1. Introduction to Genetics
Chapter 11
Introduction to Genetics

2. Golden Doodle Blending Theory - offspring are a straight mix
A Brief History
In the past, people did not understand how traits were inherited, but there were many guesses based on things that could be observed.
Two theories emerged….
Blending Theory - offspring are a straight mix
Particulate Theory
traits are inherited as "particles", offspring receive a "piece" from each parent, some pieces may hide the others
Golden Doodle

3. Mendel’s Work Gregor Mendel studied mathematics and science in Vienna.
Taught high school during the mid 1800s

4. Who was Gregor Mendel? GENETICS – study of heredity
He was known as the “FATHER OF GENETICS”
He discovered how traits were inherited
GENETICS – study of heredity
HEREDITY – the passing of traits from parents to offspring

5. Mendel is most famous for his experiments with the
pea plants (Pisum sativum)..
Flowering plants can be either
self or cross-pollinated
Plus, they reproduce quickly
AND have a fast LIFE CYCLE

6. Mendel’s Peas
Noticed the plants in the monastery garden had similar traits to their parents
Sometimes they had different traits then their parents
Mendel studied plants for 10 + years to understand hereditary

7. Mendel’s Peas Mendel did his study on pea plants
which have many traits
Traits-  A genetically determined characteristic or condition. May be physical, such as hair color or leaf shape, or they may be behavioral, such as nesting in birds and burrowing in rodents.
tall/short
purple /white flowers
round/wrinkled seed

8. Mendels Peas
Plants have traits that exist in two forms. Ex. Tall or short plants
Produce a large number of offspring in one generation making it easy to collect a large amount of data

9. Pea plants can be self-fertilized (PURE BRED) or cross-fertilized
The petal almost completely enclose the pistil and stamen

10. Mendel’s Experiments
Purebred: an offspring of an organism that has the same form of traits
Mendel’s peas were kept from cross pollinating or pollinating with other pea plants
Isolating the plants kept them from cross pollinating

11. Mendels Experiment
Mendel crossed purebred plants with different traits
He called these plants the parent generations
He designated this generation the first generation
He called the offspring filial generation
He designated this generation to be the second generation
Mendel noticed that the second generation contained no short plants even though one of the parents was short

12. Mendels Experiments

13. Mendel’s Experiment
Mendels noticed that certain traits did not appear until the F2 generation
He counted all the F2 plants and found that ¾ were tall and ¼ were short
Mendel noticed this to be the case with other traits in peas like seed shape, seed color, pod shape, and flower position

14. Mendel’s Experiments

15. True-Breeding Plants -always create plants that look like themselves
Hybrids – offspring of true- breeding plants
Tall x Short = Hybrid

16. Some genes are dominant, while others are recessive.
“Stronger” traits are called dominant.
“Weaker” traits are called recessive.
Geneticists use symbols (letters) to represent the different forms of a gene.

17. Some traits are dominant over others.
Tall x Short = all tall offspring (hybrids)
*Tall is the dominant trait
* Short is recessive trait

18. Mendel discovered that each trait is controlled by two factors (alleles)
Genes – factors that determine your traits
Genes are located on chromosomes

19. Dominant/ Recessive Alleles
Individual alleles control the inheritance of traits.
Dominant are those traits that show up in an organism when that allele is present
Recessive are masked or covered up by the dominant allele is present.
a recessive allele only shows it’s traits when the dominant allele is NOT present.

20. Dominant/ Recessive Alleles

21. 1. The “Father of Genetics” is ____________
Quick Check - What do we know so far?
1. The “Father of Genetics” is ____________
2. Genetics is the study of _____________, which is how traits are passed from _________ to ____________
3. Mendel studied what organism? ____________
4. If one trait covers up another one, we say that it is ______________, the one that is covered up is ______
5. A “true-breeding” plant is one that can only produce plants like itself a) true b) false
6. If a tall and a short plant are crossed, it will create a
a) zygote b) gene c) hybrid

22. Symbols in Genetics
Today scientists use a short hand method to write about alleles in genetic crosses
They use Letters to represent the traits
Capital Letters for dominant alleles
Lower case Letters for recessive alleles

23. Dominant traits are represented by a capital letter.
Yellow seeds are dominant…….. Y

24. Recessive genes (for the same trait) are represented by THE SAME lower case letter.
Green seeds are recessive… lower case y.
Dominant (yellow) = Y
Recessive (green) = y

