Genetics and Evolution  

What is Genetics and Evolution

Genetics is where we come from. It's deeply natural to want to know.
-Ellen Ullman

Genetics is the branch of science that deals with the transmission of information from parents to the offsprings. Although, the given definition does not attempt to give a holistic view of genetics. Let us make it functional. So, genetics is the branch of science that answers why an elephant always gives birth only to a baby elephant and not some other animal. Genetics is the reason why members in a family resemble each other closely. Genetics is the beauty behind the variation in populations like human beings. Genetics lies behind the fact that all of the cells in a body as complex as a human body can metabolize. Genetics has to be blamed, in the layman term, when somebody suffers from autism and related diseases. Hence, it can be inferred that genetics is the branch of science that deals not only with the transmission of heredity information from parents to offsprings but also the functioning of that information, defects in that information and changes or mutation in that information.

Such an astounding topic plays an important role in the NEET exam as it accounts for a massive 12% weightage. Genetics and evolution is the seventh unit in the NEET biology syllabus and it is comprehensively covered as the second unit in the NCERT textbook for class 12. 

 

 

There is no doubt in the fact that genetics and evolution is an applied filed of information. However, it is also one of those topics in the NEET syllabus that gives difficulty in comprehension and understanding. Another important aspect of genetics and evolution is that it cannot be studied if you lack a basic understanding of cell division - mitosis and meiosis, biomolecules, and reproduction. Therefore, in order to prevent the build-up of complexities, it would be wise if you brush up these concepts. 

Topics of Genetics and Evolution

Let us understand various topics of genetics and evolution as mentioned in the NEET biology syllabus along with their presentation in the NCERT textbook for class 12. This is essential because the NCERT textbook will be the first step reading for comprehending the concepts of genetics and evolution. 

 

Notes of Genetics and Evolution

1. Principles of Inheritance and Variation: As the name itself conveys, this chapter of genetics and evolution deals with the laws and theories of inheritance and variation. An arduous and fascinating description of the experiments performed by Gregor Johann Mendel, the father of genetics, is worth reading, understanding and applying in different situations. The laws so formulated, that is, the law of dominance, law of segregation and law of independent assortment talk about the rules of transmission of heredity information. Thereafter, there are some processes showing deviation from Mendelian laws. The sex determination based on genetical as well as non-genetical factors is also discussed. Lastly, there is a discussion on the chromosomal disorders based on the Mendelian laws. Therefore, the topics can be summarised as:

  • Heredity and variation
  • Deviations from Mendelism-Incomplete dominance, Co-dominance, Multiple alleles and Inheritance of blood groups, Pleiotropy
  • Elementary idea of polygenic inheritance
  • Chromosome theory of inheritance
  • Chromosomes and genes
  • Sex determination-In humans, birds, honey bee
  • Linkage and crossing over; Sex-linked inheritance-Haemophilia, Colour blindness
  • Mendelian disorders in humans-Thalassemia
  • Chromosomal disorders in humans; Down’s syndrome, Turner’s and Klinefelter’s syndromes.

 

MENDELIAN INHERITANCE

 

 

Hence, as you can already infer, the quantum of concepts is quite large and all the topics need a conceptual understanding. A mug-up of the concepts would limit your ability to apply them in different situations and this would be a big let-down in NEET exam. Therefore, take your time and prepare the topics with patience.

 

2. Molecular Basis of Inheritance: It would be appropriate to say that this chapter of genetics and evolution is the molecular version of what you have studied in the previous chapter. Hence, this chapter deals with the molecular structure of the vehicles of transmission of heredity characters - DNA (deoxyribonucleic acid). The historical experiments that were performed to find out the genetic material are elaborately described and these are crucial for the NEET exam perspective. The Watson-Crick Model is the essence of DNA structure and it offers a whole variety of questions in the NEET exam. The structure of RNA is also described. Further, you will be introduced to the spell-bounding central dogma of molecular biology. This will open up the pathway of transmission of information from the molecular structure of the DNA to the visible features of an organism. The applications of the information stored in the DNA molecules are vast and still untapped. One such application of DNA fingerprinting would be introduced in this chapter. A successful quest of molecular biologists to read the DNA of humans, that is, the Human Genome Project and its significance is also the feature of this chapter.

