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CELL AS A UNIT OF LIFE
Cell theory Prokaryotic and Eukaryotic cells
Microscopic structure of plant and animal cells
Cells as basic units of living organisms are grouped into tissue and organs
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Definition of Cell
A cell is the smallest unit that is capable of performing life
functions.
Examples of Cells
Amoeba Proteus
Plant Stem
Red Blood Cell
Nerve Cell
Bacteria
3.1 Early Discoveries
Mid 1600s •Robert Hooke observed and described cells in cork
Late 1600s •Antony van Leeuwenhoek observed sperm, microorganisms
1820s •Robert Brown observed and named nucleus in plant cells
Developing Cell Theory
Rudolf Virchow
Theodor
Schwann
Schlieden “Plant growth, he stated in 1837, came about through the production of new cells,
which, he speculated, were propagated from the nuclei of old cells,” i.e., all plants
are composed of cells.
Matthias Schleiden
CELL THEORY
Living things are made up of cells
The cell is the basic unit of structure
Cells come only from preexisting cells
Cell
Smallest unit of lifeCan survive on its
own or has potential to do so
Is highly organized for metabolism
Senses and responds to environment
Has potential to reproduce
Two types of cells :
Prokaryotic cells No true nucleus or organelles e.g : Eubacteria and cyanobacteria
Eukaryotic cells Nucleus and organelles that
surrounded by a membrane e.g: protozoa, algae, fungi, plants
and animals
Microscopes Create detailed images of something
that is otherwise too small to see
Light microscopes Simple or compound
Electron microscopes Transmission EM or Scanning EM
Slide 1
ocular lens
objective lens
stage
condenser
illuminator
prism
source of illumination
Figure 4.6bPage 58
Slide 1
ocular lens
objective lens
stage
condenser
illuminator
prism
source of illumination
Figure 4.6bPage 58
Slide 9
Click to view animation.
Light microscopy animation.
Animation
Slide 10
viewing screen
projector lens
intermediate lens
objective lens
specimencondenser lens
accelerated electron flow (top to bottom)
Figure 4.7Page 58
Slide 12
frog egg3 mm
typical plant cell10-100 µm
mitochondrion1-5 µm
chloroplast2-10 µm
human redblood cell7-8 µmdiameter
Trypanosoma(protozoan)25 µm long
Chlamydomonas(green alga)5-6 µm long
polio virus30 nm
HIV(AIDS virus)100 nm
T4 bacteriophage225 nm long
tobacco mosaic virus300 nm long
DNA molecule2 nm diameter
Unaided Vision
Electron Microscope (Down To 0.5 Nm)
Light Microscope (Down To 200 Nm)
Escherichia coli (bacterium)1-5 µm long
1 centimeter (cm) = 1/100 meter, or 0.4 inch
1 millimeter (mm) = 1/1,000 meter
1 micrometer (µm) = 1/1,000,000 meter
1 nanometer (nm) = 1/1,000,000,000 meter
1 meter = 102 cm = 103 mm = 106 µm = 109 nm
1 mm 100 µm 10 µm 1 µm 100 nm 10 nm 1 nm 0.5 nm
Figure 4.8Page 59
Limitations of Light Microscopy
Wavelengths of light are 400-750 nm
If a structure is less than one-half of a wavelength long, it will not be visible
Light microscopes can resolve objects down to about 200 nm in size
Electron Microscopy
Uses streams of accelerated electrons rather than light
Electrons are focused by magnets rather than glass lenses
Can resolve structures down to 0.5 nm
PROKARYOTIC CELLS &
EUKARYOTIC CELLS
The prokaryotic cell is much simpler in structure, lacking a nucleus and the other membrane-enclosed organelles of the eukaryotic cell.
