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Cell Theory
• All living things are composed of cells
• Cells are the basic unit of structure and
function in living things
• All cells come from preexisting cells
by way of:
binary fission (prokaryotes)
mitosis (eukaryotes)
CELLS
Prokaryote
Eukaryote
• 0.1-10 um
• 10-100 um
• No Nucleus
• True Nucleus
• Simple cellular
structure
• Complex organelle
structure
• 70s ribosomes
• 80s ribosomes
Prokaryotic Cells
• Believed to be the first
cells to evolve.
• Lack a membrane
bound nucleus and
organelles.
• Genetic material is
naked in the cytoplasm
• Ribosomes are only
organelle.
•
Http.micro.magnet.fsu.edu/cells.html
Eukaryote Cell Structure
Cells vary greatly in size and shape
Basic structure
• Cell membrane: the outer boundary
• Nucleus: the control center
• Cytoplasm: the space in between
membrane and nucleus
Overview of an animal cell
Overview of a plant cell
NUCLEUS
see fig 7.6
• Found only Eukaryotes
• Nuclear envelope: double membrane with
pores
• Nucleolus: RNA & proteins - makes
ribosomes
• Chromosomes: (condensed chromatin)
– DNA: (contains genetic information)
– Histones: proteins that organize the DNA &
provides structure for chromosomes
NUCLEUS
The nucleus and its envelope
CYTOPLASM
• Cytoplasm - area between nuclear
membrane and cell membrane
• Cytoplasmic organelles - tiny structures
that perform a specific function within
the cell
MITOCHONDRIA
• Double membrane
-outer for protection
-inner folded to increase surface area
• Function: produces ATP from glucose
• Contains DNA and 70S ribosomes
MITOCHONDRIA
CHLOROPLAST
• Double membrane for protection
• Third membrane turns radiant energy
into chemical energy (glucose). The
site of Photosynthesis
• Contain DNA and 70S ribosomes
CHLOROPLAST
RIBOSOME
• One of the smallest organelles
• Can be "free" in the cytoplasm or attached to ER
• Composed of RNA and protein
• Function: Synthesize proteins
• Eukaryotic – 80S / Prokaryotic – 70S
RIBOSOME: functions in protein synthesis
Ribosome
Http://cellbio.utmb.edu/cellbio/ribosome.htm
ENDOMEMBRANE SYSTEM
System of interrelated membranes:
 some membranes are directly connected
 some are functionally connected.
•
•
•
•
•
•
•
Nucleus (nuclear envelope)
Rough Endoplasmic Reticulum
Smooth Endoplasmic Reticulum
Golgi Apparatus
Lysosome
Vacuole
Cell membrane aka plasma membrane
Rough Endoplasmic Reticulum
• complex network of sacs
• Ribosomes are attached to the surface
• Functions in protein synthesis and the
modification of proteins destined for
export
• Modifies and Transports material
throughout the inside of the cell
Rough Endoplasmic Reticulum
• Network of continuous
sacs, studded with
ribosomes.
• Manufactures, processes, and transports
proteins for export
from cell.
• Continuous with
nuclear envelope.
•
Http://micro.magnet.fsu.edu/cels/animal/endoplasmi
creticulum.html
Rough Endoplasmic Reticulum
Http://cellbio.utmb.edu/cellbio/ribosome.htm
Smooth Endoplasmic Reticulum
• Similar in appearance to rough ER, but
without the ribosomes.
• Involved in:
• The production of lipids
• Carbohydrate metabolism
• Detoxification of drugs and poisons.
• Modifies and Transports material
throughout the inside of the cell
•
Http://micro.magnet.fsu.edu/cells/animals/endoplasmicreticulum.html
GOLGI APPARATUS
• Flattened membranous structure
• Function:
– Modify or “package” proteins for storage
in the cell or secretion outside of the cell
• Can be associated with the cell membrane
Golgi Apparatus
LYSOSOMES
• Small membrane bound structures containing
digestive enzymes & acids.
• Produced by the Golgi
• Function: breakdown of cellular material that
has outlived its usefulness
• Also involved in the breakdown (digestion) of
lipids, carbohydrates, and proteins into small
molecules that the rest of the cell can use.
• Cell breaks down if lysosome explodes
• NOT FOUND IN PLANTS
The formation and functions of lysosomes
Lysosome
VACUOLES
• Saclike structures
• Function: store various materials, such as
water, salts, proteins, carbohydrates
• An example is the central vacuole in
plants that provides structural support
Central Vacuole
CYTOSKELETON
• The supporting structure that gives
Eukaryotic cells their shape and internal
organization.
• Composed of:
– Microtubules & Microfiliments
MICROTUBULES AND MICROFILAMENTS
MICROFILIMENTS
Thin protein threads (actin) that run from
one side of cell to the other
Functions:
• Provides a flexible framework that supports
the cell
• Allow movement of the cytoplasm (cytoplasmic
streaming). Assembly and disassembly of
microfiliments allows cells, such as amoebas, to
crawl along surfaces.
MICROFILIMENTS
Provide the structure for the cytoskeleton
MICROTUBULES
Hollow tubes made of protein (tubulin)
Functions:
1) Maintain cell shape
2) Involved in cell division (mitotic spindle)
3) Structure that makeup Centrioles, which help to
organize cell division see fig. 7.6
4) Involved in cell movement (cilia and undulipodia)
see fig. 7.11 (9+2 pattern in cilia)
CENTRIOLES
Centrioles: act as “anchors” for the mitotic spindle during cell division
found only in animal cells not found in plant cells
CILIA
• Cilia: short hair-like projections that allow
movement of a cell or material near a cell
CILIA on a
PARAMECIUM
UNDULIPODIA
• Extra cellular projections
• Involved in cell propulsion
• Eukaryotic Undulipodia-composed of 9
pairs of microtubules around a central
pair
CILIA & UNDULIPODIA (FLAGELLA)
CELL SPECIALIZATION
• Some cells are designed to perform a
particular function
• They may have more or less of a particular
organelle based on their special needs
i.e.
• pancreatic cells- lots of rough ER and
Golgi
THE END