Transcript Chapter 3 The Basic Structure of a Cell

Discovery of the Cell
• Robert Hooke (1635-1703) – invented the term cell;
studied dead plant cells such as cork.
• Anton van Leeuwenhoek (1632-1723) - 1st to
observe living cells.
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Discovery of the Cell
• Matthias Schleidan (1804-1881) – concluded that all
plants are composed of cells.
• Theodor Schwann (1810-1882) - concluded all
animals were composed of cells.
• Rudolf Virchow (1821 – 1902) - reasoned that cell
come only from other cells.
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Protocells:
One theory of the origins of cells states
that the first life on earth consisted
of several types of tiny protocells, celllike organisms. These organisms were
able to survive and reproduce in a very
limited environment because of their
simplicity. Over time, some of these
protocells came together and shared
their specialization in a symbiotic
relationship. These colonies of
protocells eventually became the cells
we know today.
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Basic Structure of a Cell
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Introduction to Cell
Theory
1. Cells are the basic units of organisms
2. Cells come only from other cells
3. All living things are made of cells
Basic types of cells:
Animal Cell
Plant Cell
Bacterial Cell
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Number of Cells
Organisms may be:
• Unicellular –
composed of one cell
• Multicellularcomposed of many
cells that may
organize
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Cells May be Prokaryotic or
Eukaryotic
 Prokaryotes include bacteria &
lack a nucleus or membrane-bound
structures called organelles Ex:
blue-green algae
Eukaryotes include most other cells
& have a nucleus and membranebound organelles (plants, fungi, &
animals)
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Prokaryotes
Nucleoid region
contains the DNA
•Cell membrane &
cell wall
• Contain ribosomes
(no membrane) to
make proteins in
their cytoplasm
•Evolved 3.5 billion
years ago
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Eukaryotic Cell
Contain 3 basic cell
structures:
• Nucleus
• Cell Membrane
• Cytoplasm with
organelles
• Evolved 1.5 billion
years ago
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Two Main Types of
Eukaryotic Cells
Plant Cell
Animal Cell
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Organelles
Very small size
Can only be observed under a
microscope
Have specific functions
Found throughout cytoplasm
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Organelles Found in Cells
Examples of Organelles include:
Endoplasmic reticulum (ER) (rough &
smooth) – canals for movement
Golgi Bodies – wrap & export proteins
Nucleolus – makes ribosomes
Lysosomes – digests & gets rid of wastes
Ribosomes – makes proteins
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Golgi Bodies
• Stacks of flattened
sacs
• Have a shipping side &
a receiving side
• Receive & modify
proteins made by ER
• Transport vesicles
with modified proteins
pinch off the ends
Transport
vesicle
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Lysosome
• Contain digestive
enzymes
• Break down food and
worn out cell parts for
cells
• Programmed for cell
death (lyse & release
enzymes to break down
& recycle cell parts)
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Nucleolus
•
Cell may have 1 to 3
nucleoli
• Inside nucleus
• Disappears when cell
divides
• Makes ribosomes that
make proteins
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Smooth & Rough Endoplasmic
Reticulum
Rough ER has
ribosomes on its
surface & makes
proteins to EXPORT
Smooth ER lacks
ribosomes &
makes proteins
USED In the cell
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Cell Powerhouse
Mitochondrion
( mitochondria )
Rod shape
Site of Cellular
respiration
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In Animal Cells:
Mitochondria
Active cells like
muscles have more
mitochondria
Burn sugars to
produce energy ATP
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Surrounding the Cell
Cell (Plasma)
membrane
Lies immediately
against the cell wall
in plant cells
Made of protein and
phospholipids
“Selectively permeable”
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Cell or Plasma Membrane
Cell membrane
Living layer
Controls the
movement of
materials into and
out of the cell
Selectively
permeable
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Cytoplasm of a Cell
Cytoplasm
Jelly-like substance
enclosed by cell
membrane
Provides a medium
for chemical
reactions to take
place
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More on Cytoplasm
Cytoplasm
Contains organelles
to carry out
specific jobs
Examples:
chloroplast &
mitochondrion
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Control Organelle
Nucleus
Controls the normal
activities of the cell
Bounded by a
nuclear membrane (envelope)
Contains chromosomes
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More on the Nucleus
Nucleus
Each cell has fixed
number of
chromosomes that
carry genes
Genes control cell
characteristics
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Plant Cell Organelles
Chloroplast
Contain the green
pigment chlorophyll
Traps sunlight to
make to make
sugars (food)
Process called
photosynthesis
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Plant Cell
Cell wall
Dead layer
Large empty spaces
present between
cellulose fibers
Freely permeable
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Plant Cell
Cell wall
Made of cellulose
which forms very
thin fibers
Strong and rigid
Found in plant cells
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Plant Cell
Cell wall
Protect and support
the enclosed
substances
(protoplasm)
Resist entry of
excess water into
the cell
Give shape to the cell
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Plant Cell Organelles
Vacuole
Have a large central
vacuole
Surrounded by tonoplast
Contains cell sap
Sugars, proteins,
minerals, wastes, &
pigments
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Different kinds of plant
cells
Onion Epidermal Cells
Guard Cells
root hair
Root Hair Cell
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vacuole
cytoplasm
nucleus
mitochondrion
glycogen
granule
Animal cell
No cell wall or
chloroplast
Stores glycogen
in the
cytoplasm for
food energy
cell
membrane
