either
  adherent or free and pendulous. Homozygous
  recessives The dominant trait is for lobes to
  hang free, a bit of lobe hanging down prior to
  the point where the bottom of the ear attaches to
  the head. With the recessive phenotype, the lobes
  are attached directly to the head
• 3-Hitchhiker's thumb (H, h) Homozygous
  recessives
• can bend the distal joint of the thumb backward
  to a nearly

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• 4-Tongue rolling (R, r) Persons with a dominant
  allele in heterozygous or homozygous condition
  can roll
• 5-Bent pinky (B, b) inward toward the fourth
  (ring) finger Dominant allele causes the
  distal segment of the fifth finger to bend
  distinctly
• 6-Cleft chin  the dominant  gene causes the
  cleft chin while the recessive genotype presents
  without a cleft. 

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• 7-Thumb crossing (C, c) In a relaxed
  interlocking
• of fingers, left thumb over right indicates the
  dominant
• 8-PTC tasters (T, t) Phenylthiocarbamide (PTC)
  tastes bitter to heterozygous or homozygous
  dominant individuals, but is tasteless to
  homozygous recessives
• 9-Blue eyes (E, e) Blue-eyed persons are
  homozygous recessive and lack pigment in the iris
  
• 10-Middigital hair (M, m) People lacking hair in
  the middle segments of the fingers are homozygous
  recessive.

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11- clockwise (CW) or counterclockwise (CCW)
direction  the allele for clockwise is dominant
to the allele for counterclockwise. 
12- Darwin's tubercle The allele for Darwin's
tubercle is dominant. 
13- Toe length  
The big toe is longer than the second toe ( L),
while other people have the big toe shorter than
the second toe ("S").  The allele for S dominant
to the allele for L
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Exceptions to Simple Inheritance (Non-Mendelian
inheritance)
Non Mendelian inheritance is trait do not
segregate in accordance to Mendel Laws . Some
traits are carried on sex chromosomes X and Y .
Most traits carried are present on only the X
chromosome while the Y Chromosome is smaller and
very few genes are located on this chromosome .
There are 3 Categories of genes that may have
different effects depending on an individuals
gender 1- Sex Limited genes . 1-Beard and
Breast . 2- Milk Production . 3-White and
yellow color of special specie of butterfly .
4-Feathering in birds . 2- Sex Influenced
genes . 1- Baldness . . 3- X Linked
inheritance . 1- Dominant sex linked traits.
2- Recessive sex linked traitsa-Whit eye (rr) in
Drosphilia . b- Red / Green color blindness .c
Example Hemophilia (hh)
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1- Sex Limited genes .

• Definition
• That are inherited by both men and women but are
  normally only expressed in the phenotype of one
  of them .
• Example
• 1- Beard and Breast .
• Beard and Breast are secondary sexual
  characters that depend on sex hormones .
• In female lacks in beard and male lacks in
  developed breasts .
• 2- Milk Production .
• Is trait expressed by cows and affected by
  gene on Somatic chromosome 14 . Both Bulls and
  Cows carry this gene and both contribute an
  allele to their daughters which affects the
  quantity of milk that daughter produces .
• 3- White and yellow color of special specie of
  butterfly .
• That male always have yellow color while (WW) the
  female have in two color white and yellow (ww) .

WW Ww Ww ww
Male Yellow Yellow Yellow Yellow
Female White White White Yellow
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Example 4- Feathering in birds . Males have
long , pointed curved fringed feathers on tail
and neck , but feathers of female are shorter ,
rounded , straighter . t had been early
established that hen-feathering is a trait
controlled by a simple autosomic dominant gene,
whose expression is limited to the male sex.
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2- Sex Influenced genes .

• 1-The sex hormones of the animal affect the
  expression of a trait by the heterozygous and
  provide different cellular environments in males
  and females .
• 2-The genes behave differently in two sexes .
• Ex amount of body hair and muscle mass.

