THE CELL
Microscopy
 Micrographs
 Photograph of the view through a microscope
 Light Microscopes
 Electron Microscopes
 Scanning EM
 To look at the surface of cells/specimen
 3-D images
 Transmission EM
 To look at internal structures of cells/specimen
Microscopes
Sizes
 The body is made of 100 trillion cell (1014)
 Extremely small…The human eye can see
.01 cm, a human cell is 5x smaller
 5 to 50 micrometers…µm
 How big is a micrometer?
 1m=100cm=1,000,000 micrometers
 1 micrometer=.000001m
 Basically you can’t see it
 Remember: KHDmDCM..micro..nano..pico
Chaos chaos
 Largest protozoan
 You can see without
microscope
 1000 micrometers
 How many meters is this?
 .001 m
 How many centimeters is
this?
 0.1 cm
Cells
 Basic units of life
Robert Hook (1665)
 Englishman
 Looked at cork
 Made of dead plant cells
 1st person to observe
cells
 Coined the term “cells”
 What he saw under the
microscope looked like
the tiny, empty chambers
called cells, that the
monks lived in
 Compound microscope
Anton van Leeuwenhoek
(1660’S)
 (LAY vun Hook)
 Holland
 Single lens
microscope
 Pond water
 “animalcules”
 1st person to observe
LIVING cells
Matthias Schleiden (1838)
 German botanist
 Plant cells
Theodor Schwann (1839)
 German biologist
 Animal cells
Rudolf Virchow (1855)
 German physician
 New cells could only
come from the division
of existing cells
Cell Theory
 3 parts and key people
1. All living things are made of cells
 (Hooke, van Leeuwenhoek, Schwann and
Schleiden)
2. Cells are the basic units of structure and
function in all living things
 (Hooke, van Leeuwenhoek, Schwann and
Schleiden)
3. New cells are produced from pre-existing cells
 (Virchow)
Lots of different shapes
and sizes of cells
2 categories for cells…

Prokaryotes (pro-care-ee-ohts)
 No nucleus
 Cell’s genetic material is not
contained in the
nucleus…found in
NUCLEOID:
 Region in cytoplasm
where DNA is found
 Less complicated that
eukaryotes
 Some have internal
membranes
 Do NOT have membrane
bound organelles
 Carry out every activity
associated with living
things…which are…

Eukaryotes (you-care-ee-othts)
 Contain nucleus in which the
genetic material is separated from
the rest of the cell
 Contains dozens of structures and
internal membranes
 High Variety
 Single celled or multi-cellular
 Plants, animals, fungi, and protists
2 things in every cell…
 Surrounded by a barrier…
 Plasma/cell membrane
 At some point in their life they contain….
 DNA
Eukaryotic cell
structure
The Cell factory
 Organelles
 Highly specialized structures within the cell
 Little organs
 2 major divisions of the eukaryotic cell
 Nucleus
 The “brain”
 DNA
 Cytoplasm
 Portion outside the nucleus but inside the cell membrane
2 types of Eukaryotic cells
 Plant cells
 Animal cells
 What are the differences? (write them down!!!)
Cell Membrane
 What does it do for cell?
 Controls what goes in and out
 Regulates molecules moving from one liquid side of the
cell to the other liquid side of the cell
 Protects
 Supports
Cell Membrane
 Lipid bilayer
 What are lipids?
 What does bi- mean?
 What’s a layer?
 A cell membrane is made of two
layers of lipid molecules
Cell membrane
 Phospholipids bilayer
 Made of a negatively charged
phosphate “head”
 PO43water because the phosphate is
 Attracts
charged (-)
is a polar , slightly positive ends
 Water
and slightly negative ends
 Attached to the phosphate
group are 2 fatty acid chains
 Hydrophobic= don’t like water
 So the inside of the cell
membrane doesn’t let water in
but the outside allows cells to be
dissolved in aqueous
environments
Plasma/Cell Membrane
 Phospholipid bilayer
 Hydrophilic
 Hydophobic
 Fluid Mosaic Model
 Why?
 Controls exchange
of materials
between cell and its
environment
Other things in the
membrane…
 Proteins embedded in
lipid bilayer
 Carbohydrates
attached to proteins
 So many different
molecules in
membrane, we call it a
“mosaic” of different
molecules
What is a Nucleus?
 Plural: nuclei
 Large, membrane enclosed structure that
contains the cell’s genetic material in the form
of DNA
 What is a membrane?
 A thin layer of material that serves as a covering or
lining
Nucleus
 Brain of the cell
 Office of the factory
 Contains nearly all the cell’s DNA and with
it the coded instructions for making
PROTEINS and other important molecules
Nuclear envelope
 Surrounds nucleus
 Made of 2 membranes
 Dotted with thousands of nuclear pores
 How do we get messages, instructions and
blueprints out of the office?
