Cell
Cell Theory
Plant And Animal Cells
Transport
History of the Cell Theory
• 1500s-Eyeglass makers-several lenses magnifies
objects
• Anton van Leeuwenhoek: First to describe cells.
“Animalcules” (bacteria)
• Robert Hooke: Studied cork (dead cells of oak tree);
monastery; cells born.
• Robert Brown (1833): Dark structure near the
center of the cell (nucleus)
• Matthias Schleiden(1838): Plants made of cells
• Theodore Schwann (1839): Animals are made of
cells.
• Rudolf Virchow (1855): Cells come from pre-existing
cells
Hooke
Cell Theory
• All organisms are composed of one
or more cells.
• Basic unit of organization of
organisms.
• All cells come from pre-existing cells.
Modern Cell Theory
The cell contains hereditary information which
is passed on from cell to cell during cell
division.
All cells are basically the same in chemical
composition and metabolic activities.
Cell Size
• 5 to 50 micrometers in diameter
– Smallest Mycoplasma bacteria (0.2
micrometers across)
– Giant amoebas Chaos chaos (1000
micrometers/1 mm) in diameter; unaided eye
Cell membrane/plasma
membrane
• Thin flexible barrier
• Many cells in direct contact with fluid
portion of blood called plamsa.
Nucleus (plural: nuclei)
Large membrane enclosed structure that contains
genetic material in the form of DNA and controls
cell’s activities.
Prokaryotic vs. Eukaryotic
PROKARYOTES
PRO- “Before”
EUKARYOTES
EU- “True”
• Generally smaller and
simpler (exceptions)
• Do not separate genetic
material in a nucleus.
• All characteristics of life.
• Single Cells
• Lack organelles
• Ex. bacteria
•
•
•
•
•
Larger, more complex
Dozens of structures
Internal membranes
Highly specialized
Genetic material in
nucleus
• Single celled,
multicellular
• Ex. Plants, animals, fungi
Eukaryotic and Prokaryotic Cells
Organelles: Membrane bound structures.
Microscopes-use lenses to magify
the image of an object by
focusing light or electrons
Compound Light Microscope: Uses two or more
lenses that lets light throught to magnify objects.
Used to examine living cells, small organisms and
preserved cells.
See cells and structures as small as 1 millionth of
a meter
Magnification: Up to 1500 x
Compound Microscope
• Objective lens-just above specimen-enlarges
image
• Ocular lens-eyepiece-further magnifies image
• Most living things nearly transparent :: use
dyes.
– Toluidine blue-cell boundaries and nuclei
– Fluorescent-give off light of a particular color
when viewed under specific wavelengths of light.
• Fluorescence microscopy-identify locations of molecules
and watch movement.
Electron Microscope: beam of
electrons that are focused by a
magnetic field
Magnify object up to 500,000x
Produce realistic, 3-D pictures.
Electron Microscopes
• Transmission and scanning
• Explore cell structures and large protein
molecules.
• Electrons pass through thin samples-cells
and tissues must be cut ultrathin.
• Electrons scatter::uses a vacuum
• Chemically preserved samples
• Nonliving cells and tissues only
Scanning Tunneling Microscope: Probe is brought
near specimen. Electrons flow between the tip of
the probe and atoms on the specimen’s surface. As
probe follows surface contours, 3-D image is
created on a computer.
Magnification: hundred million times
Transmission Electron Microscope:
Aims a beam of electrons through a
specimen. Denser objects allow fewer
electrons to pass through.
Magnification: hundreds of thousands of
times
Cell structures and functions
Cell Boundaries
Cell Membrane
Cell Wall (PLANTS ONLY)
Plasma/Cell Membrane
• Structure: A lipid bilayer with protein
molecules and carbohydrate chains
embedded throughout the bilayer
• Function: A selectively permeable
membrane which controls what enters
and leaves the cell.
FLUID MOSAIC
1. Flexible
2. Phospholipids move like
water molecules in a
current of a lake
Selective Permeability: Process by which the plasma
membrane of a cell allows some molecules into the cell
while keeping others out.
Phospholipids: Lipids with a phosphate group attached to
them.
Phospholipids
•Glycerol backbone
•Two fatty acid chains
•Phospate group
Cholesterol
•Stabilize phospholipids
•Prevents fatty acid chains from
phospholipids from sticking together
Transport Proteins
•Allows substances and waste to
move through the plasma membrane.
