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Chapter 7 - Cells
7-4 THE DIVERSITY OF CELLS
Compare and contrast the differences between different types
of specialized cells
Identify the levels of organization in multicellular organizations
How many different
types of cells are
there in the human
body?
Levels of Cellular Organization
Neurons• Receives and sends
messages
• Part of the nervous
system
Thermosensitive
Nerve Cells• Primary function is to
detect temperature
• Also detect pain
Muscle Cells
• Stretch and contract
to make body
movements
• Every movement in
your body is the result
of a muscle cells
contracting and
another set
expanding.
Sperm, Egg, Pollen
• Reproduction
Red Blood Cell
• Picks up oxygen from
the lungs and delivers
it around the body.
What do you see?
Cones
• Cell in the back of
your eye that
detects color.
• Cell in the back of
your eye that
detects light, but
aren’t sensitive to
color.
Rods
Skin Cells
• Provide protection
and a barrier to the
outside world
• The cells on the
outermost layer are
dead
Absorptive Cells
• These cells absorb
nutrients from food.
7-1 LIFE IS CELLULAR
Distinguish among prokaryotic and the two major groups of
eukaryotic cells
Cell Theory’s Main Points
All living organisms are composed of one or
more cells
Cells are the most basic unit for function and
structure of all organisms
All cells come from cells that already exist
Review of the Key Scientists
• Robert Hooke
• Anton van Leeuwenhook
• Matthias Schleiden
• Theodore Schwann
• Rudolph Virchow
Coined the term “cell” in
his publication about
microscopic structures
Contribution to Cell Theory
1632 -1723
A microscopy pioneer and naturalist
who formulated early descriptions of
bacteria and spermatozoa
He devoted his time to his hobby,
which was grinding lenses and
using them to study tiny objects
Matthias Schleiden1804 – 1881
1831
Recognized the importance
of the cell nucleus and its
connection to cell division
1838
Used his observations of
plant cells to state that
organisms consist of cells or
substances made by cellsContributions
to Cell Theory
Schw
ann’s
Dis
coveries
contributions to cell knowledge
Included
• cell origin
• tissue development of nails, tooth enamel
and feathers
Theodor Schwann1810 - 1882
all animals are made of cells
best known for his theory
Omnis cellula e cellula"every cell originates from another cell"
1858
Contributions to Cell Theory
• Proposes the
Endosymbiont Theory in
1970
– Several organelles found in
eukaryotic cells appear to
be of prokaryotic origin
– Evidence includes having
their own DNA and
reproduction that occurs
independently of the cell
Two Basic Kinds of Cell
• Prokaryotes
“Before Kernel”
– no nucleus
– no organelles
– single strand of DNA
– cell wall
(not like a plant)
– small size
• 0.1 to 1.0 µm
NEXT CHAPTER
• Eukaryotes
“New Kernel”
– nucleus
– organelles
– multiple chromosomes
– cell wall
(plants only)
– larger size
• 1.0 to 10.0 µm
FOCUS of this CHAPTER
Two Basic Kinds of Cell
• Prokaryotes
“Before Kernel”
NEXT CHAPTER
• Eukaryotes
“New Kernel”
FOCUS of this CHAPTER
Eukaryotic Cells – Two Types
Animal
Plant
How do we see the microscopic
world of cells?
• Light microscopes
• Electron microscopes
– Transmission
– Scanning
• Scanning probe microscopes
Light Microscopes
Electron Microscope
Table SaltTransmission Electron
Microscope
12/16/2015
Eye of an Ant
Spider
Human hair
7-2 EUKARYOTIC CELL
STRUCTURE
Describe the structure and function of the following:
cell wall, cell membrane, cytoplasm, nucleus, chromosomes,
ER, ribosomes, Golgi bodies, lysosomes, mitochondria,
microtubules, microfilaments, centrioles, cilia, flagella,
vacuoles, and plastids.
Start with…
The Cell Membrane
• Characteristics
– thin layer of lipid
and protein
– 5 to 10 nm thick
– flexible, bilayer
– surrounds the
outside of the cell
**all types of cells
have membranes**
cell membrane
Cytoplasm
• Characteristics
– semifluid substance
– two components
• Cytosol = primarily water
and dissolved organic
materials (50% of vol.)