 Allow material to move in and out of nucleus by
using “little runners” such as proteins, RNA and
other molecules
Inside the nucleus
we see…
 Contain a granular material called…
 CHROMATIN
 Chromatin= DNA + protein
 Usually spread out in nucleus
 During cell division, chromatin clumps together or
condenses…we call this….
 CHROMOSOMES
Chromosomes
 Condensed structures that contain genetic
information (DNA) that is passed on from one
generation to the next
Nucleolus
 Small dense
region inside the
nucleus
 Function:
assembly of
ribosomes
begin…
Ribosomes
 Most important function of cell is…
 Making proteins
 Proteins regulate a zillion different things
 Like…
 Proteins are assembled ON Ribosomes
 Consists of 2 parts:
 Large subunit
 Small subunit
 Found:
 In Cytoplasm
 On Rough ER
 In nucleus
 Function:
 hold mRNA in place while tRNA brings
over specific amino acids; makes a
polypeptide chain
 Site of protein synthesis
Endoplasmic reticulum
(ER)
 Internal membrane system
 site where the lipid components of the
cell membrane are assembled, along
with proteins and other materials
exported from the cell
 2 types
 Smooth ER
 Rough ER
Rough ER
 Involved in protein making
(synthesis)
 So what are we going to see
on it?
 ribosomes
 Once a protein is made, it
leaves the ribosome and
goes into the Rough ER
 The rough ER then modifies
the protein
 All proteins that are exported
by the cell are made on the
RER
 Membrane proteins are made
on the RER too
Smooth ER
 NO ribosomes on it
 Looks smooth
 Contains collections of ENZYMES that have
specialized tasks
 What do enzymes do?
 Tasks include:
 Synthesis of membrane lipids
 Detoxification of drugs
 Liver cells
 Big in detox therefore….what do u think liver cells have a lot of?
Golgi Apparatus
 Discovered by Italian scientist Camillo
Golgi
 Once proteins are done being
“modified” in the RER, they move onto
the Golgi apparatus
 Looks like a stack of pancakes
 Function: modify, sort, and package
proteins and other materials from the
ER for STORAGE or SECRETION
outside the cell
 Proteins are “shipped” to final destination
 They are the CUSTOMIZATION SHOP
 Finishing touches on proteins before they
leave factory
Endomembrane System &
Protein Synthesis
1.
2.
3.
4.
DNA in nucleus gives message to mRNA
mRNA leave thru nuclear pore into cytoplasm
Ribsome “catches” mRNA
tRNA come over and start adding amino acids together making
polypeptide chain
5. Polypeptide chain either functions immediately or goes onto next
step
6. Ribosome deposits polypeptide chain into lumen of the RER
7. Polypeptide chain is modified (2* and 3* structure)
8. Functioning protein either stays and works in RER or…
9. Vesicle buds off RER and transports it to Golgi Apparatus
10. Protein is further modified in GA and leaves in a vesicle (either
secretory or peroxisome or membrane)
Lysosomes
 (Lie-so-soh-mz)
 The factory’s clean-up crew
 It’s an Organelle filled with
enzymes
 Function: Digestion (break
down) of lipids,
carbohydrates, and proteins
into smaller molecules that
can be used by the cell
 Also digest organelles that
have outlived their
usefulness
What do you think happens if
lysosomes malfunction?
 A bunch of “junk” build up in the
cell…why?
 Is this good?
 Many human diseases result from
malfunction of lysosome
 Tay-Sachs disease
 DNA does not make the enzyme
hexoaminidase A that breaks
down lipids in nerve cells
 Build up of lipids in nerve cells
causes those cells to stop
working
 Noticeable 3-6 months after birth,
child lives to be about 4-5 years
old
Vacuoles
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The factory’s storage place
Only in certain cells
Sac-like organelles
Function: stores material such as water,
salts, proteins, and carbohydrates
 Plant cells have a single, large central
vacuole
 Pressure of central vacuole allows plants to
support heavy structures
Single-celled organisms and
some animals also have
vacuoles…
 Paramecium
 Contractile vacuole
 Contracts rhythmically to pump excess water
out…this maintains what?
 homeostasis
Two ways cells get
energy…
 From food molecules
 From the sun
Mitochondria
 Convert chemical energy stored in
food into compounds that are more
convenient for the cell to use
 Has 2 membranes
 Inner membrane
 Lots of FOLDS (cristae)= INCREASE surface
area= more ATP being produced
 Outer membrane
 In Animal AND Plant cells
 Nearly all come from the ovum
 You get your mitochondria from your
mom!
