1. Mendelian Genetics Part 1
AP Biology
Mendelian Genetics
Part 1

2. What are genes?
DNA segments, inherited from our parents, that code for proteins
What is a polypeptide?
A protein
What processes produce proteins?
Transcription and translation

3. Who was Gregor Mendel?
Known as the “Father of Genetics”
He was an Austrian monk
He was the cook for the monastery, so he had his own garden
He observed, grew, and experimented with pea plants

4. What is a character?
An inheritable physical feature
Eye color or hair color would be examples
What is a trait?
The variation of a character
Blue eyes or black hair
Two alleles are inherited, one from each parent, in order to create the variation

5. What is an allele?
Different versions of a gene
A gene is a distinct DNA nucleotide sequence that can make one protein
There can be different versions of the same gene, but they all make the same thing (ex. Eye color)
Each trait must have two alleles

6. What are dominant alleles?
They are the genes with the genetic information
They are represented with capital letters (Tt)
What are recessive alleles?
They are the genes without genetic information
They are represented with lower case letters

7. What is a true or pure breed?
Organisms with only one type of allele for a trait
The alleles are homologous (the same)
PP or pp

8. What is hybridization?
The creation of an organism that has two different types of alleles for a trait
The organism is referred to as a hybrid
It has heterozygous alleles

9. What is a phenotype?
The physical traits that can be seen
Blue eyes
Type A blood
Black hair

10. What is a genotype?
The genetic or DNA make-up for the trait

11. How can you determine a genotype?
Perform a test cross
Mate a homozygous recessive with the unknown genotype
That way no genetic information will be covered up by a dominant allele

12. What is a Punnett square?
A chart that shows all the possible genotypic outcomes that can occur from the mating of two organisms
Monohybrid cross
4 squares
Dihybrid cross
16 squares
Trihybrid cross
64 squares

13. What is Mendel’s Law of Segregation?
During Anaphase I and II, homologous chromosomes of sister chromatids will move independently of each other

14. What is Mendel’s Law of independent Assortment?
Variations are possible on sets of chromosomes, because chromosomes line up during Metaphase I and II independently and randomly

15. What is probability?
Chance
The likelyhood of a certain outcome
The range is 0 to 1
O is 0% and 1 is 100%
.5 would be 50%

16. What is the best way to assess the probability in a mating cross?
Use the Rule of Multiplication
Using the parents’ genetics multiplied together to predict the genetics of the offspring

17. Chance has NO memory.

19. Gene expression

20. Gregor Mendel

21. Character and Trait

22. Alleles for a gene

23. One from EACH parent Sperm AND Egg

24. True breeds & Hybrids

25. Phenotype vs. Genotype Physical Trait vs. Gene allele type

26. Test Cross Dominant phenotype, unknown genotype: PP or Pp?
Recessive phenotype,
known genotype: pp
If PP,
then all offspring
purple:
If Pp,
then 1 2 offspring purple
and 1 2 offspring white: p p p p P P Pp Pp Pp Pp P P Pp Pp pp pp

27. Monohybrid

28. Dihybrid

29. Law of Segregation - Anaphase

30. Independent Assortment
Key
Maternal set of
chromosomes
Possibility 1
Possibility 2
Paternal set of
chromosomes
Two equally probable
arrangements of
chromosomes at
metaphase I
Metaphase II
Daughter
cells
Combination 1
Combination 2
Combination 3
Combination 4

31. Chance has NO memory.

32. Mendelian Genetics Part 2
AP Biology
Mendelian Genetics
Part 2

33. What produces the phenotype in an organism?
The expression of proteins
What determines the proteins that will be constructed?
Nucleotide sequences that form the codons

34. What is incomplete dominance?
Genetic information is blended
The dominant phenotype is not completely covering over the recessive
Both phenotypes are seen in a blended version

35. What is complete dominance?
The dominant allele has all the DNA nucleotide information to produce a fully functioning protein
This completely suppresses the recessive allele, so that it is not seen at all

36. What is codominance?
Both alleles are seen and are not blended
They both are expressed equally

37. What are multiple alleles?
There are several versions of the same basic gene
How do multiple alleles work in blood types?
Glycoproteins are produced on the surface of the red blood cells
One type of glycoprotein is Type A; another type of glycoprotein is Type B
If there is no information for making the glycoprotein, then it is Type O

38. What is Hemophylactic Shock?
If two blood types are mixed, the glycoprotein “hands” will not recognize each other
One of the blood types will be perceived as foreign, and the white blood cells will begin killing those blood cells

39. What is the universal donor?
This blood type is acceptable by all blood types
Type O is the universal donor
It has NO glycoproteins on the surface of the cell, therefore, there is nothing for other cells to view as “unrecognizable”

40. What is the universal recipient?
This is the blood type that will accept ANY other blood type
Type AB is the universal recipient
It has glycoproteins that will recognize the glycoproteins on any other red blood cell

41. What is pleiotropy?
One gene affects many phenotypes
Sickle Cell Anemia is a good example
This gene affects the red blood cell shape, oxygen carrying ability, resistance to Malaria, etc.

