Biochemistry - Nucleic Acid for dmlt and paramedical students

Nucleic Acid - Definition, Types, Structure, Functions and Properties:

Definition of Nucleic Acid:

Nucleic acids are the polynucleotides having high molecular weight. The monomeric unit of which is nucleotide.

Types of Nucleic Acids:
1) Ribonucleic Acid (RNA)
2) Deoxyribonucleic acid (DNA)

1) RNA: May be found in nucleus but mainly occurs in cytoplasm carry out protein synthesis work.

2) DNA: Occurs in nucleus as well as cell organells like chloroplast and mitochondria.

Types of RNA:

1) Transfer RNA (t-RNA)
2) Messenger RNA (m-RNA)
3) Ribosomal RNA (r-RNA)

Structure of Nucleic Acids: Nucleic acid components:

Sugar - ribose or dexyribose

Base + sugar = Nucleoside - N - glycoside bond.

Nucleoside + phosphoric acid = Nucleotide - Ester bond.

Nucleic Acids - condensation polymer of nucleotide (Nucleotide - nucleotide) phosphor diester bond.

Watson -Crick double helical structure of DNA and forces responsible for stability of helix.

Functions of Nucleic Acids:

1) Transmission of hereditary Characters (DNA)
2) Synthesis of Proteins (RNA)

DNA: Store house of genetic information control protein synthesis in cell. Direct synthesis of RNA. 
RNA: Direct synthesis of specific proteins.
m-RNA: To take genetic massage from RNA
t- RNA: Transfer the activated amino acids to the site of protein synthesis.
r-RNA: Function not clearly understood. Mostly present in ribosomes and responsible for stability of m-RNA.-

Properties of Nucleic Acid:
1) Optical Property: Absorbance in UV at 260 nm
2) Melting Temperature: Tm analysis

Ismail- Bio-chemistry

Biochemistry - Structures and Functions of Important Cell Organelles

Structures and Functions of Important Cell Organelles, Importance of Water

Definition of Cell:

A cell may be defined as "Structural and functional unit of all living organisms".

Two types of cells
1) Eukaryotic cell
2) Prokaryotic cells

Important Plant Cell - Organelles and their Functions:

1) Cell Wall - It Provides support, prevent cells from swelling and rupture or shrinkage, gives definite shape to cell.

2) Nucleus - Store of genetic information, which issue appropriate signal at proper time during different stages.

3) Mitochondria- Power house of energy, contain m-t RNA and DNA and protein synthesizing machinery, synthesis of ATP required for anabolism.

4) Chloroplast - The sites of photosynthetic phosphorylation. The stroma is the site of the carbon photosynthetic enzymes involved in CO 2 fixation, ribosomes, nucleic acid-synthesizing enzymes, and fatty acid synthesizing enzymes.

5) Ribosomes - Site of protein biosynthesis.

6) Golgi Apparatus - Participate in the early stage of cell wall synthesis in higher plants. Sites of secretions of proteins and polysaccharides and coupling of these two components to form glycoproteins. Intense phospholipid biosynthesis observed in these organelles.

Importance of Water:

i) Serves as a medium in which substances undergo fundamental changes.
ii) Provides hydrogen for the reduction of CO2 in photosynthesis.
iii) Water is necessary reactant for the hydrolytic splitting of carbohydrates, fats and proteins.
iv) Water is solvent and dispersion medium for all protoplasmic constituents
v) Acts as a transporting medium for all the cell nutrients.
vi) Absorption, secretion and excretion would not be possible without water. 

Some basic concept of chemistry - 4 for dmlt and paramedical students

Basic of Elements-Ions-Compounds and Valancy:

Compounds:

Valency :

AMINO ACIDS AND PROTEINS -1 for dmlt and paramedical students

          Amino Acids & Protiens:
               Amino Acids are molecules, which contain two functional groups, one is carboxylic group and another is amino group.

Acidic Amino Acid:

These amino acids contain a second carboxyl group or a potential carboxyl group in the form of carboxamide.

Basic Amino Acids:

These contain a second basic group which may be an amino group.

Essential & Non-Essential Amino Acids:
                Those amino acids which must be supplied to our diet as are not synthesized in body are known as essential amino acids.
Ex: Valine, Phenylalanine, Arganine, Lysine,Histadine.

Those amino acids which are  synthesized in body are non-essential amino acids.
Ex:Glycine, Alanine, Tyrosine, Serine, Cystine,

Zwiter Ion:
      Amino acids contain both acidic carboxyl group -(COOH) and basic amino group in the same molecules.

In aqueous solution, the acidic carboxyl group can lose a proton and basic amino group can gain a proton in a kind of internal acid – base reaction. The product of this internal reaction is called a Dipolar or a Zwitter ion.

Iso-electric Point:
At a certain pH (i.e. H+ concentration), the amino acid molecules show no tendency to migrate towards any of the electrodes and exists as a neutral dipolar ion, when placed in electric field is known as isoelectric point.

Peptide and Proteins:

Proteins are formed by joining the carboxyl group of one amino to the α - amino group of another acid.

The bond formed between two amino acids by the elimination of water molecules is called peptide linkage.

Define Proteins:

Proteins are large macromolecules consisting chain of amino acids that plays an important role in many body functions.
There are 22 different amino acids found.

Classification of Proteins:
There are two methods for classifying proteins.

1)Classification according to Composition

2)Classification according to Functions


1)Classification according to Composition:

i)Simple Proteins:

Simple proteins are those which yield only α-amino acids upon hydrolysis.

Simple proteins are composed of chain of amino acid unit only joined by peptide linkage.

Examples are: Egg (albumin); Serum (globulins); Wheat (Glutelin); Rice (Coryzenin)

2)Conjugated Proteins:

Conjugated proteins are those which yield α - amino acids plus a non protein material on hydrolysis.
The non protein material is called the prosthetic group.

Example: Casein in milk,  Hemoglobin, Chlolesterol

According to molecular shape, proteins are further classified into two types.

(A) Fibrous protein
  (a) These are made up of polypeptide chain that are parallel to the axis & are held together by strong hydrogen and disulphide bonds.
  (b) They can be stretched & contracted like thread.
   (c) They are usually insoluble in water.
     Example: Keratin (hair, wool, silk & nails); Myosin (muscle)

(B) Globular Proteins
(a)    These have more or less spherical shape (compact structure).
(b)    α - amino helix are tightly held bonding; H – bonds, disulphide bridges, ionic or salt bridges:

Examples: Albumin (egg)


Classification according to Functions
The functional classification includes following groups.

  a) Structural Proteins
 These are the fibrous proteins such as collogen (skin, cartilage & bones) which hold living system together.

  b) Blood Proteins
(i) The major proteins constituent of the blood are albumin hemoglobin & fibrinogen.
(ii) Their presence contribute to maintenance of osmotic pressure, oxygen transport system & blood coagulation respectively.

Function of Protein:
1) Storage
2) Transport
3) Structural Material
4) Metabolic Growth Regulator
5) Control of Physiological Functions
6) Catalytic Activity
7) Hormonal
8) Toxicity by Foreign Proteins

Properties of Proteins:
i) Optical Property
ii) Colloidal
iii) Solubility
iv) Amphoteric Nature

v) Denaturation of Proteins etc