2.1 Cell structure and specialized cells

1. 2. ORGANISATION OF THE
ORGANISM
2.1 Cell structure

2. LEARNING OBJECTIVES
2.1.1 Describe and compare the structure of a plant cell with
an animal cell, limited to cell wall, cell membrane, nucleus,
cytoplasm, chloroplasts, ribosomes, mitochondria and vacuoles.
2.1.2 Describe the structure of a bacterial cell, limited to cell
wall, cell membrane, cytoplasm, ribosomes, circular DNA,
plasmids.
2.1.3 Identify the cell structures listed in 2.1.1 and 2.1.2 in
diagrams and images of plant, animal and bacterial cells.
2.1.4 Describe the functions of the structures listed in 2.1.1
and 2.1.2 in plant, animal and bacterial cells.
2.1.5 State that new cells are produced by division of existing
cells.

3. Cell?
The structural,
functional and
biological unit of
all the organisms

4. Which device is used to
see the cells?

5. ? The cell was discovered by Robert Hooke in 1665

6. All cells have several basic features.
⚫ They are all bounded by a thin cell membrane.
⚫ Inside all cells is a thick, jelly-like fluid called
the cytoplasm, in which cellular components are
suspended.
⚫ All cells have one or more chromosomes carrying
genes made of DNA (genetic material)
⚫ All cells have ribosomes, tiny structures that build
proteins according to the instructions from the genes.
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2017
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Education,
Ltd.

7. THE TWO MAJOR CATEGORİES OF CELLS
The countless cells on Earth fall into two basic
categories.
Prokaryotic cells include
Bacteria
Archae
Eukaryotic cells include
1. protists
2. plants
3. fungi and
4. animals.
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2017
Pearson
Education,
Ltd.

8. CATEGORIES OF CELLS
Prokaryotic Cells Eukaryotic Cells
• Smaller
• Simpler
• Lack membrane-bound organelles
• Found in bacteria and archaea
• Larger
• More complex
• Have membrane-bound organelles
• Found in protists, plants, fungi, animals
FİGURE 4.UN11
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2017
Pearson
Education,
Ltd.
■ Prokaryotic cells are older than eukaryotic cells.
❑ Prokaryotes appeared about 3.5 billion years ago.
❑ Eukaryotes appeared about 2.1 billion years ago.
■ Prokaryotic cells are
❑ usually smaller than eukaryotic cells and
❑ simpler in structure.
The Two Major Categories of Cells

10. Basic Structural Design of a Prokaryotic Cell

11. Plant
Cell
Cell wall Golgi
Apparatus
Chloroplast
Mitochondrion
Cell Membrane
Central (Sap) Vacuole
Rough
Endoplasmic
Reticulum(RER)
Smooth
Endoplasmic
Reticulum (SER) Cytoplasm
Nucleus

12. Animal
Cell
Golgi Apparatus
Mitochondrion
Nucleolus
Nucleus
Microtubules
Ribosome
Centrioles x2
(Centrosome)
Cell Membrane
SER
RER
Lysosome
Cytoplasm

13. THE CELL MEMBRANE

14. OVERVIEW
? Cell membrane separates living cell from
nonliving surroundings
⚫ thin barrier = 8nm thick
? Controls movement of molecules in & out of
the cell
⚫ partially permeable
⚫ allows some substances to cross more easily
than others
? Made of phospholipids, proteins & other
macromolecules

15. RİBOSOMES
■ Ribosomes are very small organelles. (20 nm in diameter) They have
two subunits
■ They are composed of 65% of rRNA and 35% of proteins. (nucleoprotein
structure)
■ Because they are not membraneous structures, all prokaryotic and
eukaryotic cells include ribosome organelle
■ They synthesize proteins (and enzymes) from amino acids
■ Some ribosomes are "free" and some are attached to membranes (ER)

16. Free Ribosome:
⮚All cells have
ribosome,
⮚Synthesizes
proteins that
used in the cell

17. Cytoplasm:
⮚Supports and
protects cell
organelles,
⮚Aqueous
environment allow
chemical reaction
to occur

18. Cell Wall (plant)
⮚Outside of the cell
membrane,
⮚Made up of
cellulose,
⮚Fully permeable,
⮚Hold the plant cell
in shape and
prevent bursting

19. THE NUCLEUS
? Within the nucleus, long DNA molecules and
associated proteins form fibers called
chromatin.
? Each long chromatin fiber constitutes one
chromosome.
? The nucleolus is
⚫ a prominent structure within the nucleus and
⚫ the site where the components of ribosomes are
made.
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2017
Pearson
Education,
Ltd.

20. Chromatin fiber
Nuclear
envelope
Nuclear
pore
TEM
Surface of nuclear envelope Nuclear pores
TEM
Nucleolus
FİGURE 4.6
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2017
Pearson
Education,
Ltd.

21. Endoplasmic
Reticulum;
⮚Transport materials
through the cell,
⮚RER have ribosomes,
so that produce proteins
so as to transport them
out of the cell,
⮚SER have no ribosome,
produce lipids, steroids,
etc.

