1. Cell.pdf

© 2012 Pearson Education, Inc.
2
Foundations:
The Cell
PowerPoint® Lecture Presentations prepared by
Steven Bassett
Southeast Community College
Lincoln, Nebraska

Introduction
• There are trillions of cells in the body
• Cells are the structural “building blocks” of all
plants and animals
• Cells are produced by the division of
preexisting cells
• Cells form all the structures in the body
• Cells perform all vital functions of the body

Introduction
• There are two types of cells in the body:
• Sex cells
• germ cells or reproductive cells
• Sperm in males and oocytes in females
• Somatic cells
• All the other cells in the body that are not sex cells

The Study of Cells
• Cytology
• Study of cells
• Common techniques used:
• Light microscopy (LM)
• Transmission electron microscopy (TEM)
• Scanning electron microscopy (SEM)

The Study of Cells
• Light Microscopy
• Magnification up to 1000 times
• Sometimes 2000 maximum

Figure 2.1a Different Techniques, Different Perspectives
Cells as seen in light microscopy
(respiratory tract)
LM  400

The Study of Cells
• Transmission Electron Microscopy
• Magnifies more than light microscopy

Figure 2.1b Different Techniques, Different Perspectives
TEM  2400
Cells as seen in transmission
electron microscopy (intestinal
tract)

The Study of Cells
• Scanning Electron Microscopy
• Shows three-dimensional images

Figure 2.1c Different Techniques, Different Perspectives
SEM  14,000
Cells as seen in scanning
electron microscopy
(respiratory tract)

Figure 2.2 The Diversity of Cells in the Body
Smooth
muscle
cell
Blood
cells
Bone
cell
Oocyte Sperm
Neuron in
brain
Fat cell
Cells lining
intestinal tract

Cellular Anatomy
• The cell consists of:
• Cytoplasm
• Cytosol
• Organelles
• Plasmalemma
• Cell membrane

Figure 2.4 A Flowchart for the Study of Cell Structure
CYTOPLASM
CYTOSOL
PLASMALEMMA
ORGANELLES
NONMEMBRANOUS
ORGANELLES
MEMBRANOUS
ORGANELLES
THE CELL
• Cytoskeleton
• Microvilli
• Centrioles
• Cilia
• Flagella
• Ribosomes
• Mitochondria
• Nucleus
• Endoplasmic
reticulum
• Golgi apparatus
• Lysosomes
• Peroxisomes

Cellular Anatomy
• Anatomical structures of the cell
• Organelles
• Nonmembranous organelles
• Membranous organelles

Cellular Anatomy
• Organelles of the cell
• Nonmembranous organelles
• Cytoskeleton
• Microvilli
• Centrioles
• Cilia
• Flagella
• Ribosomes

Figure 2.3 Anatomy of a Typical Cell
Microvilli
Secretory
vesicles
Cytosol
Lysosome
Centrosome
Centriole
Chromatin
Nucleoplasm
Nucleolus
Nuclear envelope
surrounding nucleus
Cytoskeleton
Plasmalemma
Golgi apparatus
Mitochondrion
Peroxisome
Nuclear pores
Smooth
endoplasmic
reticulum
Rough
endoplasmic
reticulum
Fixed ribosomes
Free ribosomes

Table 2.1 Anatomy of a Representative Cell (Part 1 of 2)

Cellular Anatomy
• Organelles of the cell
• Membranous organelles
• Mitochondria
• Nucleus
• Endoplasmic reticulum
• Golgi apparatus
• Lysosomes
• Peroxisomes

Table 2.1-2 Anatomy of a Representative Cell (Part 2 of 2)

Cellular Anatomy
• Plasmalemma
• A cell membrane composed of:
• Phospholipids
• Glycolipids
• Protein
• Cholesterol

Figure 2.5 The Plasmalemma
Glycolipids
of glycocalyx
Phospholipid
bilayer
Integral protein
with channel
Hydrophobic
tails
Gated
channel
Cholesterol
Peripheral
proteins
Hydrophilic
heads
Cytoskeleton
(Microfilaments)
 2 nm
CYTOPLASM
The plasmalemma
The phospholipid bilayer
Hydrophobic
tails
Hydrophilic
heads
Cholesterol
Integral
glycoproteins
EXTRACELLULAR FLUID

Cellular Anatomy
• Functions of the Plasmalemma
• Cell membrane (also called phospholipid
bilayer)
• Major functions:
• Physical isolation
• Regulation of exchange with the environment
(permeability)
• Sensitivity
• Structural support

Cellular Anatomy
• Membrane permeability of the plasmalemma
• Passive processes
• Diffusion
• Osmosis
• Facilitative diffusion

Figure 2.6 Diffusion across Plasmalemmae
Plasmalemma
Channel
protein
CYTOPLASM
EXTRACELLULAR
FLUID
Lipids, lipid-soluble
molecules, and soluble
gases (O2 and CO2) can
diffuse across the lipid
bilayer of the plasmalemma.
Water, small water-
soluble molecules,
and ions diffuse
through membrane
channels.
Large molecules that
cannot fit through the
membrane channels
and cannot diffuse
through the membrane
lipids can only cross
the plasmalemma
when transported by a
carrier mechanism.