25. In pea plants, tall is dominant over short
In pea plants, tall is dominant over short. The letter used to represent the tall gene is T.
The short gene is represented by t.
Tall =T
Short = t

26. Symbols in Genetics
When a plant inherits two dominant alleles it is written as YY
When a plant inherits two recessive alleles it is written as yy

27. Explaining the Cross
When a parent makes sperm or eggs, their genes separate         (PRINCIPLE OF SEGREGATION)
The GAMETES (egg or sperm) contain either a T allele (tall) or a t allele (short)

29. Probability and genetics
Probability: the likelihood that a particular event will occur

30. Punnett Squares
A punnett square is a chart that shows a cross between two hybrid organisms.
There are four possible combinations of alleles from the F1 generation

31. GENOTYPE  -  what genes, letters, the organism has (TT, Tt, tt) or allele combinations
PHENOTYPE   - what it looks like (tall or short) or the visible traits

32. Homozygous vs. Heterozygous
Homozygous – Term used to refer to an organism that has two identical alleles for a particular trait (TT or tt)
Heterozygous - Term used to refer to an organism that has two different alleles for the same trait (Tt) RR rr Rr

33. In humans, brown eyes are dominant over blue.
Brown = B
Blue = b

34. 5. Dominant genes hide recessive genes when both are inherited by an organism.
Y + y = yellow seeds (yellow is dominant)
T + t = tall plant (tall is dominant)
B+ b = brown eyes (brown is dominant)

35. A PUREBRED organism has two of the same genes for a trait.
TT = purebred TALL
tt = purebred SHORT

36. A HYBRID organism has two different genes for a trait.
Tt = hybrid TALL (tall is dominant.)
Bb = hybrid for black feathers (black is dominant.)

37. Will a hybrid human with the genes Bb have brown or blue eyes?
Bb = Brown eyes
The dominant gene (brown), will be expressed in a hybrid.

38. Why must all blue eyed people be PUREBRED for that trait?
If the dominant gene is present, it will always be expressed.
The only possible gene combination for blue eyes is bb.

39. 2. Who was the father of genetics? _________
Check for understanding
1.   The passing of traits from parents to offspring is known as  ____________________
2.  Who was the father of genetics?  _________
3.  Genes are located on _______________
4.  Every gene is made of two
a. genotypes b. alleles c. cells
5. The organism’s outward appearance, such as wrinkled seeds are referred to as the a) phenotype b) genotype

40. 6. The letters (ex. RR) that represent the traits are referred to as the a) phenotype b) genotype
7. An organism that has two different alleles, or letters, such as Rr is: a) homozygous b) heterozygous
8. 7. An organism that has two of the same alleles, or letters, such as RR is: a) homozygous b) heterozygous
9. Which of the following sets would represent Mendel’s Parent (P) generation?
a) RR x RR b) Rr x Rr c) RR x rr
10. When two different alleles occur together, such as R r, the one that is expressed is a) dominant b) recessive

41. What does this letter actually represent?
11. What is the diagram shown below called?
What does this letter actually represent?

42. Punnett Squares

43. Punnett Square
Parent
Offspring
Parent

44. How to Complete a Punnett Square

45. Y-Yellow
y-white
Genotype:
1:2:1
(YY:Yy:yy)
Phenotype:
3 Yellow
1 White

46. Check for understanding
1.  A one-eyed purple people eater is crossed with a two eyed purple people eater.  All of their offspring have two eyes.   Which trait is dominant?

47. 2. If you use the letter E for this gene
2.  If you use the letter E for this gene.   What is the genotype of the offspring if the parents were EE x ee
    
3.  If you crossed the offspring with each other?  How many of the new offspring would you expect to have two eyes?
EE = two eyes
Ee = two eyes
ee = one eye

48. Genetics Word Problems
Dragon Genetics

49. 1. In dragons, the allele for fire breathing is dominant
1.  In dragons, the allele for fire breathing is dominant.  Dragons can be fire breathers, or non fire breathers.
Show the genotypes and phenotypes of all possible dragons.

50. If a heterozygous fire-breathing dragon is crossed with one that does not breathe fire, how many offspring will be fire breathers?

51. If two heterozygous dragons are crossed, how many offspring would you expect to NOT be fire-breathers?

52. Also in dragons, wings are a dominant trait
Also in dragons, wings are a dominant trait.  If you crossed two wingless dragons, how many of their offspring would you expect to have wings?

