1. Section Objectives:
Distinguish between alleles for incomplete dominance and codominance.
Explain the patterns of multiple allelic and polygenic inheritance.
Analyze the pattern of sex-linked inheritance.
Summarize how internal and external environments affect gene expression.

2. What You’ll Learn
You will compare the inheritance of recessive and dominant traits in humans.
You will analyze the inheritance patterns of traits with incomplete dominance and codominance.
You will determine the inheritance of sex-linked traits.

3. Telemeres
Telomeres have been compared with the plastic tips on shoelaces because they prevent chromosome ends from fraying and sticking to each other, which would scramble an organism's genetic information to cause cancer, other diseases or
death.
Yet, each time a cell divides, the telomeres get shorter. When they get too short, the cell no longer can divide and becomes inactive or "senescent" or dies. This process is associated with aging, cancer and a higher risk of death. So telomeres also have been compared with a bomb fuse.

4. Complex Patterns of Inheritance
Patterns of inheritance that are explained by Mendel’s experiments are often referred to as simple.
However, many inheritance patterns are more complex than those studied by Mendel.

5. Exceptions to Simple Mendelian Genetics
incomplete dominance-
neither gene is dominant
results in a new trait- Heterozygous- mix
-ex. red X white = pink
co-dominance- sickle-cell disease.
Both alleles expressed equally
Heterozygous- both traits are seen
ex. black X white = checkered or spotted.
Test to determine possible phenotypes

6. Sickle-cell disease- codominance
Abnormally shaped blood cells, slow blood flow, block small vessels, and result in tissue damage and pain.
Individuals who are heterozygous for the allele produce both normal and sickled hemoglobin, an example of.
Cause- the oxygen-carrying protein hemoglobin differs by one amino acid from normal hemoglobin.
Cross RR’ X RR’ and Predict offspring probability
Sickle-cell disease-
codominance
The change in shape occurs in the body’s narrow capillaries after the hemoglobin delivers oxygen to the cells.
Normal red blood cell
Sickle cell
Individuals who are heterozygous are said to have the sickle-cell trait because they can show some signs of sickle-cell-related disorders if the availability of oxygen is reduced.

7. Polygenic Inheritance
Because of embryonic development- even identical twins have different fingerprints
A group of alleles act together for one trait
Height, & eye color
Fingerprints!
Controlled by multiple genes
All are different!

8. Skin color: A polygenic trait
Although many of your traits were inherited through simple Mendelian patterns or through multiple alleles, many other human traits are determined by polygenic inheritance.
In the early 1900s, the idea that polygenic inheritance occurs in humans was first tested using data collected on skin color.
Scientists found that when light-skinned people mate with dark-skinned people, their offspring have intermediate skin colors.

9. Skin color: A polygenic trait
This graph shows the expected distribution of human skin color if controlled by one, three, or four genes.
Number of Genes Involved in Skin Color
Expected distribution- 4 genes
Observed distribution of skin color
Expected distribution- 1 gene
Number of individuals
Expected distribution- 3 genes
Light
Right
Range of skin color

10. Polygenic inheritance
Polygenic inheritance is the inheritance pattern of a trait that is controlled by two or more genes.
The genes may be on the same chromosome or on different chromosomes, and each gene may have two or more alleles.
Uppercase and lowercase letters are used to represent the alleles.

11. Polygenic inheritance
However, the allele represented by an uppercase letter is not dominant. All heterozygotes are intermediate in phenotype.
In polygenic inheritance, each allele represented by an uppercase letter contributes a small, but equal, portion to the trait being expressed.

12. Polygenic inheritance
The result is that the phenotypes usually show a continuous range of variability from the minimum value of the trait to the maximum value.