 

DNA

 

In all, the topics of this chapter of genetics and evolution can be summarised as:

  • Search for genetic material and DNA as genetic material: 
  • Transforming Principle of Frederick Griffith, Biochemical Characterisation of Transforming Principle performed by f Oswald Avery, Colin MacLeod, and Maclyn McCarty, experiments of Alfred Hershey and Martha Chase.
  • Structure of DNA and RNA
  • Properties of Genetic Material (DNA versus RNA): ) It should be able to generate its replica (Replication), It should be stable chemically and structurally, It should provide the scope for slow changes (mutation) that are required for evolution,  It should be able to express itself in the form of 'Mendelian Characters’
  • DNA packaging
  • DNA replication: Experimental proof by Matthew Meselson and Franklin Stahl; The Machinery and the Enzymes for replication; Replicating Fork
  • Central dogma 
  • Transcription: Transcription Unit, Types of RNA and the process of Transcription 
  • Genetic code: The salient features of genetic code, Mutations and Genetic Code 
  • Translation
  • Gene expression and regulation-Lac Operon
  • Genome and human genome project
  • DNA fingerprinting

Hence, this chapter of the molecular basis of inheritance provides a wide range of conceptual topics. This would also be a time-taking chapter to prepare. However, investment of time in this topic should not be feared as this will be very helpful for NEET exam.

 

3. Evolution: This is the story of the origin of life and evolution of life forms or biodiversity on planet earth in the context of the evolution of earth and against the background of the evolution of the universe itself. This is a theoretical chapter that brings up the concepts of genetics into understanding the evolution of various life forms. There are the following topics in this chapter of genetics and evolution:

  • Origin of Life: The Big Bang theory, Oparin and Haldane theory, Urey and Miller’s Experiment
  • Evidence for Evolution: Paleontological evidence, Embryological support for evolution, homologous and analogous organs, divergent and convergent evolution, Industrial melanism
  • Adaptive Radiation: Darwin’s Finches and Marsupial radiation
  • Biological evolution: Branching descent and natural selection
  • Mechanism of evolution: Natural selection, Genetic drift, Geographical isolation, Reproductive isolation, Mutations
  • Hardy-Weinberg Equilibrium
  • Origin and Evolution of Man

 

Evolution of The skull

 

Tips on Genetics and Evolution

  • Read the NCERT textbook for class 12 very thoroughly. 
  • Practice the monohybrid and dihybrid crosses taking combinations from the seven contrasting characters of peas.
  • Practice the blood-group crosses.
  • Practice the genetic maps questions.
  • Solve previous years’ questions.
  • Refrain from mugging up the concepts. 

 

Books for Genetics and Evolution

  • The NCERT textbook for class 12
  • A Textbook of CBSE Biology for Class 12 by Sarita Aggarwal
  • Trueman’s Elementary Biology Volume 2

 

Biology Units-wise Notes for Medical Exams

Units No.