53. Two winged dragons produce an offspring that does not have wings
Two winged dragons produce an offspring that does not have wings.  What are the genotypes of the parents?

54. If a purebred winged dragon is crossed with a purebred wingless dragon, how many of their offspring will be winged and what is their genotype?

55. A dragon with wings (Dd) is crossed with ones that does not have wings
A dragon with wings (Dd) is crossed with ones that does not have wings. What percentage of their offspring will be wingless?

56. Recall Mendels Simple types of Hereditary
Recessive  need two recessive alleles to have the trait (aa)
Complete dominance allele needed to have the trait (AA or Aa)

57. Codominance
Codominance - Situation in which both alleles of a gene contribute to the phenotype of the organism.
Example – A solid white cow is crossed with a solid brown cow and the resulting offspring are spotted brown and white (called roan). +

58. Incomplete Dominance
Incomplete Dominance - Situation in which one allele is not completely dominant over another.
Example – Red and white flowers are crossed and pink flowers are produced.

59. Multiple Alleles
Multiple Alleles- Three or more alleles of the same gene.
Even though three or more alleles exist for a particular trait, an individual can only have two alleles - one from the mother and one from the father.

60. Examples of Multiple Alleles
Coat color in rabbits is determined by a single gene that has at least four different alleles. Different combinations of alleles result in the four colors you see here.

61. Examples of Multiple Alleles
Blood Type – 3 alleles exist (IA, IB, and i), which results in four different possible blood types
Hair Color – Too many alleles exist to count
There are over 20 different shades of hair color.

62. Polygenic Trait
Polygenic Trait - Trait controlled by two or more genes.
Polygenic traits often show a wide range of phenotypes.
Example: The wide range of skin color in humans comes about partly because more than four different genes probably control this trait.

63. Y- linked Genes
Only affects males they either get it or they don’t

64. X- linked (sex linked) disorder or conditions

65. Sex-Linked Genes Genes that are located on the X chromosome.
Females receive 2 alleles; males receive one.
Ex. Color blindness, hemophilia
Women can be carriers when they carry one gene for the disorder and one normal gene.
Carriers can have sons with the disorder.

66. X- linked traits If recessive XNXN = Normal XN Xn = Normal Carrier
XnXn= affected
XnY= Normal
XnY= Affected

67. Normal Male and Female Carrier

68. (C= normal, c= colorblind)
A carrier is a person that has the trait on only one chromosome and does not express the trait. Carriers of sex linked traits are always women.
(C= normal, c= colorblind)
Ex. Color blind carrier XC Xc

69. Color blindness
Is sex linked and on the x chromosome
Affects males

70. Simple recessive disorders – MOST human diseases are recessive

71. Hemophilia Hemophilia is characterized by uncontrolled bleeding
It is a sex linked disorder caused by errors in the DNA that codes for the proteins involved in clotting

72. Cystic fibrosis
CF is a fairly common genetic disorder among white Americans
Approximately 1 in 28 white American carries the recessive allele
Mucus becomes thick formed in the lungs and digestive track

73. X linked Punnett Square

74. Sickle cell Anemia NN is not afflicted Nn is carrier nn is afflicted
Caused by abnormal type of hemoglobin and cells become sickle shaped when oxygen is low
Sickle cell pain crisis
“n” makes a person immune to malaria

75. Sickle cell

76. Polydactyl
Extra fingers and toes PP or Pp= extra digits 98% of all people in the world homozygous recessive pp.

77. Tracing Family Traits

78. Achondroplasia
Type of dwarfism- AA genotypes are lethal and result in spontaneous abortion.
Aa have dwarfism
99% of Americans have aa

79. PEDIGREES
Chart showing genetic relationships between members of a family
Squares represent males, circles females
Color shows infected person, ½ shaded shows carrier

80. Usually autosomal dominant, autosomal recessive or sex linked

81. Introduction The Central Dogma of Molecular Biology
Cell
DNA
mRNA
Transcription
Polypeptide
(protein)
Translation
Ribosome

82. Protein Synthesis Flow of Information: DNA RNA Proteins
Transcription Translation
Transcription is the process by which a molecule of DNA is copied into a complementary strand of RNA.
This is called messenger RNA (mRNA) because it acts as a messenger between DNA and the ribosomes where protein synthesis is carried out.

