Chromosome Imprinting
Chromosome Imprinting - Related Videos
01:22
Imprinting
0 Views •
2019
Behavioral imprinting is observed in some newborn animals and occurs when they develop strong and specific attachments to another animal (usually a parent) following brief, early-life exposures. Offspring imprint onto parents within a brief period after birth or hatching; this time window is called the critical period. Once imprinting occurs, the bond established between the parents and their offspring is usually long-lasting. Survival Mother sheep imprint onto the scent of their lambs within...
02:30
Genomic Imprinting and Inheritance
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2020
Diploid organisms inherit genetic material through chromosomes from both parents. Copies of the same gene are known as alleles. In most cases, both alleles are simultaneously expressed and allow various cellular processes to function optimally. If one of the alleles is missing or mutated, the expression of the other allele can compensate; however, this is not true for all genes. The expression of some genes depends on which parent passed the gene to the offspring, through a phenomenon known as...
02:04
Polytene Chromosomes
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2020
Polytene chromosomes are giant interphase chromosomes with several DNA strands placed side by side. They were discovered in the year 1881 by Balbiani in salivary glands, intestine, muscles, malpighian tubules, and hypoderm of larvae Chironomus plumosus. Hence, these are also called "Salivary gland chromosomes." These are found in insects of the order Diptera and Collembola; in certain organs of mammals; and synergids, antipodes of flowering plants. Polytene chromosomes are also regularly...
02:40
Chromosome Structure
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2020
A functional eukaryotic chromosome must contain three elements: a centromere, telomeres, and numerous origins of replication. The centromere is a DNA sequence that links sister chromatids. This is also where kinetochores, protein complexes to which spindle microtubules attach, are constructed after the chromosome is replicated. The kinetochores allow the spindle microtubules to move the chromosomes within the cell during cell division. Telomeres consist of non-coding repetitive nucleotide...
01:51
Lampbrush Chromosomes
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2020
In 1882, Flemming observed lampbrush chromosomes (LBC) in salamander eggs. Later in 1892, Rückert observed LBCs in shark egg cells and coined the term "lampbrush chromosomes" because they looked like brushes used to clean kerosene lamps. LBCs are made up of two pairs of conjugating homologous chromatids. Each chromatid consists of alternatively positioned regions of condensed-inactive chromatin and loosely placed-active side loops, which can be contracted and extended. The loops resemble the...
FAQs
Imprinting marks are placed during gamete formation at regulatory regions, where DNA methylation and associated chromatin changes help establish the parental state. After fertilization, those marks are preserved, allowing selected genes to remain active from only one parental allele. This continuity links events in gamete development to gene regulation in the embryo.
Parent-of-origin control matters because selected genes may be expressed from only one allele, making their effective dosage sensitive to imprinting status. If establishment or maintenance fails, the normally active parental copy may not provide the expected activity, or the inactive copy may be improperly used. Such dosage disruption can affect development and other biological outcomes.
DNA methylation and chromatin changes function as associated imprinting marks at regulatory regions. Their placement during gamete formation and preservation after fertilization provide a molecular basis for distinguishing maternal and paternal copies. Because this control acts at regulatory regions rather than by changing DNA sequence, it can alter which allele is active while the sequence itself remains unchanged.
Chromosome imprinting helps regulate embryonic growth, placental function, and broader developmental processes. These roles reflect the importance of controlling selected genes according to parental origin during early development. Changes in imprint establishment or maintenance can therefore have consequences beyond individual gene activity, influencing growth patterns, placental biology, and the progression of normal development.
The process begins when imprinting marks are placed at regulatory regions during gamete formation. Fertilization follows, but the marks are preserved rather than erased, allowing selected genes to remain active from one parental allele. That allele-specific activity then contributes to regulation of embryonic growth, placental function, and development, linking an early reproductive event to later biological outcomes.
Errors in establishing or maintaining imprinting marks can disrupt dosage-sensitive genes, whose activity depends strongly on the correct parental allele being used. The resulting imbalance may contribute to imprinting disorders, infertility, or abnormal development. These outcomes show why both the initial placement of marks and their preservation after fertilization are important for biological function.