Class 9 chapter 1 fundamental unit of life

2. CONCEPT MAP

3. ROBERT HOOKE
•HE FIRST DISCOVERED THE CELL IN THE YEAR 1665.
•HE MADE HIS OWN MICROSCOPE.
•HE OBSERVED A THIN SLICE OF CORK UNDER THE MICROSCOPE.
•THE STRUCTURE UNDER THE MICROSCOPE RESEMBLED THE
STRUCTURE OF A HONEY COMB
•HE CALLED THESE COMPARTMENTS AS ‘CELL’.

4. MICROSCOPE OF ROBERT HOOKE

5. OBSERVATION OF ROBERT HOOKE

7. ACTIVITY – 5.1 - HTTPS://YOUTU.BE/WMGXSRPVRJG (ONION PEEL)

8. CONTRIBUTION OF SCIENTIST IN THE DISCOVERY OF THE
CELL
S.N
O
SCIENTIST Contribution YEAR
1. Robert Hooke Cell (dead) 1665
2. Leeuwenhoek Free – living cell 1674
3. Robert brown Nucleus 1831
4. Purkinje Coined the term ‘Protoplasm’ 1839
5. Schwann (1839)
Schleiden
(1838)
Virchow (1855)
Cell theory

9. CELL THEORY
• POSTULATES OF CELL THEORY
• CELL IS THE FUNDAMENTAL UNIT OF LIFE.
• ALL LIVING ORGANISMS ARE COMPOSED OF CELLS.
• ALL NEW CELLS COME FROM PRE-EXISTING CELLS. THIS POSTULATE WAS
GIVEN BY VIRCHOW

10. • ACTIVITY – 5.5 -FIND OUT ABOUT ELECTRON MICROSCOPE AND THE STUDENTS WILL MAKE A CHART ON
IT AND UPLOAD IT

11. TYPES OF ORGANISMS ON THE BASIS OF NUMBER OF CELLS
• (I) UNICELLULAR ORGANISMS:
• (II) MULTICELLULAR ORGANISMS:
•

12. (I) UNICELLULAR ORGANISMS:
• ORGANISMS THAT ARE MADE UP OF
SINGLE CELL AND CONSTITUTE A
WHOLE ORGANISM, FOR EXAMPLE:
AMOEBA, PARAMECIUM, BACTERIA,
ETC.

13. MULTICELLULAR
ORGANISMS:
THE ORGANISMS WHICH ARE
COMPOSED OF A COLLECTION
OF CELLS, WITH DIFFERENT
CELLS SPECIALIZED TO
PERFORM PARTICULAR TASKS
IN THE BODY.
FOR EXAMPLE: PLANTS,
HUMAN BEINGS, ANIMALS, ETC.

14. ACTIVITY 5.2
• PREPARATION OF TEMPORARY MOUNTS OF LEAF PEELS/ STOMATA
• HTTPS://WWW.YOUTUBE.COM/WATCH?V=RUZJF178I_U
• PREPARATION OF TEMPORARY MOUNTS OF TIP OF ROOTS OF ONION
• HTTPS://WWW.YOUTUBE.COM/WATCH?V=QAMC0P_VYKG

15. SHAPES AND SIZE OF THE DIFFERENT CELLS
• CELLS VARY IN SHAPE AND SIZE.
• THEY MAY BE OVAL, SPHERICAL, RECTANGULAR,
SPINDLE SHAPED, OR TOTALLY IRREGULAR LIKE
THE NERVE CELL.
• THE SIZE OF CELL ALSO VARIES IN DIFFERENT
ANIMALS AND PLANTS.
• MOST OF THE CELLS ARE MICROSCOPIC IN SIZE
LIKE RED BLOOD CELLS (RBC) WHILE SOME CELLS
ARE FAIRLY LARGE LIKE NERVE CELLS.
• AVERAGE SIZE OF CELLS VARIES FROM 0.5 TO 20
ΜICRON.