13. Multiple phenotypes from multiple alleles
Traits controlled by more than two alleles (a single pair of genes) have multiple alleles.
These alleles may exhibit classic dominance, they may mask each other, they may add to or subtract from each other, or some combination of these effects. Adding one or more alleles to the equation exponentially increases the number of possible expressions for a gene.
Example 1:
Human Blood Type
Example 2:
Human Hair Color

14. What is the difference between the polygenic inheritance pattern and multiple alleles?
Polygenic inheritance pattern refers to many--poly--genes. It describes a trait that is the result of a combination of proteins from genes on different locations within a chromosome or on chromosomes that are not homologous, meaning not paired. The gene on one chromosome pair contributes part of the trait, and the genes on other pairs contribute other components.
Eye color is a good example of the polygenic inheritance pattern. The appearance of the eye results from flecks of colors, each resulting from the action of a different gene pair.
The polygenic inheritance pattern is also responsible for height, skin color, and hair color, among others.
Keep in mind that each of these genes still has the possibility of having two recessive alleles, two dominant, or one of each, or the alleles can be incompletely dominant. Because of the numerous combinations, there is a range of phenotypes, not just two or three, as in a single gene. With a single gene pair, there is an either/or situation; the characteristics are discontinuous, or distinct from each other.
There are many heights to which humans grow; There is a range of skin colors, not just chocolate or vanilla; the same applies to weight, hair color and texture, foot size, and some genetic disorders.
When two individuals at opposite ends of the continuum mate, the probability is greatest that the offspring's characteristic will be intermediate. If the different phenotype frequencies are graphed, their distribution resembles a bell curve

15. Alleles refer to different versions of the same gene.
A single gene can have multiple alleles.
Contrast
difference is multiple alleles refers to different versions of one gene and polygenic traits refers to a single trait which is controlled by multiple genes (each with multiple alleles). Polygenic traits don't follow patterns of mendelian inheritance

16. Multiple Alleles Govern Blood Type
Human Blood Types
Genotypes
Surface Molecules
Phenotypes A A
lA lA or lAli
lB lB or lBi B B
lA lB
A and B AB ii
None O
Determining blood type is necessary before a person can receive a blood transfusion because the red blood cells of incompatible blood types could clump together, causing death. Your immune system recognizes the red blood cells as belonging to you. If cells with a different surface molecule enter your body, your immune system will attack them.

17. Blood type Blood factors- A & B- both are dominant
O is the absence of either A or B
Genotypes possible
AA, AO, BB, BO, AB, OO
Phenotypes A, B, AB & O
A person has two alleles. May be:
- two A antigen (blood type A)
- two B antigen (blood type B)
- one each of A and B antigens (blood type AB)
- or the O antigen (blood type O)
Human blood types can be
type A (IAIA or IA i)
type B (IBIB or IBi)
type AB (IAIB)
or type 0 (ii).

18. Phenotype A
Surface molecule A
The lA allele is dominant to i, so inheriting either the lAi alleles or the lA lA alleles from both parents will give you type A blood.
Surface molecule A is produced.

19. Phenotype B The lB allele is also dominant to i.
Surface molecule B
The lB allele is also dominant to i.
To have type B blood, you must inherit the lB allele from one parent and either another lB allele or the i allele from the other.
Surface molecule B is produced.

20. Phenotype AB The lA and lB alleles are codominant.
Surface molecule B
The lA and lB alleles are codominant.
This means that if you inherit the lA allele from one parent and the lB allele from the other, your red blood cells will produce both surface molecules and you will have type AB blood.
Surface molecule A

21. Phenotype O
The i allele is recessive and produces no surface molecules.
Therefore, if you are homozygous ii, your blood cells have no surface molecules and you have blood type O.

22. Blood Types Can AB X O have a type O child? Explain
Cross the following
Using a Punnett square.
What possible offspring can they have?
A X B =__________
O X A =__________
AB X O = ________

23. Hospital Mix-up 1 2 3 3 babies have lost their bands in the hospital
Match the babies to the correct parents
A Baby - O
B Baby - B
C Baby - AB
Couples blood types 1 2 3
Mothers’ AO AB
Fathers OO BO

24. Rh negative-problem Mother Rh -, Father Rh+, Fetus Rh+
mother may build up antibodies that may cross the placenta to destroy the babies RBC.
The more pregnancies- the more antibodies
mother given a rhogram shot to stop the antibody build up

25. Environmental Influences
The genetic makeup of an organism at fertilization determines only the organism’s potential to develop and function.
As the organism develops, many factors can influence how the gene is expressed, or even whether the gene is expressed at all.
Two such influences are the organism’s external and internal environments.

