microscopes and the cell thursday, october 17 th
TRANSCRIPT
Microscopes and the CellThursday, October 17th
What is “cell theory”?
Who helped developed the cell theory?• 1665
• Robert Hooke• Observed cork under a primitive
microscope• Coined the term “cell”
• Looked like monks cells
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
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
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)
ELECTRON MICROSCOPES
LIGHT MICROSCOPE
UNAIDED EYES
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
Light Microscope
• 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?
• 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?
Surface of Tongue
Head louse clinging to a human hair
Eyelash hairs growing from the surface of human skin
The surface of a strawberry
Cut human hairs and shaving foam between two razor blades
Household dust – pollen, human hair, pet dander, leaf litter
Toothbrushbristle
Snowflake
• 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?
TEM vs. SEM
Viruses leaving a cell
Cell Structure and Function
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
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
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
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
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
Cell membrane
Endoplasmicreticulum
Microtubule
Microfilament
Ribosomes Michondrion
Go to Section:
Cytoskeleton
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
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
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
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
What are the organelles found only in plant cells?
• Central Vacuole– Large membrane covered space that
stores water and other substances
Plant Cell
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
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
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
The Cell Membrane
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
Cell Membrane
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
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
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)
Outsideof cell
Insideof cell(cytoplasm)
Cellmembrane
Proteins
Proteinchannel
Lipid bilayer
Carbohydratechains
What is the Structure of the Cell Membrane?
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
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
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!
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!
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
How do things pass in and out of the cell?
• Osmosis– The diffusion of WATER through a cell membrane
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
DRAW THIS DIAGRAM
Cellmembrane
Higher Concentrationof Water
Lower Concentrationof Water
Water molecules
Sugar molecules
Osmosis Video
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
What is another example of passive transport?
• Facilitated Diffusion– Passage of molecules
with transport proteins across a membrane
– Uses channels
– Does NOT require ENERGY
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
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
What are the types of Active Transport?
• Exocytosis– Molecules EXIT through
the cell membrane
• Endocytosis– Molecules ENTERING
the cell through the membrane
– VIDEO
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
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
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