Genetics and Plant Breeding, and Biotechnology (ICAR JRF, SRF and NET)

"Stock 6" is a haploid inducer line of maize (corn). It is a genetic stock used in plant breeding and genetics research, particularly in the production of haploid plants. Stock 6 is a specific genotype of maize that has the ability to induce haploidy in other maize plants, allowing researchers to study haploid genetics and develop new breeding techniques.

Since there are 6 different types of nucleotides (A, C, G, T, U, and I), the possible number of triplet codons can be calculated as: 6 (first position) × 6 (second position) × 6 (third position) = 216 So, there are 216 possible triplet codons. However, it's important to note that: - U (uracil) is found in RNA, not DNA. In DNA, thymine (T) replaces uracil. - I (inosine) is not a standard nucleotide in DNA or RNA. Using the standard 4 nucleotides (A, C, G, and T), the possible number of triplet codons would be: 4 (first position) × 4 (second position) × 4 (third position) = 64 So, there are 64 possible triplet codons in the standard genetic code.

A nonsense codon is a codon that does not code for any amino acid. There are three nonsense codons: 1. UAA (Urinine-Adenine-Adenine) 2. UAG (Urinine-Adenine-Guanine) 3. UGA (Urinine-Guanine-Adenine) These codons are also known as stop codons or termination codons, because they signal the end of protein synthesis and terminate the translation of a messenger RNA (mRNA) sequence into a protein. When a ribosome encounters a nonsense codon, it releases the growing protein chain and dissociates from the mRNA, ending protein synthesis.

Irradiation by UV light can have specific effects on purines and pyrimidines, which are the building blocks of DNA and RNA: Purines (Adenine and Guanine): - UV light can cause adenine to dimerize, forming cyclobutane pyrimidine dimers (CPDs) - Guanine can also form oxidative lesions, such as 8-oxoguanine (8-oxoG) Pyrimidines (Cytosine, Thymine, and Uracil): - UV light can cause cytosine to dimerize, forming CPDs - Thymine can form thymine dimers (TT dimers) - Uracil can form uracil dimers (UU dimers) These lesions can lead to mutations and genetic damage if left unrepaired. The effects of UV light on purines and pyrimidines are an important aspect of DNA damage and repair, and have implications for understanding mutagenesis and carcinogenesis.

The term "dockage" is used in the context of: - Seed testing: Dockage refers to the percentage of impurities, such as weed seeds, stems, leaves, and other foreign material, in a seed sample. - Grain trading: Dockage refers to the reduction in value or weight of grain due to the presence of impurities, such as weed seeds, stems, leaves, and other foreign material. In both cases, dockage is an important factor in determining the quality and value of seeds or grain. The term "dockage" was coined by the Association of Official Seed Analysts (AOSA) of North America. AOSA is a professional organization that develops standards and procedures for seed testing and analysis. The term "dockage" is used in the AOSA rules for seed testing to describe the percentage of impurities in a seed sample. The use of the term "dockage" has since been widely adopted in the seed industry and grain trade.

The maximum permissible size of a seed lot for peas is 10,000 kilograms, subject to a tolerance limit of 5%. Seed lots exceeding this maximum limit must be subdivided and given separate lot identification. Additionally, a sample of at least 1000 seeds is recommended for testing the genetic purity of pea seeds.

Small millets Foxtail millet (Setaria italica) 2n=2x=18 Finger millet (Eleusine coracana) 2n=4x=36 Proso millet ( Panicum miliaceum) 2n=4x=36 Little millet ( Panicum sumatrense) 2n=4x=36 Kodo millet (Paspalum scorbiculatum) 2n=4x=36 Barnyard millet (Echinocloa frumentacea or crusgali or colona) 2n=6x=54

👉some important theories and hypothesis given by👇 🤔 Central dogma- F.H.C. Crick (1958) 🤔 Chromosomal theory of inheritance- Sutton and Bovery (1902) 🤔Dosage compensation - Muller (1848) 🤔First genetic map in Drosophila- A H. Sturtevant (1913) 🤔 Fluid mosaic model of cell membranes- Singer and Nicholson (1972) 🤔 Folded- fibre model of eukaryotic chromosomes- DuPraw (1965) 🤔 Founder principle of speciation- Templeton (1980) 🤔 Hybrid DNA models of recombination- Whitehouse (1963); Holliday (1964) 🤔 Lyon hypothesis- M.F. Lyon (1969) 🤔 Model for eukaryotic promoter- D. pribnow (1975) 🤔 Mutation theory- Hugo de Vries (1901) 🤔 Neutral gene theory of molecular evolution- M. Kimura (1968) 🤔 Nucleosome-senoid model of chromatin fibres- Kornberg and Thomas (1974) 🤔 One gene one enzyme theory- Beadle and Tatum (1941) 🤔 One gene one ploypeptide hypothesis- Ingram (1957) 🤔 Operon concept of gene regulation- Jacob and Manod (1961) 🤔 Origin of new genes by duplication followed by mutation accumulation- S.Ohno (1970) 🤔 Precosity theory of synapsis- Darlington 🤔 Protoplasm theory- Hertwig 🤔 Replicon model- Manod and Brenner (1963) 🤔 Rolling circle model of DNA replication- Gilbert and Dressler (1968) 🤔 Semiconservative replication of chromosomes- Taylor (1957) 🤔 Semiconservative model of DNA replication- Meselson and Stahl (1963) 🤔 Synaptonemal complex- Moses 🤔 Theory of polyploidy as basis of evolution- Winge 🤔 Theory of sudden and rapid changes leading to macro-evolution Or Punctuational model of evolution- Goldschimds 🤔 Triple codon- Gammow (1954) 🤔 Wobble hypothesis of codon-anticodon base pairing- Crick (1966) 👍👍

See the Specific term term coined by the scientist:👇🏼👇🏼 👉Gene, genotype, phenotype: Johannsen (1909) Homozygote, heterozygote, allelomorphs, epistatic gene, F1, F2: Bateson (1902-1909)

👉👉Note some basic key points👇 1. If high heritability of a trait is high, selection for such trait will be effective 2. Pedigree, bulk, single seed descent and back cross methods are used for handling segregating generation in S.P. crops 3. Pedigree method has an objective to obtain transgressive segregants 4. Recurrent selection main aim to increase the frequency of desirable genes and genotype in the population. 5. In Recurrent selection the intermating among progenies is done to restore heterozygosity and to allow recombination to break undesirable linkage