26. Influence of external environment
Temperature, nutrition, light, chemicals, and infectious agents all can influence gene expression.

27. Influence of external environment
In arctic foxes temperature has an effect on the expression of coat color.

28. Influence of external environment
External influences can also be seen in leaves. Leaves can have different sizes, thicknesses, and shapes depending on the amount of light they receive.

29. Influence of internal environment
The internal environments of males and females are different because of hormones and structural differences.
An organism’s age can also affect gene function.

30. Sex-Linked Traits in Humans
Many human traits are determined by genes that are carried on the sex chromosomes; most of these genes are located on the X chromosome.
The pattern of sex-linked inheritance is explained by the fact that males, who are XY, pass an X chromosome to each daughter and a Y chromosome to each son.

31. Sex-Linked Traits in Humans
Females, who are XX, pass one of their X chromosomes to each child.
Male
Female
Female
Male
Sperm
Eggs
Eggs
Sperm
Female
Female
Male
Male
Female
Male
Female
Male

32. Sex-Linked Traits in Humans
If a son receives an X chromosome with a recessive allele, the recessive phenotype will be expressed because he does not inherit on the Y chromosome from his father a dominant allele that would mask the expression of the recessive allele.
Two traits that are governed by X-linked recessive inheritance in humans are red-green color blindness and hemophilia.

33. Red-green color blindness
People who have red-green color blindness can’t differentiate these two colors. Color blindness is caused by the inheritance of a recessive allele at either of two gene sites on the X chromosome.

34. Hemophilia: An X-linked disorder
Hemophilia A is an X-linked disorder that causes a problem with blood clotting.
About one male in every has hemophilia, but only about one in 100 million females inherits the same disorder.
Males inherit the allele for hemophilia on the X chromosome from their carrier mothers.
One recessive allele for hemophilia will cause the disorder in males. Females would need two recessive alleles to inherit hemophilia.

35. Changes in Chromosome Numbers
What would happen if an entire chromosome or part of a chromosome were missing from the complete set?
As you have learned, abnormal numbers of chromosomes in offspring usually, but not always, result from accidents of meiosis.
Many abnormal phenotypic effects result from such mistakes.

36. Abnormal numbers of autosomes
Humans who have an extra whole or partial autosome are trisomic—that is, they have three of a particular autosomal chromosome instead of just two. In other words, they have 47 chromosomes.
To identify an abnormal number of chromosomes, a sample of cells is obtained from an individual or from a fetus.

37. A pedigree - graphic representation of genetic inheritance
No shade-no characteristic
Shaded areas indicate the disease
1/2 is a carrier
male-square
girl-circle
vert. Line-connects parent w/offspring
horiz.= connects parents
-used to show inheritance of certain conditions in a family

38. Pedigrees illustrate inheritance
Parents
Male
Female
Pedigrees illustrate inheritance
Siblings
Affected male
Known heterozygotes for recessive allele (Carriers)
Affected female
Mating
Death

39. Pedigrees illustrate inheritance
Female
Male 1 2 II 1 2 3 4 5
In a pedigree, a circle represents a female; a square represents a male.
III 1 2 3 4 ? IV 1 2 3 4 5

40. Can be used to trace an inherited illness

41. Exp- Student observations`
Students must agree to be “tested” for an experiment.
Develop your own exp to observe traits in your group. Can be hands, hair, eyes…
Write your problem and hypothesis before you plan your exp.
Pg. 136

42. What traits in class are most common?
Dominant
Recessive
Skin color
Extra fingers or toes
Freckles
Earlobe
Tongue rolling
Widow’s peak
Chin shape

43. What traits are most common?
Dominant
Recessive
Skin color
Dark
Extra fingers or toes
6 or more
Freckles
Earlobe
Free
Tongue rolling
Roll edges
Widow’s peak
Pointed
Chin shape
indented

44. Genetically Inherited Human Disorders: Autosomal recessive disorders:
Parents can be carriers & not have disease
Show up only in the homozygous recessive person (aa) who inherits a recessive allele from both parents, who were carriers (Aa xAa).
(25% chance of this happening)

45. Simple Recessive Heredity
Most genetic disorders are caused by recessive alleles.
Cystic fibrosis
Cystic fibrosis (CF) is a fairly common genetic disorder among white Americans.

