Genetics is the study of genes, heredity, and genetic variation in living organisms. In this section, we will cover:
DNA (deoxyribonucleic acid) is the hereditary material in almost all organisms. DNA is composed of four nucleotide bases: adenine (A), thymine (T), guanine (G), and cytosine (C). The bases pair up with each other (A with T, and C with G) to form units called base pairs. DNA replicates itself during cell division, ensuring that each new cell has an exact copy of the DNA.
Genes are sections of DNA that code for specific proteins. The process by which the information in a gene is used to synthesize a functional gene product (usually a protein) is called gene expression. This involves two main steps: transcription (DNA to RNA) and translation (RNA to protein).
Mendelian inheritance refers to the way traits are passed from parents to offspring, as described by Gregor Mendel. Key concepts include dominant and recessive alleles, genotypes, phenotypes, and Punnett squares for predicting the probability of offspring inheriting certain traits.
Mutations are changes in the DNA sequence. They can be caused by errors during DNA replication or by exposure to mutagens (radiation, chemicals, viruses). Some mutations have little effect, while others can cause genetic disorders. Examples of genetic disorders include sickle cell anemia, cystic fibrosis, and Huntington's disease.