Download Prokaryotic Cells

Cell Structure and Organelle
Function
What Is the Cell Theory?
Why are cells small?
Cheek cells.
microscopyu.com
All Cells Share Common Features
• Members of Bacteria, Eukaryota, and
Archaea share common cellular features.
Plasma Membrane
• A plasma membrane encloses all cells and
regulates material flow
Cytoplasm
• Cytoplasm
– Interior fluid
– Where cell’s metabolic reactions occur
– Contains organelles
– Fluid portion (cytosol) contains water, salts,
and organic molecules
Genetic Material
• All cells use DNA (deoxyribonucleic acid) as
a hereditary blueprint
• All cells use RNA (ribonucleic acid) to copy
DNA to make proteins
All Cells Share Common Features
• All cells obtain energy and nutrients from the
environment
• All cells use common building blocks to
build the molecules of life
There Are Two Basic Cell Types
• Cells are either:
– Prokaryotic
• Before nucleus
– Eukaryotic
• True nucleus
• Membrane
bound organelles
www.ucmp.berkeley.edu/
alllife/eukaryota.html
Eukaryotic Cells
• Eukaryotic cells > 10 µm long
• Have membrane-enclosed organelles that
perform specific functions
Cell Walls
The Cytoskeleton
The Cytoskeleton
• Main functions of cytoskeleton
– Maintaining and changing cell shape
– Providing for cell movement
– Providing for organelle movement, including
vesicle endo- and exocytosis
– Facilitating cell division in chromosome
movements and cytokinesis
Cilia and Flagella
• Cilia and flagella are extensions of the
plasma membrane
• Cilia
– Short, hair-like structures, numerous
• Flagella
– Longer, whip-like, fewer in number
• Functions
– motility
– Cilia - create currents of moving fluid in
environment
The Nucleus
• Control center of cell
• Contains genetic
information (in
eukaryotes)
• Contains:
– Nuclear envelope
– Chromosomes
– Nucleolus
System of Membranes
• Membrane system includes the plasma
membrane and organelle membranes
Vesicles
• Vesicles
– membranous sacs that carry substances
throughout the cell
Endoplasmic Reticulum
• A series of enclosed, interconnected
channels within cell
• Two forms of ER
– Smooth ER
– Rough ER
Golgi Apparatus
• a set of stacked flattened sacs
Fate of Substances Made in the
Membrane System (3)
1. Secreted proteins made
in RER, travel through
Golgi, then are exported
through plasma
membrane
Fate of Substances Made in the
Membrane System (3)
2. Digestive proteins
made in RER, travel
through Golgi, and
are packaged as
lysosomes for use
in cell
• Lysosomes fuse
with food
vacuoles and
digest food into
basic nutrients
Fate of Substances Made in the
Membrane System (3)
3. Membrane proteins and lipids made in ER,
travel through Golgi, and replenish or enlarge
organelle and plasma membranes
Vacuoles Serve Many Functions
• Fluid-filled sacs with a
single membrane
• Contractile vacuoles
in freshwater
organisms used to
collect and pump
water out
Vacuoles Serve Many Functions
• Plant central vacuoles
used in several ways
• Maintain water balance
• Store hazardous
wastes, nutrients, or
pigments
• Provide turgor
pressure on cytoplasm
to keep cells rigid
Mitochondria Extract Food Energy
• Mitochondria - round, oval, or tubular sacs
of double-membranes
– Inner membrane is folded into cristae
– Intermembrane compartment lies between
inner and outer membranes
– Matrix space within inner membrane
Mitochondria Extract Food Energy
• Mitochondria may be remnants of free-living
prokaryotes (endosymbiotic hypothesis)
thebrain.mcgill.ca
Plants Use Plastids for Storage
•
Plastids found only in plants and
photosynthetic protists
–
Ex. chloroplasts
•
Surrounded by a double membrane
•
Functions
– Storage for photosynthetic products
– Storage of pigment molecules
Chloroplasts
• Chloroplasts - specialized organelles
surrounded by a double membrane
– Outer membrane
– Inner membrane encloses the stroma space
• Stacked hollow membranous sacs (grana)
within stroma are called thylakoids
Chloroplasts
• Contain chlorophyll and other pigments
that capture sunlight, CO2, and water and
are used to make sugar (photosynthesis)
Prokaryotic Cells
•
Most prokaryotic cells (bacteria) are < 5
µm long
Prokaryotic Cell Wall
•
A stiff cell wall is usually present
Prokaryotic Cells
•
Motility by flagella
•
May have capsules
or slime layers on
their surfaces
•
E. Coli with fimbriae. mgm.stonybrook.edu
Pili and fimbriae are
protein projections in
some bacteria that
further enhance
adhesion
E. Coli with fimbriae.
med.upenn.edu
Prokaryotic Cells
•
Cell shapes: bacilli, cocci, or spirilla
abe.ufl.edu
Prokaryotic Cells
•
•
Single, circular chromosome of DNA in
area called the nucleoid
Small rings of DNA (plasmids) located in
the cytoplasm
Prokaryotic Cells
•
•
•
No nuclear
membrane or
membrane-bound
organelles present
Some have internal
membranes used to
capture light
Cytoplasm may
contain food
granules
The End