You asked: What is a puff in a polytene chromosome?

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.

What are DNA puffs?

DNA puffs are genomic regions of polytene chromosomes that undergo developmentally controlled DNA amplification and transcription in salivary glands of sciarid flies. … To do that, we generated antibodies against saliva and immunoscreened a cDNA library made from salivary glands.

When polytene chromosomes puff they are?

The bands of polytene chromosomes become enlarged at certain times to form swellings called puffs. The formation of puffs is called puffing. In the regions of puffs, the chromonemata uncoil and open out to form many loops. The puffing is caused by the uncoiling of individual chromomeres in a band.

What is Balbiani puff?

Abstract. 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.

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What is polytene chromosomes explain in detail?

Polytene chromosomes are a strongly amplified form of interphase chromosomes, found, for example, in salivary gland cells of Drosophila and Chironomus. They arise through many rounds of DNA replication without subsequent separation of daughter chromatids. The chromatids run through the entire length of a chromosome.

What does a chromosome puff represent?

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.

What does polytene mean?

Definition of polytene

: relating to, being, or having chromosomes each of which consists of many strands with the corresponding chromomeres in contact.

What are polytene chromosomes 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.

What is polytene chromosome write the procedure of squash preparation of Drosophila larvae for polytene chromosome?

4. Polytene chromosome squash preparation:

  1. Rinse larvae with water and transfer to PBS in a tissue culture dish for dissection.
  2. Grasp the tip of the mouth hooks with one pair of forceps, hold the body about 2/3 of the way down with the other pair, and pull on the mouth hooks so the salivary glands are exposed.

What are polytene and Lampbrush chromosomes?

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.

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What are Balbiani rings and why do they form?

Balbiani rings are the large structure present in the polytene chromosome. They are large puffs and these puffs are used for studying the structure of the active gene and in the synthesis of RNA and protein particles.

What does crossing over results in?

In heredity: During meiosis. This exchange process, called crossing over, results in chromatids that include both paternal and maternal genes and consequently introduces new genetic combinations.

What is polytene chromosome Class 11?

Polytene chromosomes are giant chromosomes and are commonly found in the salivary glands of insects. … They are formed due to repeated duplication of chromosomes without separation. It is known as endomitosis. They have darkly stained bands and the region between two bands is lightly stained and is known as interband.

What is the karyotype?

A karyotype is an individual’s collection of chromosomes. The term also refers to a laboratory technique that produces an image of an individual’s chromosomes. The karyotype is used to look for abnormal numbers or structures of chromosomes.

Do polytene chromosomes show somatic pairing?

In salivary gland chromosomes/polytene chromosomes, pairing is formed between homologous chromosomes. A characteristics feature of these chromosomes is that somatic pairing occurs in them and hence their number appears half of normal somatic cells.