•Examples: Protein Channels and
Carrier Proteins
Proteins and Carbohydrates
• Stick out of cells to help cells
identify one another
Cell Wall
• Structure: Fairly rigid structure located
outside the plasma membrane.
• Function: Shape, support and protection.
• Found in plants cells, fungi, most bacteria, and
some protists.
• Cellulose
.
Cilia And Flagella
Cilia
• Structure: Short,
numerous, hairlike
projections, that move
in a wavelike motion.
• Function: Aid in
locomotion and feeding.
Flagella
• Structure: Long
projections that move
in a whip-like motion.
• Function: Major means
of cell locomotion—
unicellular organisms.
Cellular Control Center
Nucleus
Nucleus
• Structure: Center of the Cell
• Function : Control center of the cell; Contains
the direction to make proteins and other
important molecules (DNA).
• Prokaryotes: DNA in cytoplasm
• Plant and animal cells
Chromatin
• Structure: Strands of genetic material, DNA;
Forms Chromosomes
• Function: Master set of directions for
making proteins.
Nucleolus
• Structure: Prominent structure in the nucleus.
• Function: Make Ribosomes (RNA and
Proteins)
Nuclear Envelope
• Structure :Separates the nucleus from
the cytoplasm; Double membrane made
of two phospholipid bilayers contain
pores for substances to pass through.
• Function: Allow materials in and out of
nucleus.
Cytoplasm
• Structure: Clear, gelatinous fluid inside the
cell. Area between cell membrane and
nucleus. Dissolved in Cytosol are salts,
minerals, and organic compounds.
• Function:Contains various cell organelles.
• Organelles that Build Proteins
Ribosomes
Endoplasmic Reticulum
Golgi Apparatus
Ribosomes
• Structure: Most numerous in cell; no membrane;
found free and attached; among smallest of
organelles; Made up of RNA and Proteins
• Function: Protein Assembly (DNA directions)
Endoplasmic Reticulum
• Structure:Complex system of folded membranes
suspended in the cytoplasm.
• Function:
– transportation system between the nucleus and the
cytoplasm
– Site of chemical reactions
– Prepares proteins for export (rER)
– synthesizes steroids
– regulates calcium levels
– breaks down toxic substances (sER)
• Smooth (No Ribosomes); Rough (Ribosomes)
Golgi Apparatus/Body
• Flattened system of tubular membranes.
Flattened stack of pancakes.
• Modifies, sorts, and packages proteins
and lipids for storage and transport
(Cell’s Post Office)
Organelles that Store,
Clean-UP, and Support
Vacuoles/Vesicles
Lysosomes
Cytoskeleton
Centrioles
Vacuole
Vacule in plants/Vesicle in animals
• Structure: Sac surrounded by a
membrane.
• Function: Stores food, enzymes and other
materials needed by the cell, and some
vacuoles store waste products.
Plastids
• Function: Stores starches and lipids;
• Example chloroplast (one type) transfers
energy from light to organic compounds.
In plants, plastids may differentiate into several forms,
depending upon which function they need to play in the cell.
Chloroplasts: for photosynthesis
Chromoplasts: for pigment synthesis and storage
Amyloplasts: for starch storage
Statoliths: for detecting gravity
Elaioplasts: for storing fat
Proteinoplasts: for storing and modifying protein
Lysosomes
• Structure: Small spherical organelles that
enclose hydrolytic enzymes within a
single membrane.
• Function: Digest molecules, old
organelles, and foreign substances
(engulfs viruses or bacteria)
Cytoskeleton
• Structure: Support structure made of tiny
rods and filaments.
• Function: Form a framework for the cell.
Microtubules and Microfilaments
Assist in cell shape and assist organelles in moving from place
to place within the cell.
Microtubules: Thin hollow cylinders made of proteins.
Microfilaments: Thin, solid protein fibers.
Centrioles
•Pair of cylinder-shaped bodies found in the
cells
•Organize cell division
•Animal Cells ONLY
Organelles that capture
and release energy
• Chloroplasts (PLANT ONLY)
• Mitochondria
Chloroplast (PLANTS ONLY)
• Structure:Disc shaped (ability to change shape
and position in the cell as light intensity changes)
Contains pigment in the inner series of thylakoid
membranes.
