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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 lenseslenses together to view tiny objects. Looked at pond waterpond water First scientist to describedescribe living cells as seen through a microscope.
_____________________________________ Used the microscope to examine thin slices of corkcork. He called the tiny boxes he saw cellscells. He chose the name "cells" because
the chambers he saw reminded him of rooms in a monasterymonastery which were called cells..
• Cell Theory
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
BacteriaKingdom 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 membrane-
bound organelles suspended in cytosol Composed of
Nucleus Ribosomes Endomembrane System
o ERo Golgi Apparatuso Lysosomeso 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 proteinWill 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 layero _____________ 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 waterCell 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 baseRibose – pentose3 Phosphate groups
VIII. THE WORKING CELL, cont• ATP, cont
PhosphorylationATP 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.