42. What is epistasis? (one source [epi] affects another location [stasis]
A gene at one location on a chromosome affects a gene at another location on the chromosome
The phenotypes of hair would be a good example
Several genes interact to affect hair color, shape, thickness, texture, etc.

43. What is the ratio for most dihybrid crosses?
9:3:3:1
What is the ratio when epistasis occurs?
9:3:4

44. What is polygenic inheritance?
Many different degrees of phenotypic outcomes
What determines the outcome?
The number of alleles you inherit from your parents for that trait
Skin color is a good example (how many copies of the same gene were received by the offspring)
The number of alleles received are
referred to as Quantitative Characters

45. What is the norm of reaction?
The majority of organisms that fall on the bell curve for the trait

46. What is referred to by the term “multifactorial”?
Many environmental factors affect one phenotype
This concept is often referred to as “nature vs nurture, or “genetics vs the environment”
Most agree that it is about a 50/50 blend
Height
Intelligence
Weight

47. Phenotype by gene expression

48. 3’ T A C C A G C C G G T A A T A G G G A C C A T T 5’ DNA TEMPLATE
5’ A U G G U C G G C C A U U A U C C C U G G U A A 3’ mRNA
METH
VAL
GLY __
HIST
TYR __
PRO
TRP __ __
___
___
PROTEIN
3’ U A C C A G C C G G U A A U A G G G A C C A U U 5’ ANTI – CODON
Sequence
Does the DNA Sequence (Million Dollar Blueprint) look like the Anti-codon
Sequence? Remember, this is how the ribosome “knew” the Amino Acid was
Correct.

49. Incomplete Dominance

50. Complete Dominance

51. Codominance (AB) & Multiple Alleles

52. Pleiotropy (Sickle Cell)

53. Epistasis BbCc BbCc Sperm BC bC Bc bc BC BBCC BbCC BBCc BbCc bC BbCC1 BC 1 bC 1 Bc 1 4 4 4 4 bc 1 BC 4
BBCC
BbCC
BBCc
BbCc 1 bC
BbCC 4
bbCC
BbCc
bbCc 1 4 Bc
BBCc
BbCc
BBcc
Bbcc 1 bc
BbCc
bbCc
Bbcc
bbcc 4 9 3 4 16 16 16

54. Dihybrid – Normal 9:3:3:1 ratio

55. Polygenic Inheritance & Norm of the Reaction
AaBbCc
AaBbCc
aabbcc
Aabbcc
AaBbcc
AaBbCc
AABbCc
AABBCc
AABBCC
20/64
15/64
Fraction of progeny
6/64
1/64

56. Multifactorial example (Acid in soil changes the color)

57. Mendelian Genetics Part 3
AP Biology
Mendelian Genetics
Part 3

58. What is a pedigree?
A family history of traits
Squares are males
Circles are females
Shaded shapes are individuals that are affected
Clear shapes are normal individuals

59. Dominant trait (widow’s peak).
First generation
(grandparents) Ww ww ww Ww
Second generation
(parents plus aunts
and uncles) Ww ww ww Ww Ww ww
Third
generation
(two sisters) WW ww or Ww
Widow’s peak
No widow’s peak
Dominant trait (widow’s peak)

60. Recessive trait (attached earlobe).
First generation
(grandparents) Ff Ff ff Ff
Second generation
(parents plus aunts
and uncles)
FF or Ff ff ff Ff Ff ff
Third
generation
(two sisters) ff FF or Ff
Attached earlobe
Free earlobe
Recessive trait (attached earlobe)

61. What are recessive disorders?
These are disorders that result because there is NO information for a gene on either of the chromosomes inherited
These disorders tend to be harmful
They can only occur in a homozygous recessive genotype

