This document provides an overview of cell structure and organization. It begins by outlining the key learning outcomes, which include identifying various cell organelles and their functions, comparing plant and animal cells, and differentiating cells, tissues, organs and organ systems. It then provides details on the structures and functions of the cell membrane, cytoplasm, nucleus, mitochondria, ribosomes, vacuoles, chloroplasts, cell wall, and plant cell central vacuole. It also describes specialized plant cell organelles like the endoplasmic reticulum and Golgi apparatus. The document concludes by discussing cell specialization and how cells are organized into tissues, organs and organ systems to perform specific functions.

1. Chapter 2
CELL Structure and
organisation
1

2. Learning Outcomes
At the end of the lesson, you should be able
to:
 Identify chloroplasts, cell membrane, cell wall,
cytoplasm, cell vacuoles, nucleus, mitochondria,
ribosomes
 Identify endoplasmic reticulum and Golgi
apparatus (Pure)
 State the functions of the organelles identified above
 Compare the structure of typical animal and plant
cells

3. Learning Outcomes
 state, in simple terms, the relationship
between cell function and cell structure for
the following:
 absorption – root hair cells
 conduction and support – xylem vessels
 transport of oxygen – red blood cells
 Differentiate cell, tissue, organ and organ
system
3

4. What is a cell?
 Basic structural and functional unit of living
things
 Building block of life
 All living things are made up of one or more
cells
 How big is a cell?
http://www.cellsalive.com/howbig.htm
4

5. What are inside a cell?
 Each living cell consists of living material
called protoplasm
 Protoplasm is made up of cell membrane,
nucleus and cytoplasm.
 Protoplasm is jelly-like, containing mainly
water and many other substances
 Protoplasm in one part of the body may be
different from another part of the body
5

7. Cell Membrane
 Cell membrane (plasma membrane)
Structure Function
Thin, partially Control movement of substances
permeable in and out of the cell. Only allow
layer around some substances to pass
the cell through, small molecules such as
glucose, oxygen and water can
enter, but not others such as
waste substances.
7

8. Cytoplasm
Structure Function
Jelly-like Acts as a medium for most
substance made chemical activities of the cell to
up mainly of occur;
water (70% Contains enzymes and organelles.
water)
Organelles are subcellular structures
(structures smaller than cells) that
perform specific jobs inside the cell.
eg) mitochondria, ribosomes, chloroplasts,
vacuoles 8

9. Nucleus
Structure Function
Contains Controls cell activities, such as
chromatin / cell repair and growth;
chromosome
(genetic Controls cell division.
materials)
9

10. vacuole
Structure Function
A fluid-filled Store substances such as water
space enclosed and food temporarily.
by a membrane;
vacuoles
Exists
temporarily in
animal cells.
10

11. Mitochondria
Structure Function
Small, rod- Site where aerobic respiration
shaped takes place and energy is
organelles; released.
Highly folded
inner membrane
(singular: mitochondrion;
plural: mitochondria)
11

12. ribosomes
Structure Function
Small, round Site where protein synthesis takes
structures; place.
Can be
attached to ER
or found freely
in the
cytoplasm.
12

14. Analogy
Cell Structures: Chemical Factory:
1. Nucleus Main office
(Chromosomes that contain
genes)
2. Mitochondria Power Plant
3. Ribosomes Factory workers
4. Golgi Apparatus Packaging & Delivery
5. Lysosomes Recycling Centre

17. Endoplasmic reticulum (er)
(PURE)
 Two types:
 Rough ER
 Smooth ER
17

18. Rough ER (PURE)
Structure Function
Ribosomes are Rough ER helps to transport
attached to its proteins made by the ribosomes to
outer surface, the Golgi apparatus for secretion
hence its out of the cell.
surface appears
rough when
seen under the
microscope
18

19. Rough ER (Pure)
19

20. Smooth ER (PURE)
Structure Function
Smooth ER does not Synthesises substances
have ribosomes such as fats and steroids;
attached to its
membrane; Converts harmful
substances into harmless
Smooth ER is more substances – Detoxification
tubular than rough
ER. It is connected
to the rough ER.
20

21. Smooth ER (Pure)
21

22. Golgi apparatus (PURE)
Structure Function
The Golgi apparatus Stores and modifies
consists of flattened substances made by the
spaces surrounded by ER; and
membranes. packages these
substances in vesicles for
Vesicles (small spherical secretion out of the cell
spaces) fuse with one side
of the Golgi apparatus and
pinch off from the opposite
side.
22

23. Golgi Apparatus (Pure)
23

24. Question (Pure)
How are substances made by a cell
released out of the cell?
24

25. Overview (Pure)
 Vesicles are tiny spherical spaces enclosed
by a membrane.
 Vesicles containing substances made by the
ER are pinched off from the ER
 These vesicles then fuse with the Golgi
apparatus and release their contents into the
Golgi apparatus for modification
25

26.  Secretory vesicles containing these modified
substances are pinched off from the Golgi
apparatus and moves towards the cell
membrane
 They fuse with the cell membrane and
release their contents outside the cell
26

28. Plant Cell
28

29. mitochondrion
chloroplast
Golgi complex central vacuole
smooth endoplasmic
reticulum
vesicle
rough endoplasmic cell wall
reticulum
plasma
membrane
nucleolus
nucleus nuclear pore
chromatin
nuclear envelope
ribosomes free ribosome

30. Plant Cell
 Its structures are similar to an animal cell
except for the presence of:
 Cellulose cell wall
 Chloroplasts
 One large central vacuole
30

31. Cell wall
Structure Function
Made of cellulose The tough cellulose protects the
and surrounds the cell from injury and gives the cell a
entire plant cell, regular shape.
surrounding the cell The cell wall is fully permeable,
membrane. unlike the cell membrane.
Cellulose is a type
of carbohydrates
31

