Constituents of a Cell:Biology Notes for RRB Exams – Railway ALP and Group D – General Science

Constituents of a Cell:

·  Cell Organelles: Organelles are observed in Eukaryotic Cells which have definite shape of nucleus, Cell Organelles use membrane to distinguish their functions from the rest of the Organelles Example of Cell Organelles : Mitochondria, Golgi Apparatus, Ribosome etc…

·  Endocytosis: The process of engulfing matter by a living cell to be utilized for the energy-using process. Amoeba uses this process for processing of food

·  Substances like CO₂ and Oxygen move through the cell membrane by a process called Diffusion.

·  Osmosis is the process of movement of molecules through a semi-permeable membrane into a region of higher solute concentration in the direction that tends to equalize the solute concentration on both the sides.

·  Water molecules are transported through the cell membrane by this process of Osmosis

·  Osmosis is a case of Diffusion (through a semi-permeable membrane)

·  Protein and Fat help in building the cell membrane which is known as cell biogenesis

·  The Fluid in a cell excluding the Nucleus containing Organ Cells that perform specific functions of the cell is called Cytoplasm

·  The cell organelle which combines simple molecules into complex molecules and packages them into vesicles and sends them out of the cell is called Golgi Apparatus

·  Digestion of any foreign material is done by lysosomes to keep the cell clean, in one way it is the waste disposal system of the cell.

·  The Power House of the cell – Mitochondria, energy required for various cell processes is released by Mitochondria through ATP (Adenosine-tri-Phosphate) molecules

·  ATP (Adenosine-tri-Phosphate) is referred to as the Energy Currency of the cell

·  The Cell Division is initiated by the Centrioles

·  Chromosomes carry all the information that is required by the cell to grow, divide and reproduce

·  The cell organelles which are found only in plants are Plastids

Leucoplasts	Chloroplasts
Protein, Starch and Oil are stored in Leucoplasts	Primarily for imparting colors to fruits and flowers. Chloroplast contain chlorophyll which is the site of Photosynthesis in Plants

·  Large network of membrane bound tubes similar in structure to Plasma Membrane where Proteins, Fat Molecules are manufactured is called Endoplasmic Reticulum (ER), There are two types of Endoplasmic reticulum

Smooth Endoplasmic Reticulum	Rough Endoplasmic Reticulum
Helps in manufacturing of Fat Molecules or Lipids	Helps in manufacturing of Proteins
These lipids and proteins are used as Hormones and Enzymes in the body
One Major use of ER is detoxification of many poisons and drugs is liver cells of Animals
ER is both a manufacturer and a passage way for Intracellular transport

·  The process in which water is purified in the cell by removing the impurities when it flows from a dilute solution (hypotonic) to a concentrated solution(hypertonic) through a semi permeable membrane is called Reverse Osmosis. In this process, little pressure is applied to overcome the Osmotic Process

·  The Non-Living Part Cell Organelles of the Cell are Vacuoles and Granules

Granules	Vacuoles
Stores – Fat, Proteins and Carbohydrates.	Stores – Excess Water, Minerals, Pigments and Waste Products
Not supported by any membrane	Fluid filled spaces enclosed by Membranes

·  The Brain of the Cell – Cell Nucleus which control the different processes in the cell

Cell Nucleus consists of the following main parts
Nuclear Envelope	Chromosomes	Nucleolus	Chromatin
Membrane similar to cell membrane covering the Nucleus	v Chromosomes are the ones which carry information. v They are made up of DNA and similar pattern of DNA is called Gene v A Human-Being Usually has 23 Pairs of Chromosomes or (46 Chromosomes)	A small dense spherical structure in the nucleus of a cell Proteins are stored by the nucleolus	The DNA in the cell nucleus is packaged by special proteins called histones. The protein/DNA complex formed is called Chromatin

·  There are two types of process in cell division

Mitosis	Simplest Duplication of a cell and all its parts. Five Steps are involved in the processProphase, Metaphase, Anaphase, Telophase and Interphase
Meiosis	Four Cells are formed from the process of Meiosis during reproduction. It can be looked at as two simultaneous phases of Mitosis creating four cells from one original cell

·  On the Basis of functions performed by different tissues, they are classified into

Epithetical Tissue	– Covering or Protective tissues from Mechanical Injuries and Invading Micro organisms – These tissues are tightly packed and form a continuous sheet – The intercellular spaces in these tissue is negligible – Cells of epithelium play a crucial role in exchange of materials between the body and the external environment – The main function of the SQUAMOUS is to protect the parts from injury, germs etc is found mainly in the walls of blood vessels and air sacs of lungs
Connective Tissue	Most abundant and widely distributed tissues in the animal body There are four types of connective tissues : Arelor, Adipose, Skeletal, Fluidl
Muscular Tissue	Muscle Tissues are of three types: Skeletal(Voluntary), Smooth(Involuntary) and Cardiac(Involuntary)
Nervous Tissue	This tissue is the major tissue in the body which controls the body responsiveness to changing conditions The Brain, Nerves and Spinal Cord compose of the nervous tissue Each neuron has a single long part, called the axon, and many short, branched parts called dendrites.