Cells - Pleasantville High School

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Transcript Cells - Pleasantville High School

The History of the Cell
 The Cell
 The basic unit of an organism
 Discovery made possible by the
invention of the microscope
Microscopes
 A microscope is an optical instrument
used for viewing very small objects,
such as mineral samples or animal or
plant cells, typically magnified several
hundred times.
The Eye Piece
 Also called the ocular
 The part of the microscope you look
through
 The eye piece magnifies what you are
looking at 10x
Arm and Base
 The arm and the base are used to hold
the microscope
 You should always use two hands when
carrying the microscope. One on the
arm and one on the base.
Coarse Adjustment
 The course adjustment knob is used to
focus the object
 Only used under low power.
Fine Adjustment
 The fine adjustment knob refocuses
the object.
 Only use under high power
Objectives
 The objectives are used to magnify
what you are looking at
Diaphragm
 Used to adjust the amount of light
Microscopes and Cells
 1600’s.
 Anton van
Leeuwenhoek first
described living
cells as seen
through a simple
microscope.
Microscopes and Cells
 1830’s.
 Mathias Schleiden
identified the first
plant cells and
concluded that all
plants made of cells.
 Thomas Schwann
made the same
conclusion about
animal cells.
Cell Theory
 All organisms are made up of one or more
cells.
 The cell is the basic unit of organization of all
organisms.
 All cells come from other cells all ready in
existence.
Two Basic Cell Types
1) Prokaryote
 Lacks internal
compartments.
 No true nucleus.
 Most are single-celled
(unicellular) organisms.
 Examples: bacteria
Two Basic Cell Types
2) Eukaryote
 Has several internal structures
(organelles).
 True nucleus.
 Either unicellular or multicellular.
unicellular example: yeast
multicellular examples:
plants and animals
The Parts of The Eukaryotic Cell
1) Boundaries
A) Plasma Membrane
-- Serves as a boundary between
the cell and its external
environment.
-- Allows materials to pass in and
out of the cell.
The Parts of The Eukaryotic Cell
B) Cell Wall
-- Surrounds the plasma
membrane of the cells of
plants, bacteria, and fungi.
-- Plant cell walls contain
cellulose while fungi cell walls
contain chitin.
The Parts of The Eukaryotic Cell
2) Controls
A) Nucleus
Regulates cell function.
 Surrounded by a double-layered
membrane (nuclear enveloped) with
large pores that allow materials to
pass in and out of the nucleus.
 Contains chromatin – long tangles of
DNA.

The Parts of The Eukaryotic Cell
2) Controls
B) Nucleolus
 Found in the nucleus and
responsible for ribosome
production. Ribosomes are
the sites of protein production.
The Parts of The Eukaryotic Cell
3) Assembly
 Cytoplasm
 The jelly-like material that
surrounds the organelles.
The Parts of The Eukaryotic Cell
4) Transport
A) Endoplasmic reticulum
 Folded membrane that acts as
the cell’s delivery system.
 Smooth E.R. contains enzymes
for lipid synthesis.
 Rough E.R. is studded with
ribosomes for protein synthesis.
The Parts of The Eukaryotic Cell
4) Transport
B) Golgi apparatus (or Golgi
body)
 A series of flattened sacs
where newly made lipids and
proteins from the E.R. are
repackaged and shipped to
the plasma membrane.
The Parts of The Eukaryotic Cell
5) Storage
A) Vacuoles
 A sac of fluid surrounded by a
membrane used to store
food, fluid, or waste products.
The Parts of The Eukaryotic Cell
5) Storage
B) Lysosomes
 Contain a digestive enzyme.
 Can fuse with vacuoles to digest
food, or can digest worn cell
parts.
 Also known as “suicide sacs”
because they can also destroy
the whole cell.
The Parts of The Eukaryotic Cell
6) Energy Transformers
A) Mitochondria
 Produce the energy for the
cell.
 Also known as the
“powerhouse of the cell”.
 Has a highly folded inner
membrane (cristae).
The Parts of The Eukaryotic Cell
6) Energy Transformers
B) Chloroplasts
-- Found in plant cells and some
protists.
-- Transforms light energy into
chemical energy which is stored
in food molecules.
-- Contain chlorophyll – a green
pigment that traps light energy and
gives plants their green color.
The Parts of The Eukaryotic Cell
7) Support
 Cytoskeleton
A
network of thin, fibrous
materials that act as a scaffold
and support the organelles.
 Microtubules – hollow filaments
of protein.
 Microfilaments – solid filaments
of protein.
The Parts of The Eukaryotic Cell
8) Locomotion
A) Cilia
 Short, numerous, hair-like
projections from the plasma
membrane.
 Move with a coordinated
beating action.
The Parts of The Eukaryotic Cell
8) Locomotion
B) Flagella
 Longer, less numerous
projections from the plasma
membrane.
 Move with a whip-like
action.
The Parts of The Eukaryotic Cell
9) Cell Division
A)Centrioles
 made of protein.
 play a role in the splitting of the cell into
two cells.
 found in animal and fungi cells.
Composite Animal Cell
Cellular Organization
 Cell
 Tissue – group of cells functioning together.
 Organ – group of tissues functioning
together.
 Organ System – group of organs functioning
together.
 Organism – group of organ systems
functioning together.
Cellular Functions
 All the different parts of the cell are important to the




life of the cell.
Cellular activities require energy.
All cells are able to release energy from complex
molecules.
The energy in a sugar molecule is released by the
mitochondria in small steps.
After a cell has taken in energy-rich molecules, the
molecules are used by the mitochondria and energy is
released.
Metabolism
 Metabolism is the sum of all the chemical reactions
in a in a cell or organism.
 Important molecules, like sugar, are processed and
energy is transformed to ATP and waste materials.
 Not all energy is used immediately. Some cells, for
example, those in green plants that contain
chloroplasts, store energy in complex molecules such
as sugars.
Homeostasis and Transport
 Atoms, molecules and small particles are in constant
motion.
 Molecules tend to move from an area where they are
more concentrated to an area where they are less
concentrated, until their concentration is the
same everywhere.
 The concentrations of molecules at various points
between the high and low areas form what is called the
concentration gradient.
 Molecules are said to move down the concentration
gradient.
Homeostasis and Transport
 Water moves in and out of cells and diffuses down its
concentration gradient in the same manner as other
substances.
Passive Transport
 The diffusion of water is called the osmosis. Molecules move across a
semipermeable membrane, from an area of high concentration to low
concentration.

 Hypertonic: If concentration of water is higher inside the cell, water
diffuses out of the cell and the cell will shrink.
 Salt solution
 Plasmolysis is a loss of turgor pressure and the cell will shrink.
 Hypotonic: If concentration of water is higher outside the cell, water
diffuses into the cell and the cell will expand (burst).
 Provides the plant cell with turgor pressure.
 In an animal cell, it may result in cytolysis (bursting of the cell)
 Contractile vacuoles are used to remove excess water in protozoa. Animals
use lungs and kidneys.
 Isotonic: The concentration is the same inside and outside of the cell.
 Saline solution
Active Transport
 Movement of molecules up the concentration
gradient.
 Requires energy
 Carrier proteins can also serve as “pumps” during
active transport.
 Sodium Potassium Pump – works to maintain a
higher concentration of sodium (Na) ions inside the
cell and a higher concentration of postassium (K) ions
outside the cell.
 Requires energy to do so.
 Creates and electrical gradient across the cell membrane
which is essential for nerve impulses.