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Molecular Basis of Inheritance - Human Genome Project (HGP)

Grade 12CBSEBiology

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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The Human Genome Project (HGP) was a 13-year 'Mega Project' (1990–2003) coordinated by the U.S. Department of Energy and the National Institute of Health.

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The human genome contains approximately 3×1093 \times 10^9 base pairs (bp).

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Methodology - Expressed Sequence Tags (ESTsESTs): An approach focused on identifying all the genes that are expressed as RNARNA.

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Methodology - Sequence Annotation: Sequencing the whole set of genome (coding and non-coding) and later assigning functions to different regions.

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Vectors and Hosts: Fragments of DNA were cloned in suitable hosts like bacteria and yeast using specialized vectors called BACBAC (Bacterial Artificial Chromosomes) and YACYAC (Yeast Artificial Chromosomes).

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Salient Features: The average gene consists of 30003000 bases; the largest known human gene is DystrophinDystrophin at 2.4×1062.4 \times 10^6 bases.

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The total number of genes is estimated at 30,00030,000, and 99.9%99.9\% of nucleotide bases are exactly the same in all people.

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Less than 2%2\% of the genome codes for proteins, while a large portion consists of repetitive sequences.

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Scientists have identified about 1.41.4 million locations where single-base DNADNA differences (SNPsSNPs - Single Nucleotide Polymorphism) occur in humans.

📐Formulae

Total cost of HGP=3×109 bp×$3 per bp=$9×109\text{Total cost of HGP} = 3 \times 10^9 \text{ bp} \times \$3 \text{ per bp} = \$9 \times 10^9

Data Storage (Books)=3×109 letters1000 letters/page×1000 pages/book=3300 books\text{Data Storage (Books)} = \frac{3 \times 10^9 \text{ letters}}{1000 \text{ letters/page} \times 1000 \text{ pages/book}} = 3300 \text{ books}

Percentage of genome coding for proteins<2%\text{Percentage of genome coding for proteins} < 2\%

Total Nucleotide Bases≈3164.7 million\text{Total Nucleotide Bases} \approx 3164.7 \text{ million}

💡Examples

Problem 1:

Given that the human genome has 3×1093 \times 10^9 bp and the average cost of sequencing was $3\$3 per base pair, determine why HGP is considered a 'Mega Project' in terms of finance and data storage.

Solution:

  1. Finance: 3 \times 10^9 \text{ bp} \times 3 = \9 \text{ billion}$.
  2. Data Storage: If the sequence was stored in books with 10001000 pages each and each page had 10001000 letters, it would require 33003300 books.

Explanation:

The sheer scale of financial investment ($9×109\$9 \times 10^9) and the massive requirement for high-speed computational devices for data storage and analysis categorizes HGP as a mega project.

Problem 2:

A researcher is studying a specific sequence difference at a single base in the human population. What is this phenomenon called and how many such locations are identified in the human genome?

Solution:

The phenomenon is called SNPsSNPs (Single Nucleotide Polymorphisms), pronounced as 'snips'. There are about 1.41.4 million such locations identified.

Explanation:

These SNPsSNPs are crucial for finding chromosomal locations for disease-associated sequences and tracing human history.

Human Genome Project (HGP) - Revision Notes & Key Diagrams | CBSE Class 12 Biology