GENETICS (mendelian and non-mendelian genetics)

• Genetics

  •Is a branch of biology that deals with heredity and variation of organisms.
• GREGOR MENDEL

  (1822-1884)

  • Father of modern genetics
• GREGOR MENDEL

  • An Austrian botanist and an Augustinian monk  in the monastery of St. Thomas in Brun (now Bruno, in the Czech Republic), teacher, and biologist.
• Mendel’s peas

  Contrasting characteristics include:

  • Seeds – round or wrinkled

  • Seed Color – yellow or green

  • Height – TALL or short

  • Flowers – white or purple

  • Pod color – yellow or green

  • Position of
• Particulate Hypothesis of Inheritance states:

  “Parents pass on to their offspring separate and distinct factors (today called genes) that are responsible for inherited traits”
• ALLELE

  • One of two alternative forms of a gene; any of the alternative forms of a gene that may occur at a given locus
• DOMINANT TRAIT

  • Trait that is expressed; relating to a characteristic or condition that a child WILL HAVE if one of the child’s parents has it
• F1 GENERATION

  • “first filial” or first generation of offspring
• F2 GENERATION

  • Generation produced by interbreeding individuals of the F₁ generation
• GAMETE

  • Reproductive or sex cell; one of the cells that join together to begin making a person or other creature
• GENOTYPE

  • Genetic composition of an individual
• HETEROZYGOUS

  • Organisms that have two different alleles for the same trait
• Homozygous

  • Organisms that have two identical alleles for a particular trait
• PHENOTYPE

  • Observable characteristics of an individual
• PUNNET SQUARE

  • Diagram used to predict an outcome of a particular cross or breeding
• RECESSIVE TRAIT

  • Trait that is masked in the presence of a dominant trait
• Punnett square

  • Is a square grid used in genetics to calculate the frequencies of the different genotypes and phenotypes among the offspring of a cross

   
• Monohybrid cross

  • It determines the genotypic and phenotypic combinations of offspring for ONE particular gene
• Dihybrid Cross

  • It determines the genotypic and phenotypic combinations of offspring for TWO particular genes that are unlinked
• Genotypes

  • It refers to the entire set of genes in a cell, an organism, or an individual.
• Dominant Genes

  • One gene overshadows the other.
• Recessive Gene

  • The gene that is overshadowed by a dominant gene.
• There are three basic genotypes for a particular character:

  AA = homozygous dominant

  Aa = heterozygous

  aa = homozygous recessive
• Phenotypes

  • It is the physical appearance or other characteristic of an organism as a result of the interaction of its genotype and the environment.
• 3 LAWS OF INHERITANCE

  • Law of Segregation
  • Law of Independent Assortment
  • Law of Dominance
• Law of Segregation

  • When gametes are formed, the pairs of hereditary factors (genes) become separated, so that each sex cell (egg/sperm) receives only one kind of gene.
• Law of Independent Assortment

  • Members of one gene pair segregate independently from other gene pairs during gamete formation
• Law of Dominance

  • One allele masked another, one allele was dominant over the other in the F1 generation.
• 2 Type of NON-Mendelian Genetics

  • INCOMPLETE DOMINANCE
  • CODOMINANCE
• Incomplete dominance

  •Form of Gene interaction in which both alleles of a gene at a locus are partially expressed, often resulting in an intermediate or different phenotype.
• Incomplete dominance

  • It is also known as partial dominance.
• CODOMINANCE

  • Both alleles contribute to the phenotype of an organism.
• PEDIGREE CHART

  • it is one of the important tools in studying human genetics and patterns of inheritance.
• PEDIGREE CHART

  • it is similar to a family tree.
• PEDIGREE CHART

  • it uses symbols that show one’s family history
• PEDIGREE CHART

  • it also shows the family relations and the phenotypes of each member.
• SEX LINKAGE

  • Special pattern of inheritance
• SEX LINKAGE

  • applies to genes located on the sex chromosomes
• SEX CHROMOSOMES

  • determine if an individual is male or female
• XX - Females

  XY - Males