 Membrane permeability: active processes:
 Active transport uses enzymes and carrier proteins and ATP.
 Ion pumps are carrier proteins for charged particles.
 Ions moved regularly by active transport include:
 Na+
 Ca2+
 Mg2+
 K+
 An ion pump that moves two ions simultaneously in opposite directions is called an
exchange pump.
 Endocytosis:
 Pinocytosis: Active process for transporting liquid across the plasmalemma.
 Phagocytosis: Active process for transporting solid substances across the
plasmalemma.
 Exocytosis: Active process to eliminate waste products across the plasmalemma.
Cellular anatomy

Figure 2.7 Phagocytosis
Bacterium
Pseudopodium
Phagosome
Lysosome
Golgi
apparatus
Phagosome
fuses with a
lysosome
Secondary
lysosome
Phagocytosis
Exocytosis

Figure 2.8 Receptor–Mediated Endocytosis
Electron micrographs showing vesicle formation in receptor-mediated endocytosis
Early vesicle
formation
Plasmalemma
Cytoplasm Completed
vesicle
TEMs  60,000

Table 2.2 Summary of Mechanisms Involved in Movement across Plasmalemmae

Figure 2.9 The Cytoskeleton
The cytoskeleton provides strength
and structural support for the cell
and its organelles. Interactions
between cytoskeletal elements are
also important in moving organelles
and in changing the shape of the
cell.
A SEM image of the microfilaments
and microvilli of an intestinal cell
Microtubules in a living cell, as
seen after special fluorescent
labeling
LM  3200
SEM  30,000
Microvilli
Microfilaments
Plasmalemma
Terminal web
Mitochondrion
Intermediate
filaments
Endoplasmic
reticulum
Microtubule
Secretory
vesicle

Cellular Anatomy
• Nonmembranous Organelles (details)
• Examples of microtubules
• Centrioles
• Cilia
• Flagella

Figure 2.10 Centrioles and Cilia
A centriole consists
of nine microtubule
triplets (9  0 array).
The centrosome
contains a pair of
centrioles oriented at
right angles to one
another.
A cilium contains nine pairs of
microtubules surrounding a central pair
(9  2 array).
A single cilium swings forward and then
returns to its original position. During
the power stroke, the cilium is relatively
stiff, but during the return stroke, it
bends and moves parallel to the cell
surface.
Microtubules
Basal body
Plasmalemma
Microtubules
Power stroke Return stroke
TEM  240,000

Table 2.3 A Comparison of Centrioles, Cilia, and Flagella

• Nonmembranous Organelles (details)
• Ribosomes
• Free ribosomes: float in the cytoplasm
• Fixed ribosomes: attached to the endoplasmic
reticulum
• Both are involved in producing protein
Cellular Anatomy

Figure 2.11 Ribosomes
Nucleus Free ribosomes
Endoplasmic
reticulum with
attached fixed
ribosomes
Small ribosomal
subunit
Large ribosomal
subunit
TEM  73,600
Both free and fixed ribosomes can
be seen in the cytoplasm of this cell.
An individual ribosome,
consisting of small and
large subunits

Cellular Anatomy
• Membranous Organelles (details)
• Double-membraned organelles
• Mitochondria: produce ATP
• Nucleus: contains chromosomes
• Endoplasmic reticulum: network of hollow tubes
• Golgi apparatus: modifies protein
• Lysosomes: contain cellular digestive enzymes
• Peroxisomes: contain catalase to break down
hydrogen peroxide

Cellular Anatomy
 Mitochondria are double-membraned
organelles:
 Cristae are the folds of the inner
membrane.
 The inner fluid is the matrix.
 They produce ATP.

Figure 2.12 Mitochondria
Inner membrane
Organic molecules
and O2
CO2
ATP
Matrix Cristae Enzymes
Outer
membrane
TEM  61,776
Cytoplasm
of cell Cristae Matrix

Cellular Anatomy
• Nucleus: control center of the cell
• Nucleoplasm
• Nuclear envelope
• Perinuclear space
• Nuclear pores
• Nuclear matrix

Figure 2.13ab The Nucleus
Nuclear envelope
Perinuclear space
Nuclear pore
A nuclear pore and the
perinuclear space
Perinuclear
space
Nucleoplasm
Chromatin
Nucleolus
Nuclear envelope
Nuclear pores
TEM showing important nuclear structures
TEM  4828

Cellular Anatomy
• Membranous Organelles: Nucleus
• Chromosomes:
• DNA wrapped around proteins called histones
• Nucleosomes
• Chromatin

Figure 2.14 Chromosome Structure
Nucleus of nondividing cell
Chromatin in nucleus
Dividing cell
Visible chromosome
Supercoiled
region
Nucleosome
Histones DNA double
helix
In cells that are not
dividing, the
nucleosomes are loosely
coiled, forming a tangle
of fine filaments known
as chromatin.

