Science

Where is polytene chromosome found?


Where is polytene chromosome found? Polytene chromosomes are usually found at the interphase nuclei of some tissue of the larvae of flies. Polytene chromosomes are considered to be very useful for the analysis of many facets of eukaryotic interphase chromosome organization and the genome as a whole.

Which organ is generally used to find the polytene chromosome in Drosophila? Polytene chromosomes form in the Drosophila giant salivary gland during development by multiple rounds of genome replication without cell division to generate polytene chromosomes containing up to 1000 copies of DNA per chromosome.

What are polytene chromosomes and how are they formed? Polytene chromosomes develop from the chromosomes of diploid nuclei by successive duplication of each chromosomal element (chromatid) without their segregation. The newly formed chromatids remain associated lengthwise and together form a cable-like structure, referred to as polytene chromosomes.

Are polytene chromosome found in humans? While polytene chromosomes are most frequently found in insects, they are critical in diverse organisms from ciliates to plants to humans, and they play important roles in disease progression.

Where is polytene chromosome found? – Related Questions

What is polytene chromosome explain in detail?

polytene chromosome. (Science: cell biology) giant chromosomes produced by the successive replication of homologous pairs of chromosomes, joined together (synapsed) without chromosome separation or nuclear division.

How do you know if a chromosome is polytene?

Polytene chromosomes, at interphase, are seen to have distinct thick and thin banding patterns. These patterns were originally used to help map chromosomes, identify small chromosome mutations, and in taxonomic identification. They are now used to study the function of genes in transcription.

What are Balbiani rings?

Balbiani rings are exceptionally large puffs on the polytene chromosomes in the dipteran Chironomus tentans. These puffs are particularly well suited for studies of the structure of active genes and the synthesis and transport of specific RNA-protein (RNP) particles.

Where is lampbrush chromosome found?

Lampbrush chromosomes (LBCs) are transcriptionally active chromosomes found in the germinal vesicle (GV) of large oocytes of many vertebrate and invertebrate animals and also in the giant single-celled alga Acetabularia. These cells are all in prophase of the first meiotic division.

What is the difference between lampbrush chromosome and polytene chromosome?

The main difference between polytene and lampbrush chromosome is that polytene chromosomes occur in the salivary glands and other tissues of insects whereas lampbrush chromosomes occur in the oocytes of vertebrates except for mammals and some invertebrates.

Who discovered lampbrush chromosome?

Lampbrush chromosomes were discovered in sala- mander egg cells (Ambystoma mexicanum) by Flemming in 1882. Ten years later, LBCs were identified in shark egg cells and described by Rückert in 1982. It was Rück- ert who introduced the term “lampbrush chromosome” into biological nomenclature.

What genetic process is occurring in a puff of a polytene chromosome?

These puffs and Balbiani rings are sites of active RNA synthesis; therefore, polytene chromosomes and more specifically puffs and Balbiani rings are excellent tools to study the induction and process of transcription.

How are Lampbrush chromosomes formed?

Chromosomes transform into the lampbrush form during the diplotene stage of meiotic prophase I due to an active transcription of many genes. Each lateral loop contains one or several transcription units with polarized RNP-matrix coating the DNA axis of the loop.

Who proposed chromosomal theory of inheritance?

(a) Walter Sutton and (b) Theodor Boveri are credited with developing the Chromosomal Theory of Inheritance, which states that chromosomes carry the unit of heredity (genes).

What is a chromosome graphic?

noun. a graphic representation of the positions of genes on chromosomes, obtained by observation of chromosome bands or by determining the degree of linkage between genesSee also genetic map.

Why is acetic acid used in polytene chromosomes?

Acetic acid is another popular non-coagulative fixative component known for its swelling affect on tissues [15] that in the case of polytene chromosome squashes helps to accommodate stretching of the chromatin in the interband regions [20].

Which portion of the chromosome is referred to as the Balbiani ring?

Chromosome puffs. Electron micrographs of certain puffs, called Balbiani rings, of Chironomus salivary gland polytene chromosomes show the chromatin arranged in loops (Figures 4-42 and 4-43), much like those observed in the amphibian lampbrush chromosomes discussed earlier.

What are the Balbiani rings and where can they be found?

Balbiani rings are sites of particularly active RNA synthesis on the polytene chromosomes of Chironomids. Three such sites occur on the fourth chromosome in the salivary glands of Chironomus tentans.

Who discovered B chromosome?

B chromosomes have been a subject of interest since they were first discovered in the plant bug insect Metapodius, by Wilson in 1906, 1907 [214, 215].

What is the function of Lampbrush chromosome?

Lampbrush chromosomes are also involved in the production of “masked” mRNAs for early development. The giant granular loops could either be the sites where such mRNAs are packaged or they could be sites where specific alterations of the deoxyribonucleoprotein fiber take place.

Can a woman have Y chromosome?

Each person normally has one pair of sex chromosomes in each cell. The Y chromosome is present in males, who have one X and one Y chromosome, while females have two X chromosomes.

What are the 4 types of chromosomes?

On the basis of the location of the centromere, chromosomes are classified into four types: metacentric, submetacentric, acrocentric, and telocentric.

Which is the largest chromosome?

Chromosome 1 is the largest human chromosome, spanning about 249 million DNA building blocks (base pairs) and representing approximately 8 percent of the total DNA in cells. Identifying genes on each chromosome is an active area of genetic research.

What are puffs in polytene chromosomes?

Puffing is the term that describes structural changes in polytene chromosomes. If one observes polytene chromosomes during the late prepupal stage, different bands appear to be puffed up. For 40 years, this has been understood to be the result of gene activity.

Do humans have Lampbrush chromosomes?

Human and other mammalian chromosomes do not form recognizable lampbrush chromosomes in their own oocytes or in any somatic cells.

What is the function of the chromosomes?

The most important function of chromosomes is to carry the basic genetic material – DNA. DNA provides genetic information for various cellular functions. These functions are essential for growth, survival, and reproduction of the organisms. Histones and other proteins cover the Chromosomes.

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