• Everything Else = organelles
and the insoluble cellular
components
**all types of cells
have cytoplasm**
Cytoplasm
• Function
– suspends the organelles
– provides a medium for
dissolving and
transporting molecules
**all types of cells
have cytoplasm**
cytoplasm
Cytoskeleton
• Characteristics
– network of fibers and tubes
• microtubules
• microfilaments
• intermediate filaments
• Function
– supports cell
– transports organelles
– moves cell membrane
Cytoskeleton Fibers (filaments
and microtubules)
Nucleus
• Characteristics
– found in the center of the cell
– surrounded by a bilayer envelope with pores
• Function
– holds genetic information
– nucleolus makes ribosomes
**ONLY EUKARYOTIC CELLS**
Nucleus
Nucleolus
All the other stuff in a cell
What have we covered
already?
Nucleus
Nucleolus
Cell Membrane
Cytoplasm
Cytoskeleton
Fibers
Cell Organelles
• the following organelles are all found in
both types of eukaryotic cells
– Each organelle has a specific role (function)
**ONLY EUKARYOTIC CELLS**
Ribosomes
• Characteristics
– very small
– suspended in cytoplasm
– attached to rough
endoplasmic reticulum
– made up of two parts
• Function
– join amino acids to make
proteins
**Both EUKARYOTIC and PROKARYOTIC
CELLS but different types**
Ribosomes
Endoplasmic Reticulum (ER)
• Character
– contiguous
with the
pores of the
nuclear
membrane
– extensive
network of
membranes
ER – Rough and Smooth
• Function – Rough
– ribosomes are
embedded in the
membranes
• makes proteins and
new cell membrane
• Function – Smooth
– NO ribosomes
• makes lipids,
carbohydrates, and
modifies toxic
chemicals
Endoplasmic Reticulum
Golgi Apparatus –
Cell UPS Delivery
• Character
– series of membrane
bound sacs
– unique appearance
• like pancake stacks
Golgi Apparatus
• Function
– sorts, modifies, packages and distributes
macromolecules
– packages some molecules for secretion
Golgi Apparatus
Mitochondria – Cell Powerhouse
• Character
– double wall
membrane
– folded inner
membrane (cristae)
– inner space (matrix)
– 1000’s within a cell
Mitochondria
• Function
– breaks down food
molecules to produce
energy
– inner membrane contains
special structures for
producing large quantities
of energy
Mitochondria
Lysosomes
• Character
– saclike organelles
– contain digestive
enzymes
Lysosomes – Recycling Centers
• Function
– break down large molecules for transport and
disposal
– recycle worn out organelles
Lysosomes
Vesicles – Transport Containers
• Function
– transport of materials into and out of the cell
Vesicles – Transport Containers
• Transport
mechanism
– Vesicles travel
along cytoskeleton
structures
Vesicles
Centrioles
Plant Cells
Three Important Structures
• Cell Wall– Cellulose structure
• Central Vacuole– Large storage organelle
• Chloroplasts– Make carbohydrates!! Make
energy!!
Plant Cell Walls
• Important for holding
plants up!
– Special carbohydrate
called cellulose
• Very tough!
• Flexible enough, but
not too much
• Characteristic
appearance
http://www.ceres.net/AboutUs/Abo
utUs-Biofuels-Carbo.html
Plant Cell Wall Diagram
Central Vacuole
• Large storage organelle in the
center of plant cells
– Creates turgor pressure
– Helps store water
Chloroplasts
• Unique shape
• Found near surface
• Give plants their green color
• Make carbohydrates through
photosynthesis
• WE WILL CONTINUE THIS DISCUSSION
IN PHOTOSYNTHESIS
7-3
Cells and Their Environment
Explain how and why cells maintain a large surface to
volume ratio
Describe the roles of diffusion, facilitated diffusion, osmosis,
and active transport in maintaining homeostasis
Cell Membrane Structure
• phospholipid bilayer
– phospholipid has (a)
• hydrophilic head
• hydrophobic tails
– when placed in water
• head turns toward water
• tails turn away from water
Cell Membrane Structure
• embedded proteins
– 2 main types
– gate ports (transporters and channels)
– communication (receptor proteins)
Cell Membrane Model
• Fluid Mosaic Model
– phospholipids and proteins move around each
other freely
http://www.dnatube.com/video/360/Fluid-
Mosaic-Model
Maintaining Internal Conditions
• Cells use
– Active and passive transport to control
• Movement of water, food, ions and other
needed materials into and out of cells
Maintenance of these internal conditions
is called homeostasis.
