CHAPTER 3 REVIEW
By: Jordyn
BASIC CONCEPTS OF CELL THEORY
 Rober t Hooke was the fir st to describe cells, He used an early light
microscope to examine dried cork . When he did this he saw
thousands of tiny empty chamber s which then later called them
cells.
 Research over the next 175 year s led to the cell theor y, the concept
that cells are the fundamental par ts of all plant and animal tissues.
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Cells are the building blocks of all plants and animals.
Cells are produced by the division of preexisting cells.
Cells are the smallest units that perform all vital physiological functions
Each cell maintains homeostasis at the cellular level
Homeostasis at the tissue, organ, system, and individual level reflects the
combined and coordinated actions of many cells.
FLUID CONTENTS OF THE CELL
 Our cell floats in a watery medium known as the extracellular
fluid.
 It basically holds the rest of the fluid that the cell can’t
 The cell membrane separates the contents or cytoplasm from
the fluid. The cytoplasm then can be further subdivided into a
fluid, the cytosol, and intracellular structures collectively
known as organelles.
 The subdivisions of the extracellular fluid are:
 Tissue fluid
 Interstitial
THE CELL MEMBRANE
 The cell membrane also called the plasma membrane and
in which it forms the outer boundary of the cell.
 The cell membrane is called a phospholipid bi -layer
because they form two distinct layers.
 The main functions of the membrane are isolation from the
outside environment, protection, sensitivity, and
organization.
 The major components of the cell membrane are:
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Phospholipids
Proteins
Glycolipids
Cholesterol
INTERACTIONS WITH ITS ENVIRONMENT
 Cells in the body work together to maintain homeostasis at
the tissue, organ, and system levels. The essential
communication and coordination activities involve the cell
membrane which forms the interface between each cell and
its surroundings.
 The cell membrane regulates the dynamic exchange between
the intracellular and extracellular fluids.
NONMEMBRANOUS ORGANELLES
 Cytoskeleton- Strength, movement
of cellular structures and materials.
 Microvilli- Absorption of
extracellular materials.
 Centriole- Movement of
chromosomes during cell division.
 Cilia- Movement of materials over
sur face
 Ribosome- Protein synthesis
MEMBRANOUS ORGANELLES
Mitochondria – about 95 percent of the
energy needed to keep a cell alive .
Nucleus- control of metabolism,
storage and processing of genetic
information.
Endoplasmic reticulum- Secretory
protein synthesis, lipid, and
carbohydrate synthesis.
Golgi Apparatus – Storage, alternation,
and packing of the secretory products
and lysosomes.
Lysosomes- intracellular removal of
damaged organelles or of pathogens.
Peroxisomes- Neutralization of toxic
compounds.
HOW THEY OBTAIN ENERGY
 The sun is basically the main component in giving the cell
enough fuel to power all of the functions dealing with the cell.
 Not only does it get power from the sun it gets that and
energy from the mitochondria.
 The mitochondria has small organelles that have an unusual
double membrane.
 With the ability to use both of the energizers, it gives all the
power and energy to fuel all of the functions of the cell.
THE ROLE OF THE NUCLEUS
 The nucleus is the control center for cellular operations, most
all cells have a single nucleus skeletal muscle cells have
some exceptions.
 A nuclear envelope surrounds the nucleus and separates it
from the cytosol. It is double membrane containing a narrow
preinuclear space. Chemical communication between the
nucleus and cytosol which occurs through nuclear pores.
 The term nucleoplasm refers to fluid contents of the nucleus.
It contains ions, enzymes, RNA , and DNA nucleotides,
proteins, and small amounts of RNA and DNA .
THE LIFE CYCLE/HOW THE CELL DIVIDES
 The G1 phase occurs during interphase. The cell is doing its
everyday job, there are only two chromosomes each one has one
molecule of DNA.
 During S phase the DNA duplicates, now the chromosomes have
two molecules of DNA.
 In G2 phase the cell carries out many processes that are
necessary for mitosis to begin.
 Mitosis is the stage when the cells DNA gets divided into two
separate nuclei's.
 In Mitosis there are four stages: Prophase, Metaphase,
anaphase, and telophase.
 Cytokinesis is a separate process from the division of mitosis,
during this the two daughter cells start forming.
 At the end of the cycle, the daughter cells are formed. They are
smaller than there parents but are genetically daughter cells.
TRANSMEMBRANE POTENTIAL
 The transmembrane potential of living cells are very small.
 Two factors, one passive and one active, interact to create
and maintain the transmembrane potential.
 The passive factor is that the membrane permeability for
sodium and potassium are quite dif ferent potassium ions can
dif fuse out of the cell through potassium channels faster than
sodium channels.
 The active factor is the presence of the sodium potassium
exchange pump in the membrane surface.
 The transmembrane potential is characteristic of all living
cells because it results from the active and passive properties
of their cell membranes.
HOW ATTACHMENTS AFFECT BODY
TISSUES
 Most cells in the body are firmly attached to other cells or to
extracellular protein fibers. The attachments occur at cell
junctions that are not involved in membrane flow.
 There are four types of cell junctions:
 Gap Junctions– the two cells are held together by the interlocking of
membrane proteins.
 Tight Junctions- there is a partial fusion of the lipid portions of the two
cell membranes.
 Intermediate Junctions- the opposing cell membranes while remaining
distinct are held together by a thick layer of proteoglycans.
 Desmosomes- there is a very thin proteoglycan layer between the
opposing cell membranes reinforced by a network of intermediate
filaments that lock the two cells together.