Heterochromatin vs Euchromatin- Definition, 16 Differences, Examples

Differences Between Heterochromatin and Euchromatin

Heterochromatin Definition Heterochromatin is a tightly packed or condensed DNA that is characterized by intense stains when stained with nuclear stains, containing transcriptionally inactive sequences. It exists in multiple variations, up to four to five state, each of which is marked with combinations of epigenetic markers. The staining of heterochromatin might result in heteropycnosis; heteropycnosis is the differential staining of …

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Chromosome vs Chromatid- Definition, 11 Major Differences, Examples

Differences between Chromosome and Chromatid (Chromosome vs Chromatid)

Chromosome Definition A chromosome is a thread-like structure present in the nucleus or nuclear region of the cytoplasm that is made up of a single molecule of DNA (Deoxyribonucleic acid) and proteins, carrying some or all genetic materials of an organism. These chromosomes are only visible under the light microscope during the metaphase of the cell cycle where the chromosomes …

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Epidemiological Markers

Phenotypic and Genetic Markers

Epidemiological markers are biological markers that are used to characterize microorganisms or discriminate between genomes based on the genetic variation among microbial isolates. Uses of Epidemiological Markers Epidemiological markers are mostly used for strain typing. It is used to: Classify isolates of microorganisms Catalogue genetic variation Define relatedness or lack of it between microbial species or genera It can be …

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Non-Mendelian Inheritance

Non-Mendelian Inheritance

Mendelian inheritance patterns involve genes that directly influence the outcome of an organism’s traits and obey Mendel’s laws. Most genes in eukaryotic species follow a Mendelian pattern of inheritance. However, there are many that do not. Non-Mendelian inheritance is a general term that refers to any pattern of inheritance in which traits do not segregate in accordance with Mendel’s laws. These laws …

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Extranuclear Inheritance- Cytoplasmic Factors and Types

Extranuclear Inheritance

Though, the genes of nuclear chromosomes have a significant and key role in the inheritance of almost all traits from generations to generations, they altogether cannot be considered as the sole vehicles of inheritance. Certain experimental evidences suggest the occurrence of certain extranuclear genes or DNA molecules in the cytoplasm of many prokaryotic and eukaryotic cells. Bacterial cells such as …

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Hardy-Weinberg Equilibrium

Hardy-Weinberg Equilibrium

The Hardy–Weinberg principle, also known as the Hardy–Weinberg equilibrium, model, theorem, or law explains that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences. The law was proposed by a British mathematician Hardy and a German physician Weinberg (1908) independently. Both the ideas together is called as the Hardy-Weinberg law equilibrium after their …

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Chromosomes- Abnormalities and Disorders

Chromosomes- Abnormalities and Disorders

Chromosomes refer to any of the rod-shaped or threadlike DNA-containing structures of cellular organisms that are located in the nucleus of eukaryotes, are usually ring-shaped in prokaryotes (such as bacteria), and contain all or most of the genes of the organism. Simply put, it is a strand of DNA that is encoded with genes. Chromosomes are important because they contain the entire (or …

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Sex-linked Inheritance

Sex-linked Inheritance

Sex makes no difference in Mendel’s crosses. But the Mendel’s laws are not applicable on those genes which are exclusively located either in X or Y chromosome. Sex-Linked Inheritance is the inheritance of a trait (phenotype) that is determined by a gene located on one of the sex chromosomes. The genes which occur exclusively on the X chromosome or on …

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Linkage- Characteristics, Types and Significance


Each chromosome contains more than one gene. The genes for different characters may be either situated in the same chromosome or in different chromosomes. When the genes are situated in different chromosomes, the characters they control appear in the next generation together or apart, depending on the chance alone. They assort independently according to Mendel’s law of independent assortment. But …

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