1. Genetics & Heredity
Chapter 11 & 14

2. The Big Picture
The sequence of the nitrogen bases in your DNA contains your genetic code. This code is called your genome and is located collectively in the genes located on your chromosomes. The genes contain the instructions for the process of Protein Synthesis which makes every single protein that you need to express every trait that you will ever have.

4. Central Dogma: DNA  genes  protein  trait

5. You received 50% of your genome from your mom & the other 50% from your dad. Their haploid gametes were formed through the process of Meiosis and then came together through the process of Fertilization to produce the diploid cells of you.

6. Genetics The scientific study of heredity
Heredity discusses how your unique genome was created and passed on to you.

7. Gregor Mendel - Father of Genetics
Czechoslovakian monk
Highly educated ordained priest
Experimented with garden pea plants from
Kept very accurate records (which allowed his work to be rediscovered later on!) but never officially reported his findings
Eventually gave up experiments to be the Abbott

9. Mendel’s experiments & Their Results

10. Techniques
Used self-pollination and cross-pollination techniques to study 7 traits of garden pea plants

11. Some terms to know:
Self-pollinating--sperm cells in pollen fertilize egg cells in the same plant
Fertilization--during sexual reproduction, male and female reproductive cells join and produce a new cell.
True-breeding peas--when they self-pollinated, they would produce offspring identical to themselves.

12. Some terms to know
Cross-pollination-two different plants pollinating to produce seeds.
He wanted to produce seeds from two different plants.
He took off the pollen-bearing male parts
he dusted pollen from another plant

14. Forcing Cross-pollination

15. Genes Notation Mendel studied only 1 trait at a time.
original parents =P (parent) generation
The offspring= F1 (first filial)
filius and filia are latin for “son” and “daughter”
Hybrid-offspring of parents with two opposite traits (TT x tt = Tt.)

16. 1st set of experiments Single factor cross (looking at one trait)
Cross pollinated plants with opposite characteristics to see which trait would appear in the F1 hybrid
Two conclusions
Individual factors called genes (that have different forms called alleles) control each trait of a living thing
Principle/Law of Dominance: some alleles are dominant while some are recessive

17. 1st experiment results

18. Mendel’s lucky break!
all traits studied were controlled by a single gene
all genes were either dominant or recessive (no co-dominance)
only a limited # of traits were studied
This made it easy for Mendel to interpret results

19. 2nd set of experiments
Wanted to know what happened to recessive factors so let F1 hybrids self pollinate
Conclusions
dominant allele had covered up (masked) the recessive allele in the F1 generation
Principle/Law of Segregation: recessive allele had segregated from dominant allele in the F2 generation

21. Probability & Punnett Squares

22. Punnett Squares

23. Probability
Punnett squares are used to predict and compare the genetic variations that result from a cross using the principles of probability

24. Genetics and Probability
Probability—the likelihood that a particular event will occur.
In a coin flip, the probability that a single flip will come up heads is 1 chance in 2, or ½, or 50% - every single time!
Genetics is like coin flipping: the way alleles segregate is completely random like a coin flip.

25. Single factor (monohybrid) cross: page 316

26. Probability
According to Mendel, you could expect a 3:1 ratio of dominant traits to recessive traits in a hybrid cross (F1 cross)
In order to actually see these ratios, you would have to look at many offspring. Mendel studied many thousands of offspring.

27. Expressing probabilities for genotypes & phenotypes
Ratios:
¼ : fractions
3:1 (dominant phenotype to recessive phenotype)
1:2:1 (DD: Dd: dd)
Percentages:
½ = 50%

28. Test Cross
Process of crossing an unknown genotype individual to a homozygous recessive individual to determine what the unknown genotype is.

29. Test cross

30. Punnett Squares
We are going to practice single factor punnett squares to see how the probabilities work.
These are useful to determine the chances of a particular trait showing up in an offspring.
Open your booklet to pages 4-6

31. Probability & Punnett Squares

32. Punnett Squares

33. Probability
Punnett squares are used to predict and compare the genetic variations that result from a cross using the principles of probability

34. Genetics and Probability
Probability—the likelihood that a particular event will occur.
In a coin flip, the probability that a single flip will come up heads is 1 chance in 2, or ½, or 50% - every single time!
Genetics is like coin flipping: the way alleles segregate is completely random like a coin flip.

35. Single factor (monohybrid) cross: page 316 – know these expected monohybrid ratios

36. Expressing probabilities for genotypes & phenotypes
Ratios:
¼ : fractions (parts of the total)
3:1 (dominant phenotype to recessive phenotype)
Single factor cross genotype
1:2:1 (DD: Dd: dd)
Percentages:
½ = 50%
Need to label with trait

37. Probability Standards
When writing a single factor cross ratio, this is the accepted order.
With a 3:1 phenotype ratio
Dominant:Recessive
If none exist, place a ᴓ in its place
With a 1:2:1 genotype ratio
DD:DR:RR
Use the same order if using percentages
May also label %s
Example: 25% Rr or 25% red

38. Test Cross
Process of crossing an unknown genotype individual to a homozygous recessive individual to determine what the unknown genotype is.

39. Test cross

40. Punnett Squares
We are going to practice single factor punnett squares to see how the probabilities work.
These are useful to determine the chances of a particular trait showing up in an offspring.
Open your booklet to pages 7-8 to practice
There are some interactive links on my webpage to review & practice

41. Independent assortment

42. Two factor crosses
Looking at 2 unlinked traits (genes) NOT carried on same chromosome
We’ll talk about gene linkage later

43. Independent Assortment
The principle of independent assortment states that genes for different traits can segregate independently during the formation of gametes. Basically, they are not stuck together so they can separate & recombine in different combinations!
Accounts for the many genetic variations observed in plants, animals, and other organisms.

