CAPE_Biology_Unit_1_-_03_Cell_Structure_and_Function_v2.pptx

BIO1001
CAPE Biology Unit 1
Cell Structure and Function

Outline
• General overview of microscopes and
microscopy
• Comparison of light microscope and electron
microscope
• Distinguishing between resolution and
magnification
• General overview of Cell Theory
• Distinguishing between prokaryotic cells and
eukaryotic cells
3

Outline (cont’d)
•The structure of prokaryotic cells
•Structure and function of eukaryotic
organelles and membrane systems
•Endosymbiont theory
•Similarities and differences in structure
of plant and animal cells
•Concept of tissue and organ using the
dicotyledonous root as an example
4

Objectives:
• Explain the differences between light
microscopes and electron microscopes
• Distinguish between microscope resolution
and magnification
• State the tenets of the cell theory
• Describe and compare the structures of
prokaryotic cells and eukaryotic cells
5

Objectives (cont’d):
• Outline the structure and function of
organelles
• Compare the structures and functions of
typical animal and plant cells as seen under
the light and electron microscope
• Explain the concepts of the biological
organization of tissues and organs using the
dicotyledonous root and stem
6

Microscopy
• Microscopes are instruments used to view
cells and other structures too small to see
with the naked eye.
• Not many cells are visible to the naked eye
–Most are < 50 μm in diameter
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
9

Microscopy
• Three important parameters of microscopy:
• Magnification – the ratio of an object’s image size
to its real size
• Resolution – the measure of the clarity of the
image, or the minimum distance two points can
be apart and still be distinguished as two separate
points
• Human eye resolution = 100 μm
• Contrast – visible differences in parts of the 10

Light microscopes
Use magnifying
lenses with visible
light
Resolve structures
that are 200 nm
apart
Limit to resolution
Electron
microscopes
Use beam of
electrons
Resolve structures
that are 0.2 nm
apart
12
2 Types of Microscopes
12

Light Microscopes
• In a light microscope (LM), visible light
passes through a specimen and then
through glass lenses, which refract (bend)
the light and magnify the image.
• LMs can magnify effectively to about 1,000
times the size of the actual specimen
13

Light Microscopes
• Various techniques enhance contrast and
enable cell components to be stained or
labeled
• Most subcellular structures, including
organelles (membrane-enclosed
compartments), are too small to be
resolved by light microscopy
14

Compound Light Microscope
• Light passes through
specimen
• Focused by glass lenses
• Image formed on human
retina
• Max magnification about
1000X
• Resolves objects separated 15

Parts of a
Light
Microscop
e
17

Parts of a
Light
Microscop
e
18

Compound Light Microscope
19
eye
ocular lens
light rays
objective lens
specimen
condenser lens
85µm
amoeba, light micrograph
light source
a. Compound light microscope
© Robert Brons/Biological PhotoService
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Electron Microscopes
• Two basic types of electron microscopes (EMs) are
used to study subcellular structures
• Scanning electron microscopes (SEMs) focus a beam of
electrons onto the surface of a specimen, providing
images that look 3-D
• Transmission electron microscopes (TEMs) focus a
beam of electrons through a specimen
• TEMs are used mainly to study the internal structure of
cells
20

Transmission Electron Microscope
• Abbreviated T.E.M.
• Electrons passed through specimen
• Focused by magnetic lenses
• Image formed on fluorescent screen
• Similar to TV screen
• Image is then photographed
• Max magnification 1,000,000X
• Resolves objects separated by
0.00002 m,
100,000X better than human eye
21

Transmission Electron Microscope
22
200 nm
pseudopod segment, transmission electron
micrograph
electron source
electron beam
electromagnetic
condenser lens
specimen
electromagnetic
objective lens
electromagnetic
projector lens
observation screen
or
photographicplate
b. Transmission electron microscope
© M. Schliwa/Visuals Unlimited

Scanning Electron Microscope
• Abbreviated S.E.M.
• Specimen sprayed with thin coat of
metal
• Electron beam scanned across surface of
specimen
• Metal emits secondary electrons
• Emitted electrons focused by magnetic
lenses
• Image formed on fluorescent screen
23

Scanning Electron Microscope
24
electromagnetic
condenser
lenses
scanning coil
final
condenser
lens
secondary
electrons
specimen
electron
detector
TV
viewing
screen
c. Scanning electron microscope
© Kessel/Shih/Peter Arnold, Inc.
500µm
amoeba, scanning electron micrograph
electron gun
electron beam

Microscopy and Amoeba proteus
26
amoeba, lightmicrograph amoeba, scanning electron micrograph
lightrays
eye
ocular lens
objective lens
specimen
condenser lens
light source
a. Compound lightmicroscope
electron gun
electron beam
scanning coil
electron source
electron beam
85 µm 200 nm 500 µm
pseudopod segment, transmission electron
micrograph
electromagnetic
condenserl
enses
final
Condenser
lens
secondary
electrons
specimen
observation screen
or
photographic plate
specimen
electromagnetic
objective lens
electromagnetic
condenser lens
electromagnetic
projector lens
electron
detector
TV
Viewing
screen
b. Transmission electron microscope c. Scanning electron microscope
a: © Robert Brons/Biological Photo Service; b: © M. Schliwa/Visuals Unlimited; c: © Kessel/Shih/Peter Arnold, Inc.