• Function: Convert solar energy to chemical
energy stored in food.
Chlorophyll
• Function: Traps light energy and gives
leaves and stems their green color.
Mitochondria
• Structure: Granular and rod shaped,
with an inner membrane that forms long,
narrow folds.
• Function: Convert chemical energy in
food to usable compounds (ATP).
Animal
Cell
Diffusion—Movement of
particles from an area of higher
concentration to an area of lower
concentration
Slide 59
Net Movement
movement which changes
concentration
Slide 60
Slide 61
Factors that affect diffusion
Particle size and shape
 Temperature
 Concentration gradient—Difference in
concentration.
 Cytoplasmic streaming—Continuous
movement of materials in cytoplasm.

Slide 62
Diffuse in Membranes
1.
Passive Transport
Moving of materials across cell membrane
without using cellular energy.
• Diffusion (phospholipids)
• Facilitated Diffusion (transport proteins)
Uses Channel Proteins
Active Transport
Moving of materials across cell membrane
using cellular energy
Uses Carrier Proteins
Slide 63
Osmotic Pressure
•
•
Force produced by the net
movement of water out of or
into a cell
Water moves from an area of
HIGH water concentration (low
solute) to an area of LOW
water concentration (high
solute)
Slide 64
Aquaporins
Water channel proteins
Slide 65
Osmosis
Slide 66
Osmotic Pressure
Force produced by the net movement of
water out of or into cell.
Result:
Turgid pressure-plants straight up
Water purification (reverse osmosis)
Desalinates Salt Water
Slide 67
Osmotic Condition—Cell
concentrations versus
environmental solution
concentrations.
Isotonic
Hypotonic
Hypertonic
Slide 68
Solution concentrations inside is the same as
outside.
No net movement of water.
Animal cells: Normal
Plant Cells: Flaccid
Isotonic
“Iso” means same
Slide 69
Solute concentrations outside is
less than cell concentration.
Animal Cell : Lysed
Plant Cell: Turgid
“Hypo” - under
Slide 70
Slide 71
Solute concentration outside is
greater than cell concentration.
Animal Cell: Shrink
Plant Cell: Plasmolyzed
“Hyper” - above
Slide 72
This is why it is dangerous to drink sea water - its a myth that
drinking sea water will cause you to go insane, but people marooned
at sea will speed up dehydration (and death) by drinking sea water.
This is also why "salting fields" was a common tactic during war, it
would kill the crops in the field, thus causing food shortages.
Slide 73
Slide 74
Hypertonic, Isotonic and
Hypotonic
Slide 75
Slide 76
Slide 77
Active TransPort
Using a protein molecule to move
particles up the concentration
gradient.
Requires ATP (Adenosine
Triphosphate)
Slide 78
Example of how the cell
uses Active Transport
Pump—Proteins that use active
transport to move particles
between the interior and exterior
of the cell.
e.g. Sodium/Potassium pump:
Used to move sodium and
potassium ions across nerve
membranes.
Slide 79
Active Transport Versus
Passive Transport
Slide 80
Large Molecules
Slide 81
Endocytosis: Cell membrane
indents around molecule and
forms a vesicle.
Pinocytosis—Uptaking fluid molecules
 Phagocytosis—Uptaking solid molecules

Slide 82
Pinocytosis and Phagocytosis
Slide 83
Exocytosis
Vesicles fuse with cell membrane
to release materials.
Slide 84
Endocytosis and Exocytosis
Slide 85
Homeostasis
maintain internal physical and
chemical conditions
Unicellular organisms
•
•
•
•
Grow
Respond to environment
Transform energy
Reproduce
Multicellular organisms
• Cells become specialized (move, react,
produce substances)
– particular tasks
– communicate with one another
Levels of Organization
• Cell-basic unit of life (muscle cell)
• Tissue-Cells working together to perform
particular function (smooth muscle tissue)
• Organ-Group of tissues working together
(heart, stomach)
• Organ System-organs working together to
perform specific function (stomach,
pancreas, intestines form digestive system)
• Organism-organisms working together;
division of labor
Cellular Communication
• Receptors-on or in cell, a specific protein to
whose shape fits that of a specific molecular
messenger (hormone)