cell biology.pptx structure and cells and cognitive
1. S T U D Y O F C E L L , I T S F U N C T I O N A N D
S T R U C T U R E
CELL BIOLOGY
2.
3. THECELL THEORY
1. All living organisms are composed of
one or more cells.
2. The cell is the basic unit of structure
and organization in organisms.
3. Cells arise from pre-existing cells.
4. EMERGENCE OF CELL THEORY
• The development and refinement of magnifying lenses
and light microscopes made the observation and
description of microscopic organisms and living cells
possible.
• Many scientists contributed to the cell theory
6. RobertHooke(1635-1703)
• He observed that cork has small regular boxes in it that he
called
• “cells s”.
• The English scientist Robert Hooke first used the term “cells”
in 1665 to describe the small chambers within cork that he
observed under a microscope of his own design. To Hooke,
thin sections of cork resembled “Honey-comb,” or “small
Boxes or Bladders of Air.” He noted that each “Cavern,
Bubble, or Cell” was distinct from the others. At the time,
Hooke was not aware that the cork cells were long dead and,
therefore, lacked the internal structures found within living
cells.
8. THEODOR SCHWANN AND MATHIAS SCHLEIDEN
STATED THAT AL LIVING THINGS ARE MADE OF
CELLS.(1839)
MathiasSchleiden
(plants)
Matthias Schleiden (1804–1881), a German
botanist who made extensive microscopic
observations of plant tissues, described them
as being composed of cells. Visualizing plant
cells was relatively easy because plant cells
are clearly separated by their thick cell walls.
Schleiden believed that cells formed through
crystallization, rather than cell division.
9. CONTINUED….
Theodor Schwann (1810–1882), a noted
German physiologist, made similar
microscopic observations of animal tissue.
In 1839, after a conversation with
Schleiden, Schwann realized that
similarities existed between plant and
animal tissues. This laid the foundation for
the idea that cells are the fundamental
components of plants and animals.
10. RUDOLPH VIRCHOW (1821-1902)
• German scientist who discovered that al cells come
from pre-existing cells .
• Rudolf Virchow (1821–1902), a well-respected
pathologist, published an editorial essay entitled “Cellular
Pathology,” which popularized the concept of cell theory
using the Latin phrase omnis cellula a cellula (“all cells
arise from cells”), which is essentially the second tenet of
modern cell theory.
11. 2. TWO TYPES OF
CELLS
Eukaryotic cell Prokaryotic cell
18. 3.1 CELL
MEMBRANE
• Theoutermost covering of the cell thatseparatesthe contents of the
cell from its external environment is known ascell membrane. It is
selectively permeable andcalledfluid mosaicmodel. (1972)
• Thecell membrane holds the cell together andallows nutrients into the
cell. The plasma membrane is made up of two layers of
phospholipids (phospholipids bilayer)
•A phospholipid is a lipid made of glycerol, two fatty acid tails, and a
phosphate-linked head group. Biological membranes usually involve
two layers of phospholipids with their tails pointing inward, an
arrangement called a phospholipid bilayer.
•Cholesterol, another lipid composed of four fused carbon rings, is
found alongside phospholipids in the core of the membrane.
•Membrane proteins may extend partway into the plasma membrane,
cross the membrane entirely, or be loosely attached to its inside or
outside face.
•Carbohydrate groups are present only on the outer surface of the
plasma membrane and are attached to proteins,
forming glycoproteins, or lipids, forming glycolipids.
19. The plasma membrane (cell membrane) is the
organelle that encapsulates the contents of the cell.
Apart from encapsulating cell contents, the plasma
membrane also plays a vital role in regulating the
movement of substances in and out of the cell.
As such, it is actively involved in such both passive
and active transportation to and from the cell. These
processes also help maintain balance even when
20. 3.2 CYTOPLASM
.
CYTOPLASM is also not considered as an organelle in some books. However,
it is an important component of the cell. Cell cytoplasm is composed of
protoplasm in which all the other cell organelles are suspended.
Many of the cell processes (protein synthesis, respiration etc) take place in the
cytoplasm. The cytoplasm also plays an important role in the movement of
various materials around the cell.
21. 3.3 MITOCHONDRIA
• It is an cell organelle found in large numbers in most cells,
in which the biochemical processes of respiration and
energy production occur. It hasadouble membrane, the
inner part being folded inwards to form layers (cristae).
22. 3.3.1 FUNCTIONS OF
MITOCHONDRIA
• It is the site forrespiration.
• Theenergy required for various chemical activitiesneeded
for life is released by mitochondria in the form of A
TP
molecules.
• Theyhave their DNAand ribosomes due to which theyare
able to make some of their own proteins. Thus,they are
regarded assemiautonomous organelles.
24. 3.4.1 FUNCTIONS OF
NUCLEUS
• It helps in inheritance of features from parents to next
generation in the form of DNAmolecules present in
chromosomes which are present init.
• It controls which protein and what amount of it will be
synthesized in the cell.
• Itplays acentral role in the cell division.
