biofunda

 Presently there is no single system of classification of proteins is completely satisfactory. Following are the various system of classification of proteins on the basis of solubility, shape, structure, chemical composition and nature of amino acids.  On the basis of solubility  On the basis of solubility proteins are divided into following 7 categories .  Albumin : These are soluble in water, dil. Salt solution and dil. Acids and bases. They have property of coagulation on heating and these get precipitated with high salt concentration. Example : Egg albumin, serum albumin, lactalbumin(present in milk), legumelin (present in soyabeans ).   Globulin : These are insoluble in water but freely soluble in dil, salt solution. These are precipitated by half saturated salt solution. Example : Serum globulin, vitellin (egg yolk), Tuberin (potato), Myosinogen (muscles).    Glutelins : These are insoluble in water and salt solution but soluble in dilute acids and alkaline.  Example :Gluteni

  These are complex nitrogenous organic biopolymer of amino acids showing great diversity in their organization.  Facts about proteins  The term protein was first coined by Jones J. Berzelius from Greek word " proteious " which means 'to hold first position '. It is abundant intracellular * organic biomolecule. It contributes 12% in cellular pool . These are next to water in cellular pool.  It constitute 50% or more of dry weight of cell.  Proteins form                      20% of mammalian muscles                     7% of blood plasma                     3.5% of cow milk                     12% of cereals                     20% of peas and nuts and pulses  There are 3000 types of proteins in E. Coli ,1 lakh different types of proteins in humans . 10 raise to power 10 -10 raise to power 12 different types of biomolecules  are found in about 1.5million species.  There is a co-relation between structure of proteins and their biological function which in turn

 Maternal inheritance V/S Predetermination  Maternal inheritance : Inheritance of some traits of mother to the offspring through the cytoplasm of female gamete.  Predetermination : It is the effect of mother's genes on the characters of offspring through the cytoplasm of egg and embryo without involving plasmagenes of cytoplasm.  Shell coiling in snails 🐌  There are two types of coiling present in present in snails. 1.Dextral type 2. Sinistral type  The direction of coiling in shell is controlled by the orientation of mitotic spindle of the first cleavage of zygote. This all depends on the organization of egg before fertilisation. The spindle organisation is controlled by organisation of cytoplasm in the egg.  Dextral type : Shell is coiled clockwise (toward right when viewed from apex). It is shown by ( DD or Dd ) because D is dominant over d.  Sinistral type : Shell is coiled anticlockwise . It is shown by dd . 1.Cross between sinistral Female and Dextral male When eggs of Si

 Plastid Inheritance in mirabilis The extra nuclear Or cytoplasmic inheritance of colour in plants plastids* was first discovered by Correns in Mirabils jalapa .  Mirabilis jalapa plant can bear 3types of branches  i.e. green , variegated and pale (or white).  Correns found that : The flowers on green branches produced plants only with green leaves irrespective of genotype or phenotype of pollen parent, The flower on pale branches produced only pale plants regardless of genotype or phenotype of pollen parent. Flowers of variegated branches formed seeds which give rise to 3types of plants : green, pale, variegated.  The type of branch giving pollen grains hardly matters for this type of inheritance. This is due to random distribution of green and colorless Plastid at the time of female gamete formation.  * Plastid : These are semi -autonomous organelle which have their own DNA, replication, transcription and translation machinery. Three types of Plastid can be identified : C

 Kappa particles in Paramecium    Sonneborn   found two types of strain in paramecium .i. e. Killer and sensitive .  Killer strain : Killer strains contain Kappa particles *  .These strains produce a poisonous substance called paramecin with the help of kappa particles.  These kappa particles remain unaffected in presence of paramecin.  * kappa particles : these are self duplicating cytoplasmic particles found in Paramecium  a urelia . These particles make the animal killer when present in sufficient number.  The kappa particles can be retained one in those individuals which possess a dominant gene K (having recessive allele K) in nucleus .  Cross between killer and sensitive strain  Conjugation takes place for less time : when conjugation takes place for less than three minutes, only nuclear exchange takes place. Formation of cytoplasmic bridge doesn't takes place. After conjugation each race produces its own type.  Conjugation takes place for longer time : When conjugation

 Genetic code  It is combination of three consecutive Nitrigenous bases which code for amino acids.  Properties of genetic code  It is triplet  . The three nucleotides of mRNA which code for one amino acid represent codon. Complementary matching triplet of tRNA form the anticodon.    The codon which initiates protein synthesis is called as initiation codon  i.e.Methionine (AUG) and valine (GUG).  Some of codon do not code for any amino acid, such codon are known as non-sense codon i.e. UGA(Opal),UAA(Ochre) and UAG (amber) . They signal termination of polypeptide chain hence also called as termination or stop codons. Hence out of 64 codons 61 code for amino acids.  The code is degenerate . For a particular amino acids more than one codon can be used. One amino acid often has more than one code triplet e.g. Phenylalanine has two codon i.e. UUU and UUC. Arginin, similarly has six codon.  The genetic code is universal . Given codon in DNA and mRNA specifies same amino acid in all organism

  Replication is commonly known as self duplication.  But why DNA replicates? 🤔🤔 DNA transfer inherited characters form generation to next generation. So DNA has to produce it's duplicate copy.  Replication is autocatalytic function of DNA. A simple mechanism of replication was proposed by Watson and Crick ,  on the basis of double helical structure of DNA. To know more about structure and  function of DNA click here ( https://singhsardarni.blogspot.com/2020/09/dna-structue-and-functions.html ) The method of DNA replication is described as semi - conservative method. In this method ,the two strands will act as template strands for synthesis of new complementary strands. After replication, new DNA will have one daughter  strand and one parental strand . But where is the evidence ?  DNA replicates semi conservatively was proved by Meselson and Stahl in 1958. They performed the following experiment with E . Coli .  They grew E. Coli in medium of 15NH4Cl for many generations.