83. Protein Synthesis Transcription
Transcription process
RNA polymerase (an enzyme) attaches to DNA at a special sequence that serves as a “start signal”.
The DNA strands are separated and one strand serves as a template.
The RNA bases attach to the complementary DNA template, thus synthesizing mRNA.

84. Protein Synthesis: Transcription
Transcription process continued
The RNA polymerase recognizes a termination site on the DNA molecule and releases the new mRNA molecule.
(mRNA leaves the nucleus and travels to the ribosome in the cytoplasm.)

85. Protein Synthesis: Transcription

86. Eukaryotic Transcription
DNA
Cytoplasm
Nucleus
Nuclear
pores
RNA
Transcription G
AAAAAA
RNA
Processing
mRNA
Export G
AAAAAA

87. Protein Synthesis: Translation
Translation is the process of decoding a mRNA molecule into a polypeptide chain or protein.
Each combination of 3 nucleotides on mRNA is called a codon or three-letter code word.
Each codon specifies a particular amino acid that is to be placed in the polypeptide chain (protein).

88. Protein Synthesis: Translation

89. A Codon Guanine Arginine Adenine B A S E S SUGAR-PHOSPHATE BACKBONE O
CH2
NH2 N NH OH
Guanine
Adenine
Arginine

90. Protein Synthesis: Translation
A three-letter code is used because there are 20 different amino acids that are used to make proteins.
If a two-letter code were used there would not be enough codons to select all 20 amino acids.
That is, there are 4 bases in RNA, so 42 (4x 4)=16; where as 43 (4x4x4)=64.

91. Protein Synthesis: Translation

92. Protein Synthesis: Translation
Therefore, there is a total of 64 codons with mRNA, 61specify a particular amino acid.
This means there are more than one codon for each of the 20 amino acids.
The remaining three codons (UAA, UAG, & UGA) are stop codons, which signify the end of a polypeptide chain (protein).
Besides selecting the amino acid methionine, the codon AUG also serves as the “initiator” codon, which starts the synthesis of a protein

93. Protein Synthesis: Translation

94. Protein Synthesis: Translation
Transfer RNA (tRNA)
Each tRNA molecule has 2 important sites of attachment.
One site, called the anticodon, binds to the codon on the mRNA molecule.
The other site attaches to a particular amino acid.
During protein synthesis, the anticodon of a tRNA molecule base pairs with the appropriate mRNA codon.

95. Protein Synthesis: Translation

96. Met-tRNA Methionine 9 26 22 23 16 12 10 25 A 17 13 20 G 50 51 65 64 63U* 9 26 22 23 Pu 16 12 Py 10 25
20:1 G*
17:1 A
20:2 17 13 20 G 50 51 65 64 63 62 52 C 59 y A* T 49 39 41 42 31 29 28
Pu* 43 1 27 U 35 38 36
Py* 34 40 30
47:1
47:15 46
47:16 45 44 47 73 70 71 72 66 67 68 69 3 2 7 6 5 4 A C U
Anticodon

97. Protein Synthesis: Translation
Ribosome:
Are made up of 2 subunits, a large one and a smaller one, each subunit contains ribosomal RNA (rRNA) & proteins.
Protein synthesis starts when the two subunits bind to mRNA.
The initiator codon AUG binds to the first anticodon of tRNA, signaling the start of a protein.

98. Protein Synthesis: Translation
Ribosome:
The anticodon of another tRNA binds to the next mRNA codon, bringing the 2nd amino acid to be placed in the protein.
As each anticodon & codon bind together a peptide bond forms between the two amino acids.

99. Protein Synthesis: Translation
Ribosome:
The protein chain continues to grow until a stop codon reaches the ribosome, which results in the release of the new protein and mRNA, completing the process of translation.

100. Protein Synthesis: Translation

101. DNA Profiling
(DNA fingerprinting)

102. What is DNA Profiling?
A technique used by scientists to distinguish between individuals of the same species using only samples of their DNA

103. Who Invented it?
The process of DNA fingerprinting was invented by Alec Jeffreys at the University of Leicester in 1985.
He was knighted in

104. Stages of DNA Profiling
Cells are broken down
to release DNA
If only a small amount of DNA is available it can be amplified using the polymerase chain reaction (PCR)

105. Stages of DNA Profiling
Step 2:
The DNA is cut into fragments using restriction enzymes.
Each restriction enzyme cuts DNA at a specific base sequence.

