LEARNING OUTCOMES

Acquisition of knowledge about the bases of formal and molecular genetics: processes of transmission, expression and regulation of genetic information; relationships between genotypes and phenotypes; sources of variation of genetic information: mutation, random fertilization, and recombination between homologous chromosomes during meiosis; the genetics of quantitative characters.

AIMS AND LEARNING OUTCOMES

The teaching will lead students to understand the rules of inheritance, their molecular bases and their main applications.

Specifically, the student will acquire the knowledge concerning the formal rules of genetic transmission, the structure and function of genes, the mechanisms for repairing damage to genetic material and controlling gene expression and epigenetic phenomena.

The student will have the ability to apply the acquired knowledge to formalize hypotheses on the hereditary transmission of biological characters, to use methodologies for data analysis and to critically evaluate the analysis of experimental data for hypothesis testing.

PREREQUISITES

To deal with the contents of the course, the basic knowledge provided by the Institutions of Mathematics teaching is necessary.

TEACHING METHODS

The teaching consists of lectures, delivered through multimedia presentations.

SYLLABUS/CONTENT

The teaching program involves the presentation and discussion of the following topics:

• Mendelian genetics: models, factors and principles of inheritance. Monohybrid and dihybrid crosses: Mendel's laws. Mendel results and fundamental rules of probability. Fundamental concepts: genotype and phenotype;
genes and alleles; dominance and recessivity. Monohybrids, dihybrids, polybrides. Gametic combinations and phenotypic frequencies in F2. Testcross.
• Extensions of Mendel's laws: complex correlations between genotype and phenotype. Extensions of Mendelian analysis involving single genes: incomplete dominance, codominance, multiple alleles, pleiotropy. Genetic bases of blood groups (AB0, MN, Rh). Extensions of Mendelian analysis involving multiple genes that determine a character: complementary gene action, recessive epistasis, dominant epistasis.
• The chromosomal theory of inheritance. Chromosomes contain the genetic material. Mitosis and meiosis. Validation of chromosomal theory. Chromosomal theory correlates Mendel's laws with the behavior of chromosomes during meiosis. Specific characters are transmitted by specific chromosomes. Genetic determination of sex.
• Sex chromosomes and X-linked inheritance: Morgan's experiments. Family trees: how to decide whether the character examined is autosomal or X-linked, dominant or recessive; how to estimate the probability that the character under examination manifests itself in the progeny of a given couple.
• Association, recombination and mapping of genes on chromosomes. Genetic association and recombination. Observed and expected recombination frequencies: application of the Χ2 test. The centimorgan, unit of genetic map. Mapping: two-point and three-point test cross mapping. Interference. Crossover: physical exchange between chromatids (experimental demonstration). Multiple crossovers. Poisson distribution. Haldane's mapping function. Relation between crossing-over frequency and map distance. Neurospora crassa: calculation of the distance between a marker and the centromere.
• DNA: inheritance molecule that carries, duplicates and recombines genetic information. The experiments that identified DNA as the genetic material: experiments by Griffith (1928), Avery McLeod and Mac Carty (1944), Hershey and Chase (1952), Freankel-Conrat and Singer (1957). Experimental proof that replication is semi-conservative (Meselson and Stahl experiment).

• Organization of the hereditary material. The chromosome of viruses, bacteria and eukaryotes. The role of cytogenetics in the identification of eukaryotic chromosomes: banding techniques, karyotyping. Use of molecular cytogenetic techniques: FISH, interphase cytogenetics, CGH, multicolored karyotype.
• Analysis and genetic mapping in bacteria and bacteriophages. II chromosome of E. coli; episomi and plasmids; the factor F and F ’; strains Hfr. Transfer of genes into bacteria: transformation; conjugation; the sexduction in bacteria. Mapping by interrupted conjugation and transformation. Bacteriophages. Transduction (generalized and specialized). Transduction mapping. Gene mapping in bacteriophages: phage cross. The complementation test. Benzer experiments: analysis of the rII region of phage T4; deletion mapping.
• Sex chromosomes and sex determination. Genetic determination of sex in humans. The human X and Y chromosomes. PAR regions Dosage compensation in humans and other mammals. Barr bodies and heterochromatinization.
• Chromosomal mutations: variation in the number and structure of chromosomes. Conditions linked to aberrations in the number of sex chromosomes (Turner, Klinefelter and Jacobs syndrome) or autosomes (Down syndrome). History of the double Y.
• The genetic code. The properties of the genetic code: colinearity, non-overlapping, codon length, code ratio, degeneration. Deciphering the genetic code: Niremberg and Matthaei experiments (experiments with homopolymers, mixed copolymers, triplet binding assay) and Khorana (repeated copolymers).
• Gene mutations. Classification. Spontaneous mutations and induced mutations. Mutations origin: the fluctuation test (Luria and Delbrück) and the "replica plating" method (Lederberg). Mutagenesis test: an example, the Ames test.
• DNA repair: proofreading, mismatch repair, post-replication repair and SOS, photo-reactivation, base excision and nucleotide repair.
• Regulation of gene expression in prokaryotes. Inducible and repressible operons. Jacob and Monod model of transcriptional regulation of the lac operon. The trp operon; the phenomenon of attenuation.
• Epigenetics. DNA methylation, histone modification, RNA-mediated epigenetic effects. Imprinting. Inactivation of the X chromosome.
• Quantitative genetics. The variation continues. Sample statistics parameters (mean, variance, covariance). Genetic variation and environmental variation. Actuals of dominance, interaction and additives. Heritability in a broad and narrow sense. Estimation of heritability through phenotypic correlation of blood relatives. Selection and response to selection. Increased response to selection.

• Population genetics. Allelic and genotypic frequencies. Hardy-Weinberg law and its extensions. Estimation of allele frequencies by means of the Hardy-Weinberg law. Evolutionary processes (mutation, migration, genetic drift, natural selection) with effects on the variation of allelic frequencies. Haplotypes, bases of molecular anthropology. 

RECOMMENDED READING/BIBLIOGRAPHY

- Pierce – Genetica. Ed. Zanichelli – II ed., 2016

- Griffiths et al. Genetica - Principi di analisi formale. Ed. Zanichelli - VII ed., 2021
- Snustad e Simmons -Principi di genetica. EDISES -IV ed., 2010 

Selected presentations, used during the lessons, will be available on AulaWeb at the end of each cycle of lessons dedicated to a topic of the program.