Centromere

A centromere is a restricted region in the chromosome which takes part in an essential function concerning cell division in eukaryotic cells. This structure of DNA can be of several types and has different roles or tasks to perform. Notably, this is one of the most fundamental concepts in your Biology curricula which is not only vital for your present syllabus, but also for higher studies. Read on to know more about this concept.


What is a Centromere?

A centromere is a specific portion of the DNA or DNA sequence in chromosomes which connects the two sister chromatids during cell prophase. The chromosomes are segregated into long arm q and short arm p. Refer to the image below to see the centromere structure.

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Centromere Function

  • This is the site which connects two sister chromatids and is known to be the point of attaching spindle fibres. 

  • At the time of cell division process in eukaryotic cells, the role of centromere in cell division is to align and segregate the chromosomes. 

  • Centromeres are also responsible for sister chromatid separation and adhesion, microtubule attachment, chromosome movement, mitotic and heterochromatin checkpoint control, and other processes. 

  • Centromeres can act as signal processing centres that regulate cell cycle progression. 

  • It acts as a crucial part in the formation of new cells as it binds the two newly formed chromosomes known as sister chromatids. 


Types of Centromere

These can be divided into two sub-categories, namely 

  1. Point Centromeres 

  • In this type, mitotic spindle fibres are connected to particular DNA sequences. 

  • Here, the proteins connect with individual DNAs and make the mitotic spindle fibre bond possible. 

  • In this case, the connection between protein and the DNA is present irrespective of its location and other factors. 


  1. Regional Centromeres 

  • Regional centromeres are used mostly in humans and eukaryotic cells. 

  • Here, the DNA sequence does not determine the location of centromeres. Rather, other factors combine to contribute in calculating this site. 

  • To define centromere of this kind, the epigenetic marks inform the proteins about their location. This is required to make a connection with the mitotic spindle complex. 


Interesting Fact

These epigenetic marks are nothing but chemical changes made to the DNA with the use of enzymes. These are easily added or removed to/from the DNA without altering any information present in DNA. 


Multiple - Choice Questions 

  1. Choose the most appropriate option with respect to the centromere. 

  1. Facilitates even distribution. 

  2. Restricted chromosomal region. 

  3. Connecting sister chromatids. 

  4. Connecting to spindle fibres. 

Ans: a


  1. Centromeric proteins are the ones which connect to the spindle fibres. 

  1. True 

  2. False

Ans: b

 

  1. Initially, centromeric DNAs were identified in 

  1. Human.

  2. Bacteria.

  3. Fungi.

  4. Yeast.

Ans: d 


  1. Choose the primary reason which states why chromosomes are condensed. 

  1. For facilitating accommodation. 

  2. For facilitating cell division. 

  3. To provide cell division in daughter cells. 

  4. Always condensed. 

Ans: c 


  1. Choose the appropriate part option which is critically responsible for even distribution of parental DNA. 

  1. Spindle fibre. 

  2. Centrioles. 

  3. Telomere. 

  4. Centromere. 

Ans: b 


  1. Choose the accurate number of satellite sequence elements in yeast centromere. 

  1. 3

  2. 5

  3. 2

  4. 4

Ans: a 


Read these study notes regarding centromere meaning and ensure that you secure high grades in academics. Make sure to draft a study routine and follow it diligently, while also accessing various materials on related topics and concepts. 


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FAQ (Frequently Asked Questions)

1. Where are Centromeres Located?

Ans: As per centromere definition, these are typically assumed to be located in the central region of chromosome. However, that is not always the case as these can be present near mid-region or anywhere else. Proteins which are placed in specific sites are known as kinetochores.

2. What is the Function of Centromere?

Ans: It is a specific region of DNA which helps the replicated chromosome to transmit into the two sister chromatids during meiosis or mitosis process.

3. How many Types of Centromeres are Present?

Ans: There are typically two kinds of centromeres – point centromeres and regional centromeres. Point centromeres are the proteins that connect with specific DNA sequences, whereas regional ones rely on several factors to find the location of binding.