Download 3.1 Discovery of cells

3 The cell as the basic unit of life
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3.1 Discovery of cells (Extension)
•
3.2 Microscope (Extension)
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3.3 Basic structure of a cell
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3.4 The similarities and differences between plant and
animal cells
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3.5 The cell as a basic unit of life
•
Mind Map
3.1 Discovery of cells
3.1 Discovery of cells
1665
Robert Hooke
Bark
Take a piece of cork
Microscope
3.1 Discovery of cells
1665
Robert Hooke
Bark
Take a piece of cork
Microscope
3.1 Discovery of cells
1665
Robert Hooke
Microscope
Cork cells
3.1 Discovery of cells
In early 1800s, Schleiden,
Schwann & Virchov suggested
3.1 Discovery of cells
Three rules of cell theory :
All living things consist of cells
The cell is the basic unit of structure
and function in all living things
Every cell originates from
another preexisting cell
3.2 Microscope
3.2 Microscope
light
microscope
dissection
microscope
electron
microscope
3.2 Microscope
Eyepiece
Magnification
light
microscope
Objective
3.2 Microscope
Body tube
light
microscope
Holds eyepiece &
objectives
3.2 Microscope
Revolving
nosepiece
light
microscope
can be rotated
to bring the
objective into
line
3.2 Microscope
Coarse
adjustment
to raise or lower
the body tube for
focusing
light
microscope
3.2 Microscope
Stage
light
microscope
supports the slide & allows
the light to reach the specimen
3.2 Microscope
Clip
light
microscope
holds the slide in position
on the stage
3.2 Microscope
Mirror
light
microscope
reflects light from a light source
3.2 Microscope
Iris
diaphragm
light
microscope
regulates the amount of light
passing through the condenser
3.2 Microscope
Arm
Base
light
microscope
3.2 Microscope
Summary
light microscope
eyepiece
4
coarse
1
adjustment
arm
2
body5tube
revolving6nosepiece
objective
7
stage
8
base
3
iris diaphragm
9
mirror
10
3.2 Microscope
Experiment 3.1
Using a light microscope
A. Low Power
Observation
3.2 Microscope
Low power observation
low power
eyepiece
1. Insert the
low power
eyepiece into
the top of the
body tube
3.2 Microscope
Low power observation
2. Adjust the
mirror to reflect
light through the
hole in the stage
mirror
3.2 Microscope
Low power observation
3. Adjust the
condenser &
diaphragm to
change the
amount of light
condenser & iris diaphragm
3.2 Microscope
Low power observation
4. Select a low
power objective
3.2 Microscope
Low power observation
5. Place the
slide onto the
stage
3.2 Microscope
Low power observation
6. While watching
from the side, use
the coarse
adjustment to
lower the objective
until it is just
above the slide
3.2 Microscope
Low power observation
7. While looking
through the eyepiece,
carefully turn the
coarse adjustment in
the other direction
until the object is in
focus
3.2 Microscope
B. High Power
Observation
3.2 Microscope
High power observation
1. Observe the specimen with
low power first
2. Move the slide so that the
part to be observed is at the
centre of view
3.2 Microscope
High power observation
3. Rotate the
revolving
nosepiece until
40X objective
clicks into
position
3.2 Microscope
High power observation
4. Adjust the
fine adjustment
only until the
object is in focus
3.2 Microscope
High power observation
5. Adjust mirror,
condenser &
diaphragm to
increase the light
intensity
3.2 Microscope
What are the properties
of microscopic images?
bigger
inverted
3.2 Microscope
bigger = Magnification
= Eyepiece magnification x
objective magnification
3.2 Microscope
Magnification =
Eyepiece magnification x objective magnification
Eyepiece
magnification
Objective
magnification
Magnification
5X
40 X
200 X
10 X
10 X
100 X
15 X
40 X
600 X
3.2 Microscope
What are the properties
of microscopic images?
bigger
inverted
3.2 Microscope
inverted
Specimen
d
Image
How ?