Chloroplasts
 Plant and some Bacteria cells
only ( NOT in animal cells)
 Capture energy from the
sunlight and convert it into
chemical energy…what is this
process called?
 PHOTOSYNTHESIS
 Like solar power for plants
 2 membranes
 Inside: large stacks of other
membranes that contain
chlorophyll
Chloroplast (found in cells
in leaves)
 Concentrated in the cells of the
mesophyll (inner layer of tissue) in
leaf
 Stomata
 Tiny pores on surface of leaf
 Allows carbon dioxide and
oxygen in and out of the leaf
 Veins
 Carry water and nutrients from
roots to leaves
 Deliver organic molecules
produced in leaves to other
parts of the plant
Chloroplast
 Cellular organelle where
photosynthesis takes place
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Double membrane
Outer membrane
Stroma (fluid filled space)
Inner membrane
Thylakoids
 Thylakoid membrane contains
CHLOROPHYLL
 Granum
 Intermembrane space
 Contain chemical compound
called Chlorophyll
 This molecule gives chloroplast
its green color
Structure of
Chloroplast
 Structures organize the many
reactions that take place in
photosynthesis
 Stomata
 Small pores in the underside of leaves
that release water and oxygen and
take in carbon dioxide
 Guard cells
 Control the opening and closing of
stomata depending on environment
 Stroma
 Thick fluid enclosed by the inner
membrane
 Thylakoids
 Disc-like sacs suspended in the
stroma
 Has membrane that surrounds inner
thylakoid space
 Grana (sing. Granum)
 Stacks of thylakoids
Organelle DNA
 Chloroplasts and
mitochondria contain their
own genetic info
 In form of small, circular
DNA molecules
 mDNA
Lynn Margulis
 American biologist
 Chloroplasts and
mitochondria are
descendants of prokaryotes
She said…
 Ancient Prokaryotes from wayyyyy back in the
day had a symbiotic relationship with the
ancient eukaryotes
 What is symbiotic? (review ecology!!!)
 The prokaryotes lived inside the eukaryotes
 There were prokaryotes that used oxygen to
make energy (ATP)
 Mitochondria
 There were prokaryotes that used
photosynthesis to get energy
 Chloroplasts
Endosymbiotic Theory
 Idea that
mitochondria and
chloroplasts
evolved from
prokaryotes
Cytoskeleton
 Supporting structure and
transportation system
 Network of protein filaments that helps
the cell to maintain its shape and to help
the cell move
 2 main type of filaments
 Microtubules
 Microfilaments
(Intermediate filaments is a 3rd type)
Microfilaments
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Threadlike structures
Made of protein called ACTIN
Extensive networks
Tough, flexible framework
Help cells move
Assembly and disassembly helps cells
move (like amoebas)
Microtubules
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Hollow structures
Made of proteins called TUBULINS
Maintain cell’s shape
Important in cell division
 Make mitotic spindle (separates
chromosomes)
 Help build projections from cell surface…
Cilia and Flagella
 Plural: cilium and flagellum
 Cilia: hundreds of extension of the cell membrane that move like
the oars of a boat
 Flagella: one or two long extensions off the cell that move in a
whip like fashion
 Enable cells to swim rapidly through liquid
Centrioles
 Only animal cells
 Made of protein
TUBULIN
 What else is made of
tubulin?
 Near nucleus
 Help organize cell
division
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Antwon van Leeuwenhook
Robert Hook
Cell
bacteria
Cell Theory
Electron microscope
Prokaryote
Eukaryote
Organelles
Cytoplasm
Nuclear envelope
Chromatin
Nucleus
nucleolus
Ribosome
Smooth ER
Rough ER
Chromosome
Vacuole
Osmosis
Endocytosis
exocytosis
Proteins
DNA
RNA
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Golgi apparatus
Micrometer
Millimeter
Picameter
Lysosome
Vacuole
Mitochondria
Chloroplast
Cytoskeleton
Centriole
Mictrotubule
Microfilament
Theodor Schwann
Matthias Schleiden
Rudolph Virchow
Lynn Margulis
Endosymbiotic Theory
Cilia
Flagella
Photosynthesis
Pseudopodia
Aquaporin
Transmembrane protein
Facilitated diffusion
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Microscope
Micrograph
Magnifier
Lens
Contractile vacuole
Central Vacuole
Centrioles
Centrosomes
Nuclear pores
Nuclear-plasm
Stomata
ATP synthase
Chlorophyll
Cell membrane
Cell Wall
Cellulose
Phospholipids
Thylakoid
Cristae
Matrix
Inner membrane
Outer memebrane