Do Now
Cell membranes are composed of proteins and a type of
lipid called________________.
 Phospholipids only have 2
________ ________ chains.
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
Is the phospholipid bilayer rigid or fluid-like?
I. The Cell Builds a Diversity
of Products
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OBJECTIVES
Identify the role of the nucleus
Describe how the functions of ribosomes,
endoplasmic reticulum, and the Golgi
apparatus are related.
Distinguish between the functions of vacuoles
and lysosomes
Summarize the path of cellular products
through the membrane.
A. Structure and Function of the
Nucleus
• The nucleus of a eukaryotic cell contains
most of the cell’s DNA.
• The information stored in DNA directs the
activities of the cell.
• DNA is attached to proteins, forming long
fibers called chromatin.
Nucleus
• Nuclear envelope- surrounds the nucleus
• Nuclear pores- openings where
substances move from the nucleus into the
cytoplasm
• Nucleolus- a dense mass within the
nucleus where ribosomes are made.
B. Ribosomes
• Ribosomes- clusters of proteins and
nucleic acids.
• Ribosomes are responsible for making
proteins.
• Ribosomes are either attached to
endoplasmic reticulum or float around in
the cytoplasm.
Ribosomes attached to E.R.
C. Assembly and Transportation
• Endoplasmic Reticulum~
the site of cellular chemical reactions.
• manufactures and transports molecules
within a cell.
- Rough E.R.- studded with ribosomes.
- makes proteins
- Smooth E.R.- lacks ribosomes
- makes and stores lipids
1. Rough E.R.
• The ribosomes produce
– proteins that are inserted into the membrane
– proteins that are packaged in vesicles and
exported by the cell.
• Example: Salivary glands secrete a lot of
protein (enzymes) into your mouth… so
these cells contain a lot of Rough E.R.
2. Smooth E.R.
• This ribosome-free portion of the
membrane
• contains enzymes that perform various
functions like building lipids
• Example: Ovaries and Testes produce sex
hormones (lipids-cholesterol)…so these
cells contain a lot of smooth E.R.
Endoplasmic Reticulum
D. The Golgi Apparatus
• Proteins leave the Rough E.R.
– Transported in vesicles to the:
• Golgi apparatus~
modifies, stores, and ships proteins and
other molecules to their final destination.
E. Vacuoles &
Storage
• Vacuoles~
membrane-bound sacs
Temporary storage of
undigested nutrients,
salt, water, pigments,
waste, poisons.
Plant Vacuole
F. Lysosomes & Recycling
• Lysosomes~ membrane-bound sacs that
contain digestive enzymes
– Break down
• worn out organelles
• food particles
• viruses and bacteria
Membrane
Pathways in a Cell
DO NOW
1.
2.
3.
4.
What is the structural difference between
rough and smooth endoplasmic reticulum?
Where can you find most of the cell’s DNA?
What organelle is responsible for
modifying, storing, and shipping proteins?
What organelle contains enzymes for
breaking down food and bacteria?
II.
Chloroplasts and Mitochondria
OBJECTIVE:
COMPARE AND CONTRAST THE FUNCTIONS
OF CHLOROPLASTS AND MITOCHONDRIA
A. Chloroplasts~
– found only in plant cells and some protists
– capture light energy and convert it to chemical energy
through photosynthesis
• Plastids~
– plant organelles that are used for storage of
starches, lipids, or pigments.
– Example: chloroplast
• Chlorophyll~
– green pigment located in thylakoid discs of
chloroplast
– traps light energy
– Granum~ stack of thylakoids
– Stroma~ fluid surrounding the granum
Light-absorbing chlorophyll molecules are present in
thylakoid discs that fill the chloroplast.
B. Mitochondria- “powerhouse”
– (found in plant and animal cells)
– site of cellular respiration
– converts energy so that it is useful for powering
cellular work
Mitochondria are the powerhouses of the cell. They take in fuel
molecules derived from sugars and fats, harvest the energy in
their chemical bonds with the aid of oxygen, and spit out ATP.
III. An internal skeleton supports the
cell and enables movement
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OBJECTIVES:
Describe the roles of the cytoskeleton in cell
movement
Compare and contrast the functions of
flagella and cilia
Explain why a cell can be described as a
coordinated unit
INTRODUCTION

A cell has its own internal support system that enables it
to move, support organelles, and maintain shape.
A. Cytoskeleton~
– a network of protein fibers extending throughout the
cytoplasm.
• Two types of fibers:
– Microtubules- straight, hollow tubes
– Give rigidity and organization to cell
– EX: movement of lysosomes
to reach & fuse with a food vacuole
– Ex: centrioles
» Important for cell division
– Microfilaments- thinner, solid rods
– Allow cells to move & change shape
– Ex: movement of amoebas
– Ex: muscle fibers
» Involved in muscle contraction
B. Organelles for Movement
1. Flagella- long, thin, whip-like
structures that enable cells to move
– EX: sperm
• (S-shaped motion)
2. Cilia- shorter & more numerous than flagella
– Ex: cells lining your windpipe
• cilia sweep mucus and trapped debris out of your lungs
• (back-and-forth motion)
Sperm Cells with Flagella 
 Bronchioles lined with cilia
The Cell as a Coordinated Unit
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A cell is a living unit
that is greater than the
sum of its parts.
A cell can only work
when all of its
organelles work
together.
A white blood cell defends the body against
infections by ingesting bacteria
1.
2.
3.
4.
5.
6.
WBC moves toward bacteria using cytoplasmic
extensions
WBC engulfs bacteria
Bacteria is destroyed by lysosomes that were produced
by E.R. and Golgi apparatus
Ribosomes made the proteins of the cytoskeleton and
the enzymes inside the lysosomes
The production of these proteins was programmed by
messages dispatched from DNA in nucleus
All these processes require ATP, which is supplied by
mitochondria