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Explain what the cell theory is.
Describe a cell and the components that make it
up.
List the different cell organelles and what their
functions are.
Describe the structure of the plasma membrane.
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Cells are the structural “building blocks” of all
plants & animals
Cells are produced by the division of
preexisting cells
Cells are the smallest structural units that
perform all vital functions
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> 200 different types of cells
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Major components
◦ Plasma membrane
◦ Nucleus
◦ Cytoplasm
Chromatin
Nucleolus
Nuclear
envelope
Smooth endoplasmic
reticulum
Nucleus
Plasma
membrane
Cytosol
Lysosome
Mitochondrion
Centrioles
Rough
endoplasmic
reticulum
Ribosomes
Golgi
apparatus
Microvilli
Secretion being
released
from cell by
exocytosis
Microfilament
Microtubule
Intermediate
filaments
Peroxisome
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Physical isolation
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Regulates exchange with environment
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Sensitive to environment
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Connect with other cells
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Structure
◦ Phospholipid bilayer
 Hydrophilic heads orientate themselves towards the
extracellular and intracellular fluid
 Hydrophobic tails orientate themselves inward
Outside cell
Cytoplasm
(inside cell)
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Integral proteins
◦ Channels
◦ Carriers
◦ Receptors
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Peripheral proteins
◦ Anchoring
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Glycocalyx – serve
as biological
markers
◦ Self vs. non-self
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Cholesterol –
stabilizes membrane
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Tight junctions – impermeable junction formed
by interlocking proteins encircling the cell
◦ Keeps out enzymes, acids, microorganisms
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Desmosomes – anchoring junctions
◦ Prevent cells that are subjected to mechanical
stress from being pulled apart
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Gap Junctions – cells
are connected by
hollow cylinders
◦ Allows chemical
communication
between cells
◦ Found in smooth and
cardiac muscle
Q) What are the nonpolar parts of
phospholipids?
 a) phosphate-containing head groups
 b) fatty acid tail groups
 c) Both the head and tail groups are
nonpolar.
 d) Neither the head nor tail groups are
nonpolar.
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The correct answer is (b)
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2 main types of membrane transport
◦ Passive process- No energy required
 Simple Diffusion
 Facilitated Diffusion
 Osmosis
◦ Active process- Requires energy
 Carrier Mediated Active Transport
 Vesicular Transport
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Understanding diffusion
 Molecules or ions scatter throughout
environment
 High to low concentration
 Rate depends on gradient, temperature,
and size of molecules
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Simple diffusion
◦ Diffuse directly through
phospholipid bilayer
◦ Concentration gradient
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Ex: O2 blooddiffuses
into cells
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Facilitated diffusion
◦ Substances bind to carrier proteins
◦ Specific to molecule
 Example: glucose
◦ Can be saturated
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The net movement of water through a
selectively permeable membrane.
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Hypotonic solutions
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Hypertonic solutions
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Isotonic solutions
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Uses ATP to move
solutes across a
membrane
against
concentration
gradient
Requires carrier
proteins
Q) If the solute concentration is greater inside
of the cell than outside the cell, water will
move by osmosis
 a) into the cell.
 b) out of the cell.
 c) into and out of the cell at the same rate
resulting in no net water movement.
 d) All of these answer choices are correct.
 e) None of these answers are correct.
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The correct answer is (a)
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Transport of large particles and fluid across
plasma membranes within vesicles
◦ Exocytosis
◦ Endocytosis
 Phagocytosis
Pinocytosis
Q) Which of the following is the transport
process by which gases, like O2 and CO2, move
through a membrane?
 a) osmosis
 b) active transport
 c) secondary active transport
 d) simple diffusion
 e) endocytosis
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The correct answer is (d)
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Material between the nucleus and the plasma
membrane
Major elements
◦ Cytosol
◦ Organelles
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Specialized cellular compartments
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Membranous
◦ Mitochondria, peroxisomes, lysosomes,
endoplasmic reticulum, and Golgi apparatus
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Nonmembranous
◦ Cytoskeleton, centrioles, and ribosomes
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Mitochondria
◦ Double membrane structures with infoldings called
cristae
◦ Provides ATP for cellular energy
◦ “Powerhouses” of the cell
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Nucleus
◦ Contains genetic material (DNA)
◦ Nuclear envelope – double membrane separating the
nucleus from the cytoplasm
◦ Nucleolus – dark stained body, site of ribosome
production
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Endoplasmic reticulum (ER)
◦ Network of intracellular membranes connected to
nuclear envelope of nucleus
◦ Rough Endoplasmic Reticulum
 Studded with ribosomes
 Manufactures all secreted
proteins
◦ Smooth Endoplasmic
Reticulum
 Lipid synthesis, calcium
storage
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Golgi apparatus
◦ Stack of flat membranous sacs and vesicles
◦ Packages proteins for transport depending on
their final destination
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Secretory vesicles
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Membrane renewal vesicles
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Lysosomes – remain in cytoplasm
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Lysosomes
◦ Membranous sac of digestive enzymes
◦ Digest nonusable and damaged organelles
◦ Destroy bacteria and other foreign materials
within the cell
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Peroxisomes
◦ Membranous sacs of oxidase and catalase
(enzymes)
◦ Detoxify harmful substances like alcohol and
formaldehyde
◦ Break down free radicals (highly reactive
chemicals)
oxidase
catalase
↓
↓
Free radical → H2O2 → H2O
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Ribosomes
◦ Small dark bodies made of protein and RNA
◦ Site of protein synthesis
◦ Found free in the cytoplasm and attached to rough
endoplasmic reticulum
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Cytoskeleton – the skeleton of the cell
◦ Provides the cell with an internal framework
◦ Supports organelles
◦ Intracellular motility
◦ Consists of
 Microfilaments
 Intermediate filaments
 Microtubules
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Microtubules
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Hollow tubes made of protein
Radiate out from a region near the nucleus
Anchor and move organelles
Form mitotic spindles during cell division
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Microfilaments
◦ Concentrated under the plasma membrane
◦ Strengthens cell surface
◦ Function in cell mobility and shape
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Intermediate filaments
◦ Composed of proteins with high tensile
strength
◦ Resist pulling forces on the cell
◦ Helps form desmosomes
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Centrioles
◦ Rod-shaped bodies located near
the nucleus
◦ Composed of short microtubules
arranged in a cylindrical structure
◦ Direct formation of mitotic spindle
during cell division
◦ Form the bases of cilia and
flagellum
 Cilia
 Hair-like extension on the free surface
of the cell
 Move substances in one direction
along cell surface
 Flagellum
 Similar to cilia but single and much
longer
 Propels the cell itself
Q) Which of the following transport process
uses vesicles formed at the plasma membrane
to take up extracellular substances and import
them into the cell?
 a) endocytosis
 b) exocytosis
 c) facilitated diffusion
 d) osmosis
 e) Both endocytosis and exocytosis.
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The correct answer is (a)
 Questions?