fundamentalunitoflifeclassix-220731093151-24fe9dbf (1).pptx

THE FUNDAMENTAL UNIT OF
LIFE:CELL
CLASS IX

Cells
 Smallest living unit
 Most are microscopic

Discovery of Cells
 Robert Hooke (1665)
🞑 Observed sliver of cork
🞑 Saw “row of empty boxes”
🞑 Coined the term cell

Cell theory
 (1839)Theodor Schwann & Matthias Schleiden
“ all living things are made of cells”
 (1855) Rudolf Virchow
“Omnis cellula e cellula ” all cells arise from pre-
existing cells

Principles of Cell Theory
 All living things are made of cells
 Smallest living unit of structure and
function of all organisms is the cell
All cells arise from preexisting cells
(this principle discarded the idea of
spontaneous generation)

Cells Have Large Surface
Area-to-Volume Ratio

Characteristics of All Cells
 A surrounding membrane
 Protoplasm – cell contents in thick fluid
 Organelles – structures for cell function
 Control center with DNA

Cell Types
 Prokaryotic
 Eukaryotic

Prokaryotic Cells
 First cell type on earth
 Cell type of Bacteria and Archaea

Prokaryotic Cells
 No membrane bound nucleus
 Nucleoid = region of DNA concentration
 Organelles not bound by membranes

Eukaryotic Cells
 Nucleus bound by membrane
 Include fungi, protists, plant, and
animal cells
 Possess many organelles
Protozoan

THE UNIVERSE INSIDE OUR
CELLS
 Zoom into your own body to see the
different cells that make up your
heart, brain and bones.
 These trillions building block of cells
are communicating with each other
every moment of our lives.
 As the house is made by BRICKS.

CELL ORGANELLES
 The cellular components are called the Cell
Organelles.
 These cell organelles are membrane-bound,
present within the cells and are distinct in their
structures and functions.
 They coordinate with their functions efficiently
for the normal functioning of the cell.
 There are various organelles present within
the cell and are classified into three categories
based on the presence or absence of
membrane.

TYPES OF CELL
ORGANELLES
 Organelles without membrane: The Cell wall,
Ribosomes, Centrosome and Cytoskeleton are
without membrane-bound cell organelles.
 Single membrane-bound organelles: Vacuole,
Lysosome, Golgi Apparatus, Endoplasmic
Reticulum are single membrane-bound organelles
present only in a eukaryotic cell.
 Double membrane-bound
organelles: Mitochondria and chloroplast are
double membrane-bound organelles present only
in a eukaryotic cell.

Movement Across the Plasma Membrane
 A few molecules move freely
🞑 Water, Carbon dioxide, Ammonia, Oxygen
 Carrier proteins transport some molecules
🞑 Proteins embedded in lipid bilayer
🞑 Fluid mosaic model – describes fluid nature of a
lipid bilayer with proteins

Membrane Proteins
1. Channels or transporters
🞑 Move molecules in one direction
2. Receptors
🞑 Recognize certain chemicals

Membrane Proteins
3. Glycoproteins
🞑 Identify cell type
4. Enzymes
🞑 Catalyze production of substances

CELL MEMBRANE FUNCTION
 Passive Transport
 Active Transport
 Endocytosis
(phagocytosis & pinocytosis)
 Exocytosis

Passive Transport
 No energy required
 Move due to gradient
🞑 differences in concentration, pressure, charge
 Move to equalize gradient
🞑 High moves toward low

Types of Passive Transport
1. Diffusion
2. Osmosis
3. Facilitated diffusion

Diffusion
 Molecules move to equalize concentration

Osmosis
 Special form of diffusion
 Fluid flows from lower solute concentration
 Often involves movement of water
🞑 Into cell
🞑 Out of cell

Solution Differences & Cells
 solvent + solute = solution
 Hypotonic
🞑 Solutes in cell more than outside
🞑 Outside solvent will flow into cell And
cell will swell
 Isotonic
🞑 Solutes equal inside & out of cell no
transport
 Hypertonic
🞑 Solutes greater outside cell
🞑 Fluid will flow out and shrink