Cellular Anatomy
• Endoplasmic Reticulum (ER)
• There are two types
• Rough endoplasmic reticulum (RER)
• Smooth endoplasmic reticulum (SER)

Figure 2.15 The Endoplasmic Reticulum
Ribosomes
Cisternae
Rough endoplasmic
reticulum with
fixed (attached)
ribosomes
Free
ribosomes
Smooth
endoplasmic
reticulum
Endoplasmic
Reticulum
TEM  11,000

Cellular Anatomy
• Rough endoplasmic reticulum
• Consists of fixed ribosomes
• Proteins enter the ER

Cellular Anatomy
• Smooth endoplasmic reticulum
• Synthesizes lipids, steroids, and carbohydrates
• Storage of calcium ions
• Detoxification of toxins

Cellular Anatomy
• Golgi apparatus
• Synthesis and packaging of secretions
• Packaging of enzymes (modifies protein)
• Renewal and modification of the plasmalemma

Figure 2.16a The Golgi Apparatus
Vesicles
Maturing
(trans) face
Forming
(cis) face
A sectional view of the Golgi
apparatus of an active secretory cell
TEM  83,520

Figure 2.16b The Golgi Apparatus
EXTRACELLULAR
FLUID
CYTOSOL
Cisternae
Membrane
renewal
vesicles
Lysosome
Secretory
vesicle
Maturing
(trans) face
Forming
(cis) face
Transport
vesicle
This diagram shows the functional link between the
ER and the Golgi apparatus. Golgi structure has been
simplified to clarify the relationships between the
membranes. Transport vesicles carry the secretory
product from the endoplasmic reticulum to the Golgi
apparatus, and transfer vesicles move membrane
and materials between the Golgi cisternae. At the
maturing face, three functional categories of vesicles
develop. Secretory vesicles carry the secretion from
the Golgi to the cell surface, where exocytosis
releases the contents into the extracellular fluid.
Other vesicles add surface area and integral proteins
to the plasmalemma. Lysosomes, which remain in
the cytoplasm, are vesicles filled with enzymes.

Cellular Anatomy
• Lysosomes
• Fuse with phagosomes to digest solid materials
• Recycle damaged organelles
• Sometimes rupture, thus killing the entire cell
(called autolysis)

Figure 2.17 Lysosomal Functions
Waste products and debris are then ejected from the
cell when the vesicle fuses with the plasma membrane.
Endocytosis
Extracellular
solid or fluid
As digestion
occurs, nutrients
are reabsorbed for
recycling.
Primary
lysosomes
contain
inactive
enzymes.
As the materials
or pathogens are
broken down,
nutrients are
absorbed.
Golgi
apparatus
Function 1: A primary
lysosome may fuse with
the membrane of another
organelle, such as a
mitochondrion, forming a
secondary lysosome.
Function 2: A secondary
lysosome may also form
when a primary lysosome
fuses with a vesicle
containing fluid or solid
materials from outside the
cell.
Function 3: The lysosomal
membrane breaks down
following injury to, or death
of, the cell. The digestive
enzymes then attack the
cytoplasm in a destructive
process known as
autolysis. For this reason
lysosomes are sometimes
called “suicide packets.”

Cellular Anatomy
• Peroxisomes
• Consist of catalase
• Abundant in liver cells
• Convert hydrogen peroxide to water and oxidants

Cellular Anatomy
• Membrane flow
• This is the continuous movement and
recycling of the cell membrane
• Transport vesicles connect the endoplasmic
reticulum with the Golgi apparatus
• Secretory vesicles connect the Golgi apparatus
with the plasmalemma

Cellular Anatomy
Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
 Membrane flow is the continual movement and recycling of the plasmalemma.
The ER, Golgi apparatus, and vesicles constantly recycle the lipids, protein
channels, and enzymes of the plasmalemma.
 Passive transport:
 Diffusion: net movement of material from high concentration to low
concentration area. Example: transportation of oxygen and carbon dioxide
across the plasmalemma.
 Osmosis: diffusion of water across a membrane.
 Facilitated diffusion: diffusion of materials with the aid of carrier proteins.
Example: transportation of glucose and amino acids.
 Active transport:
 Ionic pump.
 Endocytosis
 exocytosis