1. Organisms2. Cell size3. Cell division4. Cell walls5. Organelles6. Genetic material7. Flagella8. Respiration9. Photosynthesis10.Nitrogen fixation
* refer handout
prokaryotes vs eukaryotes
MICROSCOPIC STRUCTURE OF PLANT
AND ANIMAL CELLS
animal cells
plant cells
CELLS AS BASIC UNITS OF LIVING ORGANISMS
ARE GROUPED INTO TISSUE AND ORGANS
CELLS ARE GROUPED INTO TISSUE AND
ORGANS
THE PLANT
Plant PlantGymnosperm- seed-bearing plantAngiosperm-flower-producing plant
TISSUES
Cells in plants and animals are grouped together in tissues.
A tissue is a group of similar cells that are organised to do a specific job
Angiosperm Body Plan
VASCULAR TISSUES
GROUND TISSUES
SHOOT SYSTEM
ROOT SYSTEM
EPIDERMIS
•Ground tissue system
•Vascular tissue system
•Dermal tissue system
shoot tip(terminal bud)
lateral (axillary) bud
flower
EPIDERMIS
leaf
seeds(inside fruit)
witheredcotyledon
root hairs
root tiproot cap
node
nodeinternode
VASCULAR TISSUES
GROUND TISSUES
SHOOT SYSTEM
ROOT SYSTEM
primary root
lateral root
Overview of the plant body
Ground tissue
Vascular tissue
Meristems• Regions where cell divisions produce
plant growth• Consist of unspecialised, dividing
cells.• Apical meristems
– Lengthen stems and roots– Responsible for primary growth
• Lateral meristems– Increase width of stems– Responsible for secondary growth
activity atmeristems
new cellselongateand start todifferentiateinto primarytissues
activity atmeristems
new cellselongateand start todifferentiateinto primarytissues
Figure 29.4Page 507
Root apical meristem
Shoot apical meristem
activity atmeristems
new cellselongateand start todifferentiateinto primarytissues
ROOT APICAL MERISTEMApical meristem near all root tips gives rise to protoderm, ground meristem, and procambium
These give rise to the root’s primary tissue systems: epidermis, ground tissues, and
vascular tissues
SHOOT APICAL MERISTEMSource of primary growth (lengthening)
THREE PRIMARY MERISTEMSProtoderm epidermis
Ground meristem ground tissueProcambium primary vascular tissues
activity atmeristems
new cellselongateand start todifferentiateinto primarytissues
Figure 29.4Page 507
Apical Meristems
vascular cambium
cork cambium
secondaryphloem
secondaryxylem
thickening
LATERAL MERISTEMSTwo lateral meristems in older stems and roots of woody plants produce secondary growth (increases in diameter):
Vascular cambium secondary vascular tissuesCork cambium periderm (replaces epidermis)
Figure 29.4Page 507
LATERAL MERISTEMS
Ground tissue system
• -serves basic functions:
• Food and water storage
Vascular tissue system
• -distributes water and solutes
Dermal tissue system
• Covers and protect plant surfaces
Three Plant Tissue system
GROUND TISSUE SYSTEM
Predominantly cells in the leaf, stem, roots and storage organs
e.g., potato tuber e.g., celery stem e.g., cherry seed
VASCULAR TISSUE SYSTEM
The xylem and phloem made up the plant vascular tissue system
Food, water, and other substances are transported and is continuous throughout the plant.
DERMAL TISSUE SYSTEM (OR EPIDERMIS)
Single layer of tightly packed cells covering and protecting the young parts of plant
E.g., the waxy cuticle that help plant retain water in leaves and stems
Tissue Differentiation
Protoderm Ground meristemProcambium
Epidermis
Ground tissuePrimary vascular tissue
Simple Tissues• Made up of only one
type of cell
Parenchyma
Collenchyma
Sclerenchyma
Parenchyma: A Simple Tissue
• Most of a plant’s soft primary growth
• Pliable, thin walled, many sided cells
• Cells remain alive at maturity and retain capacity to divide
• Mesophyll is a type that contains chloroplasts
Parenchyma: A Simple Tissue
• Most of a plant’s soft primary growth
• Pliable, thin walled, many sided cells
• Cells remain alive at maturity and retain capacity to divide
• Mesophyll is a type that contains chloroplasts
• Ground tissue for fruits, stems and leaves.
