Important Notes on Chromosome Structure for NEET Biology

An Overview on the Important Notes on Biology for NEET: Chromosome Structure

Chromosomes play a vital role by carrying genetic properties from one generation to the other. Therefore, they are also known as the carrier of genetic data. The genetic coding is present in the DNA in the form of nucleotide sequences.

Chromosomes are a crucial chapter for NEET 2020. Therefore, candidates appearing for this national level exam must learn about important notes of biology for NEET chromosome structure.

The study of a chromosome is vast, and you do not need to get anxious. Simply learn about the chromosome definition and its functions and types in detail to score well.

Define Chromosomes

When you are preparing for this national level exam, you must give adequate attention to Biology chapters more than that of Physics and Chemistry. Therefore, always look for important notes of biology for NEET chromosome structure.

Chromosomes are a thread-like structure present within the nucleus of each cell. Each chromosome comprises of DNA coiled multiple times surrounding proteins, also known as histones. 

A cell in a human being comprises of 23 pairs of chromosomes resulting in total 46 of them. All of the 22 pairs are autosomes or similar in both men and women, except 1 pair of a chromosome. The remaining 1 pair accounts for fusion, and they are known as sex chromosome.

Chromosomal Structure

A chromosome structure has 8 parts, and they are mentioned below: 

  1. Centromere: A constriction point known as centrosome divides the chromosome into two halves or arms. The short arm of a chromosome is known as ‘p’ arm, whereas the long arm is known as ‘q’ arm. 

  2. Chromatid: When a cell division occurs, the centromere divides the chromosome into two halves. Each half of the chromosome joined is known as a chromatid.

  3. Chromatin: A chromatin is a complex mixture of DNA, RNA and protein that forms a chromosome inside the nuclei of eukaryotic cells. 

  4. Telomere: It is a terminal part of a chromosome which restricts fusion of a chromosomal segment.

  5. Secondary Constrictions: They are present within a chromosome comprising of genes to configure nucleoli called as a nucleolar organiser.

  6. Chromonema: These are thread-like in appearance, coiled filaments along with which a chromosome gets attached. They are responsible for controlling the size of a chromosome, and it plays the role of gene bearing.

  7. Chromomeres: They appear in beads available on the Chromonema, and they get arranged row-wise along with a length of it.

  8. Matrix: Chromosomes contain a membrane called pellicle around it. Matrix is a substance having a jelly-like appearance within the pellicle, comprising of non-genetic materials.

  9. Furthermore, it comprises of DNA double helix molecules in the form of a long string-like compact structure surrounded by histones. Also, it consists of two identical chromosomes, each containing a single DNA molecule.

When you are chalking out a plan for your NEET exam, it is mandatory to allocate time for vital topics, such as cellular structure, evolution, genetics, etc. Besides do not forget to read the important notes of Biology for NEET chromosome structure.

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Functions of Chromosomes

Chromosomes play a vital role in the division of cells, replacement, mutation, repair and regrowth, etc. Some of the common chromosome functions are:

  1. In terms of heredity, the primary function of a chromosome is the transferring of genetic materials from parents to offspring. Also, they play crucial roles in mutation, repair and regrowth of cells, cellular division, etc.

  2. At the time of a cell division, each DNA present in the cells gets tightly coiled up, forming a chromosome acting as a carrier of genetic data from one generation to another. They ensure accurate distribution of DNA from the parent cell to the child’s cell.

  3. Moreover, chromosomes contain histone and non-protein materials. These histones are accountable for regulating genetic action. The proteins also protect the chromosomes by covering them from damage during cell division.

Chromosome Types

Read on the following types of chromosomes and note them for your NEET. 

  1. Metacentric: They have centromeres present right at a centre position in a chromosome. As a result, the sections or halves are symmetrical, and humans have 1 and 3 chromosome metacentric.

  2. Sub-Metacentric: In these chromosomes, a centromere is available not exactly at the centre; instead, it gets situated slightly afar. Therefore, the halves remain asymmetrical in sub-metacentric ones. 

  3. Acrocentric: These chromosomes have a centromere present away from the centre. As a result, one of the strands is short, whereas the other one is long.

  4. Telocentric: The centromere gets situated at the end of a chromosome. Humans do not have telocentric chromosomes. Such chromosomes are present in mice.

Did You Know: Few animals have multiple chromosomes, but most of the DNA molecules are empty! These are known as junk DNA.

From the above conversation, you must have a clear insight regarding important notes of Biology for NEET chromosome structure. 

Since thousands of students appear every year for NEET, you may feel anxious while preparing for it. We would advise you to go through the difficult chapters first and keep some time for revision. Try studying harder without panicking for your entrance exams.

Also, while reading more facts about the giant chromosome, do not get confused. Try to provide yourself with small breaks or listen to your favourite songs to keep the exam chills at bay!

FAQ (Frequently Asked Questions)

1. How Many Chromosomes are Present in a Human Being?

Ans. In a human being, each cell comprises of 23 pairs of chromosomes, amounting to 46 in total. Out of these 23 sets, the autosomes consisting of 22 pairs are the same in both men and women. However, the 23rd pair (sex chromosome) differs in females and males.

2. What is the Primary Role of a Chromosome?

Ans. If you are planning to appear for NEET exams, you must learn about the important notes of biology for NEET chromosome structure. The primary function of a chromosome is transferring the genetic materials from a parent to its offspring.

3. What are the Common Types of Chromosomal Disorders?

Ans. An abnormality often occurs due to an irregular, missing, or an extra portion of a chromosomal DNA. Some of the common chromosomal abnormalities are Down’s syndrome or trisomy 21, Edward’s syndrome or trisomy 18, depletion 4p syndrome, Klinefelter’s syndrome and Turner syndrome, etc.