Semi-permeable Membranes
• Cell membranes are
semipermeable
– They prevent the movement of certain
particles into and out of the cell
permeable =
allows molecules
to pass through
semi =
partial
Molecule Movement
• Can be controlled
– proteins
– carbohydrates
• large size
• Cannot be controlled
– water
• small size
• Small but controlled
– ions
• electrical charge
prevents movement
Transport Processes Through
Membranes
Passive Transport
• particles move down a conc. gradient from high to low
• includes– simple diffusion
– osmosis
Active Transport
• particles move against a conc. gradient from low to high
• used for transport of molecules to areas of high conc.
ENERGY
REQUIRED
NO
ENERGY
REQUIRED
Transport Processes Through
Membranes
Passive Transport Active Transport
ENERGY
REQUIRED
No ENERGY
REQUIRED
high
conc.
low
conc.
high
conc.
low
conc.
Passive Transport
• Includes Diffusion and Osmosis
• Start with Diffusion
– the random movement of particles from areas of high
conc. to low conc. without the input of energy
– two types of diffusion
• simple
• facilitated
REMINDER!! Concentration is
the proportion of
solute to solvent
Simple Diffusion
• rate of diffusion depends on
– temp. and size of molecules
– conc. gradient
FASTER movement
high temp.
small molecules
SLOWER movement
low temp.
large molecules
Passive
Transport
Facilitated Diffusion
• follows same rules for simple diffusion
– movement is passive down a conc. grad.
• facilitated carrier proteins help transport
the molecules across the cell
membrane
Passive
Transport
Osmosis
• special type of diffusion that results from
the passive movement of water across a
semi-permeable membrane
– follows rules of diffusion
• movement from
high WATER conc. to low WATER conc.
Passive
Transport
Word Parts for Osmosis:
• Hyper = more particles, less water
• Iso = equal particles, equal water
• Hypo = less particles, more water
• Tonic = particles in solution
Passive
Transport
Osmotic Environments
• Condition of the solution (environment) the
cell is in
– determined by comparison of the
concentration of solution
INSIDE and OUTSIDE
the cell
• three types of osmotic conditionsPassive
Transport
Osmotic Conditions
Passive
Transport
Whether or not something is HYPER,
ISO, or HYPOTONIC depends on what
you are comparing it with.
Make sure you know what you are
comparing your solution with.
For example:
The _______ is hypertonic to the
_______. Passive
Transport
Passive
Transport
Identifying Osmotic
Environments• When identifying an osmotic environment
you need to do two things:
– 1) identify the concentration
• of particles outside the cell
• of particles inside the cell
– 2) then compare and determine which
direction the water (!) will move BE
CAREFUL!!! Passive
Transport
Hypertonic Solution
• Solution
– lots of particles
– little water
• Water Movement
– out of the cell
Passive
Transport
Isotonic Solution
• Solution
– same particles
– same water
• Water Movement
– NO NET MOVEMENT
Passive
Transport
Hypotonic
• Solution
– few particles
– lots of water
• Water Movement
– into the cell
Passive
Transport
Active Transport
• Cells sometimes need
certain particles (molecules
or ions) that are already at
a high conc. inside the cell
• Need to move against the
conc. grad.
• Requires energy to move
particles Active
Transport
Movement of Large Particles
• Endocytosis
endo = into, cyto = cell
– Macromolecules or other
molecules are moved into the
cell
– Vesicles are formed from the
plasma membrane of the cell
Active
Transport
Three main types of endocytosis
1. Phagocytosis
2. Pinocytosis
3. Receptor-mediated Endocytosis
http://highered.mcgraw-hill.com/olc/dl/120068/bio02.swf
Active
Transport
Phagocytosis
• “cellular eating”
– Movement into the cell of large particles and
solids
– Can be used by white bloods cells to take in
bacteria for destruction
Active
Transport
Phagocytosis and Lysosomes
http://highered.mcgraw-
hill.com/olcweb/cgi/pluginpop.cgi?it
=swf::535::535::/sites/dl/free/00724
37316/120067/bio01.swf::Lysosom
es
Active
Transport
Pinocytosis
• “cellular drinking”
– plasma membrane encloses and pinches off
– small droplets of fluid are trapped in a vesicle
– liquid contents of the vesicle is then slowly
transferred to the cytosol
Active
Transport
Receptor-mediated Endocytosis
• Receptor proteins on the cell membrane
• Recognize specific molecules
• Receptors bind with molecule to bring it
into the cell
• Lysosomes bind with vesicle and release
contentsActive
Transport
Exocytosis
• The reverse process of endocytosis
– Used for
• Transporting wastes out of the cell
• Secretion of specific molecules
• Examples
– Tears are secreted salt and protein solution
– Cells in the pancreas secrete insulin to the
blood stream
END OF NOTES!
Study for your test!
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