p
3.2 Microscope
inverted
Specimen
Image
p
3.2 Microscope
inverted
Specimen
o
180
Image
p
3.3 Basic structure of a cell
3.3 Basic structure of a cell
Plant cell
Cell wall
Chloroplast
Cytoplasm
Nucleus
Vacuole
Mitochondrion
Cell
membrane
3.3 Basic structure of a cell
Cell wall
is made up of
Cellulose
3.3 Basic structure of a cell
Cell wall
Feature
Function
Hard
Protect & support
Large spaces
between the
cellulose fibers
Allow large particles
to penetrate the cell
wall
3.3 Basic structure of a cell
Plant cell
Cell wall
Chloroplast
Cytoplasm
Nucleus
Vacuole
Mitochondrion
Cell
membrane
3.3 Basic structure of a cell
Protein &
lipid
consists of
Cell membrane
Control
the movement of
materials in or out
of the cell
3.3 Basic structure of a cell
Control
Cell
membrane
is selectively
permeable
the movement of
materials in or out
of the cell
3.3 Basic structure of a cell
Plant cell
Cell wall
Chloroplast
Cytoplasm
Nucleus
Vacuole
Mitochondrion
Cell
membrane
3.3 Basic structure of a cell
an aqueous solution
of many substances
e.g. protein
consists of
Cytoplasm
clear, jelly-like
provides a
medium for
chemical
reactions to
take place
contains a lot
of organelles
& granules
3.3 Basic structure of a cell
Plant cell
Cell wall
Chloroplast
Cytoplasm
Nucleus
Vacuole
Mitochondrion
Cell
membrane
3.3 Basic structure of a cell
Chloroplast
absorbs
sunlight for
photosynthesis
contains
chlorophyll
3.3 Basic structure of a cell
Plant cell
Cell wall
Chloroplast
Cytoplasm
Nucleus
Vacuole
Mitochondrion
Cell
membrane
3.3 Basic structure of a cell
bounded by a nuclear membrane
Nucleus
contains chromosomes
made up of DNA
control activities of cell
3.3 Basic structure of a cell
Plant cell
Cell wall
Chloroplast
Cytoplasm
Nucleus
Vacuole
Mitochondrion
Cell
membrane
3.3 Basic structure of a cell
Respiration
takes place
Mitochondrion
release energy
3.3 Basic structure of a cell
Plant cell
Cell wall
Chloroplast
Cytoplasm
Nucleus
Vacuole
Mitochondrion
Cell
membrane
3.3 Basic structure of a cell
large, at the centre
Vacuole
contains a solution
of sugars, proteins
and minerals
provides support when it is
fully filled with water
3.3 Basic structure of a cell
contains crystals of
insoluble waste
Non-living
granules
starch granules
3.3 Basic structure of a cell
Difference ?
Plant Cell
Animal Cell
small vacuole
no chloroplast
no cell wall
3.3 Basic structure of a cell
Summary
Animal Cells
Cytoplasm
1. mitochondria
2. non-living
granules
e.g. glycogen
(in animal cells only)
e.g. starch
(in plant cells only)
3. chloroplast
(in plant cells only)
Cell
membrane
Plant Cells
Nucleus
1. bounded by
a nuclear
membrane
2. contains
chromosomes
Cell
wall
(in plant
cells only)
3.4 The similarities and differences
between plant and animal cells
3.4 The similarities and differences
between plant and animal cells
Shape
regular
irregular
Nucleus
peripheral
centre
Cell wall
present
absent
Vacuole
large
small or absent
Chloroplasts
present
absent
Food reserves
starch
glycogen
3.4 The similarities and differences
between plant and animal cells
Both plant cells &
animal cells contain
 a cell membrane
surrounding the cytoplasm
 a nucleus
 mitochondria
3.4 The similarities and differences
between plant and animal cells
Experiment 3.2
Preparing temporary slides of the plant and animal tissues
A. Onion epidermal cells
fleshy scale leaf
of onion bulb
1. Peel off a small
piece of epidermis
from the inside of
a scale leaf of an
onion.
forceps
3.4 The similarities and differences
between plant and animal cells
Experiment 3.2
Preparing temporary slides of the plant and animal tissues
A. Onion epidermal cells
2. Cut it to a
suitable size,
about 5mm2.
3.4 The similarities and differences
between plant and animal cells
Experiment 3.2
Preparing temporary slides of the plant and animal tissues
A. Onion epidermal cells
iodine solution
3. Spread the tissue
flat on a clean slide
and add one drop
of iodine solution
on top of it.
epidermis
3.4 The similarities and differences
between plant and animal cells
Experiment 3.2
Preparing temporary slides of the plant and animal tissues
A. Onion epidermal cells
cover slip
4. Gently cover it with a
cover slip and make
sure no air bubbles
are trapped in it. Then
examine the slide
under the low power
of a microscope.
3.4 The similarities and differences
between plant and animal cells
Experiment 3.2
Preparing temporary slides of the plant and animal tissues
B. Ox corneal cells
slide
ox eye
1. Gently touch
the surface of
an ox cornea
with a clean
slide.