Sizes of Living Things
Fig. 4.2
27

Figure 6.2 10 m
1 m
0.1 m
1 cm
1 mm
100 m
10 m
1 m
100 nm
10 nm
0.1 nm Atoms
1 nm
Small molecules
Proteins
Lipids
Ribosomes
Smallestbacteria
Viruses
Most plant and
animal cells
Nucleus
Most bacteria
Mitochondrion
Human egg
Frog egg
Chicken egg
Length of some
nerve and
muscle cells
Human height
Unaided
eye
Light
microscopy
Electron
microscopy
Super-
resolution
microscopy
LMs can magnify effectively
to about 1,000 times the size
of the actual specimen.
Various techniques enhance
contrast and enable cell
components to be stained or
labeled.
Most subcellular structures
like organelles are too small
to be resolved by a LM.
28

• Cells were discovered in
1665
by Robert Hooke
• Anton van Leeuwenhoek:
first observed living cells,
called them animalcules
(little animals)
• Schleiden and Schwann
proposed the Cell Theory
Cell Theory
30

Introduction – Seeing cells
• Microscope invented, 1600’s
• Things invisible to naked eye discovered
• Robert Hooke,1665
• First saw cork cells, named them cellulae
• Anton Van Leeuwenhoek, 1667
• Observed organisms in pond water.
• Matthias Schleiden (botanist) & Theodor Schwann
(zoologist), 1800’s
• Concluded that all plants and animals are composed of cells.
• Schawnn proposed the first two tenets of the cell theory
• Rudolf Virchow, a physician
• Proposed a third tenet (1855) in response to the question: “Where do
cells come from”?
31

Cell Theory (Unifying concept in biology)
1. All organisms are composed of one or more cells.
2. The cell is the basic organizational unit of life (smallest
unit to give rise to new life and sustain life).
3. All cells arise from pre-existing cells by the process
of division.
33

Features of living organisms
1. Composed of cells (membrane, cytoplasm, genetic material,
ribosomes; other organelles & structures which vary with the type of
cell)
2. Grow and develop (size, biomass, # of cells, differentiate)
3. Regulate their own metabolic processes (maintain homeostasis).
Respire to produce energy.
4. Respond to stimuli (light, temp, sound, pressure, chemicals) by
movement
5. Reproduce (sexual/asexual)
6. Adapt (structurally, physiologically, behaviourally) to
environmental change (evolve)
7. Organized in levels (eg. chemical, cell, tissue, organ, organ systems)
34

Structure – All cells have:
• Membrane
• plasma membrane surrounds cytoplasm
• keeps cell separated from environment, while allowing exchange of
materials.
• Genetic material
• allows reproduction of cell; continuation of life
• Cytoplasm containing organelles)
• cytoplasm = cytosol and organelles
• aqueous site of metabolic reactions facilitating life
• distinct part of a cell which has a particular structure and function
Ribosomes
• site of protein production
35

36
1. Genetic material
(nucleus or nucleoid region)
2. Cytoplasm
3. Ribosomes
4. Plasma membrane
ALL CELLS:
Basic Structural Similarities
36

Cell Structure
• Cells
• vary in size
• vary in shape
• are either prokaryotic or eukaryotic with
regards to basic structure.
• have internal components (types, size)
depending on their function
• are in many cases, specialized for a particular
function (e.g., nerve cells, epithelial cells,
parenchyma, red blood cells).
37

Cell Functions
Life processes performed by cells:
• Feed
• Respire
• Excrete
• Metabolize
• Osmoregulate
• Communicate
9/2/2015 BIOL00112015-16 9 38

40
CELLS:
Two types of cells:
Prokaryotes lack nucleus or other
membrane-enclosed compartments and
lack distinct organelles.
• Bacteria, Archaea
Eukaryotes have a membrane-enclosed
nucleus and other membrane-enclosed
compartments or organelles as well.
• Animals, Plants, Fungi, Protists
40

Typical eukaryotic cell = 10 – 100 μm
Human skin cells
Typical prokaryotic cell = 1 - 10 μm
1 μm = 0.000001 m
Bacterial cells
41

Prokaryotic Cells
 Lack a membrane-bound nucleus
 Structurally smaller and simpler than eukaryotic
cells (which have a nucleus).
 Prokaryotic cells are placed in two taxonomic
domains:
 Bacteria
 Archaea
 Live in extreme habitats
 Domains are structurally similar but biochemically
different 42

43
Prokaryotic Cells
• Simplest organisms
• Lack a membrane-bound nucleus
– DNA in the nucleoid
• Lacks internal membrane structures
• Cell wall outside of plasma membrane
• Possess ribosomes: protein synthesis
• Two Domains of prokaryotes: Archaea
and Bacteria
43

Cytoplasm
Ribosomes
Nucleoid (DNA)
Plasma membrane
Capsule
Cell wall
Pili
Flagellum
Pilus
0.3 µm
© Phototake
Example of
Bacterial cell
structure
44

Bacterial Cell Walls:
• Most bacterial cells possess a strong cell wall
– composed of peptidoglycan
• Functions include…
• Protection
• Maintains cell shape
• Prevents excessive H2O uptake
• Archaea lack peptidoglycan
• Capsule: gelatinous covering external to cell wall
(not always present)
45
Prokaryotic Cells
45

46
Flagella:
• Present in some prokaryotic cells
– May be one or more or none
• Used for locomotion
Prokaryotic Cells
46

47
Outer protein ring
Hook
Filament
Inner protein ring
H+ H+
Peptidoglycan
portion of
cell wall
Outer
membrane
Plasma
membrane
a. b. c.
0.5 µm
a: © Eye of Science/Photo Researchers, Inc.
Rotary motion propels the cell
Basal Body
47

The Structure of Bacteria
 Extremely small - 1–1.5 μm wide and 2–6 μm long
 Occur in three basic shapes:
 Spherical coccus,
 Rod-shaped bacillus,
 Spiral spirillum (if rigid) or spirochete (if flexible).
 Cell Envelope includes:
 Plasma membrane - lipid bilayer with embedded and peripheral proteins
 Form internal pouches (mesosomes)
 Cell wall - maintains the shape of the cell and is strengthened by
peptidoglycan
 Glycocalyx - layer of polysaccharides on the outside of the cell wall
 Well organized and resistant to removal (capsule)
48

