Mendelian Inheritance and Genetic Processes
Mendelian Inheritance
Inheritance is transmitted by hereditary factors stored in gametes. These factors are of maternal and paternal origin and join in the new individual without mixing, separating again when these individuals form reproductive cells.
Mendel’s Laws are the primary rules that govern the inheritance of characteristics from one generation to another.
Mendel’s First Law: The Law of Uniformity
Based on pure breeds, all individuals of the first generation are equal. All hybrids for the character under study were equal and identical to one of the alternative progenitors. The trait manifested in the offspring is called dominant, and the other is called recessive. Mendel inferred that the two factors are hereditary.
Mendel’s Second Law: The Law of Segregation
Hereditary factors in the hybrid are bound to segregate separately, transmitted in heredity. The factors separate when gametes form, giving rise to new combinations.
Mendel’s Third Law: The Law of Independent Assortment
Mendel performed the same earlier crosses, looking at two characters at a time. The results were the same as those obtained when the transmission was set at each one. This law only holds when the genes are located on different chromosomes.
Replication
A process by which two identical copies of DNA are synthesized, taking another strand of DNA as a template.
Repair of Damaged DNA Sequences
The damaged area is removed and restored by reference to the template strand, preventing mutations that might have undesirable consequences.
RNA Synthesis (mRNA)
Processes required to deliver DNA information to the site where proteins are made.
Transcription
The synthesis of mRNA, taking a strand of DNA as a template.
Translation and Genetic Code
The ribosomes must put the amino acids in their rightful place in the proteins that are being synthesized. Three RNA nucleotides determine the appropriate amino acid. The genetic code is universal, shared by all known living things.
The Genome
The entirety of an organism’s genetic material.
Recombinant DNA
DNA that has fragments of different origins. DNA can be cut into fragments by enzymes called restriction endonucleases. Fragments of different origins can be joined, yielding recombinant DNA.
Mutations
Changes in DNA:
- Gene Mutations: Changes affecting one or more nucleotides, or loss or gain of the same.
- Chromosome Mutations: Affect the structure of chromosomes through loss, duplication, or translation of fragments of the same.
- Numeric Mutations: Affect the number of chromosomes.
Gene Therapy
Amending anomalous genes to prevent them from manifesting or to cure a disease once manifested. Medical introduction of genes.
Artificial Insemination
Introduction of previously treated semen into the woman’s uterus.
In Vitro Fertilization
Technique of assisted reproduction in which the union of sperm and egg is done in the laboratory.
Stem Cells
Cells that have the ability to multiply and can grow and differentiate, giving rise to specialized cells.
- Embryonic Stem Cells: Part of an embryo and are capable of generating a complete organism.
- Adult or Somatic Stem Cells: Present in adults, able to generate specialized cells of different tissues.