This document provides an overview of basic concepts in biological inheritance and genetics, including: - Traits are passed from parents to offspring through genes. Offspring inherit characteristics from both parents, introducing variation. - Gregor Mendel conducted experiments with pea plants in the 1800s and established the principles of heredity, including that traits are inherited in discrete units (genes) and genes assort independently. - Monohybrid and dihybrid crosses examine the inheritance of one or two traits, respectively. Punnett squares are used to determine possible genotypes and phenotypic ratios in offspring. Probability rules apply to predicting inheritance of traits.

1. BIOLOGY 40S Unit 1 Understanding Biological Inheritance

2. Members of a family show many similarities in appearance, but are not identical (except in the case of identical twins). Why do offspring inherit certain characteristics from their parents, but not others? Unit 1 – Understanding Biological Inheritance

4. homozygous recessive heterozygous trait allele purebred dihybrid Independent assortment dominant phenotype genotype gene Unit 1 – Understanding Biological Inheritance

7. Mendel's Contribution The story of Gregor Mendel and his work provides a fascinating glimpse into the nature of science. Mendel was born in 1822 and as a young man attended the University of Vienna. There he studied chemistry, biology and physics, but left before graduating, probably for health reasons. He entered the Augustinian monastery in Brno, and with the support of the abbot, began his investigation of the inheritance of certain traits in pea plants ( Pisum sativum ). His choice of pea plants as the experimental subject was excellent as peas grow and reproduce quickly, their mating can be controlled, and the plants have a number of distinct traits that are readily observed. Over the course of the next eight years, Mendel conducted experiments and maintained detailed records of his results. His university training led him to design simple experiments that permitted him to observe the inheritance of one trait at a time. His use of mathematics allowed him to formulate conclusions based on his results. These conclusions are known as Mendel’s Laws or Principles.

8. Gregor Mendel Early Principles of Inheritance

9. Gregor Mendel Gregor Mendel’s Research & Principles

10. Gregor Mendel Using Terms in Modern Genetics to Review Mendel’s Work

16. Gene locus

17. Gene Linkage

28. Segregation and independent assortment

31. Dihybrid cross

35. Incomplete Dominance

37. Incomplete Dominance

39. Beyond Simple Inheritance Patterns

43. Inheritance of blood type

44. Multiple Allele Inheritance and Codominance

46. Beyond Simple Inheritance Patterns

49. Karyotype

50. Karyotype

54. Genetics of Parenthood

61. Meiosis Unit 1 - Genetics

64. nucleolus Overview of meiosis centromere 2n = 4 DNA replication 2n = 4 synapsis sister chromatids n = 2 n = 2 Meiosis II Sister chromatids separate, becoming daughter chromosomes. Meiosis I Homologous pairs separate. n = 2 n = 2

65. nucleolus centromere 2n = 4

66. nucleolus centromere 2n = 4 DNA replication 2n = 4 synapsis sister chromatids

67. nucleolus centromere 2n = 4 DNA replication 2n = 4 synapsis sister chromatids Meiosis I Homologous pairs separate. n = 2 n = 2

68. nucleolus centromere 2n = 4 DNA replication 2n = 4 synapsis sister chromatids n = 2 n = 2 Meiosis II Sister chromatids separate, becoming daughter chromosomes. Meiosis I Homologous pairs separate. n = 2 n = 2

72. Homologous pairs align at the metaphase plate. Metaphase I DNA Replication Homologous chromosomes separate, pulled to opposite poles by centromeric spindle fibers. Anaphase I Daughter cells have one chromosome from each homologous pair. Telophase I Homologous chromosomes pair during synapsis. Prophase I Meiosis I 2n = 4 Chromosomes still consist of two chromatids. Interkinesis n = 2

73. DNA Replication

74. DNA Replication Homologous chromosomes pair during synapsis. Prophase I Meiosis I 2n = 4

75. Homologous pairs align at the metaphase plate. Metaphase I DNA Replication Homologous chromosomes pair during synapsis. Prophase I Meiosis I 2n = 4

76. Homologous pairs align at the metaphase plate. Metaphase I DNA Replication Homologous chromosomes separate, pulled to opposite poles by centromeric spindle fibers. Anaphase I Homologous chromosomes pair during synapsis. Prophase I Meiosis I 2n = 4

77. Homologous pairs align at the metaphase plate. Metaphase I DNA Replication Homologous chromosomes separate, pulled to opposite poles by centromeric spindle fibers. Anaphase I Daughter cells have one chromosome from each homologous pair. Telophase I Homologous chromosomes pair during synapsis. Prophase I Meiosis I 2n = 4

78. Homologous pairs align at the metaphase plate. Metaphase I DNA Replication Homologous chromosomes separate, pulled to opposite poles by centromeric spindle fibers. Anaphase I Daughter cells have one chromosome from each homologous pair. Telophase I Homologous chromosomes pair during synapsis. Prophase I Meiosis I 2n = 4 Chromosomes still consist of two chromatids. Interkinesis n = 2

80. Metaphase II Chromosomes align at the metaphase plate. Anaphase II Daughter chromosomes move toward the poles. Telophase II Spindle disappears, nuclei form, and cytokinesis takes place. Meiosis II Prophase II Cells have one chromosome from each homologous pair. n = 2 n = 2 Daughter Cells Meiosis results in four haploid daughter cells. n = 2 n = 2

81. Meiosis II Prophase II Cells have one chromosome from each homologous pair. n = 2 n = 2

82. Metaphase II Chromosomes align at the metaphase plate. Meiosis II Prophase II Cells have one chromosome from each homologous pair. n = 2 n = 2

83. Metaphase II Chromosomes align at the metaphase plate. Anaphase II Daughter chromosomes move toward the poles. Meiosis II Prophase II Cells have one chromosome from each homologous pair. n = 2 n = 2

84. Metaphase II Chromosomes align at the metaphase plate. Anaphase II Daughter chromosomes move toward the poles. Telophase II Spindle disappears, nuclei form, and cytokinesis takes place. Meiosis II Prophase II Cells have one chromosome from each homologous pair. n = 2 n = 2

85. Metaphase II Chromosomes align at the metaphase plate. Anaphase II Daughter chromosomes move toward the poles. Telophase II Spindle disappears, nuclei form, and cytokinesis takes place. Meiosis II Prophase II Cells have one chromosome from each homologous pair. n = 2 n = 2 Daughter Cells Meiosis results in four haploid daughter cells. n = 2 n = 2

88. Independent alignment

89. Synapsis and crossing over

90. Chromosomal Alterations

99. Chromosomal Abnormalities

102. Deletion

104. Duplication

105. Translocation

107. Inversion

109. Pedigree Analysis - Symbols

110. Pedigree Analysis - Symbols Marriage Line: Offspring: Twins:

111. Pedigrees

116. X-linked Recessive Pedigree Chart

117. Pedigrees

122. Pedigrees