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Appunti genetics
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- Genomics and Sequencing: Explores modern DNA sequencing methods like NGS, detailing their efficiency compared to Sanger sequencing. Discusses Moore's Law and the decreasing cost/time for genome sequencing.
- Human Genome Characteristics: Defines the human genome as haploid with ~20,000 genes. Highlights the small percentage of coding sequences (1.5%) and the importance of non-coding conserved sequences (10%) as regulatory elements.
- Epigenomics: Introduces epigenetic marks as changes affecting DNA structure (chromatin, 3D organization) and gene expression, distinct from DNA sequence mutations. Emphasizes that most DNA sequences serve a biological function.
- Mendelian Genetics:
- Explains phenotype and the foundations of transmission genetics laid by Mendel.
- Contrasts pre-Mendelian theories (pangenesis, blending inheritance) with Mendel's approach of simplifying problems and studying individual traits using true-breeding strains.
- Covers Mendel's First Law: unit factors exist in pairs, with one from each parent, influencing trait expression (e.g., 3:1 ratio in F2 generation).
- Discusses Dihybrid Crosses, revealing independent assortment of traits and the appearance of new combinations in F2.
- Probability in Genetics:
- Defines probability as a mathematical measure of likelihood (empirical vs. theoretical).
- Introduces basic rules: SUM rule for mutually exclusive events (P(A or B) = P(A) + P(B)) and PRODUCT rule for independent events (P(A and B) = P(A) x P(B)).
- Provides examples of calculating probabilities in genetic crosses (e.g., specific genotypes, dominant phenotypes).
- Explains conditional probability (P(A|B) = P(A∩B) / P(B)) and its application in genetics scenarios.
- Hypothesis Testing (Chi-square test):
- Outlines the process: formulating a null hypothesis (Ho), applying a statistical test to compare observed vs. expected results, and calculating a p-value.
- Describes the Chi-square test (goodness of fit) for categorical data, using the formula Σ((o-e)²/e).
- Explains the interpretation of the p-value: high p-value suggests chance deviation, low p-value suggests a significant factor.
- Details the use of a significance level (e.g., α = 0.05) to decide whether to reject Ho, and the concept of degrees of freedom.
- Chromosomes and Cell Division:
- Chronicles the discovery of chromosomes by Walter Flemming and the subsequent chromosomal theory of inheritance by Sutton and Boveri, confirming Mendel's physical basis.
- Differentiates cell division in prokaryotes (binary fission) from eukaryotes (mitosis and meiosis).
- Mitosis: Takes place in somatic cells, producing two genetically identical daughter cells after DNA replication and a single division round.
- Meiosis: Occurs in germ cells, producing haploid gametes from diploid cells through DNA replication followed by two rounds of division, generating genetic diversity.
- Defines chromosome complement (n for haploid, 2n for diploid), distinguishing homologous chromosomes (one from each parent, potentially different alleles) from identical sister chromatids (replicated copies).
- Briefly touches upon the cell cycle phases and checkpoints.