Lecture 28 Patterns of Inheritance Fall 2024 PDF

11/3/24 BIO 311C Introductory Biology I DR. K. SATA SATHASIVAN Unit 4. Molecular Biology Lecture 28. PATTERNS OF...

11/3/24 BIO 311C Introductory Biology I DR. K. SATA SATHASIVAN Unit 4. Molecular Biology Lecture 28. PATTERNS OF INHERITANCE A. Students at Brigham Young University, arranged according to height B. Actual distribution of individuals in C. Idealized bell-shaped curve for a the photo according to height population that displays continuous variation in a trait (Line of bell- shaped curve in each height in each height indicates Number of Number of individuals individuals category continuou category s variation in 1 4 8101616161514131311 9 8 8 5 1 2 populatio n.) Shortest Range of Tallest Shortest Range of heights heights Tallest If the sample in the photo included more individuals, the distribution would more closely approach this ideal. 1 Basic Terms and Concepts down to A Unit of heredity, Ex. Gene for Purple flower passed Genes: generation generation Alleles: Alternate forms of a gene, EX. Genes for purple flower and white flower Character: Feature, Ex. Flower color Trait: Specific feature, Ex. Purple flower Homozygous: same allele on both chromosomes r Heterozygous: Different alleles in two chromosomes Dominant allele/trait: Expressed under both homozygous recessive and heterozygous condition expressed Recessive allele/trait: Expressed only under homozygous only condition forHomozygous Phenotype: Physical trait, Ex. Purple flower Genotype: Genetic make up, Ex. PP or Pp 2 1  11/3/24 fatherofgenetics Gregor Johann Mendel (1822 to 1884) and his Experiments Gregormendelflation Gregor Mendel conducted donotneedtobeascientis experiments with pea plants (Pisum hhfit.tl sativum) from 1856 to 1863 and published the results in 1866. genedetermined single 3 ftafirst Inheritance of Traits styutrilcoio Havethetiafo Geta 3 1 ratio 4 2  11/3/24 Law of Segregation Allele pairs segregate (separate) during gamete formation and the paired condition is restored during fertilization Thereisno 031 assigned dominant recessive 5 Test Cross of Unknown Genotype 6 3  11/3/24 oftwotraits crossing Law of Independent Assortment The segregation (separation) of one allele pair is independent of the segregation of other allele pairs motmunimation fi nii i together 7 Molecular Basis of a Dominant Trait 8 4  11/3/24 Recessive Genes and Carriers arenormal in 9 understandmarkers Non-Mendelian Inheritance noblendingbut Variations from Mendel’s basic i principles of dominant and recessive inheritance. Incomplete dominance K Codominance Multiple alleles Epistasis Polygenic inheritance Pleiotropy Environmental effect Epigenetics 10 5  11/3/24 Codominance in Blood Group onetraitisnotdominant Possible alleles in overother gametes from father: IA or IB or i A AB A IA IAIA IAIB IAi or Possible alleles AB B B in gamete from IB mother: IAIB IBIB IBi or A B O i IAi IBi ii universal athiversal will acceptor mantisainani 11 Epistasis Foal stains In epistasis, expression of a gene at one locus alters the phenotypic expression of a gene at a second locus For example, in Labrador retrievers and many other mammals, coat color depends on two genes One gene determines the pigment color (with alleles B for black and b for brown) The other gene (with alleles E for color and 0 0 MMoris e for no color) determines whether the pigment will be deposited in the hair O O eltressed 12 Blackdominantoverbrown onlpqt.tlcontrolled by pair another 6  11/3/24 Multiple Alleles and Genes 13 Polygenic Inheritance Heartdisease A. Students at Brigham Young University, arranged according to height obesity B. Actual distribution of individuals in the photo according to C. Idealized bell-shaped curve for a population that displays height continuous variation in a trait (Line of bell- shaped curve indicates 0 continuous variation in in each height category in each height category Number of individuals Number of individuals population.) 1 4 8 10 16 16 16 15 14 13 13 11 9 8 8 5 1 2 Shortest Range of heights Tallest Shortest Range of heights Tallest If the sample in the photo included more individuals, the distribution would more closely approach this ideal. mutts 14 7  11/3/24 onegenedefectcauses a defectinother genes Homozygous recessive individual Pleiotropy in Sickle-Cell Anemia Abnormal hemoglobin Sickling of red blood cells Rapid destruction of Clumping of cells and sickle cells leads to anemia interference with blood circulation leads to local failures in blood supply Impaired mental function Pneumonia Heart failure Heart failure Kidney failure Weakness Abdominal and fatigue pain Paralysis 15 Environmental Effect cold tiffin feelects sunlight Seasonal variation in colors Source: Nature.com Diet and obesity (Matthew Cole) 16 8  11/3/24 Epigenetics Beyondthegenes Epigenetics is the study of external factors, beyond the uthtside factors external genes, influencing the gene expression. The major causes of epigenetics are given below. DNA Methylation: Addition of methyl groups to Adenine or Cytosine alters the gene expression. This can be passed on from generation to generation as Genomic Imprinting. Histone Acetylation: Histones are the the proteins wrapped around by the DNA double helix. Addition of acetyl groups will activate gene expression. Ilana b initiation Non-coding RNA: RNA fragments that do not code for any proteins can influence the gene expression. 98 isnoncoding Microbiome: The gut bacteria can also affect the way Histone we gain or lose weight. Figure from Wikipedia theDNAmodified thespiral the effect wg way eainmooseweight memulation Aging, diet and stress: Variation in methylation and getnomic influence of diet and chemicals on microbiome. imprinting Source: CDC.gov/genomics/disease/epigenetics becomeshortershorter telomeres 17 Summary Laws of Inheritance by Gregor Mendel 1. Law of Segregation 2. Law of Independent Assortment Non-Mendelian inheritance. Incomplete dominance Codominance Multiple alleles Epistasis Polygenic inheritance Pleiotropy Environmental effect Epigenetics 18 9  BS Bs bs bs Bs BBS BBS Bbs Bbs Bs BBS BBS Bbs Bbs Bs BBS BBS Bbs Bbs Bs BBS BBss Bbss Bbss