46. Cystic fibrosis
Approximately one in 28 white Americans carries the recessive allele, and one in 2500 children born to white Americans inherits the disorder.
Due to a defective protein in the plasma membrane, cystic fibrosis results in the formation and accumulation of thick mucus in the lungs and digestive tract.

47. Autosomal recessive disorders: Cystic fibrosis:
body cannot make needed chloride channel, high concentrations of extra-cellular chloride
causes mucous to build up, infections, pneumonia.
Homozygous recessives (cc)
carriers- 1/20 white
Diet, antibiotics and treatment can extend life to 25 years or more.

48. Tay-Sachs disease
Tay-Sachs (tay saks) disease is a recessive disorder of the central nervous system.
In this disorder, a recessive allele results in the absence of an enzyme that normally breaks down a lipid produced and stored in tissues of the central nervous system.
Because this lipid fails to break down properly, it accumulates in the cells.

49. Typical Pedigree for Tay-Sachs1 2
Tay-Sachs II 4 1 2 3
III 1 2 3 1 IV

50. Autosomal recessive disorders:
Sickle-cell disease
The most common inherited disease of African-Americans (1:400 affected).
Homozygous recessives (ss) make abnormal form of hemoglobin that deforms red blood cells and causes a cascade of symptoms
(clogging of blood vessels, organ damage, kidney failure).

51. Phenylketonuria
Phenylketonuria (fen ul kee tun YOO ree uh), also called (PKU), is a recessive disorder that results from the absence of an enzyme that converts one amino acid, phenylalanine, to a different amino acid, tyrosine.
Because phenylalanine cannot be broken down, it and its by-products accumulate in the body and result in severe damage to the central nervous system.

52. Phenylketonuria
A PKU test is normally performed on all infants a few days after birth.
Infants affected by PKU are given a diet that is low in phenylalanine until their brains are fully developed.
Ironically, the success of treating phenylketonuria infants has resulted in a new problem.

53. Phenylketonuria
If a female who is homozygous recessive for PKU becomes pregnant, the high phenylalanine levels in her blood can damage her fetus—the developing baby.
This problem occurs even if the fetus is heterozygous and would be phenotypically normal.

54. Phenylketonuria
Phenylketonurics: Contains Phenylalanine

55. Simple Dominant Heredity
Many traits are inherited just as the rule of dominance predicts.
Remember that in Mendelian inheritance, a single dominant allele inherited from one parent is all that is needed for a person to show the dominant trait.

56. Simple dominant traits
A cleft chin, widow’s peak hairline, hitchhiker’s thumb, almond shaped eyes, thick lips, and the presence of hair on the middle section of your fingers all are examples of dominant traits.

57. Huntington’s disease
Huntington’s disease is a lethal genetic disorder caused by a rare dominant allele.
It results in a breakdown of certain areas of the brain.

58. Huntington’s disease
Ordinarily, a dominant allele with such severe effects would result in death before the affected individual could have children and pass the allele on to the next generation.
But because the onset of Huntington’s disease usually occurs between the ages of 30 and 50, an individual may already have had children before knowing whether he or she is affected.

59. Section Objectives: Interpret a pedigree.
Identify human genetic disorders caused by inherited recessive alleles.
Predict how a human trait can be determined by a simple dominant allele.

60. Typical Pedigree of Huntington’s Disease1 2 II 1 2 3 4 5
III 1 2 3 4 5

61. Question 1 I 1 2
What does this pedigree tell you about those who show the recessive phenotype for the disease? II 1 2 3 4
III 1 2 3 IV 1

62. I
The pedigree indicates that showing the recessive phenotype for the disease is fatal. 1 2 II 1 2 3 4
III 1 2 3 IV 1

63. http://www. google. com/imgres

64. Question 2
What must happen for a person to show a recessive phenotype?
Answer
The person must inherit a recessive allele for the trait from both parents.

