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UNIT II – CELL STRUCTURE &
FUNCTION
• Baby Campbell – Ch 4,5,11
• Big Campbell – Ch 6,7,8,11
I. DISCOVERY OF CELLS
• History of Microscopes
 _____________________________________
 First to try stacking several lenses together to view tiny objects.
 Looked at pond water
 First scientist to describe living cells as seen through a microscope.
 _____________________________________
 Used the microscope to examine thin slices of cork.
 He called the tiny boxes he saw cells. He chose the name "cells" because
the chambers he saw reminded him of rooms in a monastery which were
called cells.
• Cell Theory
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
I. DISCOVERY OF CELLS, cont.
• Types of Microscopes
 Compound Light Microscope
 ___________________
 Ratio of an objects image to its real size
 __________________
 Measure of clarity of an image
 Electron Microscope
 __________________ Electron Microscope (SEM)
 Used to study the surface of the specimen
 __________________ Electron Microscope (TEM)
 Used to study the internal structure of cells
TEM
SEM
II. CELL TYPES
• _________________ Cells
 Typically smaller than
eukaryotes
 Bacteria
 Kingdom Archaebacteria
 Kingdom Eubacteria
 No true nucleus – DNA
found as a single
chromosome in region
called ________________
II. CELL TYPES, cont
• Structure found in all
prokaryotic cells





_____________
_____________
_____________
_____________
_____________
• Additional structures
that may be present
 _____________
 _____________
 _____________
II. CELL TYPES, cont
• ___________________ Cells
 Larger, more complex
 Contain true nucleus and membranebound organelles suspended in cytosol
 Composed of
 Nucleus
 Ribosomes
 Endomembrane System
o
o
o
o
ER
Golgi Apparatus
Lysosomes
Vacuoles
 Mitochondria/Chloroplasts
 Peroxisomes
 Cytoskeleton
III. EUKARYOTIC CELL STRUCTURES
• _____________________
 Control center of eukaryotic cell
 Made up of
 ________________________
Double membrane that protects nucleus; continuous
with ER
 Contains _____________ to allow RNA to leave nucleus
 ________________________
Site of ribosome and rRNA production
 ________________________
DNA wrapped in protein
Will condense during cell division to form chromosomes
III. EUKARYOTIC CELL STRUCTURES, cont
• Endomembrane System – membranes are related either through
physical continuity or by the transfer of membrane segments as
vesicles
 Endoplasmic Reticulum (“within the cytoplasm”; “little net”)
 Interconnected network continuous with nuclear envelope
 Rough ER
 Site of __________________________
 Smooth ER
 Synthesis of _______________
 Metabolism of _________________
 ____________________ of drugs & poisons
 _________________________________
 “Cell postmaster”
 Receives transport vesicles from ER; modifies, stores, and ships
products
 Receiving side is known as the ________ face; shipping side is known
as the __________ face
III. EUKARYOTIC CELL STRUCTURES, cont
• Endomembrane System, cont
 ______________________________
 Sacs containing hydrolytic enzymes
 Used for recycling cellular materials, destroying
pathogens
 ______________________________
 Storage sac
 Plants typically have large, central vacuole surrounded
by membrane called ___________________. Absorbs
water and helps plant cell to grow larger
 Some protists have contractile vacuole to pump out
excess water
Endomembrane System
The endomembrane system plays a key role in the synthesis (and hydrolysis)
of macromolecules in the cell.
III. EUKARYOTIC CELL STRUCTURES, cont
•
____________________________
 Suspended in cytosol or found on rough ER
 Site of protein production in a cell
•
_____________________________




Site of ________________________________ (making of ATP)
Contain their own DNA, ribosomes
Found in virtually all eukaryotes cells
Enclosed by 2 membranes; inner membrane has folds called _____________
to increase surface area
III. EUKARYOTIC CELL STRUCTURES, cont
• _____________________________
 Type of plastid that carries out _____________________ by
converting solar energy to chemical energy (glucose)
 Contain membranous system of flattened sacs called
_______________ – stack is called a _____________
 Fluid surrounding thylakoids is called ___________
 Contains its own DNA, ribosomes
III. EUKARYOTIC CELL STRUCTURES, cont
•
____________________________________
 Membrane-bound compartments that use O2 to carry out metabolism
 H2O2 is produced; broken down by enzymes to produce ______ & ______
•
____________________________________
 Provides structural support to cell
 More extensive in animal cells
 Composed of three types of proteins
• ___________________________
– Thinnest filaments …….AKA………. ____________ filaments.
– Bundles of them form microvilli - extensions of the cell membrane found in some
cells to increase surface area.
– Interact with myosin in muscle cells to create movement
• _________________________________
– In between in thickness; more permanent than microtubules/microfilaments.
• _________________________________
– Hollow rods that support cell, serve as tracks for movement within cell.
– Help separate chromosomes during cell division - occurs in a region called
centrosome, which is the location of centrioles in animal cells.
– Cilia, flagella are constructed from bundles of microtubules covered by extensions
of the cell membrane.
