Transcript Chapter 3 The Basic Structure of a Cell

Introduction to Cells
Cells are the basic units of
organisms
Cells can only be observed under
microscope
Basic types of cells:
Animal Cell
Plant Cell
Bacterial Cell
Cell Structure and Function
Cells are a collection of living matter
enclosed by a barrier that separates
the cell from its surroundings
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Every Cell Contains:
• Membrane – thin layer of material that
serves as a covering or lining
• Structure containing the cells genetic material
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Number of Cells
• Organisms may
be:
• Unicellular –
composed of
one cell
• Multicellularcomposed of
many cells that
may organize
Cells May be Prokaryotic or
Eukaryotic
 Prokaryotes include bacteria &
lack a nucleus or membrane-bound
structures called organelles
Eukaryotes include most other cells
& have a nucleus and membranebound organelles
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Prokaryotes
•Genetic material is not
contained in the nucleus
•Less complicated than
eukaryotic cells
•Bacteria are examples
of prokaryotes
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Eukaryotic Cell
• Larger and more complex
than prokaryotes
• Plants, Animals, Fungi are
eukaryotes
Contain 3 basic cell
structures:
• Nucleus – contain genetic
info
• Cell Membrane
• Cytoplasm with organelles
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Nucleus
• Nucleus – a large membrane-enclosed
structure that contains the cell’s genetic
material in the form of DNA
– Controls many of the cells activities
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Cell Theory
• All living things are composed of cells.
• Cells are the basic units of structure and
function in living things.
• New cells are produced from existing cells.
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Basic Structure of a
Eukaryotic Cell
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Two Main Types of
Eukaryotic Cells
Plant Cell
Animal Cell
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Plant Cell
Smooth endoplasmic
reticulum
Vacuole
Ribosome
(free)
Chloroplast
Ribosome
(attached)
Cell
Membrane
Nuclear
envelope
Cell wall
Nucleolus
Golgi apparatus
Nucleus
Mitochondrion
Rough endoplasmic reticulum
Plant Cell
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Animal Cell
Ribosome
(attached)
Nucleolus
Nucleus
Nuclear
envelope
Ribosome
(free)
Cell
Membrane
Mitochondrion
Rough
endoplasmic
reticulum
Golgi apparatus
Smooth
endoplasmic
reticulum
Centrioles
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Organelles – “little organs”
Very small size
Can only be observed under a
microscope
Have specific functions
Found throughout cytoplasm
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Nucleus
• “The Control Center”
• Contains nearly all the cell’s
DNA with the codes for the
cells proteins and other
molecules
• Surrounded by the nuclear
envelope
– Full of nuclear pores
• Chromatin – DNA and
proteins spread throughout
the nucleus
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Nucleus
• Chromosomes –
condensed form of
chromatin
– Passes on from one
generation to the
next
• Nucleolus – place
where ribosomes are
assembled
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Ribosomes
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“Protein Factories”
Small particles of RNA and protein
Located in the cytoplasm
Organelle where proteins are assembled
Ribosomes get codes for proteins from
nucleus
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Endoplasmic Reticulum
• “Highway System
of the cell”
• Internal membrane
system
• Transports– Proteins
– Other
macromolecules
Two types:
Smooth
Rough
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Smooth & Rough Endoplasmic
Reticulum
Smooth ER lacks
ribosomes &
makes proteins
USED In the cell
Rough ER has
ribosomes on its
surface & makes
proteins to
EXPORT
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Golgi Apparatus
• “The Shippers of the
cell”
• Closely stacked
membranes,
resembles stacks of
pancakes
• Modifies, sorts, and
packages proteins
from the ER for
storage or secretion
• Sends proteins to
their final destination
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Lysosomes
• “Clean-up Crews”
• Small organelles filled with enzymes
• Breaks down lipids, carbohydrates, and proteins into
smaller molecules that can be reused by the cell
• Also breaks down old organelles
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Mitochondria
Nickname: “The Powerhouse”
Function: Energy formation
Breaks down food to make ATP
ATP: is the major fuel for all
cell activities that require
energy
Two membranes – outer and
inner
Inherit mitochondria from
mother
Contains its own
DNA
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• Saclike structure
• Stores materials
Vacuole
– Water, salts,
proteins,
carbohydrates
• Plants have a large
central vacuole
• Single-celled
organisms use a
contractile vacuole
to maintain
homeostasis
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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
Cytoplasm of a Cell
Cytoplasm
Jelly-like substance
enclosed by cell
membrane
Provides a medium for
chemical reactions to
take place
Cytoskeleton
• Supporting
framework of the
cell
• Cytoskeleton = cell
skeleton
• Many components
• Microtubules /
microfilaments
made of proteins.
• Move organelles
w/in the cell.
Cytoskeleton Continued
• Microtubules / Microfilaments make up
– Cilia
– Flagella
• Used in cellular locomotion
Different kinds of animal cells
white blood cell
Amoeba
red blood cell
muscle cell
cheek cells
sperm
nerve cell
Paramecium
• Now let’s talk about structures only
found in PLANT Cells!!
Figure 7-5 Plant and Animal Cells
Plant Cell
Section 7-2
Vacuole
Cell Membrane
Go to
Section:
Chloroplast
• Organelles that
capture energy
from sunlight and
convert it into
chemical energy
– Photosynthesis
• Two membranes
• Contains pigment
chlorophyll
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Eukaryotic Cell Organelles and
Function
Cell Wall
– Function: provides support
and protection to the cell
membrane
– Found outside the cell
membrane in plant cells
Different kinds of plant cells
Onion Epidermal Cells
root hair
Root Hair Cell
Guard Cells
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
Relatively smaller in
size
Plant cells
Relatively larger
in size
Irregular shape
Regular shape
No cell wall
Cell wall present
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
Endosymbiont Hypothesis
• Lynn Margulis U-Mass.
• Found that mitochondria / chloroplasts
did not fit the roles of organelles.
• They had unusual properties.
3 properties of Mito /
Cplasts
• Contain own DNA
• Both surrounded by 2 membranes
– Most organelles only surrounded by one membrane.
• Both reproduce separately from the rest of
the cell
Margulis’s Model
• Both Mitochondria / Chloroplasts had ancestors
that were free-living organisms.
• These formed endosymbiotic relationships with
other cells.
• Over time offsprings of these organisms lost
their independence becoming organelles of
larger cells.
Further Evidence
• Studies of DNA in chloroplasts show that they
are much like the DNA prokaryotic cells.
• Mitochondria / chloroplasts contain their own
ribosomes and make many of their own
proteins.
• These ribosomes are smaller / chemically
different from those in eukaryotic cells.
• More closely resemble ribosomes in
prokaryotic cells.
Levels of organization
• Cells are grouped
together and
work as a whole
to perform
special functions
• Known as “Cell
Specialization”
Tissue
• A group of similar cells to
perform a particular function
– Animals : epithelial tissue,
muscular tissue
– Plants : vascular tissue,
mesophyll
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
The Structures of a
Leaf (Plant Organ)
Chloroplast
Palisade Mesophyll
Cell
Spongy Mesophyll Cell
Air Space
Stoma
The Structures of a
Heart (Animal Organ)
Organ 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
Human Body Systems
Examples of systems :
Digestive System
Respiratory System
Circulatory System
Nervous System
Reproductive System
Examples of a Human Body
System
Examples of a Human Body
System
The Respiratory System
Levels of Organization
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CELLS (muscle cells,nerve cells)
TISSUES (muscle, epithelium)
ORGANS (heart, lungs, stomach)
SYSTEMS (circulatory system)
ORGANISM (human)
It’s You!