microscopes and the cell thursday, october 17 th
TRANSCRIPT
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Microscopes and the CellThursday, October 17th
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What is “cell theory”?
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Who helped developed the cell theory?• 1665
• Robert Hooke• Observed cork under a primitive
microscope• Coined the term “cell”
• Looked like monks cells
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Who helped developed the cell theory?• 1674
• Antonie van Leeuwenhoek• Observed and described the first microscopic
organisms• Father of microbiology• Improved the light microscope
• Made more than 25 different types
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Who helped developed the cell theory?
• 1830’s– Schleiden (PLANTS) & Schwann (ANIMALS)– Worked independently but upon meeting, made important
connections in regards to the cell nucleus– Summarized many observations into what is now know as
the cell theory
• 1840’s– Virchow– Studied bacteria and disease– Claimed that bacteria was also made of cells
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What is “cell theory”?
• Cell Theory (3 parts)1. All living things are made of cells. (Hooke)2. Cells are the basic unit of structure and
function in organisms. (Schleiden & Schwann)3. All cells come from other cells. (Virchow)
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ELECTRON MICROSCOPES
LIGHT MICROSCOPE
UNAIDED EYES
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What are the different types of microscopes?
• Light (or Optical)Microscope• Light passes through one or more lenses to enlarge
• Magnification = the ability to make things larger
• Resolution = the measure of clarity of an image
• Can magnify images:• 40x - 100x - 400x
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Light Microscope
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• Electron Microscopes (EMs) – Allows scientists to view a universe too small to
be seen with a light microscope
– Forms an image using a beam of electrons
– Focus a beam of electrons through a specimen (TEM) or onto its surface (SEM)
What are the different types of microscopes?
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• Scanning Electron Microscope (SEM)– Provides for detailed study of the
surface of a specimen
– Creates a 3D image
– Cannot view living specimens
What are the different types of microscopes?
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Surface of Tongue
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Head louse clinging to a human hair
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Eyelash hairs growing from the surface of human skin
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The surface of a strawberry
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Cut human hairs and shaving foam between two razor blades
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Household dust – pollen, human hair, pet dander, leaf litter
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Toothbrushbristle
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Snowflake
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• Transmission electron microscope (TEM)– Provides for detailed study of the internal
structure of cells– Electrons are passed through thin
specimens– 2 dimensional
What are the different types of microscopes?
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TEM vs. SEM
Viruses leaving a cell
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Cell Structure and Function
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What are the common features of ALL cells?
• Cell Membrane: AKA plasma membrane– Encloses the cell– Separates the inside from the outside– Regulates what goes in & out of cell
• DNA– Genetic code
• Cytoplasm: the “fluid” inside of the cell– Provide support of internal structures– Site of cellular reactions
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What are prokaryotes?
• Single celled organism that lack nuclei
• More primitive; appeared first in the geologic record
• Many have flagella, that help
them move
• Bacteria
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What are eukaryotes?
• Have a nucleus– Compartment that
houses the DNA– Controls all functions of
the cell
• Have organelles– structures that carries
out specific jobs in the cell
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What’s found in the nucleus?
• Nuclear envelope• A double membrane which encloses the nucleus– Has pores that regulate molecular traffic in and out
of the nucleus
• Chromosomes• Condensed and coiled DNA– Each species has characteristic chromosome
number
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What is the cytoskeleton?
• Skeletal system of the cell membrane– Gives the cell its shape & structure– Involved with transport AND cell division
• Microtubules– Long hollow cylinders– Movement of chromosomes during
cell division
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Cell membrane
Endoplasmicreticulum
Microtubule
Microfilament
Ribosomes Michondrion
Go to Section:
Cytoskeleton
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What organelles are found within eukaryotes?
Endoplasmic Reticulum (ER)• Moves proteins/other substances through the
cell• Makes proteins from the ribosomes
– Rough ER is covered with ribosomes• Connected to the nucleus
– Smooth ER makes lipids (fats)• Ribosomes: structures that make
proteins
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What organelles are found within eukaryotes?
• Golgi Apparatus/ Golgi Body• Packaging and distribution center• Modifies lipids and proteins from the ER• Ships out the new products to their final
destinations
• Vacuoles: Storage containers that can also provide structure
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What organelles are found within eukaryotes?
• Mitochondria– Organelle that takes energy from sugar and turns
it into ATP (energy) that the cell can use– Has its own DNA
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What are the organelles found only in plant cells?
• Cell wall– Made of proteins & carbohydrates– Helps keep the cell’s shape – Provides rigid support– Protects from cell damage– Connects the cell with adjacent cells
• Chloroplasts– Organelle that uses light energy to make
carbohydrates through photosynthesis
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What are the organelles found only in plant cells?
• Central Vacuole– Large membrane covered space that
stores water and other substances
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Plant Cell
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An Animal Cell
Rough ER Smooth ER
Centrioles
CYTOSKELETON
Microfilaments
Microtubules
Lysosome
Golgi apparatus
Ribosomes
In animal cells but not plant cells:LysosomesCentriolesFlagella (in some plant sperm)
Flagella
ENDOPLASMIC RETICULUM (ER)
Mitochondrion
Nucleolus
DNA
Nuclear envelope
Plasma membrane
NUCLEUS
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A Plant Cell
In plant cells but not animal cells:ChloroplastsCentral vacuoleCell wall
CYTO-SKELETON
Ribosomes (small brown dots)
Central vacuole
Micro-filaments
Micro-tubules
Rough endoplasmic reticulum
Smooth endoplasmic reticulum
DNANUCLEUS
Nuclear envelopeNucleolus
Chloroplast
Cell wall
Golgi
Plasma membrane
Mitochondrion
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What are the 2 different cell types?