49
spirillum
coccus
bacillus
spirochete

50
Inclusion body:
stored nutrients for
later use
Mesosome:
plasma membrane
that folds into the
cytoplasm and
increases surface area
Ribosome:
site of protein synthesis
Nucleoid:
location of the bacterial
chromosome
Plasma membrane:
sheath around cytoplasm
that regulates entrance
and exit of molecules
Cell wall:
covering that supports,
shapes, and protects cell
Glycocalyx:
gel-like coating outside
cell wall; if compact, called
a capsule; if diffuse, called
a slime layer
Fimbriae:
hairlike bristles that
allow adhesion to
the surfaces
Conjugation pilus:
elongated, hollow
appendage used for
DNA transfer to other
bacterial cells
Flagellum:
rotating filament present
in some bacteria that
pushes the cell forward
© Howard Sochurek/The Medical File/Peter Arnold, Inc.
Escherichia coli

The Structure of Bacteria Cytoplasm &
Appendages
• Cytoplasm
• Semifluid solution
• Bounded by plasma membrane
• Contains water, inorganic and organic molecules, and enzymes.
• Nucleoid is a region that contains the single, circular DNA
molecule.
• Plasmids are small accessory (extrachromosomal) rings of DNA
• Appendages
• Flagella – Provide motility
• Fimbriae – small, bristle-like fibers that sprout from the cell
surface
51

52
Eukaryotic Cells
• Possess a membrane-bound nucleus
• More complex than prokaryotic cells
• Hallmark is compartmentalization
• Possess a cytoskeleton for
• support
• maintain cell structure
52

Eukaryotic Cells
53
 Domain Eukarya includes:
 Protists
 Fungi
 Plants
 Animals
 Cells contain:
 Membrane-bound nucleus that houses DNA
 Specialized organelles
 Plasma membrane
 Much larger than prokaryotic cells
 Some cells (e.g., plant cells) have a cell wall

Cells
2015 BIOL0011 11
Pro=primitive
Karyon=nucleus
Prokaryotic Cells Eukaryotic Cells
simplest cellular
organization
may be very complex
no membrane-bound
organelles
contains membrane-
bound organelles
[Golgi body;
endoplasmic
reticulum;
mitochondria,
nucleus]
no organized nucleus;
genetic material free
well developed nucleus
which houses the
genetic material
70s ribosomes 80s ribosomes
share membrane, cytoplasm, ribosomes, walls, genetic material,
functional organelles
Eu=true
Karyon=nucleus
54

Comparison of Prokaryotic and
Eukaryotic Cells
55

Structure and Function of
Eukaryotic Organelles
56

Eukaryotic Cells: Organelles
• Eukaryotic cells are compartmentalized
• They contain small structures called organelles
• Perform specific functions
• Isolate reactions from others
• Two classes of organelles:
• Energy related organelles
• Mitochondria & chloroplasts
• Basically independent & self-sufficient
• Non-energy related organelles
• All other organelles not directly involved in making energy
available for the cell. 57

Cell Structure – Cell Wall
• Present in bacteria, fungi and plants.
• Plant cell walls:
• Cellulose microfibrils
bundled together &
embedded in
polysaccharide matrix.
• Secondary wall
impregnated with lignin
to form wood
• Rigid protective
structures,
• Slow dehydration;
• Prevent bursting of cell
• Transport of substances
in/out
• Pathway of movement
for water (apoplast).
• Plasmodesmata link to

59
Cell Structure – Cell Membrane
2015 BIOL0011 20
http://www.people.virginia.edu/~rjh9u/cellmemb.html
Phospholipid
bilayer
Hydrophobic
Hydrophillic
 Fluid Mosaic model 1972, Singer & Nicolson
Plasma membrane has a fluid, phospholipid bilayer with
protein & lipid molecules floating in it like a mosaic.

Endomembrane System
 Series of intracellular membranes that
compartmentalize the cell
 Restrict enzymatic reactions to specific compartments
within cell
 Consists of:
 Nuclear envelope
 Membranes of endoplasmic reticulum
 Golgi apparatus
 Vesicles
 Several types
 Transport materials between organelles of system
60

Anatomy of the Nucleus
61
Nuclear envelope:
inner membrane
outermembrane
nuclear pore
chromatin
nucleoplasm
nuclear
pore
phospholipid
nuclear
envelope
nucleolus
(Bottom): Courtesy Ron Milligan/Scripps Research Institute; (Top right): Courtesy E.G. Pollock

Nucleus
• Command center of cell, usually near center
• Separated from cytoplasm by nuclear envelope
• Consists of double layer of membrane
• Nuclear pores permit exchange between nucleoplasm & cytoplasm
• Contains chromatin in semifluid nucleoplasm
• Chromatin contains DNA of genes, and proteins
• Condenses to form chromosomes
• Chromosomes are formed during cell division
• Dark nucleolus composed of rRNA
• Produces subunits of ribosomes
62

Ribosomes
 Are the site of protein
synthesis in the cell
 Composed of rRNA
 Consists of a large
subunit and a small
subunit
 Subunits made in
nucleolus
63
80S

Ribosomes
 May be located:
 On the
endoplasmic
reticulum (thereby
making it “rough”),
or
 Free in the cytoplasm,
either singly or in
groups, called
polyribosomes 64

Fig. 6-11
Cytosol
Endoplasmic reticulum (ER)
Free ribosomes
Bound ribosomes
Large
subunit
Small
subunit
Diagram of a ribosome
TEM showing ER and ribosomes
0.5 µm

