Question

You isolate chromosomes from the salivary gland of an organism and prepare a glass slide of the chromosome preparation. When you look at the chromosomes on the slide, they can be seen to be extremely large and exhibit a distinct banding pattern. What name is used to describe these chromosomes?

Answer 1

Answer: the name used is polytene chromosomes.

Explanation:

Polytene chromosomes are produced when repeated rounds of deoxyribonucleic acid (DNA) replication without cell division forms a giant chromosome, they have thousand of DNA strands and provides high level of function in the salivary glands.

At interphase, polytene chromosomes are seen to have distinct thick and thin banding patterns, these bands are of 2 types, the dark band (dark stained,

contains more DNA and less RNA) and the interband (light stained, more RNA and less DNA). The bands enlarge and forms a swelling called puff in certain times, the puffing (which is the formation of puff) is caused by the uncoiling of individual chromomeres in a band. The puffs indicate the site of active genes where mRNA synthesis takes place. These distinct banding patterns are used to study the function of genes in transcription because they permit high level of gene expression.