106. Stages of DNA Profiling
The sections of DNA that are cut out are called restriction fragments.
This yields thousands of restriction fragments of all different sizes because the base sequences being cut may be far apart (long fragment) or close together (short fragment).

107. Stages of DNA Profiling
Fragments are separated on the basis of size using a process called gel electrophoresis.
DNA fragments are injected into wells and an electric current is applied along the gel.

108. Stages of DNA Profiling
DNA is negatively charged so it is attracted to the positive end of the gel.
The shorter DNA fragments move faster than the longer fragments.
DNA is separated on basis of size.

109. Stages of DNA Profiling
A radioactive material is added which combines with the DNA fragments to produce a fluorescent image.
A photographic copy of the DNA bands is obtained.

110. Stages of DNA Profiling
The pattern of fragment distribution is then analysed.

111. Uses of DNA Profiling
DNA profiling is used to solve crimes and medical problems

112. Crime
Forensic science is the use of scientific knowledge in legal situations.
The DNA profile of each individual is highly specific.
The chances of two people having exactly the same DNA profile is 30,000 million to 1 (except for identical twins).

113. Biological materials used for DNA profiling
Blood
Hair
Saliva
Semen
Body tissue cells
DNA samples have been obtained from vaginal cells transferred to the outside of a condom during sexual intercourse.

114. DNA Profiling can solve crimes
The pattern of the DNA profile is then compared with those of the victim and the suspect.
If the profile matches the suspect it provides strong evidence that the suspect was present at the crime scene (NB:it does not prove they committed the crime).
If the profile doesn’t match the suspect then that suspect may be eliminated from the enquiry.

115. Example A violent murder occurred.
The forensics team retrieved a blood sample from the crime scene.
They prepared DNA profiles of the blood sample, the victim and a suspect as follows:

116. Was the suspect at the crime scene?
Suspects Profile
Blood sample from crime scene
Victims profile

117. Solving Medical Problems
DNA profiles can be used to determine whether a particular person is the parent of a child.
A childs paternity (father) and maternity(mother) can be determined.
This information can be used in
Paternity suits
Inheritance cases
Immigration cases

118. Example: A Paternity Test
By comparing the DNA profile of a
mother and her child it is possible to
identify DNA fragments in the child
which are absent from the mother and
must therefore have been inherited
from the biological father.

119. Is this man the father of the child?
Mother
Child
Man

120. Famous cases
In 2002 Elizabeth Hurley used DNA profiling to prove that Steve Bing was the father
of her child Damien

121. Famous Cases
Colin Pitchfork was the first criminal caught based on DNA fingerprinting evidence.
He was arrested in for the rape and murder of two girls and was sentenced in 1988.

122. Famous Cases
O.J. Simpson was cleared of a double murder charge in which relied heavily on DNA evidence.
This case highlighted lab difficulties.

123. This powerpoint was kindly donated to www.worldofteaching.com
is home to over a thousand powerpoints submitted by teachers. This is a completely free site and requires no registration. Please visit and I hope it will help in your teaching.

124. HUMAN GENETICS
What can go wrong?
Chromosome Gene Mutations Mutations

125. DELETION Piece of whole chromosome is lost
________________________________________
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126. Human abnormalities caused by deletions
Wolf-Hirschhorn syndrome
Cri-du-chat syndrome
Prader- Willi syndrome

127. Wolf-Hirschhorn syndrome (4p-)
Missing piece on the short arm of chromosome 4
Developmental disabled
Low set large ears
Club feet

128. Cri-du-chat (Cat cry) (5p-)
1 in 50,000 births
More common in girls

129. Mewing cry in infancy
Missing piece of number 5
Mental retardation
50% have heart defects

130. Prader-Willi Syndrome
Deletion in chromosome 15
Feeding problems: poor weight gain in infancy, won’t eat
Ages 1-6 excessive, rapid weight gain
Under developed sex organs
Mild to moderate retardation
Obsession with food
Complications from problems associated with obesity (heart attack, high blood pressure, diabetes)

131. Prader-Willi syndrome
Victor at age Victor at age 2

132. INVERSION Segment flips and reads backwards
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133. TRANSLOCATION
Segment breaks off and joins a different non-homologous chromosome
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134. A gene that is flipped and reads backwards will not work.
A gene that is moved to
another chromosome
will not separate from
its partner during meiosis.
One cell can get 2 copies
of gene, one cell gets none.

