Biomolecules Class 11 Notes Biology Chapter 9 - CBSE

Chapter : 9

What Are Biomolecules ?

Biomolecules

(Organic molecule produced in living cell)

Macromolecule
  • Molecular Weight < 1000 Daltons
  • Polysaccharide , protein , nucleic acid, lipid
Micromolecule
  • Molecular Weight > 1000 Daltons
  • Monosaccharide , Amino acids, nucleotides

Average composition of cells

Component % of the total cellular mass
Water 70-90
Proteins 10-15
Carbohydrates 3
Lipids 2
Nucleic acids 5-7
Ions 1

Proteins

It is large, complex molecule that play very important role in our body.

Types Of Proteins

Simple

(made up of only amino acids)

Fibrous

Long, Coiled and Thread like

  • Collagen
    • Most abundant protein in animal body
    • Present in connective tissue
    • Threads of collagen known as Tendon
  • Elastin
    • In connective tissue
    • Threads of Elastin known as Ligament
  • Keratin

Globular

  • Rubisco
    • Present in chloroplast.
    • Most abundant protein on the earth
  • Albumin
    • Maintain B.C.O.P
    • In milk as Lactoalbumin
    • In egg yolk as Ovabumin
    • In blood as Serum albumin
  • Globin
    • Present with Haemoglobin
  • Histone protein
    • Present with eukaryotic DNA
    • In it Lysine and Arginine amino acids are present in more amount.
  • Compound
  • Derived

Carbohydrate

They are sugar molecules and acts as an energy source, help to control blood glucose and insulin metabolism.

Carbohydrate (Hydrates of carbon, CnH2nOn)

Monosaccharides

(sweet in taste)

  • Glucose
  • Fructose
  • Galactose
Disaccharides

(made by two monosaccharaides)

  •  Maltose= Glucose + Glucose
  • Lactose= Glucose + Galactose
  • Sucrose = Glucose + Fructose
Polysaccharides

Polysaccharides (made by thousands of monosaccharaides, also called glycan).

Amino Acids (General Structure, Classification, Significance)

Based on structure & chemical nature

  • Aliphatic side chain Glycine, Alanine, Valine, Leucine, isoleucine
  • OH group containing AA Serine, Threonine
  • “S” containing AA cysteine, Methionine
  • Acidic amino acids Aspartic acid, Asparagine, Glutamic acid, Glutamine
  • Basic amino acids Histidine, Arginine, Tyrosine, Lysine
  • Aromatic amino acids Phenylamine. Tyrosine, Tryptophan
  • Imino acids Proline

Based on Polarity

  • Hydrophilic (polar)
  • Hydrophobic (Non-polar)

Based on Metabolic fate

  • Glucogenic
  • Ketogenic
  • Both

Nutritional Classification

  • Essential
    • Phenylalanine, Valine Tryptophan PVT.
    • Threonine Isoleucine Methionine TIM
    • Histidine Arginine Leucine Lysine HALL
  • Nonessential
  • Semi essential

Lipids

They are fatty compounds that perform a variety of functions in our body. They are part of the cell membranes and help to control what goes in and out of the cells.

Nucleic Acid

Nucleic acids are polynucleotides. A nucleic acid has three chemical distinct components-heterocyclic compound (nitrogenous base), polysaccharides (ribose/ deoxyribose sugar) and phosphate or phosphoric acid.

Nitrogenous Base

Purines
  • Adenine
  • Guanine
Pyrimidines
  • Cytosine
  • Thymine
  • Uracil

Nucleic Acids

RNA
che2

Three types

  • mRNA
  • rRNA
  • tRNA
DNA
  • Genetic material in eukaryotes
  • Helical chains are bonded by hydrogen bonds between the nitrogenous bases
  • Double bonds between adenine and thymine
  • Triple bonds between guanine and cytosine

Base in Nucleic Acids

Pyrimidine

bio_1

Purine

bio_2

Enzymes

Proteinaceous substances which are capable of catalyzing chemical reactions of biological origin without themselves undergoing any change. They are commonly referred as biocatalysts. Nucleic acids that behave like enzymes are called ribozymes.

$$\text{E + S} \rightleftharpoons \text{ES} \rightleftharpoons \text{EP} \rightleftharpoons \text{E + P} $$

Factor That Affect Enzyme Activity

  • Temperature
  • pH
  • Concentration of enzymes and substrates
  • Inhibitors

Types of Enzymes

  • Oxidoreductases
  • Transferases
  • Hydrolases
  • Lyases
  • Isomerases
  • Ligases

Co-Factor

Non- protein constituents that are bound to the enzyme and make the enzyme catalytically active.

Co-Enzyme

Compounds that bind to the enzyme transiently during the course of the reaction.

Prosthetic Groups

Organic substances that are bound very tightly to the enzyme.