16. STRUCTURE OF CELL

17. CELL MEMBRANE/PLASMA MEMBRANE
• PLASMA MEMBRANE IS THE COVERING OF THE CELL THAT SEPARATES THE
CONTENTS OF THE CELL FROM ITS EXTERNAL ENVIRONMENT.
• IT IS A LIVING PART OF THE CELL.
• IT IS VERY THIN, DELICATE, ELASTIC, FLEXIBLE AND SELECTIVELY PERMEABLE
MEMBRANE. THE PLASMA MEMBRANE ALLOWS OR PERMITS THE ENTRY AND EXIT
OF SOME MATERIALS IN AND OUT OF THE CELL SO THE CELL MEMBRANE IS CALLED
A SELECTIVELY PERMEABLE MEMBRANE.
• PLASMA MEMBRANE IS COMPOSED OF LIPID AND PROTEIN.
• SOME SUBSTANCES LIKE CO2 OR O2 GASES CAN MOVE ACROSS THE CELL
MEMBRANE BY A PROCESS CALLED DIFFUSION.
• DIFFUSION OF WATER MOLECULES (LIQUID) THROUGH SUCH A SELECTIVELY
PERMEABLE MEMBRANE IS CALLED OSMOSIS.

18. DIFFUSION – IS THE
MOVEMENT OF A
SUBSTANCE FROM AN
AREA OF HIGH
CONCENTRATION TO AN
AREA OF LOW
CONCENTRATION.

19. • OSMOSIS- OSMOSIS IS THE
SPONTANEOUS NET MOVEMENT OF
SOLVENT MOLECULES THROUGH A
SELECTIVELY PERMEABLE
MEMBRANE INTO A REGION OF
HIGHER SOLUTE CONCENTRATION.

21. TYPES OF SOLUTION
HYPOTONIC SOLUTION- IF THE MEDIUM SURROUNDING THE CELL HAS A HIGHER
WATER CONCENTRATION THAN THE CELL. SUCH A SOLUTION IS KNOWN AS
HYPOTONIC SOLUTION.
 THE CELL WILL GAIN WATER BY OSMOSIS.
THIS PROCESS IS CALLED ENDOSMOSIS.
THE CELL WILL SWELL AND IS SAID TO BE TURGID.
AN ANIMAL CELL CAN BURST IF MORE WATER ENTER.
A PLANT IS PROTECTED BY RIGID CELL WALL.

22. Isotonic solution-If the medium has exactly the same water
concentration as the cell, there will be no net movement of water across
the cell membrane.
Such a solution is known as isotonic solution.
 There is no change in the shape of cell as number of water molecules
moving in and out are same.

23. Hypertonic solution.
 If the medium has a lower water
concentration then the cell will lose
water by osmosis.
 Such a solution is known as hypertonic
solution.
 The net movement of water is out of
the cell by osmosis. This process is
known as exosmosis.
 The cell shrinks.
 In plant cell, this phenomenon of
shrinkage of cell is known as
plasmolysis.

24. ACTIVITY 5.3- OSMOSIS WITH AN EGG

25. ACTIVITY 5.4
• ACTIVITY-
• TO BE DONE BY THE STUDENTS AT HOME (RAISIN ACTIVITY)

26. ACTIVITY – 5.6- PLASMOLYSIS IN FRESH RHEO LEAF

27. ENDOCYTOSIS (FUNCTION OF P.M.)

28. CELL WALL
• CELL WALL IS NON-LIVING, THICK AND FREELY PERMEABLE COVERING MADE UP OF
CELLULOSE.
• IT IS PRESENT IN EUKARYOTIC PLANT CELLS AND IN PROKARYOTIC CELLS.
• FUNCTIONS:
• IT DETERMINES THE SHAPE AND RIGIDITY TO THE PLANT CELL.
• IT PROTECTS THE PLASMA MEMBRANE.
• IT PREVENTS DESICCATION OR DRYNESS IN CELL.
• IT HELPS IN THE TRANSPORT OF VARIOUS SUBSTANCES IN AND OUT OF THE CELL.
• BECAUSE OF THE CELL WALL, THE PLANT CELL CAN WITHSTAND GREATER
CHANGES IN THE SURROUNDING MEDIUM THAN AN ANIMAL CELL.

29. NUCLEUS
• NUCLEUS IS DENSE AND SPHERICAL ORGANELLE.
• NUCLEUS IS BOUNDED BY TWO MEMBRANES.
• NUCLEAR ENVELOPE CONTAINS MANY PORES KNOWN AS NUCLEAR PORES.
• THE FLUID WHICH PRESENT INSIDE THE NUCLEUS IS CALLED
NUCLEOPLASM.
• NUCLEUS CONTAINS CHROMOSOMES AND CHROMOSOMES CONTAIN
GENES WHICH ARE THE CENTER OF GENETIC INFORMATION.
• GENE IS THE HEREDITARY UNIT OF LIFE . IT IS MADE UP OF DNA (DEOXY
RIBONUCLEIC ACID)

31. FUNCTION OF NUCLEUS
• NUCLEUS CONTROLS ALL THE METABOLIC ACTIVITIES OF THE CELL.
• IT REGULATES THE CELL CYCLE.
• NUCLEUS IS THE STOREHOUSE OF GENES. IT IS CONCERNED WITH THE
TRANSMISSION OF HEREDITARY TRAITS FROM THE PARENT TO OFFSPRING.