Collenchyma: A Simple Tissue
• Specialized for support for primary tissues
• Makes stems strong but pliable• Cells are elongated• Walls thickened with pectin• Alive at maturity
Scelerenchyma : A Simple Tissue
• Supports mature plant parts• Protects many seeds• Thick, lignified walls • Dead at maturity• Two types:
– Fibers: Long, tapered cells– Sclereids: Stubbier cells
Complex Tissues
Xylem
Phloem
Epidermis
Composed of a mix of cell types
Xylem
•Conducts water and dissolved minerals•Conducting cells are dead and hollow at maturity
vessel membertracheids
Phloem: A Complex Vascular Tissue
• Transports sugars • Main conducting
cells are sieve-tube members
• Companion cells assist in the loading of sugars
sieve plate
sieve-tubemember
companioncell
Epidermis: A Complex Plant Tissue• Covers and protects plant
surfaces• Secretes a waxy, waterproof
cuticle• In plants with secondary
growth, periderm replaces epidermis
Monocots and Dicots:
Parallel veinsNetlike veins
3 pores1 pore
4 or 5 floral parts
3 floral parts
1 cotyledon 2 cotyledons
Vascular bundles dispersed
Vascular bundles in ring
Monocots and Dicots:
Parallel veinsNetlike veins
3 pores1 pore
4 or 5 floral parts
3 floral parts
1 cotyledon 2 cotyledons
Vascular bundles dispersed
Vascular bundles in ring
Shoot Development
immature leaf
ground meristem
primary phloem
primary xylempith
procambium
cortex
procambium
protoderm
shoot apical meristem
procambium
epidermis
Figure 29.11 Page 510
Internal Structure of a Dicot Stem
Outermost layer is epidermisCortex lies beneath epidermisRing of vascular bundles separates
the cortex from the pith The pith lies in the center of the
stem
Internal Structure of a Monocot Stem
• The vascular bundles are distributed throughout the ground tissue• No division of ground tissue into cortex and pith
Ring of vascular bundlesdividing ground tissue into cortex and pith Vascular bundles distributed
throughout ground tissue
Dicot Monocot
Internal structure of Stems
Common Leaf Forms
petiole
blade
axillarybud
node
blade
sheath
node
DICOT MONOCOT
Adapted for Photosynthesis
Leaves are usually thin High surface area-to-volume ratio Promotes diffusion of carbon dioxide in,
oxygen outLeaves are arranged to capture sunlightAre held perpendicular to rays of sunArranged so they don’t shade one another
Leaf Structure
UPPEREPIDERMIS
PALISADEMESOPHYLL
SPONGYMESOPHYLL
LOWEREPIDERMIS
one stoma
cuticle
O2CO2
xylem
phloem
Root Systems
Taproot system of a California poppy
Fibrous root system of a grass plant
Figure 29.17Page 514
VASCULAR CYLINDER:
endodermispericyclexylem
phloemcortexepidermis
fully grown root hair
Vessels have matured; root hairs and vascular cylinder about to form
Cells elongate; sieve tubes form and mature; vessel members start to form
Most cells have stopped dividing
Cells are dividing rapidly at apical and primary meristems
quiescent center
root cap
Root Structure
Root cap covers tip
Apical meristem produces the cap
Cell divisions at the apical meristem cause the root to lengthen
Farther up, cells differentiate and mature
AnimalCell specialization
ANIMAL TISSUES AND ORGAN SYSTEMS
Take a rest
Animal tissue
HOMEOSTASIS
Stable operating conditions in the internal environment
Brought about by coordinated activities of cells, tissues, organs, and organ systems
TISSUE A group of cells and intercellular
substances that interact in one or more
tasks
Four typesEpithelial tissue
Muscle tissue
Connective tissue
Nervous tissue
ORGANSGroup of tissues organized to perform
a task Heart is an organ that pumps blood
through body Heart consists of muscle tissue, nervous
tissue, connective tissue, and epithelial tissue
ORGAN SYSTEMS
Organs interact physically, chemically, or both to perform a common task
Circulatory system includes the heart, the arteries, and other vessels that transport blood through the body
EPITHELIAL TISSUE
Lines the body’s surface, cavities,
ducts, and tubes
One free surface faces a body
fluid or the environment
simplesquamousepithelium
basementmembrane
connective tissue
SIMPLE EPITHELIUM
Consists of a single layer of cells
Lines body ducts, cavities, and tubes
Cell shapes:
Squamous Cuboidal Columnar
STRATIFIED EPITHELIUM
Two or more layers thick
Functions in protection, as in skin
Cells in the layers may be squamous,
columnar, or cuboidal
Glands Secretory organs
derived from epithelium
Exocrine glands have ducts or tubes
(secrete mucus, saliva, earwax)
Endocrine glands are ductless
Product-hormone
Section through the glandular epithelium of a frog.
