Transcript Cell Structure and Function

Cells Structure and Function
Cells, the units of structure and function of
living organisms, come in two main categories
based on their structural complexity.
– Prokaryotic cells are small
and simple; do not have a
nucleus to store DNA, the
genetic material; and lack
membrane bound
organelles.
– Eukaryotic cells are large
and complex; DNA is
stored in a nucleus, and
there are many membrane
bound organelles to
conduct the functions of the
cell.
All Organisms Are Composed of Cells
Eukaryotic Cells
•Animals
•Plants
•Fungi
•Protists
Prokaryotic Cells
•Bacteria
•Archea
Prokaryotic Organisms
• Bacteria and Archea are
prokaryotic organisms.
• Unicellular and very
simple, these prokaryotic
organisms are vital to life
on Earth due to their
roles in ecosystems.
• Prokaryotic cells have
ribosomes to make
proteins and their DNA is
in a nucleoid region.
• Pilli and flagella function
for attachment and
motility
In Eukaryotic Organisms Cells Have
Organelles
• Unicellular Protists
• Multicellular: Animals, Plants, Fungi
• Eukaryotic cells are
compartmentalized to increase
metabolic efficiency. They contain
many cellular organelles to conduct
specific functions.
• Organelles have the surface area
(room required to carry out work) and
the materials required for specific
functions of the cell.
All Eukaryotic Cells Have Similarities
All eukaryotic cells have many membrane bound
organelles in common.
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Plasma membrane – cell’s outer boundary
Nucleus – site of DNA replication and transcription
Endoplasmic Reticulum – involved in synthesis and transport
Mitochondria – site of intracellular cellular respiration
Gogi apparatus – involved in chemical modification and packaging
Cytoskeleton – involved in structure and motility
Plasma Membrane
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The plasma membrane is found in all types of cells.
It is the boundary (border), which defines the cell.
It controls the entrance and exit of materials.
It provides surface area for many of the cells enzymatic functions.
Organelles have membranes, which are very similar to the plasma
membrane.
Nucleus
• The nucleus
houses DNA, the
genetic material.
• The nucleus
contains an
organelle, the
nucleolus, which
deals with RNA.
• The nucleus has
pores that
selectively allow
the entrance
and/or exit of
substances
Two Types of Endoplasmic Reticulum
• RER is the Rough
Endoplasmic Reticulum,
which has ribosomes.
Within the RER proteins
are modified into
functional proteins and
packed into transport
vesicles.
• SER is the Smooth
Endoplasmic Reticulum,
which has no ribosomes.
Within the SER lipids are
synthesized. It also
detoxifies substances. It
stores Calcium ions for
muscle contractions
Gogi Apparatus/Body/Complex
• Receives and modifies substances synthesized in
the endoplasmic reticulum.
• Substances are packaged into vesicles to be used
by the cell or transported out of the cell.
Lysosomes
• Lysosomes contain
enzymes that fuse
with food vacuoles for
digestion.
• Within white blood
cells of the immune
system, enzyme filled
lysosomes fuse with
bacteria filled vacuoles
and digest the
bacterial cells.
• Lysosomes fuse with
waste vacuoles or
vesicles and recycle,
salvageable materials
for the cell.
Vacuoles
• Vacuoles are storage
vesicles, which may
contain, water, wastes,
toxins, food, chemicals, and
any other materials that the
cells need to store.
• Vacuoles are essential to
maintain homeostatic
balance in cells
• Vacuoles increase the
efficiency of the cells by
providing a high degree of
compartmentalization .
Endomembranes
• Together, the nuclear envelope; the endoplasmic reticulums, both
smooth and rough, the Gogi Apparatus; vesicles; lysosomes; and
vacuoles; compose the endomembrane system of the cell. All of these
organelles are physically or strategically connected and function in
tandem and synchrony.
Mitochondria
• Two main stages of
cellular respiration,
the Kreb’s Cycle and
the Electron
Transport Chain,
occur in the
mitochondria in order
to transform energy
from the food that
organisms eat into
chemical energy in
the bonds of ATP.
Cytoskeleton
• Composed of fibrous proteins of various diameters,
the cytoskeleton is responsible for support and
movement of organelles and the cell.
Ribosomes
• Ribosomes are not
membrane bound
organelles. Rather they
are composed of rRNA.
• Ribosomes are involved
in the synthesis of
proteins along with other
types of RNA, mainly
mRNA and tRNA.
• Ribosomes are found in
both eukaryotic and
prokaryotic cells.
Cells Are Models of Organization and
Efficiency
• Cells illustrate
the principle of
emergent
properties:
the whole is
greater than
the individual
part.