65. Autosomal dominant disorders
Polydactyl
(extra fingers or toes):
PP or Pp = extra digits,
aa = 5 digits.
98% of all people in the world are homozygous recessive (pp).

66. Sex- A genetic trait The 23rd pair of chromosomes determine sex
Male= XY & Female = XX
each time fertilization occurs, there is a 50/50 chance the offspring will be maleThe MALE determines a baby’s sex
Autosomes- all chromosomes except for the sex chromosomes
Autosomes for males & females are the same
Sex- A genetic trait

67. Sex chromosomes Weird Info A platypus has 10 sex chromosomes
Sex can be chosen
Ex. X is larger- use filter

68. Twins Fraternal vs. Identical

69. Sex-linked
Certain genes on the X chromosome are missing from the Y chromosome

70. Sex determination
In humans the diploid number of chromosomes is 46, or 23 pairs.
There are 22 pairs of homologous chromosomes called autosomes. Homologous autosomes look alike.
The 23rd pair of chromosomes differs in males and females.

71. Sex determination
These two chromosomes, which determine the sex of an individual, are called sex chromosomes and are indicated by the letters X and Y.

72. Sex determination
If you are female, your 23rd pair of chromosomes are homologous, XX. X X
Female
If you are male, your 23rd pair of chromosomes XY, look different. X Y
Male

73. Sex determination
Males usually have one X and one Y chromosome and produce two kinds of gametes, X and Y.
Females usually have two X chromosomes and produce only X gametes.
It is the male gamete that determines the sex of the offspring.

74. Sex determination XY Male X Y X XX Female XY Male XX Female X

75. Sex-linked inheritance
Traits controlled by genes located on sex chromosomes are called sex-linked traits.
The alleles for sex-linked traits are written as superscripts of the X or Y chromosomes.
Because the X and Y chromosomes are not homologous, the Y chromosome has no corresponding allele to one on the X chromosome and no superscript is used.

76. Sex-linked inheritance
Also remember that any recessive allele on the X chromosome of a male will not be masked by a corresponding dominant allele on the Y chromosome.

77. Sex-linked inheritance
White-eyed male (XrY) F2
Females:
Red-eyed female (XRXR)
all red eyed
Males:
1/2 red eyed
1/2 white eyed
F1 All red eyed

78. Sex-linked inheritance
The genes that govern sex-linked traits follow the inheritance pattern of the sex chromosome on which they are found.
Click here to view movie.

79. sex-linked traits
The mother has a 50/50 chance of passing it on to each child
If the son receives a recessive X from the mom, he will express the recessive phenotype b/c no dominant allele is available from the father.
If the father- the dominant characteristic would hide it
traits are determined by genes carried on sex chromosomes
If a trait is X linked,
males pass it to all their daughters
and none of their sons.

80. sex-linked traits
Determined by alleles carried only on the x chromosome-
Ex. Colorblindness &
Hemophilia (bleeding disease)
color blindness - on X chromosomes- can’t distinguish between some colors;
red and green
has no allele on the Y chromosome

81. sex-linked traits
Female- Xx- 1 recessive with the trait is dominated by the normal and no disease shows up
female xx- 2 recessive w. disease shows up
If the recessive X-linked trait is inherited it shows up- XY-shows up

84. Genetic Disorders & sex chromosomes
Hemophilia
Free bleeders disease
A recessive trait
Males get it more frequently
Females must get the gene from both parents
Dyslexia
- a genetic disorder that is also called word blindness
Caused by dominant gene
See & write words backwards

85. CYU 27.2 What is incomplete dominance?
Neither gene is totally dominant over the other
What 2 gene combinations can a person with type A blood have?
AO or AA
Why are there more color blind males than females?
Recessive traits on X always show up

86. Abnormal numbers of autosomes
Metaphase chromosomes are photographed; the chromosome pictures are then enlarged and arranged in pairs by a computer according to length and location of the centromere.