135.   GENE MUTATIONS Changes in the DNA code of a single gene
___________ ____________ ______________________

136. Harmful Gene Mutations
Point mutations – change a _________ base in DNA code Frame shift mutations change _____________ bases in code

137. SUBSTITUTION A T T C T A G C T Changes one base for another
A T T C G A G C T
A T T C T A G C T

138. SICKLE CELL ANEMIA CAUSE: (autosomal recessive)
A changed to T (glu to val)
gene on chromosome #11
that codes for part of
hemoglobin protein
(carries oxygen in blood)

139. SICKLE CELL ANEMIA SYMPTOMS:
Sickle shaped Red Blood Cells in hh persons
Circulatory problems
Loss of blood cells (anemia)
Organ damage
DEATH

140. SICKLE CELL ANEMIA More common in African Americans 1 in 500 = hh
1 in 10 = Hh carriers for gene
Hh persons have Sickle cell TRAIT
make some normal RBC’s’ ; some sickled cells

141. Having two copies of gene (hh) makes a person sick Having one copy (Hh)- gives person resistance to MALARIA

142. DELETION Piece of DNA code for one gene is lost
________________________________________
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143. Duchenne Muscular Dystrophy
CAUSE:
(X linked recessive)
DELETION in gene that codes for a muscle protein

144. Duchenne Muscular Dystrophy (DMD)
SYMPTOMS:
1 in 3500 male births
Appears before age 5
Progressive muscle weakening
Most in wheelchair by age 13
Eventually lethal

145. DUPLICATION Piece of DNA is copied too many times
________________________________________________
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146. FRAME SHIFT MUTATIONS Changes multiple bases in code
thefatcatranandran
____________________
DUPLICATION
thefatcatranandandandandran
___________________________
the fat cat ran and ran
the fat cat ran and and and ran

147. HUNTINGTON’S CAUSE: Autosomal dominant 40-100 CAG Repeats
at end of gene on
chromosome 4

148. HUNTINGTON’S SYMPTOMS: Seen in both males and females
Degenerative brain disorder
Symptoms appear
age 30-40
(Usually after having children)
Lose ability to walk, think, talk, reason
50/50 chance of passing it to child
SYMPTOMS: Seen in both
males and females

149. Until now people didn’t know they had the gene, until after they had already had children.
Now there is a test to tell if you have the gene before symptoms appear.
Would you want to know if there is NO cure?

150. OTHER GENETIC DISEASES
AUTOSOMAL RECESSIVE
Phenylketonuria
Cystic fibrosis
Albinism
X-LINKED RECESSIVE
Color blindness
Hemophilia
Muscular dystrophy
AUTOSOMAL DOMINANT
Achondroplasia (Dwarfism)
Huntington’s

151. HEMOPHILIA
CAUSE:
change in gene on X chromosome that codes for blood clotting protein
SYMPTOMS:
More common in males
Internal and external bleeding Can result in death transfusions/hospitalization required frequently to stop bleeding

152. ACHONDROPLASIA (Dwarfism)
CAUSE: (Autosomal Dominant on chromosome 4) Most are new mutations in egg or sperm cell, but it can be inherited from parent with gene
1 in 20,000 births
200,000 “little people” worldwide
One of oldest known – seen in Egyptian art
Normal size torso; short arms and legs
Problem with way cartilage changes to bone as bones grow

153. COLOR BLINDNESS CAUSE: X linked recessive
Mutation in gene on X chromosome
SYMPTOMS: More common in males (8% of males are colorblind)
Can’t distinguish certain colors Most common = red/green

154. Cystic Fibrosis
Mutation in gene on chromosome 7 that codes for protein in membrane that transports chloride ions

155. Cystic Fibrosis Autosomal recessive
Symptoms: More common in Caucasians
Make extra thick mucous in lungs and pancreas which leads to respiratory and digestive complications
Salty skin is clue

156. Phenylketonuria (PKU)
CAUSE: Mutation in gene for enzyme that changes the amino acid phenylalanine into tyrosine
Build up causes brain damage
ALL babies have blood test for PKU when born before leaving hospital
Treatment: Diet low in phenylalanine can extend life and prevent retardation * Nutri-sweet warning

157. All “SUGAR-FREE” foods have a warning label
* PHENYLKETONURICS: Contains phenylalanine
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