NON MENDELIAN INHERITANCE

• Gregor Johann Mendel: He is the father of genetics.
• GENETICS: The study of genes, genetic variation, and heredity in organisms. 
• HEREDITY: The passing on of physical or mental characteristics genetically, from one generation to another.
• PHENOTYPE: The appearance of an organism resulting from the interaction of the genotype and the environment
• GENOTYPE: The genetic make up of an organism or group of organisms with reference to a single trait,  set of traits, or an entire complex of traits. 
• ALLELE: A different form of a gene that controls a certain trait 
• DOMINANT: In genetics, a trait that will appear in the offspring if one of the parents contributes it 
• RECESSIVE: Can be carried in a person’s genes without appearing in that person. 
• GAMETES: Are reproductive cells that unite during sexual reproduction to form a new cell called a zygote 
• PUNNETT SQUARE: The method by which one can determine the possible genotypes and phenotypes when two parents are crossed 
• NON-MENDELIAN PATTERNS OF INHERITANCE: It is any pattern of inheritance wherein traits do no segregate following Mendel’s law. 
• MENDELIAN PATTERNS OF INHERITANCE: Refers to reproducing organisms sexually (each parent gives on or two possible alleles for a trait). 
• Incomplete Dominance is a form of intermediate inheritance in which one allele for a specific trait is not completely dominant over the other allele. This results in a third phenotype in which the expressed physical trait is a combination of the dominant and recessive phenotypes. 
• In Codominance, both alleles are expressed equally in the phenotype of the heterozygote.
• MULTIPLE ALLELES 

  When more than two alleles control the inheritance of a character. 
• In humans, there are four blood types (phenotypes): A, B, AB, O
• Blood type is controlled by three alleles: A, B, O. 
• O is recessive, two O alleles must be present for a person to have type O blood.
• A and B are codominant. If a person receives an A allele and a B allele, their blood type is type AB 
• Males have 44 body chromosomes and two sex chromosomes X and Y.  Females have 44 body chromosomes and two sex chromosomes. The total number of chromosomes in each cell of an individual is 46 or 23 pairs of chromosomes. These chromosomes contain the genes, which are the factors of heredity. 
• 1. Sex Linked Traits:  

  • Traits that are controlled by genes located on the same sex chromosome
• Males have only one X chromosome. Thus, if they inherit the affected X, they will have the disorder. 
• Females have two X chromosomes. Therefore, they can inherit/ carry the trait without being affected if it acts in a recessive manner. 
• 1. SEX LIMITED TRAITS: 

  • They are expressed exclusively in one sex of the species 
  • Sex limited traits are generally autosomal, which means that they are not found on the X or Y chromosomes.  
• 1. SEX INFLUENCED TRAITS 

  • Expressed in both sexes but more frequently in one sex than in the other 
• DEOXYRIBONUCLEIC ACID (DNA): A double-stranded helix that contains the information needed to form and control the physical make-up and chemical processes of an organism. It is the molecule that carries genetic information for the development and functioning of an organism. 
• PAIRING ARRANGEMET OF THE 4 NIYROGENOUS BASES 

  Cytosine – Guanine 

  Adenine – Thymine 

  Thymine – Adenine 

  Guanine - Cytosine 
• NUCLEOTIDE: It composed of the following: sugar and phosphate molecules, and nitrogenous bases.