THE FUNDAMENTAL UNIT THE FUNDAMENTAL UNIT OF LIFEOF LIFE

Done by- A.Raghu Raman IX BDone by- A.Raghu Raman IX B

COMPOUND MICROSCOPE(IMAGE COMPOUND MICROSCOPE(IMAGE FORMATION)FORMATION)

CELLSCELLS

• The word “cell” comes from the Latin The word “cell” comes from the Latin cellula, meaning a small room or cellula, meaning a small room or cubicle, and was first used by Robert cubicle, and was first used by Robert Hooke in his book Micrographia, Hooke in his book Micrographia, published in 1665. published in 1665.

• Hooke was describing the air-filled Hooke was describing the air-filled spaces of dead cells in a slice of cork spaces of dead cells in a slice of cork (bark from an oak tree).(bark from an oak tree).

VARIOUS CELLS FROM THE VARIOUS CELLS FROM THE HUMAN BODY(NERVE CELLS)HUMAN BODY(NERVE CELLS)

VARIOUS CELLS FROM THE VARIOUS CELLS FROM THE HUMAN BODY(SPERM CELLS)HUMAN BODY(SPERM CELLS)

VARIOUS CELLS FROM THE VARIOUS CELLS FROM THE HUMAN BODY(RED BLOOD HUMAN BODY(RED BLOOD CELLS)CELLS)

VARIOUS CELLS FROM THE VARIOUS CELLS FROM THE HUMAN BODY(WHITE BLOOD HUMAN BODY(WHITE BLOOD CELLS)CELLS)

VARIOUS CELLS FROM THE VARIOUS CELLS FROM THE HUMAN BODY(BONE CELLS)HUMAN BODY(BONE CELLS)

VARIOUS CELLS FROM THE VARIOUS CELLS FROM THE HUMAN BODY(SMOOTH HUMAN BODY(SMOOTH MUSCLE CELLS)MUSCLE CELLS)

VARIOUS CELLS FROM THE VARIOUS CELLS FROM THE HUMAN BODY(FAT CELL)HUMAN BODY(FAT CELL)

CELLS AND ITS FUNCTIONSCELLS AND ITS FUNCTIONS

• Cell, the smallest unit of an organism that can Cell, the smallest unit of an organism that can function independently.function independently.

• All living organisms are made of cells and All living organisms are made of cells and nothing less than a cell can truly be said to be nothing less than a cell can truly be said to be alive. alive.

• Some microscopic organisms, such as Some microscopic organisms, such as bacteria and protozoa, are single cells bacteria and protozoa, are single cells whereas animals and plants are composed of whereas animals and plants are composed of many millions of cells built into tissues and many millions of cells built into tissues and organs.organs.

PLASMA MEMBRANE OR CELL PLASMA MEMBRANE OR CELL MEMBRANEMEMBRANE

• All cells have a surrounding All cells have a surrounding membrane (termed the plasma membrane (termed the plasma membrane) enclosing a water-rich membrane) enclosing a water-rich substance called the cytoplasm. substance called the cytoplasm.

• Proteins embedded in the plasma Proteins embedded in the plasma membrane form channels and pumps membrane form channels and pumps that control the passage of small that control the passage of small molecules into and out of the cell.molecules into and out of the cell.

DIFFUSIONDIFFUSION

•Diffusion is the flow of energy Diffusion is the flow of energy or matter from a higher or matter from a higher concentration to a lower concentration to a lower concentration, resulting in an concentration, resulting in an even distribution.even distribution.

OSMOSISOSMOSIS

• Osmosis is the net or overall movement Osmosis is the net or overall movement of solvent molecules (often water) from of solvent molecules (often water) from a region where they are at a higher a region where they are at a higher concentration to an area where they are concentration to an area where they are at a lower concentration through a at a lower concentration through a partially permeable membrane partially permeable membrane (sometimes called a selectively (sometimes called a selectively permeable or semi-permeable permeable or semi-permeable membrane).membrane).

CELL WALLCELL WALL• Plant cells, in addition to the plasma Plant cells, in addition to the plasma

membrane, have another rigid outer membrane, have another rigid outer covering called the cell wall.covering called the cell wall.