62. What is a carrier?
These organisms are heterozygous for a trait
They inherited the recessive allele from one parent and the dominant allele from the other parent
They do not have the disorder, because the dominant allele is covering it up, but they still have a 50/50 chance of passing the recessive allele to their offspring

63. What are the characteristics of the recessive disorder called cystic fibrosis?
It is the most common lethal genetic disease
It affects 1 in 2500 births
In Caucasians 1 in 25 is a carrier
It creates a faulty protein carrier for the Cl- on the surface of cells in the lungs
This causes water to build up in the lungs

64. What can be done for people with cystic fibrosis?
There is no cure for cystic fibrosis
Infections in the lungs can be treated with antibiotics
Fluid can be drained from the lungs periodically
Medications can help reduce the amount of fluid that collects in the lungs

65. What are the characteristics of the recessive disorder called Tay-Sachs Disease?
The disorder causes the lysosomes in the brain cells to be non-functioning
The brain cells fill up with lipids and die, because lipids are what brain cells use for energy, but lysosomes have to break them down to release the energy, and the lysosomes cannot do this

66. Where is Tay-Sachs found to be more prevalent?
In the Jewish culture
This is because they tend to marry within the culture, so there are a high number of carriers
This means the offspring has a greater chance of receiving the recessive gene from both parents
Children usually die a painful death by age 5

67. What are the characteristics of the recessive disorder called Sickle-cell Disease?
This is the most common genetic disorder within the black population
It affects about 1 in 400 births
It is caused by the 6th amino acid being changed from Glutein to Valine (point mutation)
This is the primary sequence of one of the proteins needed to make red blood cells

68. How does the mutated protein affect the red blood cells?
They are misshapen from round, disc-shaped to a crescent or sickle shape
They cannot carry an adequate amount of oxygen to the cells
The sickle cell hemoglobin produces an enzyme that protects the host against Malaria by giving off carbon monoxide

69. What can be done for individuals that have sickle cell disease?
There is NO cure
Some medications help with pain and the low oxygen levels

70. What is the Heterozygous Advantage?
Homozygous dominant have normal blood cells but are not resistant to Malaria
Homozygous recessive are resistant to Malaria but have sickle disease
Heterozygous dominant have normal blood cells but are resistant to Malaria

71. What are the characteristics of dominant disorders?
Only one dominant allele is needed to express the disorder
If the individual is homozygous dominant, the disease will usually be much worse
What are some examples of human dominant disorders?
Achondroplasia
Huntingdon’s Disease

72. What is achondroplasia?
Genetic dwarfism
It occurs 1 in 10,000 births
Most people are homozygous recessive for this disorder, and therefore do not have a genetic code to express the disorder

73. Achondroplasia is a form of short-limbed dwarfism
Achondroplasia is a form of short-limbed dwarfism. The word achondroplasia literally means "without cartilage formation." Cartilage is a tough but flexible tissue that makes up much of the skeleton during early development. However, in achondroplasia the problem is not in forming cartilage but in converting it to bone (a process called ossification), particularly in the long bones of the arms and legs. The most common health problems occur in the spine.

74. The average height of an adult male with achondroplasia is 4 feet, 4 inches, and the average height for adult females is 4 feet, 1 inch. Characteristic features of achondroplasia include an average-size trunk, short arms and legs with particularly short upper arms and thighs, limited range of motion at the elbows, and an enlarged head with a prominent forehead. Fingers are typically short and the ring finger and middle finger may diverge, giving the hand a three-pronged appearance. People with achondroplasia are generally of normal intelligence.

75. What is Huntingdon’s Disease?
It is a slow degenerative disorder affecting the brain
It affects 1 in 10,000 births
It does not usually present until around age 40-50
The dominant gene is located on the very tip of autosome 4

76. Since people have usually already had children before the disease presents, it is important to study family pedigrees in order to know if this disorder is in your genes.
The defect on chromosome 4 causes a part of the DNA, called a CAG repeat, to occur many more times than normal. Usually, this section of DNA is repeated 10 to 28 times. But, in persons with Huntington disease, it is repeated 36 to 120 times.

77. As the gene is passed down through families, the number of repeats tend to get larger. The larger the number of repeats, the higher your chance of developing symptoms at an earlier age. Therefore, as the disease is passed along in families, symptoms develop at younger and younger ages.
If one of your parents has Huntington disease, you have a 50% chance of getting the gene. If you get the gene from both your parents, you will develop the disease at some point in your life. You will also pass it on to your children. If you do not get the gene from your parents, you cannot
pass the gene on to your children.