Example 1- Baldness (BB). In male
physiological factors helps in the expression of
hair ( Recessive allele ) in males than females
. The gene for baldness behaves as a dominant
in males but as a recessive in females .
Heterozygous males are bald and will pass the
gene to about 50 of their offspring of either
sex . The amount of thinning of the hair or
balding that is observed depends both on genotype
and the amount of testosterone exposure . male
BB x bb Female
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male BB x bb Female
BB Bb Bb bb
Male Baled Baled Baled Hair
Female Baled Hair Hair Hair
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3- X Linked inheritance .
Information That inheritance is different
males than females , and That inheritance
controlled by Genes on X Chromosomes . -
Mother 1- pass X-linked alleles to only sons
. 2- Females ( homozygous) have 2 allele for each
gene 3-Female can be Normal , Affected ,
Carrier . 4-Females have 2 X- Chromosomes
that good chance of having the normal gene on one
of the two . - Fathers 1-pass X-linked alleles
to only daughters . 2-Male can be Normal ,
Affected . 3- males ( hemizygous) have one X
Chromosomes and have recessive condition much
more commonly than females . 4-Males have 1 X-
Chromosome does not carry of the same genes , so
there is no normal gene to counter the defective
X .
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Probabilities inheritance of sex linked traits
1- Unaffected father with affected mother
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2- Unaffected father and carrier mother
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3- Affected father and unaffected Mother
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• 3- X-Linked Dominant Inheritance
• A male or female child of a mother affected with
  an X-Linked dominant trait has a 50 chance of
  inheriting the mutation and thus being affected
  with the disorder.
• All female children of an affected father will be
  affected (daughters possess their fathers'
  X-chromosome). No male children of an affected
  father will be affected (sons do not inherit
  their fathers' X-chromosome).

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• 4-X-Linked Recessive Inheritance
• Females possessing one X-linked recessive
  mutation are considered carriers and will
  generally not manifest clinical symptoms of the
  disorder.
• All males possessing an X-linked recessive
  mutation will be affected (males have a single
  X-chromosome and therefore have only one copy of
  X-linked genes).
• All offspring of a carrier female have a 50
  chance of inheriting the mutation.
• All female children of an affected father will
  be carriers (daughters possess their fathers'
  X-chromosome). No male children of an affected
  father will be affected (sons do not inherit
  their fathers' X-chromosome).

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Kinds of 1-Autosomal Dominant
Inheritance The child of an parent affected
with autosomal dominant inheritance has a 50
chance of inheriting the parent's mutated allele
and thus being affected with the disorder. A
mutation can be transmitted by either the mother
or the father. All children, regardless of
gender, have an equal chance of inheriting the
mutation.
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• a- An individual will be a "carrier" of autosomal
  recessive inheritance if they possess one mutated
  allele and one normal gene copy. There is a 50
  chance that a carrier will transmit a mutated
  gene to a child.
• b- If two carrier parents have a child there is a
  25 chance that both will transmit the mutated
  gene in this case, the child will inherit only
  mutated copies of the gene from both the mother
  and the father and thus will be affected with the
  disorder. There is a 50 chance that one carrier
  parent will transmit the mutated gene and the
  other will transmit the normal gene in this
  case, the child will have one mutated gene and
  one normal gene and will be a carrier of the
  disorder. Finally, there is a 25 chance that
  both carrier parents will transmit the normal
  gene in this case the child will have only
  normal genes and will not be affected.

2-Autosomal Recessive Inheritance
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Examples 1-White eye (rr) in Drosophila
. Consider the red /white eye allele of
Drosphilia . Red eyes are dominant (Normal) and
codes (RR) , (Carrier ) (Rr) and White eyes are
codes ( rr) . The recessive phenotype is more
common in males , because the R/r locus is on X
Chromosome that means the males are haploid ,
the only genotype have R or r for that R male
has red eyes and r males have white eyes .
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• Examples
• 2- Red / Green color blindness .(cc)
• Is condition of color vision . It appears to
  normal state of animals that active at night .
• Because , the vision is mediated not by cone
  receptors but by rods which respond to low
  intensity of light .
• (Normal) code (CC) , (Carrier ) (Cc) and
  Affected ( cc) .

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1- 1- CC XX c XY
1- 1- Female Normal Male Affected
Cc XX C XY C XY Cc XX Cc XX C XY
Female Carrier Male Normal Male Normal Female Carrier Female Carrier Male Normal
2- 2- cc XX C XY
2- 2- Female Affected Male Normal
Cc XX c XY c XY Cc XX Cc XX c XY
Female Carrier Male Affected Male Affected Female Carrier Female Carrier Male affected
3- 3- Cc XX c XY
3- 3- Female Carrier Male Affected
Cc XX C XY C XY cc XX cc XX c XY
Female Carrier Male Normal Male Normal Female Affected Female Affected Male Affected
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3-Example Hemophilia (hh) Most male lethal
1-Male can be Normal (HH) , Affected (hh)
. 2-Female can be Normal (HH) , Carrier (Hh) ,
Affected (hh) . When a female with hemophilia has
children , she will pass the gene to each of her
sons. .
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Question A color blindness man marries a
woman with normal vision . Her mother was color
blind . What kind of 1- Children would you
expect from this marriage ? 2- Which kind of
this inheritance?
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The experiment of today
white eye cross in Drosophila