Linkage & Gene Mapping | Morgan Experiment Crossing Over | NEET Biology Class 12 | Neela Bakore

◀ PREVIOUS VIDEO (28/36): Shell Coiling in Snails (Maternal Effect)

▶ CURRENT VIDEO (29/36): Linkage & Gene Mapping
https://www.youtube.com/watch?v=BS_zIWT5SX4

▶ NEXT VIDEO (30/36): Chromosomal Theory of Inheritance

🔗 Full Playlist: https://www.youtube.com/playlist?list=PLr5BFsBzRyFTujMChFMNDOZdHGS8u-Fng
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Linkage and Gene Mapping — Morgan’s experiments, crossing over, and centiMorgan distances.

📌 Topics Covered:
• Complete vs Incomplete Linkage
• Morgan’s Drosophila: body colour + wing type linkage
• Cis (coupling) vs Trans (repulsion) configuration
• Recombination frequency = map distance (centiMorgan)
• Three-point test cross and chromosome mapping
• Exception to Law of Independent Assortment
• NEET PYQs on linkage
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Transcript with Timestamp
0:00 Introduction — Linkage and linked genes
0:38 Genes on same chromosome — linked. Closer = less separation.
2:44 Two types: Complete Linkage & Incomplete Linkage
2:53 Complete Linkage — separation not possible
3:10 Morgan’s Drosophila: grey body + normal wings linked; black body + vestigial wings
linked
4:15 Cross: grey normal (homozygous) × black vestigial
4:46 F2 expected 9:3:3:1 BUT with complete linkage → 8:8 ratio (only 2 phenotypes)
5:25 Incomplete Linkage — genes can separate via crossing over
5:40 Other examples: rice (grain colour + productivity); cotton (corolla colour + lint index)
6:41 Significance: linked genes used as markers
7:49 Linkage Groups = number of chromosomes in ONE haploid set (n)
8:21 Humans: n = 23 → 23 linkage groups; Drosophila: n = 4 → 4 linkage groups
9:40 Gene Mapping — determining gene positions on chromosome
11:56 Recombination frequency → map units (1 map unit = 1% recombination frequency)
12:21 1 map unit = 1 centiMorgan (cM)
13:40 Example: A-B = 20 map units; A-C = 10 map units → two possible arrangements: CAB or ACB
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Amazon Brand Store at https://www.amazon.in/neelabakoretutorials.
Complete Study Notes (11th and 12th) are available at: https://amzn.to/3K4Li7k
Complete Study Notes for 12th are available at: https://amzn.to/3PRhWjm
Complete Study Notes for 11th are available at: https://amzn.to/4uw1hBa
The study notes for this unit Genetics & Evolution are available at https://amzn.to/2Sh27jW

The study notes for other units: –
Diversity in Living World – https://amzn.to/3r8qkyH
Structural Organisation in Plants and Animals – https://amzn.to/3r2cxmZ
Cell: Structure and Functions – https://amzn.to/2GPagcm
Plant Physiology – http://amzn.to/2EZR5HS
Human Physiology – http://amzn.to/2DA46ea
Reproduction – https://amzn.to/2wu43eS
Biotechnology – http://amzn.to/2EZyqf9
Biology in Human Welfare https://amzn.to/4dPRZd7
Ecology https://amzn.to/3RwuOvF
____________________________________________
For business inquiries: abhibakore@gmail.com
___________________________________________

#Linkage #GeneMapping #MorganExperiment #CrossingOver #RecombinationFrequency #NEETBiology #GeneticsClass12 #NeelaBakoreTutorials