87. Abnormal numbers of autosomes
This chart of chromosome pairs is called a karyotype, and it is valuable in identifying unusual chromosome numbers in cells.

88. Down syndrome: Trisomy 21
Down syndrome is the only autosomal trisomy in which affected individuals survive to adulthood.
It occurs in about one in 700 live births.

89. Down syndrome: Trisomy 21
Down syndrome is a group of symptoms that results from trisomy of chromosome 21.
Individuals who have Down syndrome have at least some degree of mental retardation.
The incidence of Down syndrome births is higher in older mothers, especially those over 40.

90. Abnormal numbers of sex chromosomes
Many abnormalities in the number of sex chromosomes are known to exist.
An X chromosome may be missing (designated as XO) or there may be an extra one (XXX or XXY). There may also be an extra Y chromosome (XYY).

91. Abnormal numbers of sex chromosomes
Any individual with at least one Y chromosome is a male, and any individual without a Y chromosome is a female.
Most of these individuals lead normal lives, but they cannot have children and some have varying degrees of mental retardation.

92. 27.3 Genetic Disorders Nondisjunction
About 200 genetic disorders controlled by X chromosome
produces 1 cell with an extra chromosome & one cell lacking a chromosome
Use an O for the missing
Ex. XO
Some Disorders can be prevented if couple has only girls
Would you choose the sex?
Nondisjunction

93. PKU
Genetic disorder in which some chemicals in the body do not break down as thy should
Chemicals can damage brain cells
Today- children tested at birth
Can be controlled with diet & can grow normally

94. nondisjunction
The frequency of nondisjunction is quite high in humans, but the results are usually so devastating to the growing zygote that miscarriage occurs very early in the pregnancy.
If the individual survives, he or she usually has a set of symptoms –
a syndrome - caused by the abnormal dose of each gene product from that chromosome.

95. Syndromes Extra chromosome Chromosomes missing XXY- male XO – female
YO- fetus dies
An XO female & XXY male cannot make sex cells but they can live
Extra chromosome
XXY- male
3 of the 21st chromosome causes Down’s Syndrome (Trisomy 21)

96. Human disorders due to chromosome alterations in autosomes
Down syndrome
characteristic facial features, short stature; heart defects
susceptibility to respiratory disease, shorter lifespan
prone to developing early Alzheimer's and leukemia
often sexually underdeveloped and sterile, mental retardation

97. Optical Illusions

98. Question 1
Which of the following inherited diseases would a black American be most likely to inherit?
A. cystic fibrosis
B. Tay-Sachs disease
C. phenylketonuria
D. sickle-cell disease
The answer is D.

99. Question 2 Trisomy usually results from _______.
A. polygenic inheritance
B. incomplete dominance
C. nondisjunction
D. twenty-two pairs of chromosomes
The answer is C.

100. Question 3
How do red blood cells of phenotype O differ from the cells of the other phenotypes?
Answer
Red blood cells of phenotype O display no surface molecules.

101. Mendelian Inheritance of Human Traits
A pedigree is a family tree of inheritance.
Most human genetic disorders are inherited as rare recessive alleles, but a few are inherited as dominant alleles.

102. When Heredity Follows Different Rules
Some alleles can be expressed as incomplete dominance or codominance.
There may be many alleles for one trait or many genes that interact to produce a trait.
Cells have matching pairs of homologous chromosomes called autosomes.
Sex chromosomes contain genes that determine the sex of an individual.

103. When Heredity Follows Different Rules
Inheritance patterns of genes located on sex chromosomes are due to differences in the number and kind of sex chromosomes in males and in females.
The expression of some traits is affected by the internal and external environments of the organism.

104. Complex Inheritance of Human Traits
The majority of human traits are controlled by multiple alleles or by polygenic inheritance. The inheritance patterns of these traits are highly variable.
Sex-linked traits are determined by inheritance of sex chromosomes. X-linked traits are usually passed from carrier females to their male offspring. Y-linked traits are passed only from male to male.