• It plays acrucial part, along with the environment, in
determining the way the cell will develop and what form it
will exhibit at maturity and what function it will do, by
directing the chemical activities ofthe cell.
25. 3.5 NUCLEOLUS
•Inside the nucleus, there is anotherorganelle
called the nucleolus.
•It is responsible for makingribosomes.
26. 3.6 VACUOLES
•Theyare storage sacsfor solid or liquidcontents
bounded by aunit membrane.
•In animals they are present in large numberbut
their sizeissmall.
•While plants have very few vacuoles but theirsize
is large.
27. 3.6.1 FUNCTIONS OF
VACUOLES
• Theyare storage sacsof the cells.
• Many important substances like amino acids, sugars, various
organic acids and some proteins are present in the vacuoles
of plants.
• In single celled organisms like Amoeba, food vacuoles
contains the food items thatthe Amoeba hasconsumed.
• In some unicellular organisms, specialised vacuoles alsoplay
important roles in expelling excesswater and wastes from
the cell.
28. 3.7 ENDOPLASMIC
RETICULUM
• It is a large network of membrane bound
tubes and sheets. It looks like long tubules
or round or oblong bags(vesicles).
• There are two types of endoplasmic
reticulum:
1.Rough Endoplasmic Reticulum: It has
particles called ribosomes attached to its
surface. Thus, it looks rough under a
microscope and is known as rough
endoplasmic reticulum.
2. Smooth Endoplasmic Reticulum: It
looks smooth because it doesn’t have
ribosomes on its surface and is known
as smooth endoplasmic reticulum.
29. 3.7.1 FUNCTIONS OF
ENDOPLASMIC
RETICULUM
• RoughEndoplasmic Reticulum is asite for protein synthesis.
• Smooth Endoplasmic Reticulum is asite for lipidsynthesis.
• Some of these proteins and lipids synthesized by RERand SER
respectively help in the process of building the cell membrane
which is known asmembrane biogenesis.
• It serves aschannels for the transport of materials from
nucleoplasm to cytoplasm or from one part of the cytoplasm to
the another part of the cytoplasm.
• SERin the liver cells of the group of animals called vertebrates
plays acrucial role in detoxifying many poisons anddrugs.
30. 3.8 GOLGI
APPARATUS
• It is organelle in the cell that is responsible for sorting and
correctly shipping the proteins produced in the ER.
• Golgi Apparatus is made up of membrane bound vesicles
present in the form of stacks. Such structures are called
cisterns.
• It was discovered by Camillo Golgi.
31. 3.8.1 FUNCTIONS OF GOLGI
APPARATUS
• Storage, packagingand dispatching of the substancesformed bySER
and RER.
• Formation of complex sugarsfrom simplesugars.
• Formation of lysosomes.
32.
33. 3.10 LYSOSOMES AND ITS
FUNCTIONS
• Enzymes digest their own cell.
Therefore, lysosomes are also
known as suicide bags of cell.
• Lysosomesfunction asthe
cell's recycling compartment.
• Theseare membrane bound cell organelle thatcontains
digestive enzymes.
• When the cell gets fully damaged,lysosomesmayburst andthe
34. 3.9 RIBOSOMES AND ITS
FUNCTIONS
• These are tiny particles present in all active cells and act as
the active sites for protein synthesis.
• Organelles that help in the synthesis of proteins.
• Some ribosomes are found in the cytoplasm, but most are
attached to the endoplasmic reticulum.
35. CENTRIOLES
• Centrioles are
cylindrical
organelles found in
most eukaryotic
cells. They contain
tube-shaped
molecules known as
microtubules that
help separate
chromosomes and
move them during
cell division.
36. 3.11 CELL WALL
•Plant cells, in addition to the plasma membrane,
have another rigid outer covering called the cell
wall. It lies outside theplasma membrane.
•Cell walls are only
present in plants,
fungi andbacteria.
•Cell wall is mainly
composed of cellulose
which is atype of
complex carbohydrate.
37. 3.11.1 FUNCTIONS OF
CELL WALL
•Cell wall permit the cells of plants, fungi and
bacteria to withstand very dilute(hypotonic)
external media without bursting.
•Ithasnarrow pores through which fine strands of
cytoplasm are able to crossthe cellwalls.
•Becauseof cell wall, cells can withstand changesin
the external environment, protecting the
constituents of cell.
38. 3.12
PLASTIDS
• Theseare found only in plant cell. Theyare doublelayered
and contain their own DNAandribosomes.
• Plastids are of threetypes:
1.Chloroplasts: Theseare the plastids containing
chlorophyll which gives green colour to the plant. It is
also a semiautonomous organelle.
2.Leucoplasts: Theseare the white or colourlessplastids.
Theycan change to other types ofplastids.
3.Chromoplasts: Theseare coloured
plastids.
39. 3.12.1 FUNCTIONS OF
PLASTIDS
1) Chloroplasts:Theseare important for photosynthesisin plants.
2) Leucoplasts:Thesestore materials like starch, oilsand protein granules.
3) Chromoplasts: Theseimpart colour to flowers andfruits. Theyare rich in carotenoid
pigments andlipids.
