Download The Cell - Ardsley Schools

The Wonders of the Cell
The Cell
How to build a house:
Atoms Elements
Compounds and Molecules
Sand/clay/water Bricks House
How to make a living creature:
Atoms
Elements
Compounds/Molecules
(ex. Lipids, carbs.,
proteins, nucleic
acids)
Cells
Living Creature
Little bit of cell history:
• 1600s
Anton Van
Leeuwenhoek
• 1600s
Robert Hooke
Cells
Little bit of cell history:
• 1800s
– Robert Brown
• 1800s Cell Theory
Nucleus
Cell Theory
1. All living things are made of cells
•
•
Schleiden: all plants are made of cells
Schwann: all animals are made of cells
2. Cells are the basic (smallest) unit of life
(ie. Carry on the 8 life functions)
3. Cells can only come from preexisting cells
(Virchow)
Problems?
1. Where did very first cell come from?
2. Viruses: Living or nonliving? Can you
really call a virus a cellular organism?
• Viruses have
no organelles
• Just have DNA
or RNA in a
protein head
• Uses all of host
cell’s
machinery
• Can’t replicate
without a host
cell
Cell Types
Prokaryotic Type
• Simple Structure
• Ancient (3 billion y.o.)
• Bacteria only
Eukaryotic Type
Complex Structure
Relatively recent (1.3 billion y.o.)
Plants and Animals
More later!
Eukaryotic Cells
• Animal Cell Structure
Organelles
Nucleus:
a. Cellular control center
b. Surrounded by a
nuclear membrane
c. Holds Genetic Material
d. Holds Nucleolus
(Nucleoli)=have a role in
ribosome synthesis
e. Holds Nucleoplasm
Organelles
Rough Endoplasmic
Reticulum:
a. Network of channels
for transport of proteins
b. butts up with nuclear
membrane
c. contains ribosomes
Organelles
Ribosomes:
a. synthesis proteins
b. Large and small
subunits
c. Can remain free or dock
with the ER
(Bound ribosomes make proteins
for export (ie. Secretory proteins)
and cell membrane, Free ones
make proteins for inside of cell
Let’s Take a Breather!
• DNA (Blueprints for proteins), doesn't leave
nucleus
• Make a rough copy
of segment of
blueprints (mRNA)
• mRNA leaves
nucleus through
nuclear pore
• mRNA binds
Free or ER
ribosome
• Ribosome
makes protein
Organelles
•Polypeptide injected
into
• Endoplasmic Reticulum
Protein folds in ER as it moves
through the channels
Where To Now?
Smooth ER:
• Important in lipid
synthesis for
membranes
• Steroid Synthesis
• Calcium Storage
Where To Now?
ER (Smooth
or Rough)
Transport
Vesicle
Golgi
Complex
Where to next?
Golgi Apparatus or
Complex or Bodies:
Stacks of flat sacs
Processing, sorting,
packaging, shipping,
modifying proteins
with carbs or lipids
What makes up the bulk of the
cell?
Cytoplasm (not an organelle)
Mostly water
Place where most organelles
are found
Place for chemical reactions
What powers this cell?
Mitochondria:
Performs cellular
respiration=
Converts sugar into
energy
“Powerhouse” of cell
HAVE OWN DNA
AND CAN
REPLICATE
INDEPENDENTLY
What happens to rejects and old
stuff in cell?
The LYSOSOME
Lysosome
•Has Hydrolytic Enzymes
•Cellular Digestion Function
•Can break down old organelles
•Can be involved with defense
•Can be involved with development
Autophagy (“self-eating”)
House Cleaning
• Pac-men-like globules
gobble cytoplasm with worn
out proteins and organelles
and brings it to lysosome
• Defense role against
bacteria and viruses
• Reduced Autophagy thought
to lead to Tay Sachs,
Alzheimer's, Parkinson's and
Huntington’s Diseases
When things turn bad….
Apoptosis (-Greek: “falling apart”)
• Cells that are worn out or no
longer useful (ex. webbed
fingers) kill themselves for
greater good of body
• Neighboring cells eat you
and use your parts
• Need a sequence of intracellular events and/or
external signals for cellular
death to happen
Organelles
Vacuoles:
• Small but numerous
• Mainly in plants and protists
• In animal cells
• Storage functions (pigments, food,toxins,
wastes)
• Digestive functions
• Water balance
Organelles
• Peroxisomes
– Similar to lysosomes
– Break down
substances
– Produce a waste
product, Hydrogen
peroxide
– Then then break it
down
Vacuoles
• Food Vacuoles
• Contractile vacuoles
Vacuoles
• Central Vacuole
In plant cells
– Storage
– Water balance
Cytoskeleton:
• Microtubules
• Intermediate
Filaments
• Microfilaments
• Microtubules
– Made of globular
Tubulin Protein
– Provide cell shape
– Organelle anchors and
molecular motors
– Movement of cilia and
flagella
– Make up centrioles
Click
• Intermediate
Filaments
– Anchorage and
Reinforcement Rods
inside Nucleus
– Anchor Chromatin
– Made of diverse
fibrous proteins
– Found in muscle,
epithelial tissue,
neurons,
macrophages
• Actin filaments
(Microfilaments)
– Made of globular Actin
Protein
– Involved with cellular
contraction
– Involved in cell
pinching
– Facilitate Cyclosis
• Cytoskeleton Mini
Movie
Centrioles:
• Involved with cellular
division
• 2 barrel like
structures
• Located in
centrosome region
• Made of
Microtubules
• Not found in plant
cells
Plastids: (Found only in
photosynthetic cells)
• Leucoplasts=storage site
for nutrients
• Chromoplasts=pigment
storage sites
– Ex. Chloroplast filled with
chlorophyll
– Site of Photosynthesis
– Has own DNA and can
replicate independently
– GRANA and STROMA
Cilia and Flagella:
• Cilia
– Short, numerous
– Involved with cell movement
– Connected to cell via a basal body
– Have a 9+2 microtubule arrangement
9+2
Arrangement in
cilia
Basal Body
9 triplet microtubule
arrangement (like a
centriole)
• Flagella
– Usually 1 or 2 per cell
– Long
– Can be in front or back of cell
– Connected via basal body
– 9+2 pattern of microtubules
– Note=Centrioles have a 9 Triplet Pattern
Plasma (cell) membrane:
– Holds in cytoplasm
– Selectively Permeable
– Components:
Phospholipids=Hydrophobic barrier
Cholesterol=provide fluidity
Proteins=transport (Channels/Carriers),
receptors, enzymes, anchors
Carbohydrates=cell signaling (self/nonself)
Fluid Mosaic Model of Plasma Membrane
Animal cells’ answer to absence of
cell wall….