IV. CELL BOUNDARIES
• Cell Wall
 Found in ___________,
_______, ________________,
and some _________________
 Functions
 Rigid structure; protects cell
 Maintains shape of cells
 Prevents excess water uptake
 Plant cell wall
 _________ - primary component
 Pectin - Sticky polysaccharide
found between cell walls of
adjacent cells; found in middle
lamella
 Plasmodesmata - Perforations
between adjacent cell walls that
allow for movement of materials
from one cell to another
IV. CELL BOUNDARIES, cont
• Extracellular Matrix
 Found in animal cells
 Holds cells together, protects & supports
cells
 Allows for communication between cells
 Composed primarily of ______________________ – proteins with
carbohydrate chains that are covalently-bonded
 Must abundant glycoprotein in most animals is _____________
• Intracellular Junctions
 Tight Junctions – Fuses membranes together tightly; prevents leakage
of fluid
 Desmosomes (Anchoring Junctions) – Fasten cells together in sheets
 Gap Junctions – Allow for movement of cytoplasm from one cell to
another; important in communication between cells
IV. CELL BOUNDARIES, cont
• ____________________________
 Selectively-permeable barrier found in all cells
 Composed primarily of _______________________ bilayer
 Fluid Mosaic Model
 “Fluid” – Not a rigid structure. Organization due to high
concentration of water inside & outside cell
IV. CELL BOUNDARIES, cont
 Proteins - “Mosaic” – Assortment of different proteins embedded in bilayer;
determine most of membrane’s specific functions. Act as channels, pumps,
enzymes in metabolism, binding sites, etc
o _____________ Proteins – Embedded in phospholipid layer
o _____________ Proteins – Bound to surface of membrane
 Carbohydrates – “ID tags” that identify cell. Enable cells to recognize each other
and foreign cells. May be bonded to lipids (glycolipids) or proteins (glycoproteins)
 ____________________ – Found in animal cells for stability
V. CELL TRANSPORT
V. CELL TRANSPORT, cont
• ________________ Transport – Movement of materials from
_______ to ______ concentration. No energy output
required.
 ___________________ - Random movement of a substance across
membrane down concentration gradient until equilibrium is reached.
 ________________________________________ – Passive transport
of molecules across cell membrane with the help of transport
proteins.
 Water is polar – requires protein channels called aquaporins to move in and out
of cell.
 Glucose also requires protein channels due to size.
V. CELL TRANSPORT, cont
• Passive Transport, cont
 ______________ – Diffusion of water across a membrane.
 ______________ refers to tendency of cell to gain or lose water.
 If the solution is
 Isotonic to the cell – Solute concentration is same on both sides of membrane.
No net movement of water.
 Hypertonic to the cell – Concentration of solute is greater outside cell → water
moves in until equilibrium is reached. Cell may shrivel.
 Hypotonic to the cell – Concentration of solute is lower outside cell → water
moves into cell until equilibrium is reached. Cell may swell to bursting point.
 Water moves towards the high solute concentration!!!!!
V. CELL TRANSPORT, cont
• Passive Transport/Osmosis, cont
 Osmoregulation
 Cells must have mechanism to prevent excess loss, uptake of water
 Cell wall, contractile vacuole
 _______________________ – Seen in plants; excessive water loss
causes cell membrane to pull away from cell wall
V. CELL TRANSPORT, cont
V. CELL TRANSPORT, cont
• ____________ Transport – Movement of materials against
concentration gradient. Requires energy output by cell
 Carrier Proteins – Na+ / K+ Pump
V. CELL TRANSPORT, cont
• Active Transport, cont
 _________________ –
Secretion of biomolecules by
fusion of vesicles with cell
membrane. Biomolecules
“spit out”.
 _________________ –
“Sucking In”. Cell membrane
surrounds, engulfs particle or
biomolecule, pinches in to
form vesicle.
 ______________________ –
“Sucking in” food particles
 ______________________ –
“Sucking in” fluid droplets
 Receptor-mediated
Endocytosis – Very specific
VII. CELL SIGNALING
• Coordinates cell activities, development
• Initiates series of responses known as signal
transduction pathway. Typically involves 3 steps:
 ________________ – Target cell’s detection of signal
molecule due to binding of signal molecule to receptor
protein in cell membrane
 ________________– Binding of signaling molecule
changes receptor protein; triggers a sequence of events
within cell
 ________________– Results in specific cellular response;
for example, activation of genes, enzyme catalysis, etc.
• Cyclic AMP – Intracellular compound often involved
in signal transduction pathways.
VII. CELL SIGNALING, cont
VIII. THE WORKING CELL
• Metabolism
 _____________________ Pathway – Breaks down molecules;
releases energy
 _____________________ Pathway – Pathway that synthesizes
larger molecules from smaller ones; requires energy
• Energy
 Kinetic Energy – Associated with relative motion of objects
 Potential Energy – Energy that matter possesses; stored energy
 Chemical Energy – Potential energy of molecules
• Thermodynamics
 ________ Law of Thermodynamics states that total amount of
energy in universe is constant – can be transferred or transformed,
but it cannot be created or destroyed
 ________ Law of Thermodynamics states that energy is lost to the
environment as heat; that is, some energy becomes unusable
VIII. THE WORKING CELL, cont
• Chemical Reactions are classified according to whether they
require or produce energy
 _____________________ – Requires net input of energy. Energy is then
stored in products as potential energy.
 _____________________ - Release energy.
 _____________________– Often used in cellular metabolism. Energy
released in exergonic rxn is used to drive endergonic rxn.
VIII. THE WORKING CELL, cont
• ATP – Adenosine triphosphate. Nucleotide that stores &
provides usable energy to the cell
 Structure of ATP
 Adenine – nitrogen base
 Ribose – pentose
 3 Phosphate groups
VIII. THE WORKING CELL, cont
• ATP, cont
 Phosphorylation
 ATP contains potential energy, especially between 2nd and 3rd
phosphate groups. P – P bond is unstable and easily broken by
hydrolysis. Exergonic.
 Coupled with endergonic rxn – specifically, by transferring
phosphate group from ATP to another molecule. Known as
phosphorylation.