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Figure 4.6a
Structure Meets Function
in a Cell
• Plasma Membrane and Cell Surface
• Nucleus and Ribosomes
• Endomembrane System
–
–
–
–
•
•
•
•
Endoplasmic Reticulum (ER)
Golgi Body
Lysosomes
Vacuoles
Energy Conversion: Chloroplasts and Mitochondria
Cytoskeleton
Cilia and Flagella
Plastids
Plasma Membrane
– The plasma membrane separates the living
cell from its nonliving surroundings.
Cell Surfaces
– Most cells secrete materials for coats of one
kind or another
• That are external to the plasma membrane.
– Extracellular coats
• help protect and support cells
• facilitate interactions between cellular neighbors in
tissues
– Plant cells and bacterial cells have cell walls,
• Which help protect the cells, maintain their shape,
and keep the cells from absorbing too much water.
– Animal cells have an extracellular matrix,
• Which helps hold cells together in tissues and
protects and supports them (not shown).
Structure Meets Function
in a Cell
• Plasma Membrane and Cell Surface
• Nucleus and Ribosomes
• Endomembrane System
–
–
–
–
•
•
•
•
Endoplasmic Reticulum (ER)
Golgi Body
Lysosomes
Vacuoles
Energy Conversion: Chloroplasts and Mitochondria
Cytoskeleton
Cilia and Flagella
Plastids
The Nucleus:
Genetic Control of the Cell
– The nucleus is the manager of the cell.
• Genes in the nucleus store information necessary to
produce proteins.
Prokaryotes do not have nuclei.
Their genes (on DNA) are in the nucleoid region
Structure and Function of the Nucleus
– The nucleus is bordered by a double membrane
called the nuclear envelope.
• It contains chromatin and a nucleolus.
Chromatin:
long strands
of DNA and
associated
proteins.
The DNA
stores the
genetic
information
(genes).
Nucleolus:
assembles
ribosomes
Ribosomes: Protein Synthesis
– Ribosomes are responsible for protein synthesis.
How DNA Controls the Cell
– DNA controls the cell by transferring its coded
information into RNA.
• The information in the RNA is used to make proteins.
Structure Meets Function
in a Cell
• Plasma Membrane and Cell Surface
• Nucleus and Ribosomes
• Endomembrane System
–
–
–
–
•
•
•
•
Endoplasmic Reticulum (ER)
Golgi Body
Lysosomes
Vacuoles
Energy Conversion: Chloroplasts and Mitochondria
Cytoskeleton
Cilia and Flagella
Plastids
The Endomembrane System: Manufacturing,
Distributing, and Storing Cellular Products
Not found in bacterial cells!
The Endoplasmic Reticulum
– The endoplasmic reticulum (ER)
• Produces an enormous variety of molecules.
• Is composed of smooth and rough ER.
Smooth ER
– The smooth ER lacks the surface
ribosomes of rough ER and produces
lipids, including steroids.
Rough ER
– The “roughness” of the rough ER is due to
ribosomes that stud the outside of the ER
membrane.
– The functions of the
rough ER include:
• Producing two types of
membrane proteins
– Membrane proteins
– Secretory proteins
• Producing new
membrane
Rough ER
– The “roughness” of the rough ER is due to
ribosomes that stud the outside of the ER
membrane.
– The functions of the
rough ER include:
• Producing two types of
membrane proteins
– Membrane proteins
– Secretory proteins
• Producing new
membrane
– After the rough ER synthesizes a molecule, it
packages the molecule into transport vesicles.
These vesicles head off to the Golgi Apparatus…
The Golgi Apparatus
– The Golgi apparatus
• Works in partnership with the ER.
• Refines, stores, and distributes the chemical
products of cells.
Lysosomes
– A lysosome is a
membraneenclosed sac that
contains
digestive
enzymes to
break down
macromolecules.
Vacuoles
– Vacuoles are membranous sacs.
• Contractile vacuoles of protists get rid of excess
water.
• Central vacuoles of plants store nutrients, absorb
water, contain some pigments or poisons.
– A review of the endomembrane system
An amazing
system that
manufactures,
distributes, and
stores cellular
products!
Structure Meets Function
in a Cell
• Plasma Membrane and Cell Surface
• Nucleus and Ribosomes
• Endomembrane System
–
–
–
–
•
•
•
•
Endoplasmic Reticulum (ER)
Golgi Body
Lysosomes
Vacuoles
Energy Conversion: Chloroplasts and Mitochondria
Cytoskeleton
Cilia and Flagella
Plastids
Energy Conversion:
Chloroplasts & Mitochondria
– Cells require a constant energy supply to do all
the work of life.
Not found in bacterial cells!
Chloroplasts
– Chloroplasts are the sites of
photosynthesis, the conversion of light
energy to chemical energy.
All little green
circles are
chloroplasts
Cell walls
Mitochondria
– Mitochondria are the sites of cellular
respiration, which involves the production
of ATP from food molecules.
Structure Meets Function
in a Cell
• Plasma Membrane and Cell Surface
• Nucleus and Ribosomes
• Endomembrane System
–
–
–
–
•
•
•
•
Endoplasmic Reticulum (ER)
Golgi Body
Lysosomes
Vacuoles
Energy Conversion: Chloroplasts and Mitochondria
Cytoskeleton
Cilia and Flagella
Plastids
The Cytoskeleton:
Cell Shape and Movement
– The cytoskeleton consists of a network of fibers.
Also, recently found in bacterial cells!
Cytoskeleton
– Mechanical support
to maintain cell
shape
– Can change cell
shape to allow
movement
Structure Meets Function
in a Cell
• Plasma Membrane and Cell Surface
• Nucleus and Ribosomes
• Endomembrane System
–
–
–
–
•
•
•
•
Endoplasmic Reticulum (ER)
Golgi Body
Lysosomes
Vacuoles
Energy Conversion: Chloroplasts and Mitochondria
Cytoskeleton
Cilia and Flagella
Plastids
Cilia and Flagella
– Cilia and flagella are motile appendages.
Not found on most plant cells!
– Flagella propel the cell in a whiplike
motion.
– Cilia move in a coordinated back-and-forth
motion.
Structure Meets Function
in a Cell
• Plasma Membrane and Cell Surface
• Nucleus and Ribosomes
• Endomembrane System
–
–
–
–
•
•
•
•
Endoplasmic Reticulum (ER)
Golgi Body
Lysosomes
Vacuoles
Energy Conversion: Chloroplasts and Mitochondria
Cytoskeleton
Cilia and Flagella
Plastids
Plastids
Membrane-bound organelles found only in plants
Amyloplast
stores
starch
(stained
blue with
iodine)
All little green
circles are
Cell walls
chloroplasts
Chloroplast performs
photosynthesis
Chromoplast
stores
pigments
(little orange
circles)