23 Chromosomes And Their Functions

Edited By Irshad Anwar | Updated on Sep 30, 2024 03:51 PM IST

Chromosomes are significant structures in human genetics. There are 23 in each set, and in total, there are 46 chromosomes in humans. These consist of 22 pairs of autosomes, which are chromosomes individuals do not have sex-linked; therefore, males have XY and females have XX. Each chromosome has specific genes which help in the handling of diverse functions and traits. For instance, chromosome 22 carries genes involved in the immune response and neurological functions. Conditions that include an additional copy of chromosome 21 comprise Down syndrome. The Biology Chapter "Principles of Inheritance and Variation" focuses precisely on this theme; very important for students appearing for entrance exams like NEET and JEE, who should know about the 23 chromosomes and their functions.

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This Story also Contains

Types Of Chromosomes
How Many Chromosomes Do Down Syndrome Have?
Tips, Tricks, And Strategies To Prepare For 23 Chromosomes And Their Functions
Weightage Of 23 Chromosomes And Their Functions In Different Entrance Exams
Types Of Questions Asked On The Topic 23 Chromosomes And Their Functions In Different Exams

Also Read:

Types Of Chromosomes

Humans have 23 chromosomes and their functions include determining physical traits like height and eye color.
The 23 chromosomes' names are designated by numbers from 1 to 22, with the last pair being X and Y.
Understanding how many chromosomes a female has can provide insights into sex-linked genetic conditions.
The term 23 chromosomes refers to the total number of chromosomes found in human somatic cells.

A. Autosomes And Sex Chromosomes(Allosomes)

Human chromosomes are the majority of two different types namely - autosomes and sex chromosomes.
Genetic traits that are usually associated with the sex of the person are transferred on through the sex chromosomes. The left genetic information is associated with the autosomes.
Humans possess 23 pairs of chromosomes in their cells, out of which 22 pairs are termed to be as autosomes and one pair is termed to be as sex chromosomes, making a total of 46 chromosomes in each cell.
Understanding how many chromosomes do humans have is fundamental for studying human genetics and evolution.

B. On the Basis Of Number Of Centromeres

Monocentric: These are chromosomes with one centromere.
Dicentric: These are chromosomes with two centromeres.
Polycentric:These are chromosomes with more than two centromeres
Acentric: These are chromosomes without the involvement of centromere. This type of chromosome shows freshly broken segments of chromosomes which do not live for long.
Diffused or non-located: These are chromosomes with indistinct centromeres that are usually diffused throughout the whole length of the chromosome.

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List Of Chromosomes And Their Functions:

Humans possess a total of 23 chromosomes in humans, arranged into pairs that carry genetic information.

Here's a summary table on the functions and disorders associated with each chromosome that you learned in this lesson:

Chromosome	Description
Chromosome 1	Chromosome 1 contains 2,000 to 2,100 genes responsible for instructions for making proteins. It is the largest chromosome present in the human body among the total 23 pairs of chromosomes.
Chromosome 2	It is found to be the second largest human chromosome and is responsible for the longest known protein-coding sequence, a 280,000 base pair gene for a muscle protein called titin.
Chromosome 3	This chromosome includes gene clusters responsible for coding olfactory receptors (involved in the sense of smell) and chemokine receptors that aid inflammatory processes.
Chromosome 4	Chromosome 4 codes for genes related to Huntington's disease and polycystic kidney disease, as well as muscular dystrophy and various inherited disorders.
Chromosome 5	This chromosome plays a major role in cell growth and division.
Chromosome 6	Chromosome 6 is associated with over 120 genes for major human diseases, including cancer, heart disease, and some infectious and inflammatory disorders.
Chromosome 7	Its deletion causes Williams syndrome and is involved in body growth.
Chromosome 8	This chromosome is responsible for normal brain formation and developmental variations, including small head size or facial differences.
Chromosome 9	Responsible for body growth and division; it contains a gene for hexokinase.
Chromosome 10	Contains 700-800 genes responsible for making proteins, including the gene for the ABO blood group.
Chromosome 11	Contains genes for insulin and catalase; its deficiency leads to Ataxia telangiectasia.
Chromosome 12	Contains genes for Collagen II and alpha-1 salivary protein complex; its deficiency leads to Phenylketonuria and Pallister-Killian syndrome.
Chromosome 13	Contains genes for Collagen IV alpha-1 chain and alpha-2 chain ribosomal RNA; its deficiency leads to Patau syndrome, retinoblastoma, and Wilson’s disease.
Chromosome 14	Contains genes for T-cell leukemia-1 and immunoglobulin heavy chain gene cluster ribosomal RNA; its deficiency leads to Alzheimer's, Burkitt’s lymphoma, and multiple myeloma.
Chromosome 15	Contains genes for ribosomal RNA; its deficiency leads to Tay-Sachs disease, Marfan syndrome, and Prader-Willi syndrome.
Chromosome 17	Contains growth hormone; its abnormalities can cause Charcot-Marie-Tooth disease.
Chromosome 18	Has genes related to gastric releasing peptide; its deficiency can cause Niemann-Pick disease.
Chromosome 19	Contains genes related to the Bombay phenotype (green/blue eye color); its deficiency can cause myotonic dystrophy or maple syrup urine disease.
Chromosome 20	Responsible for growth hormone-releasing factor (somatocrinin); dysfunction can lead to Alagille syndrome.
Chromosome 21	Contains ribosomal RNA; associated with genetic disorders like Down syndrome and autoimmune polyendocrine syndrome.
Chromosome 22	Responsible for several important genes related to immune system function; it also plays a role in neurological development and disorders.
Chromosome XX	Contains genes for Haemophilia A (factor VIII) and Haemophilia B (factor IX); can cause disorders like Turner syndrome and Haemophilia A.
Chromosome XY	Contains genes related to pseudoautosomal segments, testicular determining factor, azoospermia-third factor, and H-Y antigen; abnormalities can lead to genetic diseases like Y chromosome microdeletion or XYY syndrome.

