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CHAPTER 3: Cells, Tissues, and Cancer Biology
Overview of Cellular Basis of Life
 Primarily made of 4 main elements
o
o
o
o
o
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CARBON
HYDROGEN
OXYGEN
NITROGEN
PHSOPHORUS
Living cells are about 60% water.
Cells are constantly bathed in a saltwater-like solution called INTERSTITIAL FLUID.
o All exchanges between CELLS and BLOOD are made through this fluid.
Cells vary in anatomy. Describe below
STRUCTURE defines FUNCTION. Organelles present? Size? Shape? Location in the
body?

Cells vary in physiology. Describe below
Ability to move throughout the blood/body? Products made by the cell that affect other
cells? Ability to communicate?
Anatomy of the GENERALIZED Cell
 Cells are not all the same, although they share general structures
 All cells have three main regions
o Nucleus
o
o
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Cytoplasm
Plasma Membrane
The Nucleus: Control center of the cell
o Contains genetic material (DNA)
o Three regions
 Nuclear envelope (membrane)
 FUNCTION:

Control what enters/exits the nucleus
CHARACTERISTICS:
Phospholipid bilayer with pores (openings) that allow for movement
in/out.

Nucleoli
 FUNCTION:
Production of ribosomes

CHARACTERISTICS:
Dark-staining round body.

Chromatin
 FUNCTION:
DNA; carries instructions for cell structure and function through
production of proteins.

CHARACTERISTICS:
o
o
Cell dividing (Mitosis) DNA is condensed into “X” shaped
CHROMOSOMES.
Cell not dividing (Interphase) DNA is present as uncoiled
CHROMATIN (spaghetti on a plate)

The Plasma Membrane
o Barrier for CELL CONTENTS and MOVEMENT.
o Composed of a DOUBLE PHOSPHOLIPID bilayer
o Sketch a side view of a double phospholipid bilayer below.
o Contains:
 Water-LOVING: HYDROPHILIC HEADS


Water-HATING: HYDROPHOBIC TAILS
Also contains:
 Proteins: Channels
 Cholesterol: makes cells more rigid (more cholesterol, more rigid)
 Glycoproteins: glycocalyx; self vs non-self recognition.
o Plasma Membrane Specializations
 Microvilli – increased surface area of cell membrane for absorption

Membrane junctions

Tight junctions: glued together; cells of digestive system.

Desmosomes : bound together, somewhat impermeable; skin
cells.

Gap junctions : allows for communication between cells.
 Cytoplasm: Cytoplasm is the material outside the nucleus and inside the plasma
membrane.
o Contains three major elements
 Cytosol: jelly-like protein matrix that gives cell shape and volume.
Contains dissolved amino acids, electrolytes, and water.

Organelles: Metabolic machinery of the cell; “Little organs” that perform
functions for the cell

Inclusions: chemicals inside cytosol that serve specific functions.
Melanin is an inclusion chemical that allows for protection of skin/tanning.
Answer Questions, page 107
#14) Differentiate between a CELL and an ORGANELLE
A CELL is the smallest functioning unit of the human body. AN ORGANELLE is the tools that
the cell uses TO FUNCTION.
#15)
Although cells have differences, what FUNCIONAL abilities do ALL cells exhibit?
ALL CELLS can metabolize, reproduce, grow, respond to environment, move, digest food,
dispose of wastes.
ORGANELLE
Mitochondria
Contains own circular piece of DNA
GENERAL FUNCTION
Produce ATP (energy) from glucose
Ribosomes
Free in cytoplasm and attached on ER
Assemble proteins
Endoplasmic reticulum
Canal system for transport
2 forms, smooth and rough
Smooth - transport
Golgi Apparatus
Packages mainly lipids for transport
Lysosomes
Double membrane structure for protection
Contains digestive enzymes
Peroxisomes
Specialized lysosomes
Contains catalase to breakdown hydrogen
peroxide
Cytoskeleton
Cell support, structure, and framework
Centrioles
Creates spindle fibers during mitosis for
separation of chromosomes.
Specialized Structures
Cilia – moves substances over surface of cell
(respiratory cells)
Rough – transports proteins
Flagella – moves the cell itself (sperm)
Cell Diversity: 200 different cell types that vary in size, shape, and function

Cells that connect body parts: Fibroblasts and Red blood Cells (erythrocytes)

Cells that cover and line body organs: Epithelial cells

Cells that move organs and body parts: Skeletal muscle cells

Cells that store nutrients: Fat cells

Cells that fight disease: Macrophage (type of white blood cell)

Cells that gather info and control body functions: Nerve cell (neuron)
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Cells of reproduction: Oocyte (egg) and Sperm
Cell Physiology
Most cells have the ability to:
1) Metabolize: use nutrients to build new cell material, break down substances, and make ATP.
2) Digest food
3) Dispose of wastes
4) Reproduce
5) Grow
6) Move
7) Respond to a stimulus: irritability
Membrane Transport: movement of substances into and out of the cell. The Plasma membrane is
SELECTIVELY PERMEABLE; it allows some substances to pass through while excluding others.