105. Complex Inheritance of Human Traits
Nondisjunction may result in an abnormal number of chromosomes. Abnormal numbers of autosomes usually are lethal.
A karyotype can identify unusual numbers of chromosomes in an individual.

106. Why is genetics important?
Genes govern the traits of all animals and plants
Identify genetic disorders to help control them by diet or take preventive measures
Help identify couples that may pass on hereditary disease
Also- may be used in repairing damaged areas in the body in the future.

107. Genetic Counseling Traits run in families
Counselor can help answer questions
How did their baby get the disorder?
If the baby is health, does it have a problem gene?
Is the trait dominant or recessive?
What will happen to the baby’s health as it gets older?
What are the chances that future children will have the trait?

108. Genetic counselors can ID disease risk
What problems would you have if your culture valued boys over girls and only boys were born for 10 years?
Should insurance companies pay medical costs of couples who cannot afford to pay for determining the sex?

109. Amniocentesis
Cells from Fluid are grown in a nutrient solution for 10 days- growing
Using a microscope, the chromosomes are photographed
Cut out, match them in pairs
Place on chart
ID # & make sure that there are the correct #
New- Placenta test

111. Karyotype

112. Karyotyping
Cells (from blood, amniotic fluid, etc) are grown in vitro to increase their number
Cell division is then arrested in metaphase with colchicine (prevents mitotic spindle from forming)
Cells are centrifuged and lysed to release chromosomes
Chromosomes are stained, photographed, and grouped by size and banding patterns
Can help;
in genetic counseling about diseases.
ID parents
ID genetic disease characterized by the wrong number of chromosomes
Down’s Syndrome

113. Normal female karyotype
IDENTIFY
body chromosomes (autosomes) & Sex chromosomes
Normal male karyotype
Normal female karyotype

114. Genetic Engineering
Using biological or chemical means to change the DNA sequence
Can help diabetics by producing insulin
Goats producing medicine or spider silk
Improve crops
Grow more than one crop a year
Smaller plants, more grain
Frost free strawberries

115. Review Describe 2 genetic disorders
Why are males more likely to have some genetic diseases?
Describe the importance of genetic engineering

116. Human Genome Project
Human Genome Project Goal: sequencing all DNA on all the human chromosomes
Genome- chart showing the location of individual genes for human traits on a chromosome
Used to ID genes responsible for specific traits
more than genes on the 46 chromosomes
Over 3000 genetic disorders (inherited)
Potential-
ID those at risk by diagnosing disorder and eventually correcting the disorder
Now
Help control risk w/diet…
Plan on having children if at risk of problems

117. DNA sequencing DNA can be cut into pieces by enzymes
Pieces are inserted into bacteria
DNA reproduced as bacteria reproduces
DNA fragments put in gel in an electric current
DNA likes up making a map
Electrophoresis

118. New Genetic Technologies
Stem cell research
May eventually cure
Paralysis
Alzheimer's
Grow new organs

119. F1 is the first filial generation, offspring of the parental cross
F1 is the first filial generation, offspring of the parental cross. F2, or second filial generation, is the offspring of the cross of two F1 individuals.
Since each F1 parent can form four possible types of gametes, four different phenotypes occur among the offspring in the proportions shown.
The expected F2 phenotypic ratio is:
9 widow’s peak and short fingers
3 window’s peak and long fingers
3 straight hairline and short fingers
1 straight hairline and long fingers

120. Genetic Disorders Patterns of Inheritance
When studying human disorders, biologists often construct pedigree charts to show the pattern of inheritance of a characteristic within a family.
The particular pattern indicates the manner in which a characteristic is inherited.
Genetic counselors construct pedigree charts to determine the mode of inheritance of a condition.

121. Autosomal recessive disorders have these characteristics:
Affected children can have unaffected parents.
Heterozygotes (Aa) have a normal phenotype.
Two affected parents will always have affected children.
Affected individuals with homozygous dominant mates will have unaffected children.
Close unaffected relatives who reproduce are more likely to have affected children if they have joint affected relatives.
Both males ad females are affected with equal frequency.
How would you know the individual at the asterisk is heterozygous?