78. What are multifactorial diseases?
These are diseases in which the environment also plays a role, along with genetics
What are some examples?
Heart disease
Diabetes
Cancer
Alcoholism

79. What are some factors that contribute to heart disease?
Genetics
Diet
Alcohol
Smoking
Stress

80. What are some causes of diabetes?
Genetics
Diet
Race
Type 2 diabetes occurs more frequently in African Americans, Alaska Natives, American Indians, Hispanics/Latinos, and some Asian Americans, Native Hawaiians, and Pacific Islander Americans than it does in non-Hispanic whites.

81. What are the causes of cancer?
Genetics
Life style habits

82. What are some causes of alcoholism?
Genetics (abnormal levels of serotonin and dopamine may contribute)
Lifestyle (frequenting places where drinking occurs and being around other drinkers)
Mental state (frustration, anger, depression, anxiety, and stress may contribute)

83. What is penetrance?
The percentage of individuals with a certain genotype that actually present the expected phenotype
An example would be Huntington’s Disease
95% of individuals that have the dominant allele actually present the disease
5% do not express the disease
Therefore, there is a 95%
penetrance for the
Huntington’s allele

84. What is expressivity?
This refers to the degree to which the allele is expressed or seen
Expressivity is more severe when the genotype is homozygous (because that means the individual received TWO copies of the allele)

86. Sickle- Cell

87. Achondroplasia

88. Mendelian Genetics Part 4
AP Biology
Mendelian Genetics
Part 4

89. Where are genes found?
On chromosomes
What two types of chromosomes are associated with humans?
Autosomes
Sex chromosomes
From where does an individual get its chromosomes?
They are inherited from the parents

90. What are linked genes?
These are genes that are usually inherited together as a linked unit on the same chromosome
These usually refer to genes on the autosomes (Chromosomes 1-22)

91. Who is Alfred Sturtevant?
He was the pioneer of genetic mapping
What is genetic mapping?
Locating the position of genes on chromosomes

93. Chromosome 1

94. How did Sturtevant determine the location of genes on chromosomes?
How used the crossover rates of the chromosomes
The smaller the rate of crossover, the closer the genes were to each other on the chromsome
The higher the rate of crossover, the farther apart the genes were to each other on the chromosome
He measured the loci (locations) of the genes in centimorgans, also called map units
Sturtevant named
this unit in honor
of his genetics
teacher,
T. H. Morgan

95. What are sex-linked genes? Genes found on the sex chromosomes
95% of the time they will be on the X-chromosome
This is because both sexes have at least one X-chromosome
Hemophilia is a recessive disorder
H is dominant (normal; no disease)
h is recessive (will cause disease)
#1-female-will not have disease
#2-male-will not have disease
#3-female-will not have disease
#4-male-will have disease
**Females rarely get the disease
Would have to be XhXh to have it 1 2 3 4
Females are XX (homologous); Males are XY (heterologous)

96. How are sex chromosomes different from other chromosomes during crossover?
There is very little crossover with sex chromosomes
When is the sex of an organism determined?
At conception or the moment of fertilization
Fertilization occurs when either a sperm X chromosome or a sperm Y chromosomes combines with the X chromosome of the egg

97. What type of sex characteristics do all organisms have at first?
Everyone starts out female
This is why everyone has nipples
When does the change occur?
Around 2 months of development
The Y chromosome gene becomes active to make testosterone
Testosterone is made from estrogen

98. What happens to testosterone after development is completed?
It is turned off until puberty
At puberty it is turned back on to make the secondary sex characteristics (facial hair, muscle mass, Adam’s apple, larger bones, etc.)
What are primary sex characteristics?
The sex organs and gonads

99. Like any other genetic disorder, sex-linked genetic disorders have……
No cure
What are some examples of sex-linked genetic disorders?
Color blindness
Hemophilia

100. What is color blindness?
A faulty recessive gene on the X chromosome cannot make the protein that absorbs certain wavelengths of light (which determine color) in the cones on the retina of the eye
The most common is red/green color blindness, in which both colors appear gray

101. What is hemophilia?
The name means “love of bleeding”
Individuals have a faulty recessive gene and cannot make the protein that produces the Anti-hemolytic Factor
This is the clotting factor
The individual could bleed to death

102. Why is hemophilia associated with the “Royal Blue-bloods of Europe”?
Because they interbred to keep the crown “in the family”, and by doing so, the offspring had a much greater chance of getting two recessive genes for hemophilia
Or just one,
if a male

