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Science 10
Living Systems
C1.0 Imaging The Cell
C 2.0 Cell Structures and Functions
C3.0 Plants as Multicellular Organisms
The Cell
1.1 Early Microscope Technology
1.2 The Cell Theory
1.3 Imaging Technology
1.4 Cell Research
Early Microscope Technology
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The invention of the microscope
allowed scientists to study the
building blocks of living things
Two convex lenses made the first
compound microscope
Robert Hooke combined three lenses
to make a more powerful microscope
Anton van Leeuwenhoek further
refined the microscope
Cell Theory
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Louis Pasteur refuted the theory of
spontaneous generation using the
scientific method (one manipulated
variable, one responding variable,
many controlled variables)
Through careful observation Theodor
Schwann and Matthias Schleiden
proposed the cell theory to explain the
origin of life
Cell Theory
• The cell theory states that:
1. All living things are made of cells and
the materials produced by cells
2. All life functions take place in cells
making them the smallest unit of life
3. All cells are produced from preexisting cells through the process of
cell division
Imaging Technology
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Viewing cells under a microscope can
be enhanced by:
Staining
Increasing resolution
Contrast and Fluorescence
Confocal technology
Electron microscopy (transmission
versus scanning)
Cell Research
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New technologies have led to
breakthroughs in:
1. Gene Mapping: determining the DNA
sequence of a species
2. Cell Communication: cells interact with
each other using molecules that act as
chemical messengers
3. 3D Molecular Structure: visualizing
molecules as they really exist
Cell Research
4. Green Fluorescent Protein Technology:
comparing healthy cells to diseased cells
to diagnose illness
Cell Structures and
Functions
2.1 The Cell as an Open System
2.2 The Cell Membrane
2.3 Applications of Cellular Transport
2.4 Cell Size Limitations
The Cell as an Open System
• All cells are either prokaryotic or
eukaryotic
Characteristic
Prokaryote
Eukaryote
No
Yes
plasmids
chromosomes
Nucleus
No
Yes
Cell Wall
Yes
Some
Membrane bound
organelles
DNA
The Cell as an Open System
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Two types of eukaryotic cells are plant and
animal cells
• Plant and animal cells have cellular
structures called organelles
• Differences between plant and animal cells
include:
1. Plant cells have a cell wall; animal cells do
not
2. Plant cells have chloroplasts; animal cells
do not
The Cell as an Open System
3. Plant cells have one large central vacuole
that stores water; animal cells have several
small vacuoles that store water, nutrients
or wastes
4. Animal cells have centrioles, plant cells do
not
The Cell Membrane
• The cell membrane is a fluid
mosaic
• The membrane consists of a
phospholipid bilayer with
proteins interspersed
• The proteins may act as
channels, receptors or antigens
The Cell Membrane
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The cell membrane allows for particles to
move into and out of the cell
• Passive transport mechanisms involve no
energy expense by the cell and include:
1. Diffusion: particles move from where they
are more concentrated to where they are
less concentrated (ie. down the
concentration gradient)
2. Osmosis: Water moves down the
concentration gradient
The Cell Membrane
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Facilitated Diffusion: Large particles move down
the concentration gradient through channels
Active transport mechanisms move particles
against the concentration gradient using cellular
energy
Ion Pump: moves ions across the cell membrane
using specialized proteins
Endocytosis: moves large particles into the cell by
enveloping them in the cell membrane
Exocytosis: moves large particles out of the cell by
expelling them from the cell membrane
Applications of Cellular Transport
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Studying the cell membrane has led to
better understanding and treatment of
disease
A recognition protein is a protein
embedded in a cell membrane that allows
a cell to be recognized by other cells
A receptor protein is a protein embedded
in the cell membrane that bind to specific
molecules outside the cell
Applications of Cellular Transport
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Some viruses attach to receptor
proteins (example: HIV)
Cancer cells can be identified due to
recognition proteins
A liposome is a synthetic membrane
and can deliver medications to cells
Hormones are transported through
channel proteins (example: insulin)
Applications of Cellular Transport
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Dialysis uses diffusion to treat kidney