32. NUCLEOID
• IN SOME ORGANISMS LIKE BACTERIA,
THE NUCLEAR MATERIAL IS NOT
ENCLOSED BY NUCLEAR MEMBRANE
SUCH NUCLEUS IS CALLED NUCLEOID.
• SUCH CELLS ARE KNOWN AS
PROKARYOTIC CELL.
• SUCH CELLS HAVE SINGLE
CHROMOSOME.
• MEMBRANE BOUND CELL ORGANELLE
ARE ABSENT ARE ABSENT IN THEM.

33. CYTOPLASM
• IT IS A JELLY-LIKE, VISCOUS, COLOURLESS SEMI-FLUID SUBSTANCE THAT
OCCURS BETWEEN THE PLASMA MEMBRANE AND THE NUCLEAR MEMBRANE.
• CONTAINS A VARIETY OF CELL ORGANELLES AND OTHER INSOLUBLE WASTE
PRODUCTS AND STORAGE PRODUCTS, LIKE STARCH, GLYCOGEN, LIPID, ETC.
• PROTOPLASM = CYTOPLASM+ NUCLEUS
• FUNCTIONS:
• PROTOPLASM ACTS AS A STORE OF VITAL CHEMICALS LIKE AMINO ACIDS,
PROTEINS, SUGARS, VITAMINS, ETC.
• IT IS THE SITE OF CERTAIN METABOLIC REACTIONS,

34. EUKARYOTIC CELLS
• CELLS HAVING WELL DEFINED NUCLEUS AND HAVING MEMBRANE BOUND CELL
ORGANELLE IS TERMED AS EUKARYOTIC CELL.
• SUCH CELLS HAVE MORE THAN ONE CHROMOSOMES.
• THE DIFFERENT COMPONENTS OF CELL PERFORM DIFFERENT FUNCTION AND
THESE COMPONENTS ARE CALLED CELL ORGANELLES.

35. DIFFERENCE BETWEEN PROKARYOTIC AND EUKARYOTIC
CELLS

36. ACTIVE LEARNING
• AL ACTIVITY- LARGE GROUP DISCUSSION- BREAKOUT ROOMS. THE STUDENTS WILL BE
DIVIDED INTO GROUPS AND TOPIC IS GIVEN TO EACH GROUP. TIME FOR DISCUSSION IS
GIVEN TO THE STUDENTS. A MEMBER FROM EACH GROUP WILL EXPLAIN THE GIVEN TOPIC.
• ER, GOLGI BODY,
• MITOCHONDRIA ,
• PLASTIDS
• VACUOLES,
• RIBOSOMES, LYSOSOMES

37. ENDOPLASMIC RETICULUM
• IT IS A MEMBRANOUS NETWORK OF TUBE LIKE STRUCTURES
EXTENDING FROM NUCLEAR MEMBRANE TO PLASMA MEMBRANE.
• IT IS ABSENT IN PROKARYOTIC CELLS AND MATURED RBCS OF
MAMMALS.
• THERE ARE TWO TYPES OF ENDOPLASMIC RETICULUM:
1. ROUGH ENDOPLASMIC RETICULUM (RER): HERE RIBOSOMES ARE
PRESENT ON THE SURFACE FOR THE SYNTHESIS OF PROTEINS.
2. SMOOTH ENDOPLASMIC RETICULUM (SER): HERE RIBOSOMES ARE
ABSENT AND IS MEANT FOR SECRETING LIPIDS.

38. • FUNCTIONS:
• THE ONE FUNCTION OF ER IS TO SERVE AS CHANNELS FOR THE TRANSPORT
OF MATERIALS BETWEEN VARIOUS REGIONS OF THE CYTOPLASM OR
BETWEEN THE CYTOPLASM AND THE NUCLEUS.
• THE ER ALSO FUNCTIONS AS A CYTOPLASMIC FRAMEWORK PROVIDING A
SURFACE FOR SOME OF THE BIOCHEMICAL ACTIVITIES OF THE CELL.
• RER HELPS IN SYNTHESIS AND TRANSPORTATION OF PROTEINS.