44. Provides different combinations of alleles

45. Demonstrates Principle of Dominance
Demonstrates Principle of Independent Assortment

46. Expressing probabilities for genotypes & phenotypes (2 factor cross)
Ratios:
4/16 : fractions (parts of the total – don’t reduce)
Genotype ratios are typically not used in 2 factor crosses
Phenotype ratios use the DD:DR:RD:RR pattern
Example- 9:3:3:1 (DD: DR: RD: RR)
Percentages:
Need to label with trait

51. Chromosome theory

52. Chromosome Theory
Mendel’s work was incomplete because he never asked, “Where in the cell are the factors that control heredity?”
His work was rediscovered in the early 1900s

53. Discoveries that made it possible
Cell biologists by that time had discovered:
Most of major cell structures
Sequence of events in mitosis & meiosis
Behavior of chromosomes in mitosis & meiosis

54. Chromosome Theory – know the 3 statements
This info lead to the conclusion of Chromosome Theory by Walter Sutton in 1902
Genes are located on chromosomes
Each gene occupies a specific place on a chromosome
Genes may exist in several alleles and each chromosome contains one allele for each gene

55. Walter Sutton

56. Review: Chromosome Mutations
May involve segments off chromosomes, whole chromosomes, and entire sets of chromosomes
There is a change in the number or structure of the chromosomes
Make sure you can recognize examples & descriptions of each type

57. Chromosome Mutations

58. Inversion & Translocation Mutations

59. Nondisjunction Mutations

60. All Mutations

61. Polyploidy – Middle plant

62. Genetics & Heredity
Sections VIII - end

63. Gene Linkage & Gene mapping

64. Thomas Hunt Morgan
American: established many of basic principles of transmission genetics

65. More of Hunt’s Findings
Genes located closely together on the same chromosome are linked together
they are inherited together and do NOT undergo independent assortment
only genes that are located on different chromosomes (or far apart on same one) undergo independent assortment

66. Linkage groups

67. More of Hunt’s findings
Crossing over occurs during the 1st meiotic division when homologous chromosomes are paired. This produces new combos of alleles & increases genetic variety.
Genes that are close together like JKL in the diagram may be linked and swapped as a group.
Genes that are farther apart like genes C and K may get crossed over & independently sorted.

68. Crossing Over

69. Alfred Sturtevant Morgan’s graduate student
Reasoned that the distance between genes on a chromosome determine how often crossing-over occurs between them.
further apart on gene = higher probability of crossing over so …..
knowing frequency of crossing over makes it possible to map the location of genes on a chromosome
Damaged chromosomes are also useful in mapping chromosomes

70. Chromosome mapping Chromosome Map - Human Diseases
WS - How to map a chromosome
Complete the example in class
Do the practice problems for HWEC

71. Human Genome Project
In 2003, the mapping of the human genome was considered completed at 99% given the current technology of the times
Increased processes continue to develop easier sequencing and identification methods
Example: 23 and me - Your personal genetic report

72. See Information in notes and the following Examples and Problems
Human Inheritance
See Information in notes and the following
Examples and Problems

73. Dominant/Recessive Polydactyly: Dominant PKU: Recessive
Cystic Fibrosis: Recessive

74. Some Examples of human traits on link & following slides
10 Human traits exhibiting complete dominance
Some Examples of human traits on link & following slides

75. Attached Lobe Unattached Lobe
                          
                            
Unattached Earlobe—dominant—chromosome 21

76. Cheek Dimples
                                                   
Cheek Dimples Dominant---Chromosome 5

77. Widow's Peak
                                                                  
Widow’s peak --- dominant---chromosome 4

78. Straight Thumb is dominant---chromosome 17
Hitchhiker's Thumb
Regular Thumb
                        
Straight Thumb is dominant---chromosome 17

79. Mid-digital Hair is dominant. Carried on chromosome 10

80. Freckles –dominant Carried on chromosome 9

81. Long Second Toe Dominant---Chromosome 20 TT or Tt
Short Second Toe
Long Second Toe
                               
                                  
Long Second Toe Dominant---Chromosome TT or Tt

82. Tongue Rolling
                                                          
Dominant---on chromosome RR, Rr

83. Cleft Chin
                                                                
Dominant—on chromosome 16 CC, Cc

84. Incomplete Dominance Blending: Red and White flowers R=Red W=White
RW=Pink

85. Codominance Sickle Cell Anemia AA=Normal SS=Sickle Cell disease
SA= Sickle Cell Trait (Resist Malaria)

86. Multiple Alleles Blood Type: Type A=AA, AO Type B=BB, BO Type O=OO
Type AB=AB

87. Polygenic Produced by interaction of several genes
Show wide ranges of phenotypes
Example: human skin and hair color and other complex traits

90. Sex linked inheritance

91. Sex Linked Sex Chromosomes X & Y Female=XX Male=XY
Colorblindness: X linked recessive
Hemophilia:
Duchenne M.D.
Male Baldness

92. Barr Body Barr body – inactivated X chromosome in females
Prevents cell from being “overloaded” on proteins made by X chromosome

93. Genes
Genes alone do not determine phenotype. They only determine our maximum genetic potential.
Environmental factors also affect appearance: nutrition, exercise, healthy practices

94. Pedigrees
Notes information in your booklet

95. Normal Karyotypes
arrangement of chromosomes in pairs by size starting with the longest pair and ending with the sex chromosomes
Can be used to detect genetic disorders caused by non-disjunction of chromosomes during meiosis

96. Non-disjunction

97. Normal Karyotypes

98. Karyotypes - Anomalies