Genetics notes covering genes, DNA, chromosomes, Mendelian inheritance, non-Mendelian inheritance, linkage, mutation, population genetics, molecular genetics, genomics, and genetic variation.
What is Transposition? Transposition is the process in which a particular DNA sequence is shifted from one position of the genome to another position. It is the movement of a transposable element or jumping gene, and it is not dependent on any homologous sequence at the target site. It is the process that may occur
What is Gal operon? The galactose operon is the unit in bacteria that is responsible for the metabolism of D-galactose, and it is organized with four structural genes (galE, galT, galK and galM). It is the process where these genes are required both for catabolic breakdown of galactose and for anabolic formation of compounds like
Ribozymes are catalytic RNA molecules, and it is the process where RNA itself act as an enzyme in different biochemical reactions. It is the first biological evidence that RNA can work both as a genetic material and also as a catalyst. This is referred to as the dual activity of RNA, and it gives support
A dihybrid crossing is a gene-cross between people who have homozygous or heterozygous genotypes that have two distinct characteristics or traits. Dihybrid crosses differ from the monohybrid crossing that only involves one genetic character or characteristic.
What is Nondisjunction? Types of Nondisjunction Causes of Nondisjunction Molecular Biology of Nondisjunction Consequences of Nondisjunction The nondisjunction is the failure when chromosomes don’t separate properly during cell division (like meiosis/mitosis), causing abnormal number of chromosomes in daughter cells. Such imbalance is termed as aneuploidy, sometimes loss of one (monosomy 2n–1) or gain of one
What are plasmids? Copy Number and Physical Nature of Plasmids Properties of Plasmids Plasmid Replication Mechanism 1. Rolling circle Mode of Replication Rolling-Circle Replication (RCR) is described as a method of DNA replication that is used by some viruses, plasmids and circular genetic elements. A single-strand nick is introduced at the origin and the 5′-end
What is genetic variation? Genetic variation is the differences that are found in the DNA sequences among individuals of the same species. It’s what makes every organism a bit different from others even they belong to same population. Inside populations, variation is mostly caused by mutations, recombination / crossing over (during meiosis), and sometimes by
What is Artificial Selection? Artificial selection is a process by which humans are intentionally choosing certain organisms / traits for reproduction, it has been used for centuries actually even before the mechanism of genes was understood properly. In artificial selection, individuals that show desirable features (like color, yield, behavior etc.) are allowed to breed, while
DNA replication is the process by which genetic material is copied before cell division happens, it’s considered essential for inheritance. Among different models, the main ones observed are Theta model, Rolling Circle model, and Linear DNA replication. Each model are used by different organisms or DNA types (like plasmids, viruses, or eukaryotic chromosomes). The three
An codon chart is presented as a compact key, that maps three-nucleotide codons to amino acids, and it is usually shown as a table or circular map. In the chart, each codon is represented by three bases (A, U, G, C) and is read in the 5’→3’ direction, misreading the direction will alter meaning. Sixty-four