103. What can be done for hemophiliacs?
They must keep AHF (clotting factor) with them at all times, in case of injury
They must take a shot of AHF the moment they start bleeding, or even if they get a bruise

104. Who does hemophilia affect?
Mainly males
Even if they get the recessive gene on an X chromosome, there is nothing on the Y chromosome to counteract it
Can females get hemophilia?
Yes, but they would have to receive two recessive genes, one on each X chromosome
If a female receives only one recessive gene, she will be a carrier, but will not have the disorder

105. Why does hemophilia seem to skip a generation?
Because the mother is usually only a carrier
Therefore, the trait does not present in her
Then, if she has a son, he can be affected

106. What kind of genes do not follow Mendel’s Laws of Inheritance at normal or expected rates?
Linked genes
Sex-linked genes
Mendel’s laws were really referring to one chromosome….not pairs of chromosomes, which is what we inherit
What is associated with variation?
Crossover frequency
Which chromosome is referred to with sex-linked?
The X chromosome only

107. Genes on Chromosomes

108. Autosomes and linked genes

109. Linkage Map based on Crossover frequency
Recombination
frequencies 9%
9.5%
17% b cn vg
Chromosome

110. Locus Gene Maps

111. Sex –Linked Female – TWO Xs

112. Sex-Linked Male – ONE X

113. One from EACH parent Sperm AND Egg

114. Pedigree of Color Blindness

115. Pedigree of Hemophila

116. Mendelian Genetics Part 5
AP Biology
Mendelian Genetics
Part 5

117. What are some examples of gene mistakes?
Point mutations
Reading frame mutations

118. When can chromosomal errors occur?
During mitosis or meiosis
During Anaphase when the chromosomes are moving
During crossover when DNA segments are moving

119. What are some types of errors that can occur with the chromosomes?
Chromosome number
Chromosome structure
What is aneuploidy?
An abnormal number of chromosomes
What causes this abnormal number of chromosomes?
Nondisjunction during Anaphase

120. What is nondisjunction?
A failure of chromosomes to separate during Anaphase
What are some of the results of nondisjunction?
Trisomy
Monosomy
Polyploidy

121. What is trisomy?
Having three of one kind of chromosome in a cell, instead of two

122. What is monosomy?
Having only one chromosome in a cell instead of two
Turner’s Syndrome

123. What is polyploidy?
Having extra sets of chromosomes
Usually deadly in animals
Plants unaffected
Bigger fruits
Larger flowers

124. What usually changes the individual chromosome structure?
Faulty crossover
What are some examples of faulty crossover?
Deletion
Duplication
Inversion
Translocation

125. What occurs during deletion?
A chromosome segment will be missing on one chromosome, because it got stuck on the other homologous chromosome during crossover

126. What occurs during duplication?
Two copies of a segment of the chromosome will be on one chromosome and missing on the other homologous chromosome

127. What occurs during inversion?
A chromosome segment is turned around backwards during crossover

128. What occurs during translocation?
A segment from one chromosome becomes attached to a different autosome

129. What is a syndrome?
Possessing identifying traits of a particular genetic disorder
What are some examples of human genetic syndromes?
Down’s Syndrome
Turner’s Syndrome
Edward’s Syndrome
Crouzon Syndrome

130. What is Down’s Syndrome?
Trisomy 21
An extra copy of chromosome 21 (three instead of two)
Often caused when older women have babies
What are some identifying characteristics?
Mental retardation
Flat face
Squinting eyes
Smaller stature

131. What is Crouzon Syndrome?
A faulty protein causes abnormal growth of the bones of the jaw

132. What is Treacher Collins Syndrome?
Characteristics are a high arched palate, malformed ears, bird or fishlike face, lower eyelids, and deformities of the jaw bones

133. What is extranuclear DNA?
DNA that is outside the nucleus
This DNA would be inside other organelles, such as chloroplasts, mitochondria, and other plastids
This DNA can only be inherited through the mother, because the egg cell alone has cytoplasm and organelles (sperm only has DNA)
These sources are cloned (exactly alike), so they help in identification

134. What is Mitochondrial Myopathy?
Mitochondria that lack the ability to make adequate amounts of ATP
They have faulty DNA segments for making some of the enzymes or proton pump proteins
Individuals that have this disorder are usually very tired all the time

136. Non-Disjunction

137. Trisomy 21

138. Chromosome Structure Errors

139. Extranuclear DNA (This DNA CAN can affect an organism)