lesson 2&3 genbio

• Genetics - field of science that deals with the study of heredity and variation
• heredity - the transmission of traits from one generation to the next
• variation - differences among individuals in a species or differences among species in a population
• alleles - genes found in the same loci of homologous chromosomes, alternative versions of genes.
• homozygous - genes that are morphologically alike, they have the same genes. Ex. TT = tall, tt = short
• Genes - Dna molecules or information carried by each individual organism which determines the visible traits of an organism. Dictate to make enzymes and protein
• Dominant genes - gene or factor that masks another gene
• recessive genes - genes or factor that is masked by the dominant gene.
• genotype - genetic makeup or genetic composition for a particular trait
• Phenotype - appearance or characteristic of an organism or the trait that is expressed as determines by the genotype.
• Character - distinct heritable features. Ex. skin color, height
• Phenotypes: observable traits, genotypes: consists of two letters
• Gregor Johann Mendel - Austrian monk, father of genetics. Presented nature of inheritance in 1866. Used the garden pea as his main specimen for his genetic experiments.
• Garden pea (pisum sativum) - presence of observable traits with contrasting forms. Produces many offspring in one cross. Short life cycle. Ease in manipulating pollination
• stamen - sperm, carpel - egg
• law of dominance - when an organism has 2 different alleles for a given trait , that allele is expressed, overshadowing the expression of the other allele is said to be dominant. The recessive gene is overshadowed.
• law of segregation - states that each pair of alleles segregates or separates during meiosis
• law of independent assortment - members of one gene pair segregate independently from other gene parishes during gamete formation. happens during meiosis I
• Monohybrid cross - considers only one trait at a time. Ex. crossing 2 pea plants that differ in stem size
• dihybrid - cross considers the inheritance of 2 traits at a time.
• incomplete dominance - one alelle isnt fully dominant over its partner so heterozygous phenotype is somewhere in between the two homozygous phenotypes emerges.
• degrees of dominance - complete, incomplete, and codominance
• codominance - both affect the phenotype of the offspring
• multiple allele system - when 3 or more alleles of a gene are present among members of a population
• antibodies - found in the plasma protein and are seen in the surface of red blood cell
• landsteiner (1900).- developed a system of determining blood types of man
• compatibility of blood types - agglutination, agglutinogens, agglutinins
• agglutination - antibodies circulating in plasma act against foreign cells that causes the clumping of blood cells
• agglutinogens - antigens present in the erythocytes
• agglutinins - antibodies found in the blood plasma