Satellite DNA (Repetitive DNA)   It is observed that after Denaturation(for more details click here https://singhsardarni.blogspot.com/2020/09/dna-structue-and-functions.html ), DNA fails to come back into original form easily. This may be due to two reasons : They are degraded molecules from heterogeneous populations. They are of high molecular weight.  However, Britten noticed that DNA can broken into small fragments. It gave conclusion that certain short sequences of bases are repeated hundreds of times in DNA .Such type of DNAs are known as repetitive DNA.  Such repetitive form of DNA observed in chromosome near to centromere.  Sometimes, repeating sequences of DNA may be similar to that of rest of DNA.  This type of DNA can be easily separated out by process of ultracentrifugation.  Prokaryotic DNA doesn't bear repetitive DNA sequences. Except yeast repetitive DNA has been observed in all eukaryotes. In human beings 30% of DNA is repetitive which is repeated more than 20 times

 Physical Properties DNA is usually double stranded.  Molecular configuration of DNA is three dimensional(3D). It's diameter is 2nm. Number of bases in one turn of DNA are 10. Angle of one complete turn is 360 degree.  Length of H-bond is near about3 angstrom.  Diameter of base pair between two stands is about 11 angstrom . Distance between two adjacent bases about 3.4 angstrom. Distance between two  complete turn is 34 angstrom.  Nitrogenous bases are A ,T, G, C.   Nitrogenous composition is always A\T =1 and G / C =1.  Purines and pyrimidines are in equal ratio . DNA behaves like polyelectrolyte because of phosphate group that lies on outer surface of DNA . Size of DNA varies. For example DNA of phage T2 bears 2 into 10 raise to power 5 pairs of nucleotides with molecular weight of 130 million. In eukaryotes DNA is always associated with histones which are basic in nature and positively charged. DNA molecules are very large and can be fragmented. DNA reacts with Fuelgen's rea

  Deoxyribose nucleotide acid is polymer of deoxyribonucleotide . Each deoxyribonucleotide is made up of Ribose sugar , phosphate , and Nitrigenous base .  Sugar: DNA consist deoxyribose* sugar . Nitrigenous Base : It is of two types.  Purines : Adenine (A), Guanine (G) are purines,9_membraned double ring structure having N at 1,3,7,9 position  Add caption Pyrimidines : Thymime (T) ,Cytosine (C)  are Pyrimidines, 6_memberaned single ring structure having N at 1,3 position.  Bonding in DNA  There are two types of binding present in DNA i .e. Hydrogen bonding and covalent bonding.  Hydrogen bonding is present between nitrogenous bases. Adenine joined by  double bond with Thymime . Guanine joined with cytosine by Triple bond.  Covalent bonding :  Phosphodiester bond is formed between 5'phoshphate group of one  nucleotide with 3'OH of another nucleotide.  Bond between nitrogenous base and sugar is known as glycosidic bonds .  X-ray diffraction method    Maurice Wilkins,  R

 DNA is genetic material in all living beings except few plant viruses. But why ? 🤔 Properties of genetic material  It must be Chemically   and structurally stable . It can produce it's replica .  It should provide scope for mutation that is required for evolution.  It should be able to express itself in the form of ' Mendelian characters . ' How DNA fulfill this criteria? Mendel believed that factor /genes contain the information which is required to express particular traits in successive  generations.As DNA consist genes and passes the heredity characters from one generation to next generation. So it fulfill the Mendelians character criteria.  Due to condition of producing replica, proteins fail to fulfill the criteria. Whereas DNA and RNA fulfills the criteria.  Both DNA and RNA are able to mutate. Because of presence of 2'-OH group (present at every nucleotide in RNA)  makes RNA labile and easily degrade. Due to this Unstability in structure RNA mutates at f

 Nucleic acid is biopolymer,essensial for all living beings. They were first reported by Friedrich Miescher (1871) in nuclei of pus cell. He named them nucleic. They can be found in both nucleus and cytoplasm . Altman renamed nuclein and called them Nucleic acid . Nucleoprotein  Nucleic acid along with basic proteins make nucleoprotein which is sub unit of chromosome.   In nucleoprotein, nucleic acid is prosthetic group and protein part consist of protamine and histone (basic nature).  They are very complex and high molecular proteins.  Composition  Basic structure of nucleic acid consist of Sugar, nitrogenous base *(adenine,guanine,thymine,cytosine,uracil) and phosphorus. This combined structure of sugar, phosphorus and nitrogenous base is known as nucleotide.   DNA is made up of deoxyribonucleotides  which is further made up of Deoxyribose sugar, phosphorus, and nitrogenenous bases (adenine,thymine guanine, cytosine) RNA is made up of ribonucleotides which is further composed of Ri