3.4 The similarities and differences
between plant and animal cells
Experiment 3.2
Preparing temporary slides of the plant and animal tissues
B. Ox corneal cells
methylene
blue stain
2. Add a drop of
methylene blue
stain on the
slide.
3.4 The similarities and differences
between plant and animal cells
Experiment 3.2
Preparing temporary slides of the plant and animal tissues
B. Ox corneal cells
cover slip
3. Gently cover it with
a cover slip. Then
examine the slide
under the low
power of a
microscope.
3.4 The similarities and differences
between plant and animal cells
Experiment 3.2
Preparing temporary slides of the plant and animal tissues
C. Hydrilla leaf
1. Put a drop of
water on a clean
slide.
water
slide
3.4 The similarities and differences
between plant and animal cells
Experiment 3.2
Preparing temporary slides of the plant and animal tissues
C. Hydrilla leaf
Hydrilla
2. Put a piece of Hydrilla leaf into
it. Gently cover it with a cover
slip. Look at it under the low
power of a microscope.
3.4 The similarities and differences
between plant and animal cells
Experiment 3.2
Preparing temporary slides of the plant and animal tissues
D. Pollen grains
1. Take a big flower
with ripe stamens.
Touch the anther
with sellotape.
pollen grains
anther
3.4 The similarities and differences
between plant and animal cells
Experiment 3.2
Preparing temporary slides of the plant and animal tissues
D. Pollen grains
sellotape
2. Stick the pollen grains
onto a slide. Look at it
under a microscope.
slide
3.4 The similarities and differences
between plant and animal cells
Experiment 3.4
Measuring and comparing the size of plant and animal cells
Method of measuring the size of the cells
1. Put a transparent ruler on the
stage of a microscope. Move the
ruler into the centre of the field
of view. Measure the diameter
of the field of view. For
example, in the diagram, the
diameter is 3.5mm .
3.4 The similarities and differences
between plant and animal cells
Experiment 3.4
Measuring and comparing the size of plant and animal cells
Method of measuring the size of the cells
2. Still using the microscope, observe a
slide containing plant cells to be
measured. Count the number of cells
(end to end ) it takes to span the
diameter of the field of view. In the
diagram, 14 cells span the field of
view. Therefore the average cell size
is 3.5 ÷ 14 = 0.25mm.
3.5 The cell as a basic unit of life
3.5 The cell as a basic unit of life
with different shapes
Muscle cell
Epithelial
cell
Nerve cell
3.5 The cell as a basic unit of life
Cells
Tissue level
Three levels of
organisation
Organ level
of cell
System level
3.5 The cell as a basic unit of life
Cells
A tissue is a group of similar cells
working together as a unit
Tissue level
Muscle cell
Epithelial
tissue
Muscle
tissue
Epithelial
cell
3.5 The cell as a basic unit of life
Cells
Tissue level
Animal Tissue
Plant Tissue
muscular tissue
mesophyll tissue
connective tissue
vascular tissue
epithelial tissue
epithelial tissue
nervous tissue
3.5 The cell as a basic unit of life
Cells
Tissue level
Organ level
3.5 The cell as a basic unit of life
Cells
Tissue level
Organ level
Connective
Epithelial
Muscular
Blood
tissue
Stomach
An organ is composed of several different tissues
group together to make a functional unit
3.5 The cell as a basic unit of life
Cells
Tissue level
Examples of
Organ level
organs in mammals
organs in plants
heart
leaves
stomach
stems
eyes
roots
kidneys
flowers
lungs
fruits
3.5 The cell as a basic unit of life
Cells
Tissue level
Organ level
System level
Several organs and tissues
working together to form a
system. These organs and
tissues are co-ordinated in
the organisms.
3.5 The cell as a basic unit of life
Digestive system
mouth
+
oesophagus
+
stomach
+
small intestine
+
large intestine
Mind Map
working together to form
Cells
can be observed with
consist of
microscope
Animal cells
Plant cells
contain
tissues
contain
working together
to form
nucleus
cytoplasm
vacuole
contains
contains
chromosomes
function
control cells’
activities
mitochondria
are used in
respiration
cell membrane
cell sap
contains
function
support
the cells
non-living
granules
which are
food or waste
materials
function
control of
materials in
and out of
the cell
chloroplasts
(in plant cells only)
are used in
photosynthesis
cell wall
function
support and
prevent entry
of excess
water
organs
working together
to form
system