32. chloroplast
Structure Function
Has stacks of disc- Chlorophyll enables light energy to
like structures which be trapped and be converted into
contain the green chemical energy stored in food
substance called (glucose) during the process
chlorophyll. photosynthesis.
32

33. vacuole
Structure Function
A plant cell has one Cell sap contains water and
large central dissolved substances such as
vacuole containing sugars, mineral salts and amino
cell sap. acids.
The large vacuole is
enclosed by a
membrane called
the tonoplast.
33

34. Light micrograph of plant cells
Plant cells – from epidermis of onion leaf

35. Light micrograph of animal cells
http://iws.ccccd.edu/jbeck/Cellsweb/Cheekcells4.JPG
Animal cells – from lining epithelium of cheek

36. MicroQues 1 - Differences
structure Animal cell Plant cell
Cellulose cell Absent Present
wall
Chloroplasts Absent Present
Vacuoles Small, temporary Large, normally
and many one present
36

37. Micro Ques 2
The diagram shows four types of cells.
Which cell does not contain a nucleus?
( A, B )

38. Micro Ques 3
The diagram below shows a plant cell.
Which of the following is not a function of part T?
A to store food substances
B to secrete substances
C to store wastes
D to store water
( B )

39. Micro Ques 4
Which of the following statements describing the cell
membrane is incorrect?
A It is supported by lignin to give it a regular shape.
B It is a thin and elastic layer.
C It is a partially permeable membrane.
D It is mainly composed of fats and proteins.
( A )

40. Micro Ques 5
Which of the following is a correct description of the
permeability of the cell membrane and cell wall in a plant?
Cell wall Cell membrane
A fully fully
B fully partially
C partially fully
D partially partially
( B )

41. SPECIALISED CELLS,
TISSUES AND ORGANS

42. Cell Organisation
 Cell is the smallest working unit in a
multicellular organism.
42

43. Different cells do different
work
 Each cell type carries out its own particular
kind of work.
 Cells have different shapes and structures to
carry out different functions.
43

44. Specialised Cells

45. Tissue Formation
 A tissue is a group of similar cells which
work together to perform a specific function
Muscle Nerve
tissue tissue 45

46. Specialised Tissues
Tissues Main Function
Animal
Blood Tissue Transports food and oxygen
Muscle Tissue Produces Movement
Nerve Tissue Transmits impulses
Epithelial Tissue Protects Cell
Plant
Epidermal Tissue Forms and protects surface of cell
Xylem Tissue Transports water and mineral salts
Phloem Tissue Transports food

48. Organ Formation
 An organ is made up of different tissues
working together to perform a particular
function
48

49. Organ in animals
Made up of:
•Glandular tissue
•Muscle tissue
•Connective tissue
•Nervous tissue
Stomach Etc.
49

51. Organs in plants
 Plants also have
organs such as
leaves, stems,
roots and flower.
51

52. Micro Ques 6
 Can you name some examples?
 Eg) In Animals:
Respiratory system – Lungs
Circulatory system – Heart
Excretory system – Kidney
Digestive system – Intestines, Stomach
Reproductive System – Ovary, Testes
In Plants:
Reproductive System – flowers
Transport system – Stem (xylem and phloem),roots

53. System Formation
 An organ system is made up of different
organs working together to perform a main
body function
Respiratory system
digestive system 53

55. Multicellular organism –
Human Body Systems

56. Differentiation
 Differentiation is the process by which a cell
becomes specialised for a specific function
 3 examples:
 Red blood cell
 Xylem vessel
 Root hair cell
56

57. Red Blood Cells

58. Red Blood Cell
Function:
 Haemoglobin (red pigment) in cytoplasm
transports oxygen from the lungs to all parts
of the body.
 When haemoglobin combines
with oxygen, oxyhaemoglobin is
formed.
58

59. Red Blood Cell
Adaptations:
i. Absence of nucleus so as to contain more
haemoglobin and hence more oxygen
ii. Circular biconcave shape – increases surface area
to volume ratio for faster diffusion of gases in and
out of cell
iii. Elastic and can turn bell-shaped in order to allow the
cell to squeeze through small blood vessels
iv. Contain a red pigment, haemoglobin, to allow
oxygen to bind to the RBC to form oxyhaemoglobin.
59

60. Red Blood Cells

61. Xylem Vessels

62. Xylem Vessels

63. Xylem Vessel
Function
i. Transport water and mineral salts from roots
up the stem and to the leaves
ii. Provide mechanical support for the plant
when bundled together
63

64. Xylem Vessel
Adaptations
i. Absence of cross-walls and protoplasm
enable water to move easily through the
lumen (central space).
ii. Lignin deposited in the walls of xylem
vessels strengthens it and prevents the
vessel from collapsing.
iii. Narrow and hollow lumen allows water to
be moved easily up the stem.
64

65. Xylem vessels

66. Root Hair Cell
 Function
Absorb water via osmosis and mineral salts
from soil via diffusion.
66

67. Root Hair Cell
 Adaptations
1. long and narrow protrusion/ extension of an
epidermal cell to increase surface area to volume
ratio for more efficient absorption of water and
mineral salts from soil.
2. It has a very large vacuole that contains
concentrated cell sap solution, resulting in a
lower water potential thus allowing absorption
of water from the soil.
67

68. Root Hair Cell

69. Root hair cell
Vacuole
Nucleus
Root hair (long and narrow protrusion)

70. Micro Ques 7
The table shows the presence, absence of a nucleus in three
types of cells. Which of the following is correct?
Red blood cell Root hair cell Xylem Vessel
A Present Absent Absent
B Present Absent Present
C Absent Present Absent
D Absent Present Present
( C )

71. The End
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