Intracellular fluid: WITHIN THE CELL; nucleoplasm and cytosol. Small amounts of gases
(O2 and CO2), nutrients and salts dissolved in water.

Interstitial fluid: OUTSIDE OF CELL; rich and nutritious. Contains nutrients, hormones,
neurotransmitters, salts, and waste products. Cells must EXTRACT needed substances
from this fluid in order to maintain HOMEOSTASIS.
What happens to membrane permeability in UNHEALTHY cells? Explain below.
SELECTIVE PERMEABILITY is a property of healthy, functioning cells. When cells
are damaged or dying, they lose the ability to control the movement of substances across the
cell membrane therefore losing HOMEOSTASIS.
Two basic methods of transport
 Passive transport: No energy is required
 Active transport: Cell must provide metabolic energy (ATP)
Passive Transport Processes
 Diffusion: Particles tend to distribute themselves EVENLY within a solution.
o Movement is from HIGH concentration to LOW concentration.
o Molecules will diffuse through the plasma membrane if:
1) They are small enough to pass through pores (membrane proteins).
2) They can dissolve in the fatty portion of the membrane.
3) They are assisted by a membrane carrier.
Types of diffusion
o Simple diffusion: unassisted movement through the membrane. Solutes are lipidsoluble materials or small enough to pass through membrane pores
 What materials will pass through the membrane by SIMPLE DIFFUSION?
Lipid-soluble (fats, gases, some vitamins) or small enough to pass (ions)
through pores.
o Osmosis: simple diffusion of WATER.
o Facilitated diffusion
 Transports lipid-INSOLUBLE and large substances.
 Substances require a MEMBRANE carrier for passive transport.
*QUESTION: What type of molecules pass through the plasma membrane by diffusion? How is
diffusion beneficial to cells? What does it save?
DIFFUSION allows needed substances to move through the cell without the cell needing to
expend any energy in the form of ATP. Vital substances such as oxygen, carbon dioxide,
water, and glucose can move AS NEEDED by the cell.

Filtration: Water and solutes are forced through a membrane by fluid, or HYDROSTATIC
pressure.
Hydrostatic pressure is usually exerted by the BLOOD.
Filtration is necessary for the KIDNEYS to do their job properly.
Solute-containing fluid is pushed from a HIGHER- pressure area to a LOWER- pressure area.
Active Transport Processes: ATP is used for transport
 Needed when:
1) Substances are transported that are unable to pass by diffusion.
2) Substances may be too LARGE.
3) Substances may not be able to dissolve in the FAT CORE (lipid) of the membrane.
4) Substances may have to move AGAINST a concentration gradient.
Types of active transport
 Active transport/Solute Pumping
o Amino acids, some sugars, and most ions are transported by Solute Pumps.
o Sodium-Potassium Pump: what purpose does this Solute Pump serve?
Carries sodium ions out of an potassium ions into the cell. This is needed for
normal transmission of impulses by nerve cells. These ions move against their
concentration gradients, from LOW to HIGH so they must be PUMPED (forced)
into the desired locations across the cell membrane; this rewuires ENERGY in the
form of ATP.
*In most cases, substances are moved AGAINST concentration gradients.

Vesicular transport: moves substances that cannot pass THROUGH the membrane
o Exocytosis: Moves materials OUT OF of the cell
 Material is carried in a membranous VESICLE or SAC.
 Vesicle migrates to plasma membrane
 Vesicle combines with plasma membrane
 Material is emptied to the outside
SKETCH the process of EXOCYTOSIS below.
o
Endocytosis: Extracellular substances are engulfed by being enclosed in a membranous
vesicle.
 Phagocytosis: “cell eating”
 Describe the process of phagocytosis below.
Needed by white blood cells to consume and digest foreign particles.
The vesicle fuses with a lysosome to digest contents and detoxify.
 What types of cells perform phagocytosis?
SOME white blood cells
 Pinocytosis: “cell drinking”
 Receptor-mediated endocytosis: SELECTIVE uptake of products needed by the
cell.
 What products are taken into cells by this process?
Enzymes, hormones, cholesterol, and iron. SOME viruses.