Nucleus, Ribosomes, & ER
4. An enzyme removes
the signalpeptide.
66
protein
enzyme
ER membrane
receptor
Lumen ofER
signalpeptide
ribosome
mRNA
mRNA
ribosomal
subunits nuclear pore
Nucleus
mRNA DNA
SRP
signalrecognition
particle (SRP)
5. Ribosomal subunits and
mRNA break away. The
protein remains in the ER
and folds into its finalshape.
3. SRP attaches to receptor (purple);
a channel opens; and the
polypeptide enters ER..
2. Signal recognition
particle (SRP) binds
to signalpeptide.
1. mRNA is leaving the
nucleus and is attached
to the ribosome;protein
synthesis is occurring.
Cytoplasm
Endoplasmic
reticulum(ER)

Endomembrane System:
The Endoplasmic Reticulum
 A system of membrane channels and saccules (flattened vesicles)
continuous with the outer membrane of the nuclear envelope
 Rough ER
 Studded with ribosomes on cytoplasmic side
 Protein anabolism
 Synthesizes proteins
 Modifies and processes proteins
 Adds sugar to protein
 Results in glycoproteins
 Smooth ER
 No ribosomes
 Synthesis of lipids
 Site of various synthetic processes, detoxification, and storage
 Forms transport vesicles
67

•A system of membrane channels and
saccules (flattened vesicles) continuous
with the outer membrane of the nuclear
envelope
•Rough ER
•Smooth ER
68

•Rough ER
•Studded with ribosomes on cytoplasmic
side
•Protein anabolism
•Synthesizes proteins
•Modifies and processes proteins
• Adds sugar to protein
• Results in glycoproteins
69

•Smooth ER
•No ribosomes
•Synthesis of lipids
•Site of various synthetic processes,
detoxification, and storage
•Forms transport vesicles
70

Endoplasmic Reticulum
71
ribosomes nuclear envelope
0.08 m
rough
endoplasmic
reticulum
smooth
endoplasmic
reticulum
© R. Bolender & D. Fawcett/Visuals Unlimited

The Golgi Apparatus
• Golgi Apparatus
• Consists of 3-20 flattened, curved
saccules
• Resembles stack of hollow pancakes
• Modifies proteins and lipids
• Receives vesicles from ER on cis (or
inner face)
• Packages them in vesicles
• Prepares for “shipment” in vesicles
• Packages them in vesicles from trans
(or outer face)
• Within cell
• Export from cell (secretion, exocytosis) 72

Endomembrane System: Lysosomes
 Membrane-bound vesicles (not in
plants)
 Produced by the Golgi apparatus
 Contain powerful digestive enzymes and
are highly acidic
 Digestion of large molecules
 Recycling of cellular resources
 Apoptosis (programmed cell death, like
tadpole losing tail)
 Some genetic diseases
 Caused by defect in lysosomal enzyme
 Lysosomal storage diseases (Tay-Sachs)
73

Peroxisomes
 Similar to lysosomes
 Membrane-bounded vesicles
 Enclose enzymes
 However
 Enzymes synthesized by free
ribosomes in cytoplasm (instead
of ER)
 Active in lipid metabolism
 Catalyze reactions that
produce hydrogen peroxide
H2O2
 Toxic
 Broken down to water & O by 74

Endomembrane System: Summary
• Proteins produced in rough ER and lipids from
smooth ER are carried in vesicles to the Golgi
apparatus.
• The Golgi apparatus modifies these products and
then sorts and packages them into vesicles that go to
various cell destinations.
• Secretory vesicles carry products to the membrane
where exocytosis produces secretions.
• Lysosomes fuse with incoming vesicles and digest
75

Endomembrane System: A Visual Summary
76
protein
enzyme
ribosome Nucleus
lysosome
contains digestive enzymes
that break downworn-out
cell parts or substances
entering the cell at the
plasma membrane
transportvesicle
shuttles lipids to various
locations such asthe
Golgiapparatus
lipid
smoothendoplasmic
reticulum
synthesizes lipids and
also performs various
other functions
incoming vesicle
brings substances into the
cell that are digestedwhen
the vesicle fuses with a
lysosome
transport vesicle
shuttles proteinsto
various locations suchas
the Golgiapparatus
Golgiapparatus
modifies lipids andproteins
from the ER; sorts them
and packages them in
vesicles
secretory vesicle
fuses with theplasma
membrane as secretion
occurs
roughendoplasmic
reticulum
synthesizes proteins and
packages them in vesicles;
vesicles commonly go to
the Golgiapparatus
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction ordisplay.
secretion
plasma
membrane

Vacuoles
 Membranous sacs that are larger than vesicles
 Store materials that occur in excess
 Others very specialized (contractile vacuole)
 Plants cells typically have a central vacuole
 Up to 90% volume of some cells
 Functions in:
 Storage of water, nutrients, pigments, and waste products
 Development of turgor pressure
 Some functions performed by lysosomes in other eukaryotes
77

78
Vacuoles
• Membrane-bounded structures in plants
• Various functions depending on the cell type
• There are different types of vacuoles:
1. Central vacuole: plant cells
2. Contractile vacuole: some fungi and
protists
3. Storage vacuoles
Central Vacuole
In plants, helps
maintains turgor
pressure
78

Vacuoles: Diverse Maintenance
Compartments
• A plant cell or fungal cell may have one or several
vacuoles, derived from endoplasmic reticulum and
Golgi apparatus.
• 3 types of vacuoles and their function-
• Food vacuoles are formed by phagocytosis
• Contractile vacuoles, found in many freshwater
protists, pump excess water out of cells
• Central vacuoles, found in many mature plant 79

Vacuoles
80
100 nm
© Newcomb/Wergin/Biological Photo Service

Fig. 6-14
Central vacuole
Cytosol
Central
vacuole
Nucleus
Cell wall
Chloroplast
5 µm 81

