Transmission Genetics

• The disease alleles can be X-linked (on the X chromosome) or autosomal.
• Transmission genetics is the study of patterns of inheritance from generation to generation, also known as Mendelian genetics, discovered by Gregor Mendel.
• Population genetics is concerned with genetic traits in large numbers of individuals, examining the relationship among genotype frequencies in a population and allele frequencies in its gene pool.
• Cellular genetics, also known as cytogenetics, is a branch of genetics that studies the cell's genetic material.
• Molecular genetics is a branch of genetics that studies the structure and function of genes.
• Gregor Mendel was an Austrian monk who worked in a monastery of St. Thomas in Brunn, Czech Republic.
• Gregor Mendel was a teacher and was in charge of the monastery garden where he conducted his famous experiments.
• Gregor Mendel worked with garden peas (Pisum sativum) as his model.
• Gregor Mendel found that pea plants were easy to grow and maintain, had many distinct and contrasting characters, reproduced quickly, and could reproduce hundreds of offspring.
• Gregor Mendel studied seven different pea plant traits, each with a contrasting form.
• In Mendel's genetic process, each original pair of plants is referred to as the P1 generation (parental), and their offspring are referred to as the F1 generation.
• The parental/pure generation is always homozygous, either dominant or recessive, and is represented by the genotype "RR" or "rr".
• The F1 generation, or the first filial generation, is always heterozygous, represented by the genotype "Rr".
• Mendel found that when he crossed plants with different traits, all of the offspring had the character of only one of the parents, and the nature of the other parent seemed to have disappeared.
• Genes and alleles exist usually in pairs.
• Alleles are the alternate forms of a gene.
• Each gene is passed on to the next generation on its own.
• Offspring that are hybrid for a trait will have only the dominant trait in the phenotype.
• In a cross of parents that are pure for contrasting traits, only one form of the trait will appear in the next generation.
• F1 cross is the first filial generation, where recessive traits reappeared roughly ¼ of the F2 plants showed a recessive trait.
• Phenotype is the physical trait or the trait expressed by the genotype, such as Tall and Short.
• Dihybrid cross is a two-factor cross.
• F2 generation is the second filial generation, where 25% are homozygous dominant, 25% are homozygous recessive, and 50% are heterozygous.
• The principal of dominance states that some alleles are dominant and some are recessive.
• Tall is dominant and short is recessive in plant height.
• Some alleles are dominant and others are recessive.
• Peas have genes for height.
• Testcross is a cross between an organism that is heterozygous for one or more gene (for example, Aa) and an organism that is homozygous for the recessive alleles (for example, aa).
• Monohybrid cross is when we only cross one trait or one factor.
• Mendel drew two conclusions about inheritance: it is determined by factors (elements) that are passed from generation to generation, and these factors are today known as genes.
• Alleles for height are tall and short.
• Genes occur in pairs, such as TT – tall (homozygous dominant), tt – short (homozygous recessive), Tt – Tall (heterozygous).
• Punnett Square is a diagram used to determine genetic crosses, with steps to determine the genotype of the parent organisms, write down your “cross” (mating), draw a p-square, and determine the genotype of the offspring.
• Genotype is the genetic composition represented by letters, such as TT, tt and Tt.
• Law of segregation, Mendel’s first law, states that alleles pairs separate or segregate during gamete formation, and randomly unite at fertilization.
• Mendel’s P generation were true breeding peas.
• A mutant type is a trait that is alternative to the wild type and is a variant of a gene’s expression that arise when the gene undergoes a change.
• Pairs of alleles segregate independently of one another during gamete formation, as per the law of independent assortment.
• A pedigree chart displays a family tree and shows the members of the family who are affected by a genetic trait.
• Crossing two genes (factors) is an example of the law of independent assortment.