Intercellular Attachment
• Examples of Intercellular Attachment:
• Communicating junctions
• Gap junctions
• Adhering junctions
• Tight junctions
• Anchoring junctions
• Desmosome
• hemidesmosome

Figure 2.18ab Cell Attachments (Part 1 of 4)
Communicating junctions permit
the free diffusion of ions and small
molecules between two cells.
Embedded
proteins
(connexons)
Hemidesmosome
A diagrammatic view of an
epithelial cell shows the
major types of intercellular
connections.
Tight junction
Zonula adherens
Terminal web
Button
desmosome
Communicating
junction
Anchoring junction

Figure 2.18ac Cell Attachments (Part 2 of 4)
Hemidesmosome
connections.
Tight junction
Interlocking
junctional
proteins
Zonula adherens
Terminal web
Button
desmosome
Communicating
junction
Anchoring junction
Tight junction
Zonula
adherens
A tight junction is formed by the
fusion of the outer layers of two
plasmalemmae. Tight junctions
prevent the diffusion of fluids and
solutes between the cells.

Figure 2.18ad Cell Attachments (Part 3 of 4)
Hemidesmosome
connections.
Tight junction
Zonula adherens
Terminal web
Button
desmosome
Communicating
junction
Anchoring junction
Intermediate
filaments
(cytokeratin)
Cell adhesion
molecules
(CAMs)
Dense area
Intercellular
cement
Anchoring junctions attach
one cell to another. A macula
adherens has a more
organized network of
intermediate filaments. An
adhesion belt is a form of
anchoring junction that
encircles the cell. This complex
is tied to the microfilaments of
the terminal web.

The Cell Life Cycle
• Cell reproduction consists of special events
• Interphase
• Mitosis
• Prophase
• Metaphase
• Anaphase
• Telophase
• Cytokinesis
• Overlaps with anaphase and telophase

The Cell Life Cycle
• Cell reproduction (Interphase)
• Everything inside the cell is duplicating
• Consists of G1, S, and G2 phases
• G1: duplication of organelles and protein synthesis
• S: DNA replication
• G2: protein synthesis

Figure 2.20 DNA Replication
KEY
Adenine
Guanine
Cytosine
Thymine
Segment 2
DNA polymerase
DNA nucleotide
DNA
polymerase
Segment 1

The Cell Life Cycle
• Cell Reproduction (Mitosis)
• Prophase
• The first phase of mitosis
• Metaphase
• Paired chromatids line up in the middle of the nuclear
region
• Anaphase
• Paired chromatids separate to opposite poles of the
cell
• Telophase
• Two new nuclear membranes begin to form

The Cell Life Cycle
• Cell Reproduction (Cytokinesis)
• Cell membrane begins to invaginate, thus
forming two new cells
• Many times this phase actually begins during
anaphase
• This is the conclusion of cell reproduction

The Cell Life Cycle
Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
 Mitosis—the distribution process of genetic
information
 Mitosis consists of four stages:
 Prophase
 Metaphase
 Anaphase
 Telophase
 Cytokinesis:
 Separation of daughter cells after mitosis.

Figure 2.19 The Cell Life Cycle
INTERPHASE
THE
CELL
CYCLE
MITOSIS AND
CYTOKINESIS
(See Figure 2.21)
Indefinite period
G0
Specialized
cell functions
G1
Normal
cell functions
plus cell growth,
duplication of
organelles,
protein
synthesis
G2
Protein
synthesis
S
DNA
replication,
synthesis
of
histones
M

Figure 2.21 Interphase and Mitosis
INTERPHASE
MITOSIS BEGINS
EARLY PROPHASE LATE PROPHASE METAPHASE ANAPHASE TELOPHASE INTERPHASE
CYTOKINESIS
Nucleus
Centrioles
(two pairs)
Astral rays Spindle
fibers
Centriole Chromosome
with two sister
chromatids
Metaphase
plate
Chromosomal
microtubule
Daughter
chromosomes
Cleavage
furrow
Daughter
cells

Figure 2.21 Interphase and Mitosis (Part 1 of 2)
INTERPHASE
MITOSIS BEGINS
EARLY PROPHASE LATE PROPHASE
Nucleus
Centrioles
(two pairs)
Astral rays Spindle
fibers
Centriole Chromosome
with two sister
chromatids

Figure 2.21 Interphase and Mitosis (Part 2 of 2)
METAPHASE ANAPHASE TELOPHASE INTERPHASE
CYTOKINESIS
Metaphase
plate
Chromosomal
microtubule
Daughter
chromosomes
Cleavage
furrow
Daughter
cells

1. Cell.pdf

Recommended

Recommended

More Related Content

Similar to 1. Cell.pdf

Similar to 1. Cell.pdf (20)

Recently uploaded

Recently uploaded (20)

1. Cell.pdf