PROGRAM LEARNING

MATERIAL

By sangam singh

NUCLEUS

CYTOPLASM

CELL THEORY

ANIMAL CELL

ORGANELLES

E.R RIBOSOMEGOLGI

APPARATUSMITOCHONDRIA LYSOSOME

NUCLEOLUS

NUCLEOPLASM

Cell

All living organisms are made up of cells. Cell is the basic structural and

functional unit of complex organisms. Cells perform all the metabolic

activities taking place at cellular level. The discovery of cells was possible

with the invention of microscope.

History of cell

• Marcello Malpighi, in 1661, proposed that plants are made of tiny

structural units called 'Utricles'.

• Robert Hooke, in 1665, observed many tiny, hollow, room like

structures in a thin slice of cork through a compound microscope and

called them ‘cells’.

• Leeuwenhoek, in 1674, with the improved microscope, discovered

free-living cells in pond water for the first time.

• Robert Brown in 1831 discovered the nucleus in the cell.

• Purkinje in 1839 coined the term 'protoplasm' for the fluid part of the

cell.

• Schleiden in 1838 and Schwann in 1839 proposed the cell theory

which stated that all plants and animals are composed of cells.

• Rudolf Virchow in 1855 further expanded the cell theory by saying

‘omniscellula-e-cellula’, which means all cells arise from pre-existing

cells.

• Cell is derived from the Latin word "Cellula" which means "a little

room".

Cell theory

M.J.Scleiden and TheodreSchwann proposed cell theory for the first time.

• Cell is the basic structural unit of all the organisms.

• Preexisting cells only gave rise to new cells.

• An organism has its body composed of cells.

• A single cell transfers life from one generation to another generation.

Microscopic examination of cells

Plant and animal cells are only visible only under a microscope.

• The microscopic examination of a plant cell enables us view a prominent

vacuole, nucleus, and cytoplasm.

• For the microscopic examination of an animal cell, spread the specimen on a

glass slide, and add a drop of water and methylene blue. Cells with darkly stained

spherical nuclei at their centre can be observed.

Nucleus: A true nucleus acts as the control centre of the cell. It is covered by a

two layered, perforated nuclear membrane allowing substances to enter and leave

the nucleus.

Nucleus is filled with semifluid colloidal substance called as nucleoplasm in which

float the nucleolus and the chromatin fibres. The nucleus contains chromosomes, which

are composed of Deoxyribonucleic acid (DNA) and proteins.

Functions of nucleus

Nucleus controls all the activities of cell

• As the nucleus carries genetic information in the form of DNA, it plays a major

role in cell division and cell development. The functional segments of DNA are

called genes.

• Nucleus plays an important role in protein synthesis and transmission of

characters from one generation to another generation.

Endoplasmic reticulum:

It is a network of tubules and flattened sacs perform various activities in the

cell. The space inside the endoplasmic reticulum is called as lumen.

Endoplasmic reticulum serves as a channel for the transport of proteins

between various regions of the cytoplasm.

Two types of endoplasmic reticulum areRough Endoplasmic Reticulum (RER) and

Smooth Endoplasmic Reticulum (SER).

Ribosomes: These are naked granules with no membrane. They are found

scattered in the cytoplasm or attached to the outside of the endoplasmic

reticulum.

They are the biofactories of proteins.

Ribosomes can be free ribosomes scattered in the cytoplasm or bound

ribosomes seen attached to endoplasmic reticulum.

Ribosomes are made up of two subunits, the larger subunit and the smaller

subunit. 70s ribosomes are present in prokaryotes and 80s ribosomes are

present in eukaryotes.

Functions of ribosomes

• Ribosomes are considered to be the biofactories since they are the sites of

protein synthesis.

• They are the lodging sites for many enzymes participating in the process of

protein synthesis.

Golgi apparatus:

These cell organelles are named after the biologist, Camillo Golgi, who first

described it. The Golgi consists of a stack of membrane-bounded cisternae located

between the endoplasmic reticulum and the cell surface.

Functions of Golgi apparatus

• It synthesises certain biopolymers.

• It also consists of some processing enzymes which alter some proteins and

phospholipids synthesised by endoplasmic reticulum.

Mitochondria:

These are cellular organelles termed as ‘power houses of the cells’. These are bounded

by a double membrane. The outer membrane is smooth while the inner membrane is

thrown into folds called as cristae. The cristae increase the area of cellular respiration.

Both the membranes are separated by intermembrane space. Mitochondrial matrix is

rich in respiratory enzymes

The enzymes in the mitochondria oxidise glucose molecules to produce energy in the

form of Adenosine Triphosphate or ATP.

Functions of mitochondria

• These synthesise energy rich ATP molecules.

• These help in the synthesis of fatty acid, amino acids, steroids by providing them with

biological intermediates.

Lysosomes:

Lysosomes are membranous sacs filled with enzymes. The enzymes are hydrolytic

enzymes which are capable of digesting cellular macromolecules. When the cell gets

damaged, the lysosome may burst and its enzymes may digest the cell itself. Hence,

lysosomes are called as ‘suicidal bags’.

Functions of lysosomes

• Help in killing foreign cells referred to as pathogens.

• Help in destroying the diseased cells.

INSTRUCTIONS

Read the content thoroughly.

The questions are based on the content of

slide.

There are total five multiple choice

questions.

All the questions are compulsory to answer.

1. Which statement of cell is a part of cell theory

a) Cells are found in most living things

b) Cells come only from other living cells

c) All cells capture energy from sunlight

d) Cells with cell walls do not have cell membranes

2. The smallest unit that perform the basic

activities of life is…….

a) a tissue

b) a cell

c) an organ

d) an organism

3. One of the organelles which is considered

as bio factories synthesizing protein………

a) Ribosome

b) Endoplasmic reticulum

c) Golgi apparatus

d) Lysosome

4. Which organelles known as power house of

cell……..

a) Mitochondria

b) Ribosome

c) Endoplasmic reticulum

d) Lysosome

5. Which organelles helps in destroying the

diseased cells…….

a) Nucleus

b) Chloroplast

c) Lysosome

d) Ribosome

THANK YOU