The Cytoskeleton
 Maintains cell shape
 Assists in movement of cell and organelles
 Three types of macromolecular fibers
 Actin Filaments (Microfilaments)
 Intermediate Filaments
 Microtubules
 Assemble and disassemble as needed
82

The Cytoskeleton: Actin Filaments
 Extremely thin filaments like twisted pearl necklace
 Dense web just under plasma membrane maintains
cell shape
 Support for microvilli in intestinal cells
 Intracellular traffic control
 For moving stuff around within cell
 Cytoplasmic streaming
 Function in pseudopods of amoeboid cells
 Pinch mother cell in two after animal mitosis
 Important component in muscle contraction (other is myosin)
83

The Cytoskeleton: Actin Filament Operation
84
A
TP
tail head membrane
myosin
molecules
ADP + P
actin filament

The Cytoskeleton: Intermediate Filaments
 Intermediate in size between actin filaments and
microtubules
 Rope-like assembly of fibrous polypeptides
 Vary in nature
 From tissue to tissue
 From time to time
 Functions:
 Support nuclear envelope
 Cell-cell junctions, like those holding skin cells tightly together
85

The Cytoskeleton: Microtubules
 Hollow cylinders made of two globular proteins called α
and ß tubulin
 Spontaneous pairing of α and ß tubulin molecules form
structures called dimers
 Dimers then arrange themselves into tubular spirals of
13 dimers around
 Assembly:
 Under control of Microtubule Organizing Center (MTOC)
 Most important MTOC is centrosome
 Interacts with proteins kinesin and dynein to cause
movement of organelles
86

The Cytoskeleton: Microtubule
Operation
87
vesicle moves, not microtubule
kinesin
receptor
vesicle
kinesin
ATP

The Cytoskeleton
88
b. Intermediate filaments
chameleon
Chara
peacock
actin
subunit
fibrous
subunits
tubulin
dimer
a. Actin filaments
c. Microtubules
a(Actin): © M. Schliwa/Visuals Unlimited; b, c(Intermediate, Microtubules): © K.G. Murti/Visuals Unlimited; a(Chara): The McGraw-Hill Companies, Inc./photo by
Dennis Strete and Darrell Vodopich; b(Peacock): © Vol. 86/Corbis; c(Chameleon): © Photodisc/Vol. 6/GettyImages

Microtubular Arrays: Centrioles
 Short, hollow cylinders
 Composed of 27 microtubules
 Microtubules arranged into 9 overlapping
triplets
 One pair per animal cell
 Located in centrosome of animal cells
 Oriented at right angles to each other
 Separate during mitosis to determine plane
of division
 May give rise to basal bodies of cilia and
flagella
89

Microtubular Arrays: Cilia and Flagella
 Hair-like projections from cell surface that aid in
cell movement
 Very different from prokaryote flagella
 Outer covering of plasma membrane
 Inside this is a cylinder of 18 microtubules arranged in
9 pairs
 In center are two single microtubules
 This 9 + 2 pattern used by all cilia & flagella
 In eukaryotes, cilia are much shorter than flagella
 Cilia move in coordinated waves like oars
 Flagella move like a propeller or cork screw 90

Structure of a Flagellum
91
Basal body
Flagellum
shaft
Sperm
triplets
Flagellum cross section
25 nm
Basal body cross section 100 nm
The shaft of the
flagellum has a ring
of nine microtubule
doublets anchored
to a central pair of
microtubules.
dynein
side arms
dynein
side arm
central
microtubules
outer
microtubule
doublet
radial
spoke
The side arms
of each doublet
are composed
of dynein, a
motormolecule.
plasma
membrane
The basal body of a flagellum has
a ring of nine microtubule triplets
with no central microtubules.
In the presence of
ATP, the dynein side
arms reach out to
their neighbors,
and bending occurs.
ATP
(Flagellum, Basal body): © William L. Dentler/Biological PhotoService

Energy-Related Organelles: Chloroplast
Structure
 Bounded by double membrane
 Inner membrane infolded
 Forms disc-like thylakoids, which are stacked to form grana
 Suspended in semi-fluid stroma
 Green due to chlorophyll
 Green photosynthetic pigment
 Found ONLY in inner membranes of chloroplast
92

Energy-Related Organelles:
Chloroplasts
 Membranous organelles (a type of plastid) that serve as
the site of photosynthesis
 Captures light energy to drive cellular machinery
 Photosynthesis
 Synthesizes carbohydrates from CO2 & H2O
 Makes own food using CO2 as only carbon source
 Energy-poor compounds converted to energy-rich
compounds
solar energy + carbon dioxide + water →
carbohydrate + oxygen
 Only plants, algae, and certain bacteria are capable of conducting 93

Energy-Related Organelles:
Chloroplasts
 Bound by a double membrane organized into
flattened disc-like sacs called thylakoids
 Chlorophyll and other pigments capture solar
energy
 Enzymes synthesize carbohydrates
94

Chloroplast Structure
95
double
membrane
outer
membrane
inner
membrane
grana
thylakoid
space thylakoid membrane
stroma
a. 500 nm
b.
a: Courtesy Herbert W. Israel, Cornell University

96
Ribosome DNA
Stroma
Stroma
Thylakoid
membrane
Outer
membrane
Inner
membrane
Thylakoid disk
Granum
Granum
1.5 µm
(inset): © Dr. Jeremy Burgess/Photo Researchers, Inc.

