Mendelian Genetics

• This is the study of how genes bring about characteristics, or traits, in living things and how those characteristics are inherited.

  Genetics
• These are specific sequences of nucleotides that code for particular proteins.

  Genes
• How are genes transmitted from one generation to the next?

  Through meiosis and sexual reproduction
• Who developed the science of genetics?

  Gregor Mendel
• Mendelian genetics is also called as classical genetics.
• Diploid cells have a double set of chromosomes, one from each parent.
• In preparation for sexual reproduction, the diploid number of chromosomes is reduced to a haploid number.
• Gametes are also called as:

  sex cells
• The different forms of a gene.

  alleles
• gene composition of a living organism

  genotype
• The set of all genes that specify an organism's traits is known as

  genome
• expression of the genes

  phenotype
• condition when two identical alleles are present for a particular characteristic

  homozygous
• condition when two different alleles are present for a particular characteristic

  heterozygous
• allele expressing itself


  dominant allele
• overshadowed allele


  recessive allele
• He was the first scientist to develop a method for predicting the outcome of inheritance patterns.

  Gregor Mendel
• Mendel performed his experiments on what?

  pea plants
• This is the generation that is a result of continuous breeding and have become homozygous for a particular trait.

  pure lines
• F₁ generation

  first filial generation
• F₂ generation

  second filial generation
• What are the traits that Mendel studied on the pea plants?

  plant height, pod shape, pod color, seed shape, seed color, flower color, and flower location
• When an organism has two different alleles for a trait, one allele dominates.


  Mendel's law of dominance
• During gamete formation by a diploid organism, the pair of alleles for a particular trait separate, or segregate

  Mendel's law of segregation
• The members of a gene pair separate from one another independent of the members of other gene pairs

  Mendel's law of independent assortment
• This is used to determine the probabilities of the genotypes and phenotypes in the offspring of a genetic cross.

  Punnett square
• Two characteristics are equally expressed in incomplete dominance.
• More than two alleles exist for a particular characteristics.

  Multiple alleles
• both alleles are expressed

  codominant
• Some characteristics are determined by an interaction of genes on several chromosomes or at several places on one chromosome.

  Polygenic inheritance
• trait that is expressed when one or both alleles are present

  dominant traits
• represented by a lowercase letter


  recessive trait
• trait that is only expressed when both alleles are present

  recessive traits
• expressed in both homozygous and heterozygous individuals

  dominant traits
• less common in populations

  recessive traits
• only one copy of this is needed to express a trait

  dominant traits