122. Autosomal dominant disorders have these characteristics:
Affected children will have at least one affected parent.
Heterozygotes (Aa) are affected.
Two affected parents can produce an unaffected child.
Two unaffected parents will not have affected children.
Both males and females are affected with equal frequency.
How would you know the individual at the asterisk is heterozygous?

123. Height is a multifactorial trait.
When you record the heights of a large group of young men, the values follow a bell-shaped curve. Such a continuous distribution is due to control of a trait by several sets of alleles. Environmental effects (i.e., differences in nutrition) are also involved.

124. CYU
How can an error in meiosis cause a sex cell to have the wrong number of chromosomes?
Name 3 genetic disorders and tell how each one of them is controlled by genes.
How can a genetic counselor use a pedigree to help families with genetic disorders?
Why do you think an XO female can survive but a YO male will die before birth?

125. EOC 27.1 The role of chromosomes
Each human sex cell has 23 chromosomes. Each human body cell has 46 chromosomes arranged in pairs
Amniocentesis is a way to look at the chromosomes of a fetus
The sex of a person is determined by a pair of sex chromosomes.
Human females have XX and males have XY

126. 27.2 Human Traits
If a person has a dominant trait, one or both of the parents will also have the trait.
If a person has a recessive trait, both of the parents will also carry the gene for the trait.
Traits in which neither gene is totally dominant over the other show incomplete dominance
Three genes control blood types in humans but each person has only 2 genes for this trait Males show recessive traits located on the X chromosomes more often than females do.

127. 27.3 Genetic disorders Nondisjunction
If chromosome pairs do not pull apart during meiosis, errors in chromosome number result. Hemophilia, cystic fibrosis, and dyslexia are genetic disorders.
A genetic counselor uses knowledge of genetics to predict & explain disorders in children

128. Why doesn’t it always come up with the perfect %?
What sex chromosome does the mother pass on? Is there any option?
What sex chromosome does the father pass on?
Who determines if a boy is born?
What are the chances of having a boy?
If you Flip a coin, how often would you expect to get heads?
Do you?

134. Question 1 Which of the following is NOT a sex-linked trait?
A. hemophilia
B. sickle-cell disease
C. male patterned baldness
D. red-green color blindness
The answer is B.

135. Question 2 Human eye color is determined by _______.
A. the influence of hormones
B. sex-linked inheritance
C. codominance
D. polygenic inheritance
The answer is D.

136. Question 3 Answer What are blood phenotypes based on?
Blood phenotypes are based on a molecule that attaches to a membrane protein found on the surface of red blood cells.

137. Question 4 Cob length in corn is the result of _______.
A. sex-linked inheritance
B. incomplete dominance
C. polygenic inheritance
D. simple dominance
The answer is C.

138. Question 5 A cleft chin is the result of _______. A. simple dominance
B. incomplete dominance
C. polygenic inheritance
D. sex-linked inheritance
The answer is A.

139. Question 6
What is the difference between simple Mendelian inheritance and inheritance by incomplete dominance?

140. In Mendelian inheritance, heterozygous individuals will display the inherited dominant trait of the homozygotes. However, when traits are inherited in an incomplete dominance pattern, the phenotype of heterozygous individuals is intermediate between those of the two homozygotes.

141. Question 7
If a trait is Y-linked, males pass the Y-linked allele to _______ of their daughters.
A. a quarter
B. half
C. all
D. none

142. The answer is D. Y-linked traits are only passed to males.

143. Question 8
What is necessary for a person to show a dominant trait?
Answer
The person must inherit at least a single dominant allele from one parent for the trait to appear.

144. Question 9
Why is sickle-cell disease considered to be an example of codominant inheritance?
Answer
Individuals who are heterozygous for the sickle-cell allele produce both normal and sickled hemoglobin. This is an example of codominance.

145. Question 10 Answer What sex is an XXY individual?
Any individual with at least one Y chromosome is a male.