23. GOLGI BODY (GOLGI APPARATUS)
■ It is the package and
secretion unit in the cell
■ Golgi apparatus consists
of flattened sacs but the
sacs are not
interconnected like ER
sacs.
■ It receives and modifies
substances (proteins)
produced by the ER
■ It is involved in transport
of lipids in the cell
■ It synthesizes lysosome
organelle

24. Mitochondrion:
⮚Have double membrane,
its own DNA, RNA and
ribosome,
⮚Inner membrane have
many folding (cristae),
cytoplasm is called
matrix,
⮚Site of aerobic
respiration (break down
of sugar molecules to
relese energy)
Which cells contain more
mitochondria ? Why?

25. Chloroplast (only in plant cell)
⮚Contains green pigment,
chlorophyll,
⮚Have own DNA, RNA and
ribosome
⮚Double membrane with inner
membrane modified to sacs
(thylakoid),
⮚Jelly structure inside (stroma),
⮚Uses energy from sun to make
food (glucose) for the plant,
⮚Process called photosynthesis,
⮚Release oxygen

26. Vacuole:
⮚Fluid filled sacs,
⮚Fluid is called cell sap in
plant (water, sugar, amino
acids, etc.),
⮚Plants cells have large,
central vacuole, whereas
animal cells have small and
many numbers,
⮚Store food, water, metabolic
& toxic wastes,
⮚Store large amounts of food
or sugars in plants.

27. Lysosome (only in
animal cells);
⮚Contains digestive
enzymes,
⮚Breaks down larger
food molecules into
smaller molecules,
⮚Digests old cell parts

28. Centrioles x2 =
Centrosome (only in
animal cells):
⮚Near to nucleus,
⮚Separate replicated
chromosomes during cell
division

29. Compare plant and animal cell
Animal Plant
Both
2.1.1 Describe and compare the structure of a plant cell with an animal cell,
limited to cell wall, cell membrane, nucleus, cytoplasm, chloroplasts,
ribosomes, mitochondria and vacuoles.

30. LEARNING OBJECTIVES
2.1.6 State that specialised cells have specific functions,
limited to:
(a)ciliated cells - movement of mucus in the trachea and
bronchi
(b)root hair cells - absorption
(c) palisade mesophyll cell - photosynthesis
(d)neurones - conduction of electrical impulses
(e) red blood cells - transport oxygen
(f) sperm and egg cells (gametes) - reproduction
2.1.7 Describe the meaning of the terms: cell, tissue, organ,
organ system and organism as illustrated by examples given in
the syllabus.

31. The human body is
constructed from
more than 200
different types of
cell.

33. 1-Animal Specialized Cells:
❖Ciliated cells
❖Blood Cells: Red Blood & White
Blood Cells,
❖Nerve Cells,
❖Sex Cells: Sperm & Egg
2.2.1 Relate the structure of the following to their functions:
•ciliated cells - movement of mucus in the trachea and bronchi,
•root hair cells – absorption,
•xylem vessels conduction and support,
•palisade mesophyll cells– photosynthesis,
•nerve cells – conduction of impulses,
•red blood cells transport of oxygen,
•sperm and egg cells – reproduction.

34. Ciliated Cell
✔Location?
Air passage in lungs (trachea and
bronchi) & oviducts in female
reproductive system
A-Human Specialized Cells
✔Structural feature to carry out its function?
Have cilia (tiny extension) on their surface. Cilia beat back and
forth to create a current in the fluid next to the cell surfaces. Cilia
move mucus that traps dust particles & pathogens up to the nose and
throat
&
moving egg from the ovary to the uterus.

35. A-Human Specialized Cells
❖ Contain the protein – Haemoglobin
to carry oxygen
❖ No nucleus: Provide many space to
have many numbers of haemoglobin
❖ Like flattened discs to provide
large surface area for efficient
absorption of oxygen.

36. A-Human Specialized Cells
Nerve
Cell
(Neurone)
Function?
❖Conduct electrical signal /
nerve impulse
❖Long dendrites has long
extention so as to bring the
electrical signal to cell body,
❖Axon transmits impulse from
one neuron to another neuron
Telephone Pole+Caple

37. Reproduction
A-Human Specialized Cells

38. B- Plant Specialized Cells:
❖Xylem Cells,
❖Root Hair Cells,
❖Palisade Mesophyll
2.2.1 Relate the structure of the following to their functions:
•ciliated cells - movement of mucus in the trachea and bronchi,
•root hair cells – absorption,
•xylem vessels conduction and support,
•palisade mesophyll cells– photosynthesis,
•nerve cells – conduction of impulses,
•red blood cells transport of oxygen,
•sperm and egg cells – reproduction.

39. Root hair cells
Mop
Root
hair cell
Has long extension
to increase surface
area for absorption
of water and mineral
ions from soil
Is there any chloroplast in
the root hair cells?

40. Xylem
vessels
❖ Cylindrical, empty, lost
its end wall to form long
continuous tube.
❖ Its cell wall is thickened
by a waterproof material
called lignin.
Functions:
❖ Transport water &
mineral ions from root to
rest of the plant
(Conduction).
❖ Support stem and leaves.

41. Palisade
Mesophyll Cells
❖Have many
chloroplast in
which
photosynthesis
occur

42. Learning Check
Question 1

43. Learning Check
Question 2