हिंदी

Genetic Bases of Development - Chromosome

Topics

Estimated time: 7 minutes

Introduction
Chromosome Formation at Conception
Genes – The Carriers of Heredity
Role in Inheritance
Scientific Understanding
Key Points: Chromosome

CISCE: Class 12

Introduction

Chromosomes are thread-like structures present inside the nucleus of every cell. They carry genes, which are the units of heredity that determine our characteristics.

CISCE: Class 12

Chromosome Formation at Conception

During fertilization, the sperm from the father and the ovum (egg) from the mother combine.
Each contributes 23 chromosomes (half the total).
The fertilized egg (called a zygote) then has 46 chromosomes (23 pairs).

CISCE: Class 12

Genes – The Carriers of Heredity

Each chromosome has smaller units called genes.
Genes control hereditary traits like eye color, height, and blood type.
They are made of DNA (Deoxyribonucleic Acid).

CISCE: Class 12

Role in Inheritance

Genes transfer traits from parents to offspring.
This process is called heredity.
Each child inherits a unique genetic combination from both parents.

CISCE: Class 12

Scientific Understanding

The concept that chromosomes and genes carry hereditary information was supported by the research of August Weismann (1889).
He stated that these hereditary materials remain unchanged when passed from one generation to the next.

CISCE: Class 12

Key Points: Chromosome

Chromosomes are thread-like structures in cells that carry genes, which determine our traits.
At conception, the sperm and ovum each contribute 23 chromosomes, forming a zygote with 46 chromosomes.
Genes are made of DNA and control characteristics like height, eye colour, and blood type.
Heredity is the process by which genes pass traits from parents to children.
August Weismann showed that hereditary information is passed unchanged across generations.