Genetics is the branch of biology concerned with heredity and genetic variation. By exploring genetics concepts covered in NCERT class 11 biology and NCERT solutions for class 11 biology, we can understand how characteristics are passed from parents to offspring and the molecular basis of inheritance.
Mendel’s Genius and the Laws of Inheritance
NCERT class 11 biology covers how Gregor Mendel’s seminal 19th century experiments with pea plants elucidated the fundamental laws of inheritance. By tracking dominant and recessive traits like flower color across generations, Mendel demonstrated that discreet units of inheritance, now called genes, segregate and assort independently. This laid the foundation for modern genetics.
DNA as Genetic Material and the Double Helix
As described in NCERT Solutions for Class 11 Biology, experiments by Griffith, Avery and others proved DNA is the hereditary material. Later, Watson and Crick determined DNA’s 3D double helix structure, with complementary nucleotide base pairing of A-T and G-C. The sequencing of the human genome revealed our complete genetic blueprint encoded in DNA.
Patterns of Inheritance and Variation
NCERT class 11 biology explains inheritance patterns observed in Mendelian genetics. Complete dominance, incomplete dominance, codominance, and multiple alleles expanding beyond Mendel’s factors account for variations in expressed traits. Alterations in chromosome number or structure also lead to genetic conditions. Meiosis generates genetic diversity via independent assortment and cross over.
Molecular Basis of Inheritance
The molecular basis of inheritance is revealed through DNA replication and protein synthesis processes. DNA replication occurs through enzymatic unwinding of the double helix and synthesis of complementary strands. In transcription, DNA is encoded into mRNA sequences, which are translated into amino acid chains by tRNA molecules binding to ribosomes.
By studying genetics, we gain remarkable insight into the biological mechanisms behind heredity and diversity of lifeforms. From Mendel’s peas to gene editing technologies, genetics continues illuminating the molecular intricacies of life.
Frequently Asked Questions (FAQs) on Heredity
Q1. What are Mendel’s laws of inheritance?
A1. Mendel’s laws are the Law of Segregation, where genes segregate randomly into gametes, and the Law of Independent Assortment, where genes assort independently of each other.
Q2. What is the sequence of bases along a strand of DNA called?
A2. The sequence of bases along a DNA strand is called its nucleotide sequence. Adenine, thymine, cytosine and guanine are the four nucleotide bases.
Q3. What happens in transcription and translation?
A3. In transcription, DNA is transcribed into mRNA. In translation, mRNA base sequences are translated into amino acid sequences to build proteins.
Q4. What are gametes?
A4. Gametes are reproductive cells like sperm and eggs that contain half of an organism’s chromosome number for sexual reproduction.
Q5. What enables genetic diversity?
A5. Independent assortment of chromosomes during meiosis and crossing over between homologous chromosomes enable genetic diversity.