MOLECULAR BASIS OF INHERITANCE

In continuation with preparation for Board 2020, let's practise some objective questions from Chapter 6,

 Molecular Basis of Inheritance

These questions will also be very useful for NEET preparation.

OBJECTIVE QUESTIONS

1. The ________________ biomolecule is a characteristic feature of an organism.
2. If the amount of haploid DNA in a human child is 3.3×10⁹bp, the amount of DNA in a normal human adult would be ________________.
3. The _______________ pyrimidine is present in both m RNA & tRNA but not in DNA.
4. The N bases are attached to __ C of deoxyribose sugar while the PO₄ are present on ____ C.
5. The __________________________ technique helped Wilkins & Franklin to study the structure of DNA.
6. The law of complementarity of N bases was given by ______________
7. Stability of double strand of DNA is due to stacking of bases & ____ bonds.
8. Central dogma of molecular biology was given by _________________.
9. The circumference of a sphere is 2.2 m. what would be the number of base pairs of DNA required to encircle the sphere once?
10. The protein involved in packing of DNA of eukaryotes but absent in DNA of prokaryotes is _____________
11. The ‘beads’ in “beads on String” structure is made of ____________, which is further made of __________
12. Euchromatin is active _______________, but heterochromatin is not.

Do not forget to leave comments, queries and doubts. All the Best

Key Points: Chapter 1 Reproduction In Organisms

XII	Chapter 1:  Reproduction In Organisms
QUESTIONS	NOTES
	Life Span: Period frm birth to natural death
Why unicellular org immortal?	Life span not related to size (e.g. mango – short; peepal – long)
	Reproduction significance: Continuity of species
Sexual vs asexual rep	Factors on which mode of reproduction depends: habitat, internal physiology etc.
Y asexual rep progeny k/a clones?	Cell div mode of rep in unicellular org.
	In favourable condition - Binary fission: In amoeba & paramecium (two equal halves) In Unfav conditions: Encystation & Sporulation (formation of minute Amoeba or Pseudopodiospores)
	Budding: yeast (2 unequal halves)
Asexual vs vegetative What are veg. Propagules?	In Fungi & Algae: Asexual rep through spores: Types: Zoospores – motile; zygospores – non motile Conidia – in Penicillium; Gemmules – in Sponges Fragmentation – Hydra
	Water Hyacinth (terror of Bengal), high rate of veg propagation.
	Veg propagules: Potato: Buds (eyes), Banana & Ginger: Rhizome;  Bryophyllum: Adventitious buds on leaf margins…… Key feature: NODE
	In simple org: asexual rep in fav conditions; sexual in unfav (provides variations, enables protection by hard seed coat) In higher org: sexual rep common, asex rare. In animals only sexual
	Sexual Rep: Elaborate, Complex & Slow. Offspring not identical to parents
Veg, rep & senescent phase in annual, biennial & Perennials	Common pattern of sexual rep: Complete juvenile/vegetative (in plants) phase Beginning of rep phase (flowering in plants) senescent phase Length of the 3 phases variable in different organisms Hormones responsible for transition between 3 phases. Unique: Bamboo perennial but flowering once in lifetime Strobilanthus kunthiana once in 12 yrs.
Seasonal Breeders vs Continuous breeders.	Animals: e.g. birds seasonal breeders in nature (in captivity; exploited) Placental Mammals: Cyclical changes in ovaries & Hormones Non primate mammals: Oestrous Cycle Primate mammals: Menstrual cycle
Events: Pre-fertilization, Fertilization & Post fertilization
	Gametogenesis: Male & Female, haploid, may be homogametes (isogametes) or heterogametes. Male: antherozoid or sperm; female: egg or ovum
	Sexuality in plants: Unisexual/Dioecious/Heterothallic e.g. papaya, date palm OR Bisexual/Monoecious/Homothallic Male: staminate; Female: Pistillate If make and female flower on different plants: dioecious If male & female flower on same plant: Monoecious
	Sexuality in animals: Bisexual (Hermaphrodite): Earthworm, Sponges, tapeworm & leech Unisexual: Rest
	Gamete Formation: Haploid

Why DNA is preferred Genetic Material

Genetic material should be capable of:

1. Stability: storing genetic information, chemical & Structural stability
2. Expression: able to express in from of traits or 'Mendelian Characters'
3. Replication: Be able to duplicate genetic material accurately
4. Inheritance: pass on copies of genetic information to next generation 
5. Evolution: allow production of variations through mutation or recombination

DNA vs RNA as genetic material

Both DNA and RNA have ability to act as genetic material but RNA preferred because:

1. DNA has Deoxyribose while RNA has Ribose - Chemical stability
2. Thymine in DNA while Uracil In RNA - Chemical stability

Chemically less reactive

➤Stability proved by Transformation (Griffith's experiment)

1. DNA double stranded, RNA single stranded - structural stability
   
2. Ability to replicate: complementary base pairing in dsDNA allows accurate copying during semiconservative replication 

Both DNA & RNA can express themselves through proteins. In fact protein synthesis cannot occur without RNA.

Ability to undergo mutation: both DNA & RNA able to mutate. In fact RNA mutates faster than DNA.

RNA being more reactive, and DNA being more stable; DNA was preferred over RNA as genetic material.

Now having read the topic try answering these questions:

1. Why is RNA more suitable in a catalytic role?
2. It is difficult to develop vaccines against RNA viruses s/a Rhinovirus (common cold Virus) or HIV?  
3. Justify, RNA is better suited for transmission of genetic information.

BOARD PREPARATION

UNIT 7

LESSON: MOLECULAR BASIS OF INHERITANCE

Topics for Board 2019

1.       Structure of Nucleosomes

2.       Why DNA is preferred genetic material?

DNA vs RNA

3.       Hershey Chase Experiment

4.       Replication: key points

5.       Meselson & Stahl Experiment

6.       Transcription Unit (diagram & Key Points)

7.       Transcription: Prokaryotes vs Eukaryotes

8.       Translation: Key Points

9.       Regulation of gene expression: Lac operon

10.   DNA Fingerprinting

11.   Human genome Project

1. Nucleosomes

Key Features: 

• DNA (200 bp) + Histone Octamer →  Nucleosomes + H1 histone → Chromatin
• Histone: positively charged Protein (rich in Lysine & arginine)
• Histone octamer made of 8 subunits
• Chromatin packed with help of NHC (non-histone chromosomal proteins) - SCAFFOLDING