Transcript Chapter 7: Cell Structure and Function

Chapter 7: Cell Structure and Function
Section 7-1: Life is Cellular
Harvard - Inner Life of the Cell
The observations and conclusions of
many scientists helped to develop the
current understanding of the cell
Put it in perspective:
1605 – English settlers found the colony at
Jamestown, Virginia
The Cell Theory
Robert Hooke (1665)
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English physicist used
primitive compound
microscope to look at plant
tissue (cork).
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He called the chambers
“cells” because they
reminded him of the small
rooms in a monastery
The Cell Theory
Rudolph Virchow (1855)
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Proposes that all cells come from existing
cells
Where did the first cell come from?
THE CELL THEORY
1.
All living things are composed of cells.
2.
Cells are the basic unit of structure and
function in living things.
3.
New cells are produced from existing
cells.
How small are cells?
How much is a micrometer?
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1 micrometer (µm) = 1/1,000,000 m
Typical cell size = 5 to 50 µm in diameter
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In a dice that is 1 cm3
We could fit 1,000,000 cells
Cells Alive
How small are cells?
Two categories of cells
1. Prokaryotic Cells
pro = before; karyon = nucleus or kernel
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contain cell membranes and cytoplasm but no
nucleus
DNA is scattered through cytoplasm
examples: bacteria
Two categories of cells
2. Eukaryotic Cells
eu = true; karyon = nucleus or kernel
contain a nucleus that holds DNA and
membrane bound organelles that have specific
functions
examples: all plants, animals, some fungi,
some microorganisms
Two categories of cells
Prokaryotic
-No Nucleus
Eukaryotic
-Nucleus
-Cell wall
(plants and
-Complex
-Less complex
bacteria)
-Membrane bound
-Smaller Ribosomes -Cell membrane organelles
less complex
-DNA
- Ribosomes larger
-Cytoplasm
and complex
-DNA is circular
-Ribosomes
-DNA is linear
Plant Cell - Eukaryotic
Prokaryotic
Animal Cell - Eukaryotic
7-2 Cell Structures
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Organelle – a specialized structure that
performs a specific function inside a cell
Cytoplasm
 Found – between the nucleus and cell
membrane
 Structure – a clear jelly-like fluid
 Function – supports the organelles
The Nucleus
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Nuclear Envelope
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Found: around the outside of the nucleus
Structure: two thin membranes with
thousands of pores
Function: allows materials to move in and
out of the nucleus.
The Nucleus
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Chromatin
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Found: between the nucleolus and the nuclear
membrane
Structure: DNA bound to proteins
Function: contain genetic information
The Nucleus
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Nucleolus
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Found: In center of the nucleus
Structure: a small, dense, round sphere
Function: Produces the ribosomes.
The Nucleus
Found: In the cytoplasm of the cell
Structure: a sphere covered by a porous membrane
Function: Contains the cell’s DNA and all instruction for
making protein and directing cell activities.
Nucleolus
Chromatin
Nucleus
Nuclear
Envelope
Cytoskeleton
Found: Throughout the cell
Structure: A network of
protein filaments
 Microtubules (25 nm)
 Microfilaments (7nm)
Function: Helps support the
cell & maintain shape
 Involved in several types
of movement
Cytoskeleton
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Microfilaments (7nm)
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Thread like structures made of protein
(actin)
Support the cell
Responsible for cytoplasm streaming – the
movement of cytoplasm within a cell
(amoeba crawls)
Microtubules (25 nm)
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Tube-like structure made of proteins
(tubulins)
Important in cell division
Used to build cilia and flagella
Vacuoles
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Found: In the cytoplasm
Structure: Saclike
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Very large in plant cells
Smaller in animal cells
Function: Storage (water
proteins, carbs, salts)
Vesicles
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Found: In the cytoplasm
Structure: membrane
bounded sac
Function: transports
and/or stores cellular
products
Lysosomes
“The Cells Clean-up Crew”
 Found: In the cytoplasm
 Structure: Small enzyme filled organelles
 Function: Breakdown large organic
molecules, and old nonfunctioning
organelles
Ribosomes
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Found: In the cytoplasm
Structure: Small and grain-like, made of
large and small subunits
Function: produce proteins from directions
given by DNA
Endoplasmic Reticulum
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Found: just outside the
nucleus
Structure: a maze of
membranes
Rough ER: (ribosomes
imbedded in membrane)
produces and transports Smooth ER: (no
ribosomes) produces
proteins.
lipids and detoxifies
drugs.
Golgi Apparatus
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Found: In the cytoplasm
Structure: A stack of membranes
Function: to modify, sort and package
materials from the ER for storage or to be
transported outside the cell.
Chloroplast
Found: In the cytoplasm of plant cells
Structure: Stack of membranes that contain
photosynthetic pigments (chlorophyll)
Function: Use energy from the sun to make
food (photosynthesis)
Mitochondria
“Powerhouse of the Cell”
Found: In the cytoplasm
Structure: Rod-shaped with a folded double
membrane
Function: Provide the cell with energy.
Cell Wall
Found: Located outside the cell membrane
Structure: Fibers of carbohydrate, cellulose in
plant cells
Function: Provide support and protection for
the cell
Cell Membrane
Found: Located around the perimeter of the cell
Structure: Made of a phospholipid bilayer
Function: Regulates what leaves and enters the
cell and provides protection and support
Centrioles
Found: Within the cytoplasm only in animal
cells
Structure: Made of a microtubules (tubulin)
Function: Help organize the cell during cell
division.
Centrioles - Miosis