Chapter2
Cells
Part1 Cells and
Microscope
are made up of
Different types of
Let’s compare animal cell with plant cell!
What are organelles?
• Definition: tiny structures that have specific functions in the
cells.
• Example: nucleus(细胞核)，mitochondria(线粒体),
chloroplast(叶绿体), vacuole(液泡).
Similarity1: Both surrounded by cell membrane
 Function:form a barrier between the cell and its surroundings;
control the exchange of substances(物质) .
 It is selectively/ partially permeable.
Similarity2: Both have Cytoplasm (细胞质)
 Function:
provide space for chemical reaction/enzymes and
organelles inside the cell
Similarity3: Both have nucleus(细胞核)
Contain chromosomes(染色体) which
carry genetic information and can be
copied to the next generation.
Function: control cell activities/growth/
division/ reproduction
nucleolus核仁
nuclear pore 核孔
nuclear envelope
核膜
Chromosomes(染色体) in nucleus
(染色体)
Similarity4: Both have endoplasmic reticulum
• structure: a complex of double membranes
(内质网)
• types:
with ribosomes: rough ER to transport protein made by
ribosomes
without ribosomes:smooth ER to make fat (lipid)
Similarity5: Both have ribosomes(核糖体)
• Structure: very tiny, can only be seen under electron
microscope
• only organelle that prokaryotic cell has
• Function: site of making protein
Many cells need to be ‘paid' when they
do their jobs!
Similarity6:Both have mitochondria(线粒体)
Singular: Mitochondrion
Function: site of respiration (呼吸
作用) to provide energy.
Difference1: All plant cells have cell wall
cell membrane
 Cell wall is rigid and inflexible
and is made up of cellulose (纤
维素).
 Function：
Protect and support for the cell.
 Fully permeable
Where does the juice of a lemon or orange come from?
Difference2:Most Plant cell has vacuole(液泡)
In animal cells
vesicle
In plant cells
vacuole
Most plant cells contain large
permanent vacuoles.
 Function:
1. contain cell sap: store
water, sugar, salts and so on;
2. help maintain cell shape.
Why are most of the leaves green?
Difference3: Most Plant cell has chloroplast
 Chloroplasts contain green pigment called chlorophyll
to absorb light energy for photosyntheis
 Most plant cells have chloroplasts, but some only have
chlorophyll
 Function:
1. the site of photosynthesis;
2. store starch.
Comparison between plant and animal cell
animal cell
cell wall
cell membrane
cytoplasm
nucleus
chloroplast
vacuole
endoplasmic reticulum
mitochondria
ribosome
plant cell
Function
ribosome
Prokaryotic Cells VS Eukaryotic Cells
bacterial cell
• Organism does not have
nucleus, called
prokaryote, made up of
prokaryotic cells.
• e.g. bacteria
• Organism has nucleus, called
eukaryote, made up of
eukaryotic cells.
• e.g. animal, plant
a layer of sugar
nucleus
eukaryotic cells
prokaryotic
cells
form of
genetic
materials
cell size
organelles
Exercise-01&02:
How to observe
cells?
By microscope
Light Microscope and Electron Microscope
光学显微镜
电子显微镜
Magnification of Microscope
Exercise-03:
An egg measured 6.5 cm in diameter. A student made a
drawing of this egg and the diameter was measured as
19.5 cm. What was the magnification of the drawing?
Part2 Specialised
Cells
Are all cells in your body same?
Who is Mr.undifferentiate?
speciliased
cells
• Stem cells: with the ability to develop into other kind of cells;
• This process is called cell differentiation.
Specialised Cells
 When cells are specialised:
a. they do one particular job
b. they develop a different shape
c. special kinds of chemical
change take place in their
cytoplasm.
Cells have special shape/feature for
better carrying out its function.
We call it ‘adapation’.
Structures are adapted for functions.
1. Red Blood Cell (红细胞)
 Function:
carry, transport,and release oxygen
 Adaptation:
1. Contain haemoglobin(血红蛋白): a protein
which can combine with oxygen
2. No nucleus and other organelles: provide more ___________
for haemoglobin to bind with oxygen; more flexible shape to
move through ____________
3. biconvace shape: larger _____________ for oxygen to get
through
2.Sperm and Egg Cells
• acrsome(顶体): produce ________ to
digest egg membrane
• mid-piece: many mitochondria
• __________: for movement
• Much larger: more
cytoplasm contains many
_____________
Function: Reproduction (生殖)
3. Ciliated Cells (纤毛细胞)
cilia 纤毛
Function: Remove mucus(粘液)
away from lungs through bronchi
(支气管) and trachea(气管).
4. Nerve Cells (神经细胞)
nucleus
nerve fibre
Function: Conduction of nerve/ electrical impulse (电冲动)
5. Root Hair Cells (根毛细胞)
Function: Absorb water and mineral salts (矿物盐)
Adaptations of Root hair cells
Root hair cells absorb water by________and minerals
by____________ from soil
 Adaptation:
1. extensions to increase
______________
2. thin wall for ______________
3. concentrated cell sap for ________
6. Xylem Vessels (木质部导管细胞)
• Structure:
1. dead
2. thickened cell wall by lignin(木质素) to
withstand pressure and prevent
collapsing
• Function:
transport water and mineral salts
upwards
(栅栏叶肉细胞)
7. Palisade Mesophyll Cells
（栅栏叶肉细胞）
 Adaptation:
1. just under the transparent
cuticle:
2. arrange closely:
3. contain much more
chloroplasts:
 Function:
main place of photosynthesis
Exercise-04&05:
Exercise-06:
Exercise-07:
Part3 Levels of
Organisation
How can cells organise into living organisms?
eukaryotic cell
prokaryotic cell: bacteria
VS
Definition: A tissue is a group of cells with similar
structures, working together to perform a shared
function.
Xylem and phloem are
transporting tissues.
Definition: An organ is a structure made up of a
group of tissues, working together to perform a
specific function.
Plant Organs
Special organs in plants:
bulb:鳞茎
tuber:块茎
runner/stolon:匍匐茎
Definition: A system is a group of organs with
related functions, working together to perform a
body function.
Human organ system
循环系统
神经系统
骨骼系统
呼吸系统
消化系统
肌肉系统
生殖系统
Do plants have organ system?
轴系统
根系统
 Definition: An organism is
formed by the organs and
systems working together to
produce an independent plant
or animal.
Exercise-08:
Exercise-09&10:
Checklist
Checklist
THANKS