• The cell wall lies outside the plasma The cell wall lies outside the plasma membrane.membrane.

• The cell wall is mainly composed of The cell wall is mainly composed of cellulose.cellulose.

• Cellulose is a complex substance and Cellulose is a complex substance and provides structural strength to plants.provides structural strength to plants.

CELL WALL SURROUNDING CELL WALL SURROUNDING THE PLANT CELL THE PLANT CELL

NUCLEUSNUCLEUS• The most conspicuous organelle in most plant The most conspicuous organelle in most plant

and animal cells is the nucleus, typically a and animal cells is the nucleus, typically a membrane-enclosed, roughly spherical body membrane-enclosed, roughly spherical body about 5 µm in diameter.about 5 µm in diameter.

• Within the nucleus, molecules of DNA and Within the nucleus, molecules of DNA and proteins are organized into long chromosomes, proteins are organized into long chromosomes, which usually occur in identical pairs.which usually occur in identical pairs.

• Chromosomes are too stringy and intertwined Chromosomes are too stringy and intertwined to be identified separately unless the cell is to be identified separately unless the cell is dividing.dividing.

• Just before a cell divides, however, its Just before a cell divides, however, its chromosomes become condensed and thick chromosomes become condensed and thick enough to be seen as separate structures.enough to be seen as separate structures.

NUCLEUSNUCLEUS

• The DNA inside each chromosome is The DNA inside each chromosome is a single very long, highly coiled a single very long, highly coiled molecule containing a linear molecule containing a linear sequence of genes. sequence of genes.

• Genes contain the coded instructions Genes contain the coded instructions for the assembly of RNA molecules for the assembly of RNA molecules and proteins needed to produce a and proteins needed to produce a functioning copy of the cell.functioning copy of the cell.

NUCLEUS IN EUKARYOTIC NUCLEUS IN EUKARYOTIC CELLCELL

PROKARYOTIC CELLPROKARYOTIC CELL

•Cells of organisms which lack a Cells of organisms which lack a nuclear membrane, are called nuclear membrane, are called prokaryotes(Pro=primitive or prokaryotes(Pro=primitive or primary;karyote=nucleus).primary;karyote=nucleus).

•Organisms with cells having a Organisms with cells having a nuclear membrane are called nuclear membrane are called eukaryotes.eukaryotes.

PROKARYOTIC CELLPROKARYOTIC CELL

EUKARYOTIC CELLEUKARYOTIC CELL

CELL ORGANELLESCELL ORGANELLES

•Some important cell organelles are: Some important cell organelles are: endoplasmic reticulum, Golgi endoplasmic reticulum, Golgi apparatus, lysosomes, apparatus, lysosomes, mitochondria, plastids and mitochondria, plastids and vacuoles.vacuoles.

•They are important because they They are important because they carry out some very crucial carry out some very crucial functions in cells.functions in cells.

ANIMAL CELLANIMAL CELL

PLANT CELLPLANT CELL

ENDOPLASMIC RETICULUMENDOPLASMIC RETICULUM

• In addition, a complex membrane In addition, a complex membrane system called the endoplasmic system called the endoplasmic reticulum runs through much of the reticulum runs through much of the cytoplasm and appears to function as cytoplasm and appears to function as a communication system; various a communication system; various kinds of cellular substances are kinds of cellular substances are channeled through it from place to channeled through it from place to place. place.

ENDOPLASMIC ENDOPLASMIC RETICULUM(ROUGH)RETICULUM(ROUGH)

• RER looks rough under a microscope RER looks rough under a microscope because it has particle called because it has particle called ribosomes attached to its surface ribosomes attached to its surface

• The ribosomes , which are present in The ribosomes , which are present in all active cells , are the sites of all active cells , are the sites of protein manufacture . protein manufacture .

ENDOPLASMIC ENDOPLASMIC RETICULUM(SMOOTH)RETICULUM(SMOOTH)

• The SER helps in the manufacture of The SER helps in the manufacture of fat molecule , are lipids , important fat molecule , are lipids , important for cell function. for cell function.

• Some of these proteins and lipids Some of these proteins and lipids help in building the cell membrane . help in building the cell membrane . This process is known as This process is known as membrane biogenesis. membrane biogenesis.