disease
Reverse osmosis is used to purify water
Cell Size Limitations
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The ratio of surface area to volume limits
the size of cells
The greater the surface area to volume
ratio the more efficient cellular transport
can be
Small cells have a high surface area to
volume ratio
Large cells have a low surface area to
volume ratio
Plants
3.1 Cells, Tissues and Systems
3.2 The Leaf and Photosynthesis
3.3 Gas Exchange in Plants
3.4 Transport in Plants
3.5 Control Systems
Cells, Tissues and Systems
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The advantages of multicellular organisms
include:
1. Division of Labour: many specialized cells
can be more efficient one generalized cell
2. Size: Many small cells have sufficient
surface area to support larger sized
organisms
3. Interdependence of Cells: if one cell dies a
multicellular organism still survives
Cells, Tissues and Systems
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Cells of multicellular organisms can be
organized into:
1. Tissue: a group of similar cells contributing
to the same function
2. Organ: a group of related tissues
contributing to the same function
3. Organ System: a group of related organs
contributing to the same function
Cells, Tissues and Systems
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Plants have two organ systems
Shoot System: above ground structures
including the stem, leaves, buds, flowers
fruits and tubers
Root System: underground structures
including roots and buttresses
Plants grow from the meristems of the
roots and shoots
Cells, Tissues and Systems
• Plant tissues include:
1. Epidermis: the outer layer of cells that
covers all herbaceous plants that in leaves
and roots is covered in a cuticle
2. Ground Tissue: the majority of plant cells
that provide support, storage and strength
3. Vascular Tissue: cells that transport
nutrient, water and sap (includes xylem and
phloem)
Cells, Tissues and Systems
4. Root Hairs: extensions of epidermal cells in
roots that increase surface area for
absorption of water and minerals
5. Guard Cells: create pores called stomata
for gas exchange
The Leaf and Photosynthesis
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A leaf has different tissues to help the
plant do photosynthesis efficiently
Photosynthesis is carried out inside
chloroplasts
Chloroplasts contain a molecule
called chlorophyll
Chloroplasts move within a plant cell
due to cytoplasmic streaming
The Leaf and Photosynthesis
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Plant cells carry out both cellular
respiration and photosynthesis
The rate of net production of a plant
can be determined by measuring the
amount of oxygen gas produced or
the amount of carbon dioxide
consumed
Gas Exchange in Plants
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Stomata allow for oxygen to be
excreted and carbon dioxide to be
ingested by a leaf
Stomata remain closed during the day
when the rate of transpiration is high
and open at night
Guard cells open and close the
stomata
Gas Exchange in Plants
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Once inside the leaf, carbon dioxide
can diffuse around the mesophyll cell
(palisade and spongy)
Vascular tissue bring water into the
leaf for photosynthesis
Gas exchange occurs on stems and
roots through lenticels
Transport in Plants
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Water moves through plants due to its
properties of adhesion and cohesion
Water is polar so it has relatively strong
intermolecular forces
Root pressure causes water to flow up the
plant and accumulate in the leaves and
stems at night
Transpiration is the movement of water
from the roots, through the stem and out
the stomata of the leaves of a plant
Transport in Plants
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Transpiration pull is the effect of water
molecules evaporating off of leaves and
pulling adjacent water molecules along
A plant cell in a hypertonic environment will
exhibit plasmolysis
A plant cell in a hypotonic environment will
exhibit turgor
Sugars move down the plant from the
source (leaves) to the sink (root or fruit)
Control Systems
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Plants can respond to stimuli but less
obviously than animals
Plants respond to light using phototropism
Phototropism allows plant shoots to grow
toward light using elongation due to auxin
Plants respond to direction using
gravitropism
Gravitropism involves the plant sensing the
location of starch granules inside cells
Control Systems
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Tropisms can be positive or negative
Plant System
Stimulus
Tropism
Shoot
Light
Positive phototropism
Root
Light
Negative phototropism
Shoot
Gravity
Negative gravitropism
Root
Gravity
Positive gravitropism
Plants exhibit tropisms in response to
temperature, water, touch and others