Reading Time: 5 minutes MEMBRANE
A membrane is the outermost boundary of any cell.
It is the non-living part of the cell
Membrane gives the cell support and shape and serves as a boundary regulating the inflow and outflow of materials from the cell
Membrane is of two type
Plasma membrane, also called cell membrane, is the outermost boundary of an animal cell however in most plant cells, it is covered externally by a cell wall.
COMPOSITION OF PLASMA MEMBRANE:
Plasma membrane is mainly composed of lipids and proteins,
60-80% are proteins
20-40% are lipids
In addition, carbohydrates are present in minute quantities
Reading Time: 12 minutes PROTOPLASM
The living contents of a cell are termed as protoplasm
Protoplasm consists of
Cytoplasm is the protoplasm of a cell outside the nucleus
COMPONENTS OF CYTOPLASM:
Cytoplasm has three main components which are
The soluble part of cytoplasm is the cytosol and forms the ground substance of cytoplasm.
Chemically cytosol is 90% water forming a solution containing all the fundamental molecules of life.
In cytosol, small molecules and ions may form true solutions and some large molecules form colloidal solutions.
Colloidal solution may be a sol (non-viscous) or a gel (viscous). Peripheral parts of the cytoplasm are often gel like.
Nucleus serves as a centre for controlling all the activities of the cell Reading Time: 5 minutes DISCOVERY:
Robert Brown in 1831 was the first individual to observe nucleus.
The discovery of nucleus was a revolutionary step which disregarded the concept of cell being an empty compartment bound by thick walls
In animal cell, the nucleus occupies a central position.
In plant cell, the nucleus is pushed towards the periphery by the central vacuole.
NUCLEI PER CELL:
Generally, cells contain a single nucleus and are termed as mono-nucleate cells.
Cells containing two or more nuclei are termed as multi-nucleate cells.
Nucleus is only visible under the microscope when cell is in non-dividing stage. It contains chromatin material and soluble sap called nucleoplasm.
In dividing cell, the nucleus disappears and the chromatin material in it is replaced by chromosomes.
Reading Time: 4 minutes INTRODUCTION
All living things are made up of certain chemical compounds that are broadly classified as organic and inorganic compounds.
The organic compounds encompass the biological molecules present in the living system.
Biological molecules or biomolecules is a broad term used for representing the molecules or ions present in a living system that take part in the chemical processes carried out by the living systems.
The study of biological molecules is carried out by correlating Molecular biology with Biochemistry.
It is the branch of biology in which we study the structure and functions of biological molecules along with molecular synthesis, modifications, mechanisms, and interactions.
Biochemistry is a sub-discipline which deals with the study of chemical processes occurring within and related to living organisms.
TYPES OF BIOMOLECULES:
There are four main types of biological molecules
Reading Time: 3 minutes INTRODUCTION
Water is the medium of life and is the most abundant compound in all organisms.
It is the most important component of the cell, typically forming between 70% to 95% of the mass of the cell.
Almost all reactions of the cell occur in the presence of water, taking part in various biochemical processes such as hydrolysis of macromolecules.
The following are some important properties of water holding biochemical significance.
WATER AS A SOLVENT:
Due to the polar nature of water, it acts as an excellent solvent for polar molecules and ions
A carbohydrate is either sugar or polymer of sugars consisting of carbon, hydrogen, and oxygen. Reading Time: 6 minutes DEFINITION:
Carbohydrates are polyhydroxy aldehydes or ketones or compounds which yield them upon hydrolysis
The empirical formula for carbohydrates is C
m(H 2O) n. BACKGROUND:
The term carbohydrates literally mean “hydrates of carbon”.
This name was assigned because, in most of the carbohydrates, the ratio of hydrogen and oxygen is the same as water (2:1).
However, there are several non-carbohydrate compounds that appear to be hydrates of carbon i.e. Acetic Acid (C
2H 4O 2). Further, some carbohydrates do not satisfy the empirical formula such as rhamnohexose (C
6H 12H 5). Therefore, carbohydrates cannot always be regarded as hydrates of carbon.
Reading Time: 7 minutes INTRODUCTION
Proteins are polymers of amino acids and are the most abundant organic molecules of the living system constituting about 50% of the cellular dry weight.
Amino acids are organic compounds containing two functional groups i.e. amino (-NH
2) group and carboxyl (-COOH) group along with a side chain specific to each amino acid. STRUCTURE OF AMINO ACIDS:
Chemically, an amino acid consists of four components
Carboxylic group (-COOH), which is basic in nature.
Amino group (-NH
2), which is acidic in nature. R side chain which is specific for each amino acid and accounts for the different types of amino acids.
Hydrogen atom linked to the central carbon atom.
If both the carboxyl group and amino groups are attached to the same carbon, the amino acid is termed as α amino acid.
There are almost 400 identified amino acids occurring in nature however, only 20 are involved in protein formation in living organisms.
These 20 proteins arrange in various combinations to produce different types of proteins in living organism.
The adjacent amino acids in a polypeptide protein chain are linked together via peptide bonds.
Reading Time: 5 minutes INTROUCTION
Lipids are heterogenous group of organic compounds that are relatively insoluble in water and soluble in organic solvents, actually or potentially related to fatty acids and utilized by the living cells
chemically, lipids are esters of fatty acids with alcohol
Fatty acids are carboxylic acids with a hydrocarbon side chain.
Fatty acids are of two types
When there is no double bond present in the hydrocarbon chain of fatty acids, these fatty acids are termed as
saturated fatty acids
When the hydrocarbon side chain of fatty acids contains double bonds, such fatty acids are termed as
unsaturated fatty acids.
Alcohols are a group of organic compounds containing on or more hydroxyl groups attached to a carbon atom.
Reading Time: 7 minutes DEFINITION
Nucleic acids are polymers resulting from the linkage of smaller units called nucleotides.
Nucleic acids were first isolated in 1869, by Fredrich Miescher from the nuclei of pus cells.
Nucleotides are small molecules acting as monomers and join together into a chain forming nucleic acids. Nucleic acids are therefore also known as polynucleotides.
COMPONENTS OF NUCLEOTIDE:
A nucleotide is composed of three components namely
Nitrogen containing base
Pentose sugar (5 carbon monosaccharide)
The nitrogenous bases found in nucleotides (and hence nucleic acids) are heterocyclic compounds.