Facilitated Diffusion
 Differentially permeable membrane
 Channels (are specific) help molecule or
ions enter or leave the cell
 Channels usually are transport proteins
(aquaporins facilitate the movement of
water)
 No energy is used

Process of Facilitated Transport
 Protein binds with molecule
 Shape of protein changes
 Molecule moves across membrane

Active Transport
 Molecular movement
 Requires energy (against gradient)
 Example is sodium-potassium pump

Endocytosis
 Movement of large material
🞑 Particles
🞑 Organisms
🞑 Large molecules
 Movement is into cells
 Types of endocytosis
🞑 bulk-phase (nonspecific)
🞑 receptor-mediated (specific)

Process of Endocytosis
 Plasma membrane surrounds material
 Edges of membrane meet
 Membranes fuse to form vesicle

Forms of Endocytosis
 Phagocytosis – cell eating
 Pinocytosis – cell drinking

Exocytosis
 Reverse of endocytosis
 Cell discharges material

Exocytosis
 Vesicle moves to cell surface
 Membrane of vesicle fuses
 Materials expelled

Cell Walls
 Found in plants, fungi, & many protists
 Surrounds plasma membrane

Cell Wall Differences
 Plants – mostly cellulose
 Fungi – contain chitin
 Bactria- Peptidoglycon or Murin

Cytoplasm
 Viscous fluid containing organelles
 components of cytoplasm
🞑 Interconnected filaments & fibers
🞑 Fluid = cytosol
🞑 Organelles (not nucleus)
🞑 storage substances

Centrioles
 Pairs of microtubular structures
 Play a role in cell division

DNA
 Hereditary material
 Chromosomes
🞑 DNA
🞑 Protiens
🞑 Form for cell division
 Chromatin

Nucleolus
 Most cells have 2 or more
 Directs synthesis of RNA
 Forms ribosomes

Endoplasmic Reticulum
 Helps move substances within cells
 Network of interconnected membranes
 Two types
🞑 Rough endoplasmic reticulum
🞑 Smooth endoplasmic reticulum

Rough Endoplasmic Reticulum
 Ribosomes attached to surface
🞑 Manufacture protiens
🞑 Not all ribosomes attached to rough ER
 May modify proteins from ribosomes

Smooth Endoplasmic Reticulum
 No attached ribosome
 Has enzymes that help build molecules
🞑 Carbohydrates
🞑 Lipids

Golgi Apparatus
 Involved in synthesis of plant cell wall
 Packaging & shipping station of cell

Golgi Apparatus Function
1. Molecules come in vesicles
2. Vesicles fuse with Golgi membrane
3. Molecules may be modified by Golgi

Golgi Apparatus Function
(Continued)
4. Molecules pinched-off in separate vesicle
5. Vesicle leaves Golgi apparatus
6.Vesicles may combine with plasma membrane
to secrete contents

Lysosomes
 Contain digestive enzymes
 Functions
🞑 Aid in cell renewal
🞑 Break down old cell parts
🞑 Digests invaders

CELL ORGANELLES DISCOVERY
1 NUCLEUS 1 ROBERT BROWN(1831)
2 GOLGI BODY 2 CAMEILLIO GOLGI
3 PLASMA MEMBRANE 3 SCHWANN(1838)
4 CYTOPLASM 4 STRASBURGER(1882)
5 ENDOPLASMIC RETICULUM 5 PORTER(1943)AND NAMED
IN(1953)
6 MITOCHONDRIA 6 ALTAMAN(1894)AND
NAMED BY BENDA(1897)
7 LYSOSOME 7 de DUVE(1955)
8 VACUOLES 8 SPALLANZONI
9 RIBOSOMES 9 ROBINSON AND BROWN
(1953) IN PLANT CELL AND
PALADE(1955) IN ANIMAL
CELL
10 MICROBODIES 10 RHODIN(1954)
(a)PEROXIXOMES (a)de DUVE(1965)
(b)GLYOXYSOME (b)BRIEDENBACH(1967)

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