How Many Chromosomes Do Down Syndrome Have?

People with Down syndrome have an extra chromosome; therefore, how many chromosomes do they have? The answer is 47.
The number of chromosomes in the case of Down syndrome is necessary to understand for early diagnosis and subsequently, intervention strategies.
Trisomy 21 is the number of chromosomes found in Down syndrome; it consequently explains how many chromosomes lead to various developmental challenges.
As a matter of fact, testing with genetics often tells how many chromosomes Down syndrome has and this helps to confirm the diagnosis.
The number of chromosomes, which the children suffer from in Down syndrome helps the medical professionals provide appropriate care and support.

Understanding the 23 chromosomes and their functions is crucial for identifying genetic disorders that can arise from mutations.The 23 chromosomes names help in diagnosing genetic conditions by identifying which chromosome is affected.Knowing how many chromosomes do humans have plays a crucial role in identifying chromosomal abnormalities during medical assessments.

Tips, Tricks, And Strategies To Prepare For 23 Chromosomes And Their Functions

Here’s a table summarizing Tips, Tricks, and Strategies to Prepare for 23 Chromosomes and Their Functions:

Tip/Strategy	Description
Mnemonic Devices	Create memorable phrases to recall the 23 chromosomes and their functions easily.
Visual Aids	Use endocrine system diagrams and labelled images to visualize chromosome structures.
Flashcards	Make flashcards for each chromosome, including its name, function, and associated disorders.
Group Study	Discuss the 23 chromosomes names and their functions with peers to enhance understanding.
Practice Questions	Solve previous years' exam questions related to the topic to familiarize yourself with formats.

Here’s a concise mnemonic table summarizing the key points from the article about chromosomes:

Key Concept	Mnemonic Phrase	Summary
Total Chromosomes	"46 Total, 23 Pairs"	Humans have 46 chromosomes arranged in 23 pairs: 22 autosomes and 1 pair of sex chromosomes (XX/XY).
Functions of Chromosomes	"Genes Determine Traits"	Chromosomes carry genes that determine traits like height and eye color, and play roles in various diseases.
Down Syndrome	"Extra 21"	Individuals with Down syndrome have an extra chromosome, totaling 47 chromosomes (Trisomy 21).
Chromosome 22	"Immune and Neurological"	Chromosome 22 is responsible for genes related to immune function and neurological development.
Chromosome Disorders	"Specific Deficiencies"	Each chromosome is linked to specific disorders, such as Huntington's disease (Chromosome 4) and Tay-Sachs disease (Chromosome 15).

Weightage Of 23 Chromosomes And Their Functions In Different Entrance Exams

The weightage of the topic 23 Chromosomes and Their Functions have been discussed below:

Entrance Exam	Weightage for Chromosomes
NEET	High
JEE Main	Moderate
JEE Advanced	Moderate
AIIMS	High
UPSC (Biology Section)	Moderate
State Medical Exams	High
CBSE Class 12 Biology	High

Types Of Questions Asked On The Topic 23 Chromosomes And Their Functions In Different Exams

The types of questions asked on 23 Chromosomes and Their Functions are discussed below:

Entrance Exam	Types of Questions
NEET	MCQs on functions and disorders
JEE Main	Conceptual questions on genetics
JEE Advanced	Application-based problems
AIIMS	Assertion-reason type questions
UPSC (Biology Section)	Descriptive questions on chromosome roles
State Medical Exams	Multiple-choice questions on disorders
CBSE Class 12 Biology	Short answer questions on definitions

Also Read:

Genetics Definition	Genetics
Gene Definition	Allele Definition
Mendelian Genetics	Mendel's Laws of Inheritance
Law Of Inheritance: Mendel's Contribution	Monohybrid Cross - Inheritance Of One Gene
What Are The Three Laws Of Inheritance?	Mendel's Law of Dominance

Frequently Asked Questions (FAQs)

1. What is the function of chromosome 16?

It contains genes for Nonhistone chromosomal protein 1 and also for Hemoglobin alpha and Haemoglobin zeta. Its deficiency leads to Familial Mediterranean fever and Thalassemia.

2. What is the function of sex chromosomes?

Sex chromosomes play a great role in the determination of sex of the child. If the X chromosome comes from the male and X chromosome comes from the female then it will be a female child and if X comes from female and Y chromosome comes from the male then it will be a male child.

3. What is genetic mapping?

Geneticists make the use of 'map unit’ to calculate the distance between linked genes. It is defined as a diagrammatic graphical representation that shows the exact arrangement, and combination of genes in a linkage group of chromosomes.

4. What is meant by karyotype and idiogram?

Karyotype is defined as the entire set of chromosomes of a cell or individual, as represented during mitotic metaphase.Idiogram is defined as the diagrammatic representation of a karyotype. in an ideogram, the chromosomes of a haploid set of an organism are numbered in a series of decreasing sizes