science

• Recessive – is a variety of genetic code that does not create a phenotype if dominant allele is present.
• Dominant – refers to the relationship between two versions of a gene
• Genetics is a special field of biology that studies heredity and the factors that affect heredity
• Allele – is a variant form of gene
• The transmission of traits or characteristics from parents to their offspring is called heredity.
• Phenotype – an observable traits.
• Heterozygous – having two different alleles of a particular gene or genes.
• Homozygous – presence of two identical alleles at a particular gene locus.
• Hybrid – an organism produced by interbreeding if two animals or plants of different species or of genetically distinct populations with a species.
• Genotype – an individuals collection of genes. It determines the traits which will be expressed.
• Punnett square – a tabular summary of possible combinations of maternal alleles with paternal alleles.
• Dihybrid – a mating experiment between two organisms that are identically hybrid for two traits.
• Monohybrid – a hybrid between two species that only have a difference of one gene.
• Variation – another source of variation occurs in fertilization.
• Variation – result partly, from the recombination of DNA that occurs during the crossing over of Meiosis.
• Variation – crossing over, random separation of homologous pair, independent assortment of chromatids during meiosis and random combination of chromosome during fertilization contribute to genetic variation.
• Gregor Mendel – Father of genetics
• Mendel concluded that the sex cells or gametes of garden peas contains factors that induced the appearance of a particular trait. For example in seed color, a certain factor caused the apperance of yellow seeds, and another factor caused the appearance of green seeds. These factors were later called genes by the Danish biologist, Wilhelm Ludvig Johannsen, in 1909
• Out of curiosity about what had happened to the traits that seemed to have disappeared in the F1 generation, Mendel crossed the garden peas among theselves which he termed as F2 generation. Both the dominant and recessive traits reappeared. Both traits appear in the ratio 3:1 or three plants with dominant traits to one plant with recessive traits.
• F1 generation in other terms is referred to as a first filial generation offspring resulted by parental types that are distinctly different to each other. The F1 generation contains characteristics of both parents with a distinctly unique genotype and a uniform phenotype. In modern-day genetics, F1 hybrids are utilized at a higher scale.
• Mendel concluded that each of the seven characteristics that he investigated must contain at least two genes that were contributed by each parent. The different form of genes is called alleles.
• An organism’s phenotype is set of observable traits. (ex: height which describes as either tall or short.) on the other hand genotype refers to the genetic makeup pertaining to the trait. For this purpose, consider the trait tall as denoted by allele (T) and the small trait by the allele (t). Biologist represents a dominant allele with a capital letter and a recessive with the small letter
• Organisms that have an identical pair of allele for a trait such as TT (for tall) or tt (for short) are said to be homozygous for the trait. Organisms that have a mixed paired of alleles, such as Tt (also for tall) are said to be heterozygous for the trait
• Dominant allele is always expressed while recessive allele is masked when combined with dominant. The only time it will be expressed is when it is combined with another recessive allele.
• Genotype – always represented by PAIRS of letters. A genotype refers to the genetic characteristics of an organism.
• Recessive traits – are masked and represented by small letters. Example:
• Dominant traits – Express traits. Representative by Capital Letter
• Allele is a pair of similar or contrasting characters. Types: Dominant allele and Recessive allele
• Homozygous dominant = 2 Dominant alleles Example : BB
• Heterozygous = 1 Recessive, 1 Dominant Example: Bb
• Homozygous Recessive = 2 recessive allelles Example : bb
• Phenotype – these are traits for letter. Refers to the physical characteristic
• Principle of dominance – The dominant trait, dominates or prevents the expression of the recessive trait.
• Law of segregation – States that two alleles coding for the same trait separate during gamete formation
• Punnet Square –

  Enables one to see instantly all possible combinations of genes among offspring.

  Enables one to see instantly all
• Law of Independent Assortment –States that genes for one trait are not inherited together with another trait.