Cytoplasmic Matrix

Dr. V Mishra

Physical Nature of Cytoplasmic matrix

Colourlesss, Greyish, translucent, gelatinous

Various theories have been propounded to delineate the Physical structure of CM:-

1.Reticular theory:- Matrix is composed of reticulum of fibres orparticles in the ground substance2. Alveolar theory:-Matrix is composed of many suspended dropletsresembling the foam of emulsions3. Granular theory:- Matrix consists of large and small granules4. Fibrillar theory:- Fibrils make up the matrix5. Colloidal theory:- most recent, made up of colloids

Colloidal system:- Particle size ranges from 1/10,00,000 to 1/10,000

Solution:- Solvent and Solute Particle size maximum is 1/10,000

Colloidal system:- 2 Phases:- Discontinuous or Dispersed phase and Continuous or Dispersion phase

Chemical Organisation of CM

92 Natural Elements

46 found in cytoplasmic matrix

24 are essential for life

6 play imp role in the functioning of living system

Major Elements:

Carbon:-20%Hydrogen:-10%Nitrogen:-3%Oxygen:-62%Phosphorous:-1.14%Sulphur:-0.14%

And

CalciumPotassiumSodiumChlorinMagnesium

Trace Elements:

IronIodinMolybdenumMgCoZnSeCuNiFBoron etc.

Electrolytes :-Maintenance of the Osmotic PressureAcid-base equilibrium in the matrixExamples:- Mg ions, Phosphate etc.

Non-electrolytes:-(Non-ionising minerals)The examples are:- Na, K, Ca, Mg, Mn, Cu, Fe, Zn etc.The Fe occur in haemoglobin, cytochromes, ferritin, some enzymes as catalase, cytochrome oxidase etc.The ca occur in blood, matrix and bones; The Cu, Mo, Zn occur as co-factors for enzyme actionsThe iodine and fluoride are essential for thyroid and enamel metabolism.

Types of compounds of cytosol:-

Water:-65%Protein:-18%Fat:-10%Carbohydrate:-5%Other organic substances:-1%Inorganic compounds:-1%

Organic (>30%):- Substances containing Carbon and formed in combination with nitrogen, hydrogen and sulphur.Monomers:- Compounds with similar or dissimilar unit structureOligomers:-Small no of monomersPolymers:- Large no of monomers

Carbohydrates:-Main source of energy for cellsGreen plants alone can synthesize themChemically carbohydrates are polyhydroxy aldehydes

Or ketones.monosaccharides, oligosaccharides and polysaccharides

Trioses (Glyceraldehyde, DHAP)Tetroses (Erythrose, erythrulose)Pentoses (riboses, ribuoses)Hexoses (glucose, mannose, fructose)Heptoses (sedoheptulose)

2 to 10 monomersPresence of glycosidic bonds betweenthe monomersDisaccharide(sucrose, maltose, lactose)Trisacch (mannotriose, rhabinose etc)

10 to many thousand monomersForm colloidal compoundsCan be hydrolysed into monosachharidesDivided into structural and nutrient polysachharides

Structural Polysachh Nutrient Polysachh

Serve as extracellular or intracellularsupport materiale.g., cellulose, mannan (homopolymer of mannose & chitin, hyaluronic acid, keratin sulphate & chondroitin sulphate (cartilage & other connective tissue)Peptidoglycans (bacterial cell walls)

Serves as the reserve of monosachharidesE.G., Starch (plant cells and bacteria), glycogen (animal cells)

Polysachharides: Major Characteristics

Branched or UnbranchedHomopolysachharides or heteropolysaccharides

Similar monosaccharides

Starch, Glycogen, cellulose

Made up of Amylose & Amylopectin

Made up of branched chains ofAlpha-Glucose molecules

Made up of unbranchedGlucose molecules

Made up of different kindsOf monosachharides and Amino-nitrogen, suphuric Acid or phosphoric acid in Their molecules.

Heteropolysaccharides The most common examplesAre:- hyaluronic acid, keratin sulphate & chondroitin sulphate, Heparin, Proteoglycans etc.

Hyaluronic acid, Keratin sulphate Chondroitin sulphate

Unbranched heteropolysachhContaining N-acetyl glucosamineAnd glucuronic acidOccurs in the conective tissue,Sinovial fluid of joints, the vitrous Humor of the eyes etc.

Unbranched heteropolysachhContaining D-galactose & suphatedN-acetyl glucosamine.Found in Cartilage & cornea.

Repeating disaccharide alternating with Glucuronic acid and sulphated N-acetylGalactosamine.Found in cartilage, bone, umbilical chord, notochord,etc.

Lipids

Made up primarily of carbon and hydrogen and sometimes Oxygen.Natural fats are compounds of glycerol and fatty acids.They are esters which are formed due to reaction of organic acids withAlcohols.The formula of glycerol is C3H8O3.

Glycerol Fatty Acid

Only one type occurs everywhereAmphipathic molecule :2 distinct regions:-A.Long Hydrocarbon chain (Hydrophobic) B. Hydrophillic carboxylic acidGroup, which ionises in solution &Forms amides and esters in solu-tion.

oIn cells, fatty acids occur primarily as forming esterified structuresoA fatty acid molecule may be saturated or unsaturated

oA saturated fatty acid consists of long hydrocarbon chain terminating into a carboxyl group (-COOH), while so does not happen with unsaturated fatty acidsoAn unsaturated fatty acid has 2 to 6 double bonds between C-C atoms, which gives the molecule flexibility for maintaining the fluidity of the biomembrane.

Essential fatty acid:- are those which are not synthesized by animals or us. Hence required to be supplemented in our diet.

Examples include:- Linoleic acid, linolenic acid and arachidonic acid.

Occurrence as Constituents of cell organelles

As reserve material, e.g. starch & glycogen

Types of LIPIDS:-1.Simple Lipids:- are alcohol esters of fatty acids, e.g., glycerides, waxes etc.2.Compound Lipids:-contain fatty acids, glycerol & other substances e.g., Phosphorous, amino-nitrogen carbohydrates etc. Examples are Phospholipids (inositol, choline etc.), Sphingolipids & Glycolipids. 3. Derived Lipids:- Do not contain fatty acids in their constituents, e.g., terpenes (Vitamins A E & K, Carotenoids, Co-enzyme Q or Ubiquinone etc.), Steroids (hormones progesterone, testesterone, Vitamin D, alcohols of steroids, called Sterols such as Cholesterol etc.), Prostaglandins (Hydroxy derivatives of poly Saturated fatty acids, found in seminal fluid, testis, stomach, brain, lung, heart etc.)

Proteins

Form more than 50% cell’s dry wt.Structural componentsMade up of amino acids (20 in no.)Classification based on biological function:-1.Structural Proteins:- Keratin, collagen2.Dynamic or Functional Proteins:- EnzymesClassification based on shape of proteins:-1.Fibrous proteins:-muscle contractile proteins (myosin), elastic functionality (elastin, collagen)2. Globular protein:-water soluble, roughly spheriodalOr globoidal in shape, enzymes, hormones, immungl-Obulins etc.

3.