genetic

• Dominant genes are expressed in an individual's phenotype, while recessive genes are only expressed if both copies are present.
• Genetics is the study of how traits are passed from parent to offspring.
• Chromosomes are the molecular structures that contain genetic information in the form of genes.
• Humans contain 23 pairs of chromosomes that are located in the nucleus of all human living cells.
• Chromosomes can be classified into types based on their gene structures and DNA composition.
• Deoxyribonucleic acid (DNA) is the hereditary molecule that contains the complete instructions an organism needs to develop, grow, function and reproduce.
• DNA is made up of sugar, phosphate and nucleotides and consists of two chains of nucleotides held together by hydrogen bonds that form a double helix (two-stranded, spiraled, anti-parallel structure).
• The sugar-phosphate backbone is located outside of the helix and the nitrogenous bases are paired in the interior of the helix.
• Bioinfo tools used in linkage analysis include LOD score and NPL.
• Statistical methods used in linkage analysis include hypothesis testing, Z-test and T-test, probability and statistical significance.
• Multiple testing correction in linkage analysis can be achieved by adjusting the genome-wide significance level.
• A false negative in linkage analysis is when the test incorrectly identifies a hypothesis as false, also known as type II error.
• Multiple testing correction in linkage analysis can also be done using Bonferroni correction, false discovery rate (FDR), and permutation test.
• Multiple testing correction is used in linkage analysis to control the false positive rate and ensure that associations observed are reliable, not simply due to chance.
• Linkage analysis identifies genetic markers associated with the trait or condition.
• A false positive in linkage analysis is when the test incorrectly identifies a hypothesis as true, also known as type I error.
• Cytogenetics is the branch of genetics that studies the structure and behavior of chromosomes and their relation to human disease and disease processes.
• Karyotyping, karyogram, ideogram are techniques used in cytogenetics.
• Banding techniques used in cytogenetics include G-Banding (Giemsa banding), Q-Banding (Quinacrine), R-Banding (reverse staining pattern of G-Banding), T-Banding (subset of R-Banding), and C-Banding (centromere staining).
• Molecular cytogenetics is a branch of cytogenetics that studies the structure and behavior of chromosomes through molecular techniques.
• Mendel’s law of inheritance is a fundamental principle in genetics.
• Genotypic sex determination systems include the X-Y system (human and mammals), the X-O system (insects), the Z-W system (birds and some fishes), and the haplo-diploid system.
• The control of gene expression, ensuring that genes are turned on or off in response to cellular needs, is a fundamental aspect of gene regulation.
• Genetic recombination frequencies were first calculated by A. Sturtevant’s Genetic Distance Concept.
• Examples of X-linked recessive inheritance include haemophilia, duchenne muscular dystrophy, and red-green color blindness.
• The discovery of genetic recombination was made by T. Morgan’s fruit flies experiment.
• X-linked recessive inheritance: A mutated gene on X chromosome causes the phenotype to be always expressed in males and females who are homozygous for the mutation.
• Different types of genetic recombinations include reciprocal epistasis, epistasis and incomplete dominance, and dominant and recessive interaction.
• Environmental determination of sex can be temperature dependent, as in all crocodiles, most turtles, and some lizards, or location dependent.
• Homologous recombination involves independent assortment and the chromosome theory.
• Dosage compensation of X-linked gene can involve hyperactivation of X-linked gene in male Drosophila or inactivation of X-linked genes in female mammals.
• Genetic mapping is a method used in population genetics.
• Clinical cases, haploid, diploid, polyploid are studied in molecular cytogenetics.
• X-linked recessive inheritance is more common in males because only one copy is needed to be affected.
• Pleiotropy: One gene influences more than one trait, for example, beta-globin gene mutation (blindness, liver failure, heart attack).
• Non-mendelian inheritance: Polygenic inheritance, epistasis, and genetic linkage.
• Law of independent assortment: The alleles of two or more different genes get sorted into gametes independently of one another, meaning inheritance of one gene does not influence the inheritance of another gene located on a different chromosome.
• Incomplete dominance: Formation of an intermediate phenotype, where the dominant alleles are not enough dominant, for example, snapdragon flower.
• Law of dominance: Certain forms (alleles) express their traits over others when an individual possesses two different forms (alleles) of the same gene.
• Translation: [mRNA → immature protein].