• SER plays a crucial role in detoxifying SER plays a crucial role in detoxifying many poisons and drugs. many poisons and drugs.

ROUGH ENDOPLASMIC ROUGH ENDOPLASMIC RETICULUMRETICULUM

GOLGI APPARATUSGOLGI APPARATUS

• Stacks of membrane-bounded flattened Stacks of membrane-bounded flattened sacs constitute the Golgi apparatus, sacs constitute the Golgi apparatus, which receives the molecules made in which receives the molecules made in the endoplasmic reticulum, processes the endoplasmic reticulum, processes them, and then directs them to various them, and then directs them to various locations in the cell.locations in the cell.

• Golgi apparatus also plays a role in the Golgi apparatus also plays a role in the secretion of materials from cells.secretion of materials from cells.

GOLGI APPARATUSGOLGI APPARATUS

LYSOSOMESLYSOSOMES

• Lysosomes are small, irregularly shaped Lysosomes are small, irregularly shaped organelles that contain stores of enzymes organelles that contain stores of enzymes responsible for the digestion of many responsible for the digestion of many unwanted molecules in cells. unwanted molecules in cells.

• During the disturbance in cellular During the disturbance in cellular metabolism, for example, when the cell metabolism, for example, when the cell gets damaged, lysosomes may burst and gets damaged, lysosomes may burst and the enzymes digest their own cell.the enzymes digest their own cell.

• Therefore, lysosomes are also known as Therefore, lysosomes are also known as the ‘suicide bags’ of a cell. the ‘suicide bags’ of a cell.

MITOCHONDRIAMITOCHONDRIA• The name mitochondria comes from two Greek The name mitochondria comes from two Greek

words, “mito” meaning “filaments” and words, “mito” meaning “filaments” and “chondros” meaning “grains”, which were used “chondros” meaning “grains”, which were used in the 19th century to describe the appearance in the 19th century to describe the appearance of parts of cells under the light microscope. of parts of cells under the light microscope.

• Mitochondria have two membranes, inner and Mitochondria have two membranes, inner and outer. The latter serves largely as an outer outer. The latter serves largely as an outer boundary and is not the locus of major boundary and is not the locus of major mitochondrial functions, whereas the inner mitochondrial functions, whereas the inner membrane contains many proteins with membrane contains many proteins with important functions, including those that allow important functions, including those that allow molecules to enter into, or exit from, the molecules to enter into, or exit from, the mitochondrial matrix.mitochondrial matrix.

MITOCHONDRIAMITOCHONDRIA

PLASTIDSPLASTIDS• Plastids are organelles—specialized cellular Plastids are organelles—specialized cellular

parts that are analogous to organs—bounded by parts that are analogous to organs—bounded by two membranes.two membranes.

• Three kinds of plastids are important here. Three kinds of plastids are important here. Chloroplasts contain chlorophylls and carotenoid Chloroplasts contain chlorophylls and carotenoid pigments; they are the site of photosynthesis, pigments; they are the site of photosynthesis, the process in which light energy from the Sun is the process in which light energy from the Sun is fixed as chemical energy in the bonds of various fixed as chemical energy in the bonds of various carbon compounds.carbon compounds.

• Leucoplasts, which contain no pigments, are Leucoplasts, which contain no pigments, are involved in the synthesis of starch, oils, and involved in the synthesis of starch, oils, and proteins. Chromoplasts manufacture proteins. Chromoplasts manufacture carotenoids.carotenoids.

VACUOLESVACUOLES

• Vacuoles are membrane-bound Vacuoles are membrane-bound cavities filled with cell sap, which is cavities filled with cell sap, which is made up mostly of water containing made up mostly of water containing various dissolved sugars, salts, and various dissolved sugars, salts, and other chemicals.other chemicals.

• The central vacuole of some plant The central vacuole of some plant cells may occupy 50-90% of the cell cells may occupy 50-90% of the cell volume. volume.

THANK YOU FOR THANK YOU FOR WATCHING MY PROJECTWATCHING MY PROJECT

By-A.Raghu Raman By-A.Raghu Raman

IX BIX B