pore that opens at skin surface
mucous gland
poison gland
pigmented gland
CELL JUNCTIONS
a type of structure that exists within the tissue of a
multicellular organism. They consist of protein
complexes and provide contact between
neighbouring cells, between a cell and the
extracellular matrix, or
Tight junctions prevent leaks
Gap junctions connect abutting cytoplasms
Adhering junctions cement cells together
TightJunction
AdheringJunction
GapJunction
CONNECTIVE TISSUE
Most abundant tissue in the bodyCells are scattered in an
extracellular matrixMatrix is collagen and/or elastin
fibers in a polysaccharide ground substance
collagenous fiberfibroblast
elastic fiber
Loose connective tissue
cartilage cell(chondrocyte)
Cartilage
collagenous fibers
collagenous fibers
fibroblast
Dense, regular connective tissue
ground substance with collagen fibers
cell bulging with fat droplet
nucleus
Adipose tissue (fat storage) Dense, irregular connective tissue
compactbone tissueblood vessel
bone cell(osteocyte)
Bone
SOFT CONNECTIVE TISSUESSPECIALIZED CONNECTIVE TISSUES
location of cartilage on knobby end of along bone
bone tissue
Figure 33.6Page 571
Blood
Classified as a connective tissue because blood cells arise in bone
Serves as the body’s transport medium
Red cells, white cells, and platelets are dispersed in a fluid medium called plasma
MUSCLE TISSUE
Composed of cells that contract when
stimulated
Helps move the body and specific body parts
Types of tissue- Skeletal, cardiac, smooth
SKELETAL MUSCLE
Located in muscles that attach to bones
Long, cylindrical cells are striated
Cells are bundled closely together in parallel arrays
Figure 33.8, page 572
SMOOTH MUSCLE
In walls of many internal organs
(stomach, lungs etc) and
some blood vessels
Cells are not striped and taper
at the ends
Figure 33.8, page 572
one muscle cell
one bundle of musclecells in its own sheath
outer connective tissue sheath around one muscle
one whole muscle, a biceps
Figure 33.9Page 572
CARDIAC MUSCLE
Present only in the heart
Cells are striated and
branching
Ends of cells are joined by
communication junctions
nucleus
NERVOUS TISSUE
Detects stimuli, integrates information, and
relays commands for response
Consists of excitable neurons and supporting
neuroglial cells
NEUROGLIA
Constitute more than half of the nervous
tissue
Protect and support the neurons, both
structurally and metabolically
Major Organ Systems
IntegumentaryMuscularSkeletalNervousEndocrine
•Lymphatic•Respiratory•Urinary•Circulatory•Reproductive
IntegumentarySystem
MuscularSystem
SkeletalSystem
NervousSystem
EndocrineSystem
CirculatorySystem
Fig. 33.11(1)Page 574
LymphaticSystem
RespiratorySystem
DigestiveSystem
UrinarySystem
ReproductionSystem
Fig. 33.11(2)Page 575
Organ systems carry out the major body functions of most animals. Each organ system consists of several organs and has
specific functions.
Thank you for your attention
^_^
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perbezaan antara mereka yang berjaya dengan yang lain bukanlah kerana kekurangan kekuatan atau ilmu,tetapi lebih kepada kekurangan kesungguhan dan kemahuan