Which statement concerning telomeres is not true? A. They...

Which statement concerning telomeres is not true?
A. They are found on the ends of chromosomes.
B. They consist of DNA and sugars.
C. They protect chromosomes.
D. Replication is a problem in most cells.

Key Concepts

Telomeres

Telomeres are specialized structures located at the ends of linear chromosomes. They consist of tandemly repeated DNA sequences along with binding proteins. Their primary role is to protect chromosome ends from deterioration and fusion with neighboring chromosomes, ensuring genomic stability during cell division.

Telomere Composition

Telomeres are primarily composed of repetitive DNA sequences with a backbone that includes deoxyribose sugars as part of the nucleotide structure. However, their functional composition involves associated proteins that help maintain their integrity. They are not made up chiefly of free sugars, and the protective complex is essential for their role in chromosome stability.

End Replication Problem

The end replication problem refers to the challenge that conventional DNA polymerases face in completely replicating the 3' ends of linear DNA molecules during cell division. This results in the gradual shortening of telomeres, a phenomenon that is mitigated in some cells by the action of the enzyme telomerase, but remains a limiting factor in most somatic cells.

Transcript

00:01 So for this problem, we are looking at a structure known as a telomere or telomeres for plural.

00:07 And this is going to be a structure that's a part of a chromosome.

00:10 So if we have a close -up look, let's say this is one of the arms of a chromosome.

00:15 And let's say that this is all in blue here, just normal portions that is going to code for different things, just normal nucleic acids with genes and all the loci and all those structures we might be familiar.

00:30 Familiar with, then the telomere would be sort of like the end cap.

00:34 You could think of it as maybe the lead on a pencil.

00:38 And so if this is the distal end, so furthest away from the kinetic core or the centromere, then the telomere could be this structure in red.

00:45 So it's the end cap.

00:48 And scientists have found that it actually has a lot of significance for aging and cancer potentially.

00:54 It has a large role in mitosis.

00:58 And apparently your cell can only divide so many times.

01:00 And the telomerex, ptolemyr will shorten marginally or almost what seems to be negligibly, but over however many replications take place, it'll eventually not be able to divide anymore.

01:13 And that's where aging can be seen in regards to telomeres.

01:19 So we have to identify which of the statements mentioned are not true about telomeres.

01:26 So statement a is that they are found on the ends of chromosomes, which we know is true because as the diagram here indicates, it is literally on the distal end of each chromosome arm.

01:42 So there would be, if we saw a chromosome, we could have an arm here, an arm here, an arm here, and we'd see telomeres on each end like this.

01:54 That definitely is true.

01:56 So let's look at options b and so forth.

02:00 So option b is that it's consisted of dna and sugar.

02:05 So glycate acid and carbohydrates.

02:10 Dna and sugar.

02:13 I'll use sug.

02:15 We have option c, which is protect chromosomes...