Units Name

Unit 1

Diversity in Living World

Unit 2

Structural Organisation in Animals and Plants

Unit 3

Cell Structure and Function

Unit 4

Plant Physiology

Unit 5

Human Physiology

Unit 6

Reproduction

Unit 8

Biology and Human Welfare

Unit 9

Biotechnology and Its Applications 

Unit 10

Ecology and Environment 

Topics from Genetics and Evolution

  • Heredity and variation: Mendelian Inheritance ( NEET, AIIMS MBBS, JIPMER MBBS, BITSAT Pharmacy, KVPY SA, KVPY SB/SX ) (31 concepts)
  • Deviations from Mendelism-Incomplete dominance, Co-dominance, Multiple alleles and Inheritance of blood groups, Pleiotropy ( NEET, AIIMS MBBS, JIPMER MBBS, BITSAT Pharmacy, KVPY SA, KVPY SB/SX ) (12 concepts)
  • Chromosome theory of inheritance ( NEET, AIIMS MBBS, JIPMER MBBS, BITSAT Pharmacy, KVPY SA, KVPY SB/SX ) (8 concepts)
  • Chromosomes and genes ( NEET, AIIMS MBBS, JIPMER MBBS, BITSAT Pharmacy, KVPY SA, KVPY SB/SX ) (2 concepts)
  • Sex determination-In humans, birds, honey bee ( NEET, AIIMS MBBS, JIPMER MBBS, BITSAT Pharmacy, KVPY SA, KVPY SB/SX ) (13 concepts)
  • Linkage and crossing over ( NEET, AIIMS MBBS, JIPMER MBBS, BITSAT Pharmacy, KVPY SA, KVPY SB/SX ) (3 concepts)
  • Sex linked inheritance-Haemophilia, Colour blindness ( NEET, AIIMS MBBS, JIPMER MBBS, BITSAT Pharmacy, KVPY SA, KVPY SB/SX ) (16 concepts)
  • Mendelian disorders in humans-Thalassemia ( NEET, AIIMS MBBS, JIPMER MBBS, BITSAT Pharmacy, KVPY SA, KVPY SB/SX ) (4 concepts)
  • Chromosomal disorders in humans ( NEET, AIIMS MBBS, JIPMER MBBS, BITSAT Pharmacy, KVPY SA, KVPY SB/SX ) (8 concepts)
  • Downs syndrome, Turners and Klinefelters syndromes ( NEET, AIIMS MBBS, JIPMER MBBS, BITSAT Pharmacy, KVPY SA, KVPY SB/SX ) (6 concepts)
  • Molecular basis of Inheritance: Search for genetic material and DNA as genetic material ( NEET, AIIMS MBBS, JIPMER MBBS, BITSAT Pharmacy, KVPY SA, KVPY SB/SX ) (19 concepts)
  • Structure of DNA and RNA ( NEET, AIIMS MBBS, JIPMER MBBS, BITSAT Pharmacy, KVPY SA, KVPY SB/SX ) (16 concepts)
  • DNA packaging ( NEET, AIIMS MBBS, JIPMER MBBS, BITSAT Pharmacy, KVPY SA, KVPY SB/SX ) (6 concepts)
  • DNA replication ( NEET, AIIMS MBBS, JIPMER MBBS, BITSAT Pharmacy, KVPY SA, KVPY SB/SX ) (13 concepts)
  • Central dogma ( NEET, AIIMS MBBS, JIPMER MBBS, BITSAT Pharmacy, KVPY SA, KVPY SB/SX ) (1 concepts)
  • Transcription, genetic code, translation ( NEET, AIIMS MBBS, JIPMER MBBS, BITSAT Pharmacy, KVPY SA, KVPY SB/SX ) (29 concepts)
  • Gene expression and regulation-Lac Operon ( NEET, AIIMS MBBS, JIPMER MBBS, BITSAT Pharmacy, KVPY SA, KVPY SB/SX ) (10 concepts)
  • Genome and human genome project ( NEET, AIIMS MBBS, JIPMER MBBS, BITSAT Pharmacy, KVPY SA, KVPY SB/SX ) (17 concepts)
  • DNA finger printing ( NEET, AIIMS MBBS, JIPMER MBBS, BITSAT Pharmacy, KVPY SA, KVPY SB/SX ) (5 concepts)
  • Evolution: Origin of life ( NEET, AIIMS MBBS, JIPMER MBBS, BITSAT Pharmacy, KVPY SA, KVPY SB/SX ) (57 concepts)
  • Biological evolution and evidences for biological evolution from Paleontology, comparative anatomy, embryology and molecular evidence) ( NEET, AIIMS MBBS, JIPMER MBBS, BITSAT Pharmacy, KVPY SA, KVPY SB/SX ) (15 concepts)
  • Darwins contribution, Modern Synthetic theory of Evolution ( NEET, AIIMS MBBS, JIPMER MBBS, BITSAT Pharmacy, KVPY SA, KVPY SB/SX ) (2 concepts)
  • Mechanism of evolution-Variation (Mutation and Recombination) and Natural Selection with examples, types of natural selection ( NEET, AIIMS MBBS, JIPMER MBBS, BITSAT Pharmacy, KVPY SA, KVPY SB/SX ) (19 concepts)
  • Gene flow and genetic drift ( NEET, AIIMS MBBS, JIPMER MBBS, BITSAT Pharmacy, KVPY SA, KVPY SB/SX ) (5 concepts)
  • Hardy-Weinbergs principle ( NEET, AIIMS MBBS, JIPMER MBBS, BITSAT Pharmacy, KVPY SA, KVPY SB/SX ) (13 concepts)
  • Adaptive Radiation ( NEET, AIIMS MBBS, JIPMER MBBS, BITSAT Pharmacy, KVPY SA, KVPY SB/SX ) (9 concepts)
  • Human evolution ( NEET, AIIMS MBBS, JIPMER MBBS, BITSAT Pharmacy, KVPY SA, KVPY SB/SX ) (3 concepts)

Important Books for Genetics and Evolution

  • Genetics and Evolution Book
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