Energy-Related Organelles: Mitochondria
 Smaller than chloroplast
 Contain ribosomes and their own DNA
 Surrounded by a double membrane
 Inner membrane surrounds the matrix and is convoluted (folds)
to form cristae.
 Matrix – Inner semifluid containing respiratory enzymes
 Break down carbohydrates
 Involved in cellular respiration
 Produce most of ATP utilized by the cell
97

Mitochondrial Structure
98
cristae matrix
a. 200 nm
double
membrane
outer
membrane
inner
membrane
b.
a: Courtesy Dr. Keith Porter

99
Intermembrane
space
Inner membrane
Outer membrane
Ribosome
Matrix
DNA
Crista
0.2 µm
(inset): © Dr. Donald Fawcett & Dr. Porter/Visuals Unlimited

The Evolutionary Origins of Mitochondria
and Chloroplasts
• Mitochondria and chloroplasts have
similarities with bacteria
–Enveloped by a double membrane.
–Contain free ribosomes and circular DNA
molecules.
–Grow and reproduce somewhat independently
in cells as semiautonomous organelles.
• These similarities led to the endosymbiont theory.
101
© 2014 Pearson Education, Inc.

Endosymbiont theory
• Postulates that chloroplasts and mitochondria in
cells are the result of years of evolution initiated
by the endocytosis of bacteria and cyanobacteria
which were not digested but instead became
symbiotic.
102
Mitochondria & chloroplast have
membranes, aqueous cytoplasm,ribosomes
and genetic material…..
suggesting the may have beencells.

103
Endosymbiosis
• Proposes that some of today’s eukaryotic
organelles evolved by a symbiosis arising
between two cells that were each free-living
• One cell, a prokaryote, was engulfed by and
became part of another cell, which was the
precursor of modern eukaryotes
• Origin of Mitochondria and chloroplasts
103

• The endosymbiont theory suggests that an early
ancestor of eukaryotes engulfed an oxygen-
using nonphotosynthetic prokaryotic cell.
• The engulfed cell formed a relationship with the
host cell, becoming an endosymbiont.
– The host cell and endosymbionst merged into
a single organism,a eukaryotic cell with a
mitochondrion.
– At least one of these cells may have taken up a
photosynthetic prokaryote, becoming the
ancestor of cells that contain chloroplasts.
104

Nucleus
Endoplasmic
reticulum
Nuclear
envelope
Ancestor of
eukaryotic cells
(host cell)
Engulfing of oxygen-
using nonphotosynthetic
prokaryote, which
becomes a mitochondrion
Mitochondrion
Nonphotosynthetic
eukaryote
At least
one cell
Mitochondrion
Photosynthetic eukaryote
Engulfing of
photosynthetic
prokaryote
Chloroplast
Figure 6.16
105

Mitochondria and Chloroplast
Similarities
• Mitochondria and chloroplasts
• Are not part of the endomembrane system
• Have a double membrane
• Have proteins made by free ribosomes
• Contain their own DNA
• grow and reproduce as semiautonomous
organelles
• Move within the cell
106

Structure of Plant Cells and
Animal Cells
108

2015 BIOL0011
Generalized eukaryotic (plant & animal)
cell
109
• Cells of plants & unicellular photosynthetic
organisms have cells walls & a tonoplast
(membrane) bound fluid filled vacuole.
Photosynthetic cells have chloroplasts.

Figure 6.8a
ENDOPLASMIC RETICULUM (ER)
Rough
ER
Smooth
ER
Nuclear
envelope
Nucleolus
Chromatin
Plasma
membrane
Ribosomes
Golgi apparatus
Lysosome
Mitochondrion
Peroxisome
Microvilli
Centrosome
CYTOSKELETON:
Microfilaments
Intermediate filaments
Microtubules
Flagellum NUCLEUS
110

NUCLEUS
Nuclear
envelope
Nucleolus
Chromatin
Golgi
apparatus
Mitochondrion
Peroxisome
Plasma membrane
Cell wall
Wall of adjacent cell
Plasmodesmata
Chloroplast
Microfilaments
Intermediate
filaments
Microtubules
CYTOSKELETON
Ribosomes
Central vacuole
Smooth
endoplasmic
reticulum
Rough
endoplasmic
reticulum
Figure 6.8c
111

Plant Cell vs Animal Cell
112
9/2/2015 BIOL00112015-16 13
Plant Cell Animal Cell
Cell Wall present, cellulose absent.
Chloroplasts present absent
Vacuoles large for sap absent or >1 small
Lysosomes absent present
Nucleus near the edge central
Golgi bodies simple elaborate
Endoplasmic
reticulum Present Present
Ribosomes Present Present
Mitochondria Present Present

113
9/2/2015 BIOL00112015-16 14
Plant Cell Animal Cell
Centrioles
absent except in
some
lower plant.
Present
Microtubules/
microfilaments Present Present
Flagella usually absent may be present
Cilia usually absent may be present
Growth
continuously
elongate &
differentiate from
apical meristem
stops at
maturation,
replaced.
Shape rigid, regtangular flexible, round
Storage starch glycogen
Plant Cell vs Animal Cell (cont’d)

Animal Cell Anatomy
114
*not in plant cells
phospholipid
Cytoskeleton: maintains
cell shape and assists movement
of cell parts:
Microtubules: protein
cylinders that move
organelles
Intermediate filaments:
protein fibers that provide
stability of shape
Actin filaments: protein
fibers that play a role in
change of shape
Centrioles*: short
cylinders of microtubules
of unknown function
Centrosome: microtubule
organizing center that
contains a pair of centrioles
Lysosome*: vesicle that
digests macromolecules
and even cell parts
Vesicle: small membrane-
bounded sac that stores
and transports substances
Cytoplasm: semifluid
matrix outside nucleus
that contains organelles
Nucleus: command center of cell
Golgi apparatus: processes, packages,
and secretes modified proteins
Rough ER: studded with
ribosomes that synthesize
proteins
Smooth ER: lacks
ribosomes, synthesizes
lipid molecules
Mitochondrion: organelle
that carries out cellular respiration,
producing ATP molecules
Peroxisome: vesicle
that is involved in
fatty acid metabolism
Ribosomes:
particles that carry
out protein synthesis
Polyribosome: string of
ribosomes simultaneously
synthesizing same protein
Nuclear envelope: double
membrane with nuclear pores
that encloses nucleus
Chromatin: diffuse threads
containing DNA and protein
Nucleolus: region that produces
subunits of ribosomes
Endoplasmic reticulum:
protein and lipid metabolism
Plasma membrane:
outer surface that
regulates entrance and
exit of molecules
protein
*Please take
note of the
annotations.

