The document summarizes key aspects of cell biology. It defines the cell as the basic structural and functional unit of life. It describes some of the major discoveries in cell theory and outlines the basic structures of plant and animal cells, including the cell membrane, cytoplasm, nucleus, mitochondria, chloroplasts, and other organelles. It also discusses cell size, types of cells (prokaryotic vs. eukaryotic), and methods of transport across the cell membrane.

1. SHIV JYOTI CONVENTSHIV JYOTI CONVENT
SCHOOLSCHOOL
HOME ASSIGNMENT
SCINCESCINCE
TO : Eesha Ma’am
By : Anshul Agrawal
ix - A
2013

2. Chapter – 5Chapter – 5
The Fundamental Unit ofThe Fundamental Unit of
LifeLife

3. Introduction :Introduction :
Cell is a Latin word for a little room.
Cell is the structural and functional unit of life .
“Cell Biology” is the study of cell in all respect of
structure and function .
Cell

4. Discovery of cell :Discovery of cell :
a.Robert Hooke - (1665) observed dead cell which
resembled honeycomb like structures in cork (comes from
bark tree) .He called these boxes cell .
b.Anton Von Leeuwenhoek – (1674)first to observe
living cell in pond water .
c.Robert Brown – (1831) discovered the nucleus .

5. Cell theory :Cell theory :
The “cell theory” was formulated by two German
biologists , M.J.Schleiden in 1838 , a botanist and
T.Schwann , a zoologist in 1839 .
According to them , the cell is the structural and
functional unit of all living beings . The cell theory
was further expanded by virchow .

6. Size of cell :Size of cell :
Normal size in human – 20um to 30um in diameter
Largest cell : In animals – Ostrich egg
In plants – Acetabularia
Longest cell : In animals – Nerve cell
In plants – Hemp fibre
Smallest cell : PPLO - Pleuro Pneumonia Like Organism

7. On the basis of numbers of cells , the cellsOn the basis of numbers of cells , the cells
are of three types :are of three types :
a.Unicellular – amoeba , bacteria
b.Multicellular - human beings , plants
c.Acellular - virus

8. Two types of cellTwo types of cell
ProkaryoticProkaryotic
a.a. No organized nucleusNo organized nucleus
b.b. No membrane boundNo membrane bound
organellesorganelles
c.c. Found in bacteria andFound in bacteria and
cyanobacteria .cyanobacteria .
EukaryoticEukaryotic
a.a. Organized nucleusOrganized nucleus
b.b. Membrane boundMembrane bound
organelles such asorganelles such as
Golgi apparatus andGolgi apparatus and
mitochondria .mitochondria .

9. Structure of cell :Structure of cell :
a.Cell membrane
b.Cytoplasm : Mitochondria
Chloroplast
Endoplasmic Reticulum
Golgi body
Lysosomes
Ribosomes
Vacuole
c.Nucleus

10. Cell membrane or plasma membrane :Cell membrane or plasma membrane :
a. Boundary that separates the living cell from it’s
non-living surroundings.
b. Outer membrane of cell that controls movement in
and out of the cell .
c. Double layer of phospholipids & proteins .
d. Protect cell .
e. Selectively permeable - allows some molecules in
and others are kept out .

11. Methods of Transport Across MembranesMethods of Transport Across Membranes
Diffusion : Movement of molecules from an area of
high concentration to an area of low
concentration
Osmosis : The diffusion of water across a selectively
permeable membrane.

12. Types of OsmosisTypes of Osmosis
Hypotonic SolutionHypotonic Solution - One solution has a lower
concentration of solute than another :- water moves in .
Hypertonic SolutionHypertonic Solution - one solution has a higher
concentra tion of solute than another :- Water moves out.
Isotonic SolutionIsotonic Solution - both solutions have same concentra-
-tion of solute :- water moves back .

13. a. Cell walls are present in plant cells and fungi .
b. They make the cell strong and rigid .
Cell WallCell Wall
c. Supports and protects cell .
d. Surrounds plasma membrane

14. a. Control center of cell
b. Double membrane
c. Contains
a. Chromosomes
b. Nucleolus
NucleusNucleus
a. Separates nucleus from
rest of cell
b. Double membrane
c. Has pores
Nuclear MembraneNuclear Membrane

15. a. Hereditary material
b. Chromosomes
a. DNA
b. Proteins
c. Chromatin
DNADNA
a. Most cells have 2 or more
b. Directs synthesis of RNA
c. Forms ribosomes
NucleolusNucleolus

16. a. Viscous fluid containing organelles
b. components of cytoplasm
a. Interconnected filaments & fibers
b. Fluid = cytosol
c. Organelles (not nucleus)
d. storage substances
CytoplasmCytoplasm

17. OrganellesOrganelles
a. Cellular machinery
b. Two general kinds
a. Derived from membranes
b. Bacteria-like organelles

18. a. Helps move substances within cells
b. Network of interconnected membranes
c. Two types :-
Endoplasmic ReticulumEndoplasmic Reticulum
Rough ER
a.Ribosomes attached to
surface
b.May modify proteins
from ribosomes
Smooth ER
a.No attached ribosome's
b.Has enzymes that help build
molecules
a. Carbohydrates
b. Lipids

19. a. Involved in synthesis of plant cell wall
b. Packaging & shipping station of cell
Golgi ApparatusGolgi Apparatus
Function
a. Molecules come in vesicles from ER
b. Vesicles fuse with Golgi membrane
c. Molecules may be modified by Golgi
d. Molecules pinched-off in separate vesicle
e. Vesicle leaves Golgi apparatus
f. Vesicles may combine with plasma membrane to secrete
contents

20. a. Lysosomes are vesicles produced by the Golgi apparatus.
b. Lysosomes contain hydrolytic enzymes and are involved in
intracellular digestion.
c. Digestion within the cell disposes of worn-out cell parts and is
necessary for cell rejuvenation.
d. Vacuoles (large) and vesicles (small) are membranous sacs in
the cell that store substances.
e. Vacuoles and vesicles can store a variety of substances for the
cell. Anything from water to plant pigments and toxic
substances are stored in these membranous sacs.
Lysosomes and VacuolesLysosomes and Vacuoles

21. a. Have their own DNA
b. Bound by double membrane
c. Also known as Powerhouse of the cell
a. Glucose
b. Fatty acids
d. Release energy
a. ATP
MitochondriaMitochondria

22. a. Chloroplasts are only in plant cells
b. They contain chlorophyll, which helps
make energy/food from sunlight
c. Chlorophyll is green in color.
PlastidsPlastids
Chloroplast :
Chromoplasts : a. Pigment synthesis and storage
b. Chromoplasts are red yellow and
orange in colour
c. Found in petals of flower and fruits
Leucoplast : a. Leucoplasts are colourless or white
plastid .
b. Synthesis of oil and proteins
c. Occur in plant cell not exposed to light .

23. Bibliography
http://www.cbc.umn.edu/~mwd/cell_www/chapter2/me
mbrane.html
http://http://microscopy.bio-microscopy.bio-
rad.com/moviesandimages/Neuroscience.htmrad.com/moviesandimages/Neuroscience.htm
http://micro.magnet.fsu.edu/cells/mitochondria/mitohttp://micro.magnet.fsu.edu/cells/mitochondria/mito
chondria.htmlchondria.html
http://cellbio.utmb.edu/cellbio/mitochondria_1.htm#ihttp://cellbio.utmb.edu/cellbio/mitochondria_1.htm#i
nner%20membranenner%20membrane