Transcript Cell_structure-function_ppt

Cell Structure
& Function
Definition of a Cell
• A cell is the smallest unit that is capable of
performing life functions.
Robert Hook
• Credited for discovering cells. Viewed cork
cells through a compound light microscope
in the mid-1600’s
Cell theory
• All living things are made up of cells.
• The basic unit of living things is the cell
• All cells come from preexisting cells
through cell division.
Compound light microscope
• Uses light and multiple objective lenses to
look at objects
• Can view a living organism
• Magnifies to micrometers
Electron Microscope
• Uses a beam of electrons to magnify
objects
• Usually kills organisms
• Magnifies to nanometers so organelles
can be seen
2 types of electron microscopes
• Scanning electron microscope (SEM)looks at the surface of the specimen
• Transmission Electron Microscope (TEM)looks at the interior of the specimen
Examples of Cells
Amoeba Proteus
Plant Stem
Bacteria
Red Blood Cell
Nerve Cell
Two Types of Cells
•Prokaryotic
•Eukaryotic
Prokaryotic
• No nucleus and no
membrane bound
organelles
• Examples: bacteria
(anything Kingdom
Monera)
http://library.thinkquest.org/C004535/prokaryotic_cells.html
Eukaryotic
• Contains a nucleus and membrane bound
organelles (ex: fungi, plants, animals)
Plant
http://library.thinkquest.org/C004535/eukaryotic_cells.html
Animal
“Typical” Animal Cell
“Typical” Plant Cell
Surrounding the Cell
Plasma (Cell) Membrane
• Found in both plant
and animal cells
• Boundary between
the cell and it’s
environment, allows
a steady supply of
nutrients to come into
the cell
http://library.thinkquest.org/12413/structures.html
Selectively Permeable
• It allows only certain particles to enter and
leave the cell
Structures of the cell membrane
• Phospholipid bilayer- phosphorus head
(hydrophilic) and lipid tail (hydrophobic)
• Proteins- aids in transport of particles into
and out of a cell
• Carbohydrates
• cholesterol
Fluid mosaic model
• Called this because it contains a number
of different compounds (mosaic) and many
of the compounds move around in the
membrane
Inside the Cell
Nucleus
• Found in both plant and animal
• Control center of the cell because it
contains chromatin (DNA and protein)
• Enclosed by a porous nuclear envelope
Nucleolus
• Region within
• nucleus that makes
• ribosomes
Cytoplasm
Watery/Gel-like mixture
Found between nucleus an
cell membrane
Contains organelles
Cell Wall
• Found in plant cells
only
• Strong/stiff nonliving
layer outside of the cell
• Not selectively
permeable, very porous
• Contains cellulose to
provide
support/protection
Organells
Ribosomes
• Small grain like body
made primarily of
RNA.
• Produced by
nucleolus. Can be
attached or floating
free in the cytoplasm
http://library.thinkquest.org/12413/structures.html
Ribosomes cont..
Function: make
protein
Found in plants and
animals
Endoplasmic Reticulum
Moves materials
around in cell
Smooth type:
lacks ribosomes
Rough type
(pictured):
ribosomes
embedded in
surface
Rough ER
• Series of highly folded membranes that
contain ribosomes
• Produce proteins and transport them to
the golgi. Releases proteins to be
transported in the vesicle
Smooth ER
• Series of highly folded membranes that do
NOT contain ribosomes
• Produce lipids and transports to golgi
• Releases lipids to be transported into
vesicle
• Found in both plants and animals
Golgi Bodies
• Flattened tubular
membranes
• Sorts, stores,
modifies, packages,
and transports
materials.
Golgi cont..
• Releases materials into vesicle to be
transported to other areas of the cell
or to be released from the cell
• Found in plant and animal cells
Chloroplast
• Large green
structures that contain
chlorophyll (green
pigment)
• Captures light energy
and converts it to
chemical energy
(glucose)
Found in plants only
http://library.thinkquest.org/12413/structures.html
Mitochondria
• Rod-shaped.
• Has a greatly folded inner
membrane to increase
surface area
• Site for cellular respiration,
converts chemical energy
(glucose) to usable energy
(ATP)
• Found in plants an animals
Vacuoles
• Sacs in the cytoplasm
used for temporary
storage
• Stores food, water,
wastes and other
materials
http://library.thinkquest.org/12413/structures.html
• Plant cells have a large Central Vacuole
that makes a plant turgid
• Vacuoles are found in plant and animal
cells
Lysosome
• Small round sacs in
cytoplasm that contain
enzymes
• Break down excess or
worn out organelles,
food, particles, old cells,
viruses, and bacteria.
• Found in animal cells
only
Cytoskeleton
• Support structure composed of tiny rods
(microfilaments) and filaments
• Forms framework for the cell. Maintains
cells shape and assist organelles in
moving from place to place. Microtubules
that extend outside of the cell membrane
cilia and flagella
Centriole
• A cylinder shaped structure
• Aids in cell division
• Found in animal cells only