Plant Cell Anatomy
115
*not in animal cells
Ribosomes: carry
out proteinsynthesis
Cytoplasm: semifluid matrix outside
nucleus that contains organelles
Centrosome:
microtubule organizing
center (lacks centrioles)
Endoplasmic
reticulum: protein
and lipid metabolism
Rough ER: studded
with ribosomes that
synthesize proteins
Smooth ER: lacks
ribosomes, synthesizes
lipid molecules
Peroxisome: vesicle that
is involved in fatty acid
metabolism
Golgi apparatus: processes,
packages, and secretes
modified proteins
Nucleus: command center of cell
Nuclear envelope: double membrane with
nuclear pores that encloses nucleus
Nucleolus: produces subunits of ribosomes
Chromatin: diffuse threads containing
DNA and protein
Nuclear pore: permits passage of
proteins into nucleus and ribosomal
subunits out of nucleus
Plasma membrane: surrounds
cytoplasm, and regulates entrance
and exit of molecules
Cell wall*: outer surface that shapes,
supports, and protects cell
Middle lamella:
cements together the
primary cell walls of
adjacent plant cells
Chloroplast*: carries
out photosynthesis,
producing sugars
Granum*: a stack
of chlorophyll-containing
thylakoids
in a chloroplast
Cell wall of adjacent cell
Mitochondrion:organelle
that carries out cellular
respiration, producing
ATP molecules
Microtubules: protein cylinders
that aid movement oforganelles
Actin filaments: protein fibers
that play a role in movement of
cell and organelles
Central vacuole*: large, fluid-filled
sac that stores metabolites and
helps maintain turgor pressure
*Please take
note of the
annotations.

Tissues and Organs
Example: Dicotyledonous Root
116

Tissues and Organs
• In a multicellular organism such as an animals or
plants, different cells are specialized (modified) to
carry out particular functions.
• Both plant and animal bodies are made up of tissues
and organs.
• Grouping tissues and organs allows efficiency and
coordination of activities so that the organism
functions properly.
117

Tissues and Organs
• A tissue is a group of similar cells organised into a
structural or functional unit.
• Tissues that are composed of only one type of cell are
called simple tissues.
• Tissues consisting of two or more types of cell are
complex tissues.
• An organ is a structure composed of different
tissues that carries out a specific function.
118

• An individual organ is usually part of an organ
system.
• Examples of organ systems are:
• the respiratory system in which the heart and lungs
are organs
• the digestive system in which the stomach,
pancreas, gall bladder, liver and intestines are
organs
• the root system of plants where the roots are 119

Organ Systems in Mammals (Part 1)
Table 32.1 Organ
Systems in Mammals
Organ System Main Components
Digestive Mouth, pharynx, esophagus, stomach, intestines, liver, pancreas,
anus
Circulatory Heart, blood vessels, blood
Respiratory Lungs, trachea, other breathing tubes
Immune and
lymphatic
Bone marrow, lymph nodes, thymus, spleen, lymph vessels,
white blood cells
Excretory Kidneys, ureters, urinary bladder, urethra
Endocrine Pituitary, thyroid, pancreas, adrenal, and other
hormone-secreting glands
Reproductive Ovaries or testes and associated organs
Nervous Brain, spinal cord, nerves, sensory organs
Integumentary Skin and its derivatives (such as hair, claws, sweat glands)
Skeletal Skeleton (bones, tendons, ligaments, cartilage)
Muscular Skeletal muscles

Organ Systems in Mammals (Part 2)
Table 32.1 Organ
Systems in Mammals
Organ System Main Components
Digestive Food processing (ingestion, digestion, absorption,
elimination)
Circulatory Internal distribution of materials
Respiratory Gas exchange (uptake of oxygen; disposal of carbon
dioxide)
Immune and
lymphatic
Body defense (fighting infections and virally induced
cancers)
Excretory Disposal of metabolic wastes; regulation of osmotic
balance of blood
Endocrine Coordination of body activities (such as digestion and
metabolism)
Reproductive Reproduction
Nervous Coordination of body activities; detection of stimuli and
formulation of responses to them
Integumentary Protection against mechanical injury, infection,
dehydration; thermoregulation
Skeletal Body support, protection of internal organs, movement

Animal Tissues and Organs
• The four main types of tissue in the animal body
are:
• epithelial
• connective
• muscle
• nervous
• The major organs of the mammalian body are:
brain, heart, lungs, kidneys, liver, reproductive 123

Animal Tissues: Epithelial Tissue -
Covering & Lining
• Epithelial tissue covers the outside of the
body and lines the organs and cavities within
the body.
• It contains cells that are closely joined.
• The shape of epithelial cells may be cuboidal
(like dice), columnar (like bricks on end), or
squamous (like floor tiles).

Epithelial Tissue
Cuboidal
epithelium
Simple
columnar
epithelium
Pseudostratified
ciliated
columnar
epithelium
Stratified
squamous
epithelium
Simple
squamous
epithelium

Animal Tissues: Connective Tissue
• Connective tissue mainly binds and supports
other tissues.
• It contains sparsely packed cells scattered
throughout an extracellular matrix.
• The matrix consists of fibers in a liquid,
jellylike, or solid foundation.