• Extracellular Matrix:
– Network of fibrous collagen,
and glycoproteins
– Connected to cytoskeleton
via Integrin proteins in
membrane
– Gives support, strength and
resilience
More Complete Look at Model
Endomembrane System
Cell Junctions
• Tight Junctions
– Fused membranes
– Force material
through cells rather
to sides
• Gap Junction
– Cytoplasm of cells
connected through
channel
Plant Cell vs. Animal Cell
Plant Cell
Cell Wall
Chloroplasts
No Centrioles
One, large vacuole
Cell Wall:
a) In bacterial, yeast and plant cells
b) Exterior to plasma membrane
c) Provides shape and protection
d) Made of cellulose in plant cells
Prokaryotic vs. Eukaryotic
Revisited
Prokaryotic Type
Eukaryotic Type
• Simple Structure
Complex Structure
• Ancient
Relatively recent
• Bacteria only
Plants and Animals
• No membrane-bound
organelles
• Many ribosomes (Don’t have
membranes)
• No Nucleus
• Has Nucleiod Region
Origin of Eukaryotic Cell:
Endosymbiotic Theory
Mitochondria and Chloroplasts evolved from
bacteria that were gobbled up by an ancient
Cell. These organisms then lived inside the
ancient cell and were a benefit to the ancient
cell (endosymbiosis)
Proof of theory
• Mitochondria and Chloroplast have own
DNA
• They can replicate independent
• Same size as present bacteria
• They have own ribosomes and are
bacterial-like
Why don’t cells grow to infinity?
Why are most cells very small?
Surface Area to Volume Ratio
• As a cell gets larger (ie. As its volume
increases)….
• Volume increases proportionally larger
than surface area
Long time to get rid of toxic wastes
Getting nutrients in takes more time
Too much volume for surface area to handle
Movement of materials into and out
of the cell
• Cell membrane selectively permeable
– Maintains Homeostasis
What can cross the membrane
freely?
• Lipid-like molecules
• Small uncharged molecules (ex. H20, CO2,
02,amino acids)
• Some small molecules can cross freely but
need a helper membrane transport protein
(ex. Glucose)
• Charged substances also need help to
cross
• Large molecules like polymers can’t cross
Current Research
• Water flow across the membrane also
facilitated by “aquaporin” channels
Mechanism for freely crossing:
• Diffusion
– Molecules move from a region of high
concentration to a region of lower
concentration until equilibrium
– No energy needed
– Need a concentration gradient to drive
movement
Facilitated Diffusion
• Passive-No Energy Needed but requires
transport protein (ex. Glucose and ions)
• Need gradient
Diffusion of water=Osmosis
• Goes from high water concentration to a
low water concentration
• Or from a low solute concentration to a
high solute concentration
Osmosis
Solute
Effects of Osmosis:
• Relative Terms:
– Hypertonic= Contains more solute than
something else
– Hypotonic= Contains less solute than
something else
– Isotonic= Contains the same amount of solute
as something else
Cell in hypertonic environment
Cell in Hypotonic Environment
Cell in Isotonic Environment
Animal Cells in Different
Environment
Lysed Cell
Crenated Cell
Plant Cells in Different
Environments
a.k.a.
Plasmolyzed
Active Transport
• Requires Energy (ie. Need ATP)
• Move materials against a concentration
gradient
Active Transport-Pumps
Active Transport-Endocytosis
• Endocytosis=transporting things into a cell
– Ex. Pinocytosis=Taking small amounts of
dissolved materials into the cell via vesicles
– Ex. Phagocytosis=Taking large solid materials
into a cell via food vacuoles
Pinocytosis
(Nonspecific)
Phagocytosis
(Nonspecific)
Receptor-Mediated Endocytosis
Specific
Uptake
(ex. LDLs)
Active Transport-Exocytosis
• Cell mini movie
Cells and Living Creatures
1. Unicellular Creature
•
Ex. Protozoa,
Bacteria, Algae
Cells and Living Creatures
2. Colonial Organisms
• Individual cells loosely connected
• No Specialization, they all are the same and act
like independent unicellular creatures
• Ex. Volvox
Cells and Living Creatures
3. True Multicellular Organisms
=has many cells who divide the labor
and perform specialized function
=Each cell dependent on other cells
=Cells organized into tissues
• Tissue=Cells similar and perform same function
(Read section in SAT2 Book)
– Ex. Epithelial Tissue, Connective Tissue, Blood,
Muscle, Nerve
• Organ=Group of different tissues working
together for a common function
– Ex. Stomach, pancreas, liver
• Organ System: Group
of organs working for
a common function
– Ex. Digestive System,
Nervous System