BIOLOGY UNIT 4: Cells
BIG IDEA
What is a cell?
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_________________________________________________________________________
Cell Theory Timeline
_________________________________________________
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Builds compound microscopes and first to observe cork cells.
__________________________________________________
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Builds simple, powerful microscopes and _____________________________________________________
like blood cells, animal sperm cells, & bacteria from his own teeth! He called them
“animalcules”
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_______________________________________________________are the scientists who contribute to
developing a unifying cell theory
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1838: Matthias Schleiden ___________________________________________________________________
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1839: Theodor Schwann ______________________________________________________________________
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1855: Virchow _________________________________________________________________________________
Cell Theory
1. ________________________________________________________________________________
2. Cells are the basic units of ______________________________________________ in an organism.
3. Cells come only from the _______________________________________________________________
Cell Diversity
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Shape: There are many cell shapes. ___________________________________________________________
For example, skin cells are flat, nerve cells have extensions.
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Size: Different types of cells have different sizes.
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The size of a cell is ______________________by the surface area-to volume ratio.
Surface area-to-volume Ratio
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As the cell gets ______________, the surface-area-to-volume ratio gets ________________________.
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If a cell is too ___________________________, there is ______________________________ to allow materials
to pass through quickly enough.
Types of Cells
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Prokaryotes
1. _________________________________
2. Generally _________________________________
3. NO membrane-bound organelles (compartments)
4. No true nucleus.
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DNA is found in the nucleoid region and is NOT separated by a membrane.
5. Example is __________________________________
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Eukaryotes
1. More complex cells
2. Generally _________________________________
3. Contains membrane-bound _________________________________
4. Has a true nucleus
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Region of where DNA is stored and is separated by a membrane.
5. Examples are _________________________________________________
Overview of Cell Organelles:
Use the textbook and the following website to complete the chart:
www.cellsalive.com
ORGANELLE /STRUCTURE
LOCATION
FUNCTION
WHAT CELL HAS IT
(plant, animal.
Prokaryote)
Cell Membrane (include def.
of selectively permeable)
Cell Wall
Nucleus
Nucleolus:
Nuclear Envelope:
Chromatin/Chromosomes:
Cytoplasm:
Smooth Endoplasmic
Reticulum:
Rough Endoplasmic
Reticulum
Ribosomes:
Goligi Bodies or Complex
Lysosome
Mitochondria
Microtubules
Microfilaments
Cilia and Flagella
Vacuoles – include
difference between animal
and plant vacuole
Plastids
Chloroplast
Centrioles
What is Endosymbiosis?
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Theory that _____________________________________were really once ___________________ or
prokaryotes
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They were engulfed by other cells and became organelles!
Organization of Cells in Living Things:
______________________________ Organisms
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Example: bacteria, fungi, algae
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Able to carry on all life processes
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Usually colonial organisms
Multicellular Organisms
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________________________________________________________________________________
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Tissue
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•
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Group of cells that are _____________________________________________________
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Types: epithelial (skin), connective (bone), and muscle to name a few
Organ
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Group of ___________________________________________________________________
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EX: Stomach, Liver
Organ System
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Group of _____________________________________________________________________
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EX: digestive system
Moving Through the Plasma Membrane
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What is homeostasis?
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What is the job of the plasma membrane?
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How do you think the cell membrane helps a cell maintain homeostasis?
Structure and Function of the Plasma Membrane
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Phospholipid bilayer with carbohydrates and proteins imbedded into itself
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__________________________________________________________________________________________
What does a phospholipid look like?
Plasma Membrane: The Fluid Mosaic Model
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Fluid because
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the ____________________________________________ can move around. Not stuck in one place.
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Mosaic because
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the membrane contains a variety of _________________________embedded with the
phospholipids.
Permeability of a membrane
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Permeable: anything can pass through
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Semi-permeable: ______________________________________________________________________________
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Impermeable: nothing can pass through
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The plasma membrane is described as semi-permeable because __________________substances
can move through it:
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________________________________
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_______________________________
How do particles move in and out of the cell?
1. Passive Transport
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No additional ______________________ is required because every particle has its own energy
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This energy produces ________________________ movement in particles.
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Diffusion
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Diffusion is the movement of substances from a ______________ concentration to a
______________________concentration.
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Diffusion is caused by
________________________________
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Concentration is the _________________ of something in a given ________________.
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How does it work?
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Particles move down the concentration gradient, until the concentration is ___________
throughout an area.
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Then the system is said to have reached dynamic equilibrium.
Osmosis
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Diffusion of ________________ across a membrane
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Water molecules can pass through pores or openings created by __________ in the plasma
membrane
The Cell’s Environment: ___________________________
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In an isotonic environment the solute concentrations are ___________ and there is no NET
movement of water.
The Cell’s Environment:___________________________
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In a hypotonic environment, there are __________ solutes outside than inside and water moves
into the cell.
The Cell’s Environment: ____________________________
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In a hypertonic environment there are _________ solutes outside than inside and water moves
out of the cell.
Environment outside cell
Hypotonic
Hypertonic
Isotonic
Water moves…
Effect on ANIMAL cell
Effect on PLANT cell
What if a cell needs large or charged/polar molecules? Can they move across the
membrane? _______
Selectively Permeable Membrane
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The cell membrane “picks” what molecules can enter and exit the cell because proteins in
the membrane allow specific macromolecules or ions in or out of the cell.
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Facilitated diffusion
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Proteins help particles move across the membrane
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Transport proteins span the phospholipid bilayer, but allow only __________________
molecules through.
>>
Selectivity
Types of transport proteins
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____ __________ are non–polar on the outside and polar on the inside. They provide a
pore for ions and polar particles to move through.
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_________ _______________ bind to specific particles, carry them through the membrane,
and release them on the other side.
Remember
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In diffusion-particles (solutes) move from an area of HIGH concentration to LOW. In
osmosis- water moves from a HYPOTONIC environment to a HYPERTONIC environment
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Diffusion requires _______________________________________
Simple vs. Facilitated
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In simple diffusion, particles move ___________________________________________ of the membrane.
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In facilitated diffusion, particles move through _______________________ in the membrane.
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______________________________________________. Particles must move down the concentration
gradient.
But what if you needed to move particles AGAINST their concentration gradient?
2. Active Transport – REQUIRES ENERGY!!!!!
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Transport proteins use _________________to move particles against their concentration
gradient, from a low concentration to a high concentration.
Sodium-Potassium Pump:
Vesicle Mediated Transport – The fluid plasma membrane can “pinch” off forming
vesicles that can move very large particles or lots of small particles.
THIS REQUIRES ENERGY!!!
1. Endocytosis
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Outside materials are brought __________ the cell.
There are two kinds of endocytosis:
a. Phagocytosis
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“Cell eating”
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Cell engulfs large food particles and the vesicle is a food vacuole.
b. Pinocytosis
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“cell drinking”
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Cell engulfs small droplets of surrounding fluid.
2. Exocytosis
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Material from inside the cell is released _________ by vesicles.
Reflection Questions:
1. What does cell structure have to do with its function?
2. How is a cell like a city?