• Prokaryotic vs Eukaryotic– YOU are eukaryotic
• Larger cells• Found in all other kingdoms• Often multicellular• Nucleus• Contains membrane bound
organelles• Linear DNA• Asexual OR sexual
reproduction
• Small cells• Bacteria types• ALWAYS unicellular• No nucleus• No membrane bound organelles• Circular DNA• Asexual reproduction
EukaryoticProkaryotic
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The Cell Membrane
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What is the cell membrane made of?
• Provides protection and support for cells– Separates the cell from the outside environment
• Phospholipid– Molecule that allows the CM to be selectively
permeable • Certain substances can pass in and out of the cell
• Lipid Bilayer (2 layers)– Phospholipids - phosphate and 2 fatty acids
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Cell Membrane
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What is the cell membrane made of?• They are SELECTIVELY impermeable
• Some substances (not all) can pass across the membrane
• Hydrophobic tails…– Water HATING– Fats & oils
• Hydrophilic heads...– Water LOVING
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What is the cell membrane made of?
• Protein channels– Allow nutrients (sugars or amino acids) to enter
the cell– Allow products of metabolism to leave (waste
products)– These channels are quite specific
• Recognize only a limited group of chemical substances to pass through the membrane
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What is the function of the cell membrane?
• Gives the cell a flexible structure
• Forms a barrier between the cell and its environment
• Anchors the cytoskeleton to provide shape to the cell
• Attaches to the extracellular matrix to help group cells together (tissues)
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Outsideof cell
Insideof cell(cytoplasm)
Cellmembrane
Proteins
Proteinchannel
Lipid bilayer
Carbohydratechains
What is the Structure of the Cell Membrane?
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What is the Structure of the Cell Membrane?
• Carbohydrates– Act like chemical ID cards– Allows individual cells to identify one another
• Membrane allows the following materials in and out of the cell:– Water, Glucose (sugars), Oxygen, chemical compounds
& wastes
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How do things pass in and out of the cell?
• Concentration– # of molecules
present
• Diffusion– Spreading of
molecules OUT into available space
– From MORE concentratedto LESS concentrated
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How do things pass in and out of the cell?
• Concentration– # of molecules
present
• DIFFUSION– Spreading out of
molecules into available space
– From MORE concentratedto LESS concentrated
DRAW THIS!
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How do things pass in and out of the cell?
• Notice it’s not the MOLECULES THAT MOVE
• IT’S THE WATER/LIQUID SOLUTION
• Passive transport clip
DRAW THIS!
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How do things pass in and out of the cell?
• Diffusion depends on random particle movements– Doesn’t require cellular ENERGY– Called PASSIVE TRANSPORT
Equilibrium
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How do things pass in and out of the cell?
• Osmosis– The diffusion of WATER through a cell membrane
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How do things pass in and out of the cell?
• Isotonic = Same strength– Concentrations are the same on either side of the
membrane• Hypertonic = Above strength
– More concentrated solution OUTSIDE of cell membrane
• Hypotonic = Below strength– Less concentrated solution OUTSIDE of cell
membrane
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DRAW THIS DIAGRAM
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Cellmembrane
Higher Concentrationof Water
Lower Concentrationof Water
Water molecules
Sugar molecules
Osmosis Video
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Osmosis vs Diffusion
Diffusion Osmosis
Water? Doesn’t need Needs water for movement
What it is Spontaneous movement of molecules from high to low concentration
Spontaneous movement of WATER across a semipermeable mebrane, from high to low conc.
Process Mainly occurs in gases and liquids
Occurs when the medium (liquid) around a cell has a higher WATER concentration than the cell
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What is another example of passive transport?
• Facilitated Diffusion– Passage of molecules
with transport proteins across a membrane
– Uses channels
– Does NOT require ENERGY
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What is Active Transport?
• Movement of a substance against its concentration gradient with the use of ENERGY• Moving in the OPPOSITE direction• From LOW to HIGH concentration
• Active transport uses MOST of the energy a cell has for daily activities
• Active transport clip
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What is Active Transport?
• Cells try to accumulate high concentrations of molecules they need:• Ions• Glucose (sugar)• Amino acids (proteins)
• Carried out by protein channels
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What are the types of Active Transport?
• Exocytosis– Molecules EXIT through
the cell membrane
• Endocytosis– Molecules ENTERING
the cell through the membrane
– VIDEO
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How is Passive different from Active Transport?
Passive Active
Does not use any type of energy
Uses energy (Active)
Examples: Examples:
Diffusion Exocytosis
Osmosis Endocytosis
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Specialization vs Differentiation• SPECIALIZATION - Multicellular organisms have cells
that perform SPECIFIC jobs • Ex – blood cells carry nutrients, skin cells
protect the interior of the body– Cells work together to perform a specific function
for TISSUES• Similar tissue types make up ORGANS• Organs function together make up ORGAN
SYSTEMSCells Tissues Organs Organ Systems Organisms
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Specialization vs Differentiation
• DIFFERENTIATION– Normal process where less specialized cells
develop to perform a function– A fertilized egg (zygote) will develop into an
adult human being– Stem cells will develop into neurons,
somatic cells and germ cells
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