39. • SER HELPS IN THE MANUFACTURE OF FAT MOLECULES, OR LIPIDS, IMPORTANT
FOR CELL FUNCTION.
• SOME OF THESE PROTEINS AND LIPIDS HELP IN BUILDING THE CELL
MEMBRANE. THIS PROCESS IS KNOWN AS MEMBRANE BIOGENESIS.
• SOME OTHER PROTEINS AND LIPIDS FUNCTION AS ENZYMES AND HORMONES.
• IN THE LIVER CELLS OF VERTEBRATES, IT PLAY A ROLE OF DETOXICATION OF
POISONS AND DRUGS.

41. GOLGI APPARATUS
• FIRST DESCRIBED BY CAMILLO GOLGI,
• GOLGI APPARATUS CONSISTS OF A SET OF MEMBRANE BOUND, FLUID FILLED
VESICLES AND FLATTENED CISTERNAE (CLOSED SACKS).
• CISTERNAE ARE USUALLY ARRANGED PARALLEL TO EACH OTHER.
• FUNCTIONS:
• IT IS ALSO INVOLVED IN THE SYNTHESIS OF LYSOSOMES.
• IN SOME CASES COMPLEX SUGAR MAY BE MADE FROM SIMPLE SUGAR IN THE
GOLGI APPARATUS
• IT'S FUNCTION INCLUDE THE STORAGE, MODIFICATION AND PACKAGES OF
PRODUCTS IN VESICLES IN AND OUT OF THE CELL.

43. LYSOSOMES
• LYSOSOMES ARE SMALL, SPHERICAL, SAC LIKE STRUCTURES WHICH CONTAIN
SEVERAL DIGESTIVE ENZYMES ENCLOSED IN A MEMBRANE.
• THEY ARE FOUND IN EUKARYOTIC CELLS MOSTLY IN ANIMALS.
• FUNCTIONS:
• LYSOSOMES HELP IN DIGESTION OF FOREIGN SUBSTANCES AND WORN-OUT CELL
ORGANELLES.SO CALLED WASTE DISPOSABLE OF THE CELL
• THEY PROVIDE PROTECTION AGAINST BACTERIA AND VIRUS.
• THEY HELP TO KEEP THE CELL CLEAN.
• DURING THE DISTURBANCE IN CELLULAR METABOLISM, FOR EXAMPLE WHEN THE
CELL GETS DAMAGED, LYSOSOMES MAY BURST AND THE ENZYMES DIGEST THEIR
OWN CELL. THEREFORE, LYSOSOMES ARE ALSO KNOWN AS SUICIDE BAGS OF A
CELL

45. MITOCHONDRIA
• THEY ARE SMALL ROD-SHAPED
ORGANELLES.
• IT IS A DOUBLE MEMBRANE
STRUCTURE WITH OUTER
MEMBRANE BEING SMOOTH AND
POROUS WHEREAS INNER
MEMBRANE BEING THROWN INTO A
NUMBER OF FOLDS CALLED
CRISTAE.
• THEY CONTAIN THEIR OWN DNA AND
RIBOSOMES.
• THEY ARE ABSENT IN PROKARYOTIC
CELLS

46. FUNCTION OF MITOCHONDRIA
• THEY ARE THE SITES OF CELLULAR RESPIRATION, HENCE PROVIDE ENERGY
FOR THE VITAL ACTIVITIES OF LIVING CELLS.
• THEY STORE ENERGY RELEASES DURING REACTIONS, IN THE FORM OF ATP
(ENERGY CURRENCY OF THE CELL). THEREFORE, THEY ARE ALSO CALLED
‘POWER HOUSE’ OF THE CELL.
• ATP – ADENOSINE TRIPHOSPHATE
• IT HAS ITS OWN RIBOSOMES AND DNA. THEREFORE, THEY CAN MAKE SOME OF
THEIR OWN PROTEIN SO THEY ARE KNOWN AS SEMI- AUTONOMOUS CELL
ORGANELLE.