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Animal Cell Organelles
• Near the nucleus
• Paired structures
• Help cell divide
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Different kinds of animal
cells
white blood cell
Amoeba
red blood cell
muscle cell
cheek cells
sperm
nerve cell
Paramecium
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Similarities between plant
cells and animal cells
Both have a cell membrane
surrounding the cytoplasm
Both have a nucleus
Both contain mitochondria
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Differences between plant
cells and animal cells
Animal cells
Plant cells
Relatively
smaller in size
Relatively
larger in size
Irregular shape
Regular shape
No cell wall
Cell wall present
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Differences between Plant
Cells and Animal Cells
Animal cells
Plant cells
Vacuole small or
absent
Large central
vacuole
Glycogen as food
storage
Starch as food
storage
Nucleus at the
center
Nucleus near cell
wall
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Compound Microscope
• Instrument for
observing small
objects
• Magnify images
up to 2000X
their size
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Different parts of
a microscope
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Revolving
nosepiece
Eyepiece
Clip
Body tube
Coarse
adjustment
Fine adjustment
Condenser
Arm
Iris diaphragm
Stage
Objective
Mirror
Condenser
control knob
Base
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Observing an Object:
Because the light rays from an object cross
before reaching your eye, the image you see
through most microscopes will be inverted
and upside down.
Magnification: the increase of an object's
apparent size.
Resolution: the power to show details clearly.
Resolution allows the viewer to see two objects
that are very close together as two objects
rather than as one. Resolution is controlled by
the quality of the lenses being used - the
better the lenses, the better the resolution.
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Care and handling:
A microscope is a delicate piece of equipment
and should be treated gently. Always use two
hands when moving the microscope. Place one
hand around the arm of the microscope and
the other under the base for support. Always
carry the microscope upright and close to the
body when moving any distance. Place the
microscope flat on the table, but not too near
the edge where it might be knocked off.
If it becomes necessary to clean the lenses on
the microscope, ask your facilitator for a piece
of "lens paper". Other materials, such as paper
towel, can scratch the surface of the lens.
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Preparing Specimens for
Viewing:
• In most instances, light must pass through any
object to be viewed with a light microscope.
For this reason, the object must be fairly thin.
Thick objects must be sliced into thin
sections for viewing.
• Many objects do not have distinct, contrasting
colors. This makes it difficult to see details.
To improve the viewing of these objects, they
are stained. Staining is the use of a biological
to make the details visible.
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Making a Slide:
• Place a clean slide on the table.
• For liquid samples, place one or two drops in the center of the
slide. For solid samples, place the sample in the center of the
slide and add one drop of water or staining solution.
• Hold the plastic cover slip by the edges. Do not get
fingerprints on the cover slip. Set one edge against the slide
and lower it until it contacts the liquid. The liquid should
spread across the whole area of the cover slip.
• Never use a slide under the microscope without a cover slip.
Its major purpose is to protect the objective lens for the
liquid on the slide.
• Unless otherwise instructed, wipe the sample and cover slip off
the slide with a paper towel when finished. Throw the paper
towel and its contents away. Return the microscope slide to
its container.
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The cell is the Basic Unit
of Life
• Cell is the smallest unit of living organisms
• Unicellular organisms are made of one cell
only
• The cells of multicellular organisms are
specialized to perform different functions
– e.g. mesophyll cells for photosynthesis
and root hair cells for water absorption
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Levels of organization
• Cells are
grouped
together and
work as a
whole to
perform special
functions
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Tissue
• A group of similar cells to
perform a particular function
– Animals : epithelial tissue,
muscular tissue
– Plants : vascular tissue,
mesophyll
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Organ
• Different tissues group together
to carry out specialized functions
– Heart : consists of muscles,
nervous tissue and blood
vessels
– Leaf : consists of epidermis,
mesophyll and vascular tissue
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The Structures of a Leaf
(Plant Organ)
Chloroplast
Palisade
Mesophyll Cell
Spongy Mesophyll
Cell
Air Space
Stoma
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The Structures of a Heart
(Animal Organ)
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System
• Several organs and tissues work together
to carry out a particular set of functions in a
co-ordinated way
– Human : digestive, respiratory, excretory,
circulatory and reproductive systems
– Plant : root and shoot systems
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Human Body Systems
Examples of systems :
 Digestive System
 Respiratory System
 Circulatory System
 Nervous System
 Reproductive System
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Examples of a Human Body System
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Examples of a Human Body System
The Respiratory System
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Examples of a Human Body System
Circulatory System
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Examples of a Human Body System
Nervous System
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Levels of Organization
CELLS
(muscle cells,nerve cells)
TISSUES (muscle, epithelium)
ORGANS (heart, lungs,
stomach)
SYSTEMS (circulatory system)
ORGANISM (human)
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It’s You!
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