Connective Tissue
Collagenous fiber
Loose
connective
tissue
Elastic fiber
120
µm
Cartilage
Chondrocytes
100
µm
Chondroitin
sulfate
Adipose
tissue
Fat droplets
150
µm
White blood cells
55
µm
Plasma Red blood
cells
Blood
Nuclei
Fibrous
connective
tissue
30
µm
Osteon
Bone
Central canal
700
µm

Animal Tissues: Muscle Tissue
• Muscle tissue consists of long cells called
muscle fibers, which contract in response to
nerve signals.
• It is divided in the vertebrate body into three
types:
• Skeletal muscle, or striated muscle, is attached
to bones and is responsible for voluntary
movement.
• Smooth muscle mainly lines internal organs and
is responsible for involuntary body activities.

Muscle Tissue
50 µm
Skeletal
muscle
Multiple
nuclei
Muscle fiber
Sarcomere
100 µm
Smooth
muscle
Cardiac muscle
Nucleus
Muscle
fibers
25 µm
Nucleus Intercalated
disk

Animal Tissues: Nervous Tissue
• Nervous tissue senses stimuli and transmits
signals throughout the animal.
• Nervous tissue contains:
• Neurons, or nerve cells, that transmit nerve
impulses.
• Glial cells, or glia, that help nourish, insulate,
and replenish neurons.

Glial cells
Nervous Tissue
15 µm
Dendrites
Cell body
Axon
Neuron
Axons
Blood vessel
40 µm

Plant Tissues
• Like any multicellular organism, a plant is
characterized by cellular differentiation, the
specialization of cells in structure and function
• The major types of plant cells are:
• Parenchyma
• Collenchyma
• Sclerenchyma
• Water-conducting cells of the xylem
• Sugar-conducting cells of the phloem

Parenchyma Cells
• Mature parenchyma cells
– Have thin and flexible
primary walls
– Lack secondary walls
– Are the least specialized
– Perform the most
metabolic functions
– Retain the ability to divide
and differentiate
Figure 35.10a

Collenchyma Cells
• Collenchyma cells are
grouped in strands and help
support young parts of the
plant shoot
• They have thicker and uneven
cell walls
• They lack secondary walls
• These cells provide flexible
support without restraining
growth

Sclerenchyma Cells
• Sclerenchyma cells are rigid
because of thick secondary
walls strengthened with lignin
• They are dead at functional
maturity
• There are two types:
• Sclereids are short and
irregular in shape and have
thick lignified secondary
walls
• Fibers are long and slender
and arranged in threads

Plant tissues and organs
• The principal tissues of vascular plants are grouped together
based on their continuity throughout the plant body.
• Vascular plants are those plants that have conducting vessels
– xylem and phloem.
• Plant tissue systems are the:
• dermal tissue system,
• vascular tissue system
• ground tissue system
• Examples of the major organs in plants are leaves, roots,
flowers and stems.
137

Tissue System:
Each plant organ has:
* dermal
* vascular
* ground tissues
Dermal
tissue
Ground
tissue Vascular
tissue

Plant Tissues
• In nonwoody plants, the dermal tissue system
consists of the epidermis.
• A waxy coating called the cuticle helps prevent water
loss from the epidermis.
• In woody plants, protective tissues called periderm
replace the epidermis in older regions of stems and
roots.
• Trichomes are outgrowths of the shoot epidermis and
can help with insect defense.

Plant Tissues
• The vascular tissue system carries out long-
distance transport of materials between
roots and shoots.
• Xylem conveys water and dissolved minerals
upward from roots into the shoots.
• Phloem transports organic nutrients from
where they are made to where they are
needed.

Plant Tissues
• Tissues that are neither dermal nor vascular
are the ground tissue system.
• Ground tissue internal to the vascular tissue
is pith; ground tissue external to the
vascular tissue is cortex. Both have plastids
for storage.
• Ground tissue includes cells specialized for
storage, photosynthesis, and support.

Plant Tissues: Diversity
•Vascular flowering plants can be divided
into two groups–based partly on the
number of cotyledons, or seed leaves, in
the embryo:
•Monocotyledons
•Dicotyledons
142

Figure 30.16
Comparison of Monocot and Dicot
Characteristics
Embryos Leaf venation Stems
Monocot
Characteristics
One
cotyledon
Veins usually
parallel
Vascular tissue
scattered
Root system
usually fibrous
(no main root)
Pollen grain
with one
opening
Floral organs
usually in
multiples of
three
Floral organs
usually in
multiples of
four or five
Pollen grain
with three
openings
Taproot (main
root)
usually present
Vascular tissue
usually arranged in
ring
Veins usually
netlike
Two
cotyledons
Eudicot
Characteristics
Roots Pollen Flowers

Comparison of Monocot & Dicot
Roots
144

Epidermis
Cortex
Endodermis
Vascular
cylinder
Pericycle
Core of
parenchyma
cells
Xylem
Phloem
100 µm
Root with xylem and phloem in the center
(typical of eudicots)
(a)
Root with parenchyma in the center (typical of
monocots)
(b)
100 µm
Endodermis
Pericycle
Xylem
Phloem
50 µm
Key
to labels
Dermal
Ground
Vascular
Organization of primary tissues
in young roots

Phloem Xylem
Sclerenchyma
(fiber cells)
Ground tissue
connecting
pith to cortex
Pith
Cortex
1 mm
Epidermis
Vascular
bundle
Cross section of stem with vascular bundles forming
a ring (typical of eudicots)
(a)
Key
to labels
Dermal
Ground
Vascular
Cross section of stem with scattered vascular bundles
(typical of monocots)
(b)
1 mm
Epidermis
Vascular
bundles
Ground
tissue
Organization of primary tissues in
young stems

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