47. PLASTIDS
• PLASTIDS ARE PRESENT IN MOST OF THE PLANT CELLS AND ABSENT IN ANIMAL
CELLS.
• THEY ARE USUALLY SPHERICAL OR DISCOIDAL IN SHAPED AND DOUBLE
MEMBRANE BOUND ORGANELLES
• THEY ALSO HAVE THEIR OWN DNA AND RIBOSOMES
• PLASTIDS ARE OF THREE TYPES:
• (A) CHLOROPLASTS: THESE ARE THE GREEN COLOURED PLASTIDS
CONTAINING CHLOROPHYLL. CHLOROPLASTS AID IN THE MANUFACTURE FOOD
BY THE PROCESS OF PHOTOSYNTHESIS.
(B) CHROMOPLASTS: THESE ARE THE COLOURFUL PLASTIDS (EXCEPT GREEN
COLOUR).YELLOW , RED AND ORANGE
(C) LEUCOPLASTS: THESE ARE THE COLOURLESS PLASTIDS.

48. STRUCTURE OF PLASTID

49. FUNCTION OF PLASTIDS
• CHLOROPLASTS TRAP SOLAR ENERGY AND UTILIZE IT TO MANUFACTURE
FOOD FOR THE PLANT.
• CHROMOPLASTS IMPART VARIOUS COLOURS TO FLOWERS TO ATTRACT
INSECTS FOR POLLINATION.
• LEUCOPLASTS HELP IN THE STORAGE OF FOOD IN THE FORM OF STARCH,
PROTEINS AND FATS.

50. VACUOLE
• VACUOLES ARE LIQUID/SOLID FILLED
AND MEMBRANE BOUND ORGANELLES.
• IN PLANT CELLS, VACUOLES ARE
LARGE AND PERMANENT. IN ANIMAL
CELLS, VACUOLES ARE SMALL IN SIZE
AND TEMPORARY.
• IN MATURE PLANT CELL, IT OCCUPIES
90% SPACE OF CELL VOLUME.
• DUE TO ITS SIZE, OTHER ORGANELLES,
INCLUDING NUCLEUS SHIFT TOWARDS
PLASMA MEMBRANE.

51. FUNCTION OF VACUOLES
• THEY HELP TO MAINTAIN THE OSMOTIC PRESSURE IN A CELL.
• VACUOLES STORE SUBSTANCES IMPORTANT FOR THE LIFE LIKE AMINO ACIDS,
SUGARS, ORGANIC ACIDS AND SOME PROTEINS.
• THEY PROVIDE TURGIDITY AND RIGIDITY TO THE PLANT CELL.
• IN AMOEBA, THE FOOD VACUOLE CONTAIN THE FOOD ITEMS THAT IS
CONSUMED BY IT
• CONTRACTILE VACUOLES EXPELS EXCESS WATER AND SOME WASTES FROM
THE CELL.

52. DIFFERENCE BETWEEN ANIMAL CELL AND PLANT CELL
S.
No.
Animal cell Plant cell
1.
Animal cells are
generally small in size.
Plant cells are larger than
animal cells.
2.
Cell wall is absent. Plasma membrane of plant
cell is surrounded by a rigid
cell wall of cellulose.
3
Plastids are absent
except in case of
protozoan Euglena.
Plastids are present.
4.
Here vacuoles are many,
small and temporary.
They have a permanent and
large central sap vacuole.
5.
They have centrosome
and centrioles.
They lack centrosome and
centrioles.

53. STRUCTURE OF ANIMAL CELL

54. CELL DIVISION
• CELL DIVISION IS THE PROCESS BY WHICH A PARENT CELL DIVIDES INTO TWO
OR MORE DAUGHTER CELLS.
IMPORTANCE OF CELLDIVISION
• REGULATES CELL GROWTH, DEVELOPMENT, AND REPAIR IN MULTICELLULAR
ORGANISMS.
• IT HELPS IN PRODUCING GAMETES IN MULTICELLULAR ORGANISMS.
• IN CASE OF UNICELLULAR ORGANISM LIKE AMOEBA CELL DIVISION IS
NECESSARY FOR REPRODUCTION.

55. TYPES OF CELL DIVISION
• 1. MITOSIS
• 2. MEIOSIS

56. MITOSIS
• IT TAKES PLACE IN SOMATIC
CELL (BODY CELL).
• IN THIS DIVISION TWO
IDENTICAL CELLS ARE
PRODUCED.
• ALTHOUGH CELL IS DIVIDED
BUT NUMBER OF
CHROMOSOMES REMAINS THE
SAME

57. MEIOSIS
• IT TAKES PLACE IN GAMETES
• IN THIS DIVISION FOUR
DAUGHTER CELLS ARE
PRODUCED.
• ALTHOUGH CELL IS DIVIDED BUT
NUMBER OF CHROMOSOMES
BECOMES HALF.