Download Section 7.1 Notes

7.1 Life is Cellular
• Janssen 1590
Invented the first compound
microscope
Discovery of Cells
Robert Hooke (1665)
- English Scientist
- used a light microscope to observe cork (dead plant
cells)
- observed many small “boxes” and named them cells
Cell Wall
Anton van Leeuwenhoek - 1674
• Dutch Lens Maker
• Looked at pond water under a microscope and
saw green, single cell organisms moving
around!
• Also looked at teeth scrapings through his
microscope and noticed bacteria.
VOLVOX
UNDER
DARK
FIELD
Robert Brown (1832)
• Botanist
• Identified cell nuclei
Matthias Schleiden (1838)
• Suggested that plants are composed of cells!
Theodor Schwann (1839)
• German Physiologist
• Stated that the cell was the basic unit of
structure in animals.
Rudolf Virchow (1855)
• German Doctor
• Stated that new cells come from existing cells
–Cells divide to make more
Ernst Ruska (1939)
• Won the Nobel Prize in physics for
electron optics.
–Invented the electron microscope
Compound Light Microscope
• Description
– Most common microscope
– Uses two lenses and light to
view specimen
• Maximum Magnification
– Up to 1500x
• Image of Specimen
– Allows you to view specimen
that light can pass through.
Compound Light Microscope
• Benefits
– Most affordable
– Can be used to view living specimen
– Easy to use
• Disadvantages
– Limited magnification
– Requires light to function
– Must stain some specimen in order to see
them. (No longer alive)
Scanning Electron Microscope (SEM)
• Description
– Shoots electrons at a specimen and collects them
as they bounce off the surface of organisms
• Helps scientists study the exterior structure of
specimen.
• Maximum Magnification
• Up to 500,000x magnification
• Description of Image
– Used to view exterior structures in great detail.
– Images are viewed on a developed film or
computer screen
Scanning Electron Microscope (SEM)
• Benefits – Very high magnification and
detailed images. Able to view the exterior
structures of the specimen in 3D.
• Disadvantages – Can only view dead or nonliving specimen. Difficult to prepare
specimen for viewing. Very expensive to
purchase and maintain.
• Bounces electrons off specimens to study
SURFACE structures.
Simple but Amazing SEM
images
Dentist Drill
Velcro
Split end of a hair
Mites on skin
Scanning Electron Microscope
•A scanning electron microscope picture of a nerve
ending. It has been broken open to reveal vesicles
(orange and blue) containing chemicals used to
pass messages in the nervous system.
Transmission Electron Microscope
(TEM)
• Electrons pass through specimens to study the
INTERIOR structures
Transmission Electron Microscope (TEM)
• Description
– Shoots electrons through specimens
– Allows scientists to study the INSIDE of specimen at
great detail.
• Maximum Magnification
– Up to 5,000,000x magnification
• Description of Image
– Used to view interior structures of the specimen in great
detail.
– Images are viewed on a developed film or computer
screen
Transmission Electron Microscope (TEM)
• Benefits – Very high magnification and
detailed images. Able to view interior
structures of the specimen.
• Disadvantages – Can only view dead or
non-living specimen. Difficult to prepare
specimen for viewing. Very expensive to
purchase and maintain. 2D images only.
Transmission Electron Microscope
Transmission Electron Microscope
7.2 Cell Structure
Lesson Overview
Lesson Overview
Life Is Cellular
The Discovery of the Cell
The Cell Theory:
1. All living things are made up of
cells.
2. Cells are the basic units of structure
and function in living things.
3. New cells are produced from
existing cells.
Prokaryotes and Eukaryotes
– Prokaryote =
• Cell that do not
contain a nucleus or
nucleus
membrane bound
organelles.
– Eukaryote=
organelles
• Cells that contain a
nucleus and
cell membrane
membrane bound
organelles.
Lesson Overview
Life Is Cellular
Prokaryotes and Eukaryotes
Lesson Overview
Life Is Cellular
Prokaryotes
• Prokaryotic cells are generally smaller and
simpler than eukaryotic cells.
• They are SIMPLE yet, still fully alive!!
• Example: Bacteria
Lesson Overview
Life Is Cellular
Eukaryotes
• Eukaryotic cells are generally larger and
more complex.
• Most contain dozens of structures and
internal membranes.
• Many eukaryotes are highly specialized.
• Types of eukaryotes: plants, animals, fungi,
and Protists.
Cell Diversity
 Size
 Shape
 Function
 Location
 Parts
Cell Diversity
Figure 3.7; 1, 2
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 3.19a
Cell Diversity
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 3.19b
Differences between Plant Cells and
Animal Cells
Plant Cell:
•Cell wall
•Large central vacuole
•Chloroplasts
•Box-like shape
Animal Cell:
•No cell wall
•Many small vacuoles
•No chloroplasts
•Rounded shape
Life Is Cellular
Cell Organization
Lesson Overview
Eukaryotic cells can be divided into two
major parts:
• Nucleus
• Cytoplasm.
Prokaryotic cells have cytoplasm, but not
a nucleus
Life Is Cellular
Cell Organization
Lesson Overview
• Organelles – specialized structure that
performs important functions within a cell.
• Literally “Little Organ”
• Similar to a body organ!!
Lesson Overview
Life Is Cellular
Cell Structure
The Nucleus
• Cellular Control Center
• Contains DNA (Genetic Information)
• Prokaryotic – DNA is in cytoplasm
• Three main parts
• Nucleolus
• Nuclear envelope
• Chromatin
Lesson Overview
Life Is Cellular
Cell Structure
Nuclear Envelope
• Membrane that surrounds the nucleus
• Controls what enters and exits!
Lesson Overview
Life Is Cellular
Cell Structure
Chromatin
• DNA bound to proteins and condensed.
Lesson Overview
Life Is Cellular
Cell Structure
Nucleolus
• Small dense region in the nucleus.
• Creates ribosome
Cell Structure
Cytoplasm
 Mostly H20 and Nutrients
Suspends organelles - fills up all the
space between the cell membrane and
nucleus.
Lesson Overview
Life Is Cellular
Cell Structure
Vacuoles
• Membrane enclosed structure that is
used to store materials.
» Ex: water, salts, proteins, and
carbohydrates.
Lesson Overview
Life Is Cellular
Cell Structure
Vesicle
• Small membrane-enclosed structures
used to move materials between
organelles, as well as to and from the
cell surface.
Lesson Overview
Life Is Cellular
Cell Structure
Lysosome
• Small organelles filled with enzymes
that breakdown and recycle organic
molecules or harmful bacteria.
• “Waste” removal crew for the cell.
Lesson Overview
Life Is Cellular
Cell Structure
Ribosome
• Small organelles that produce proteins.
• Found in the cytoplasm and on the ER
Lesson Overview
Life Is Cellular
Cell Structure
Endoplasmic Reticulum
• Internal membrane system
• Assembles lipids, proteins and other
materials
• Known as the “ER”
Lesson Overview
Life Is Cellular
Cell Structure
Rough Endoplasmic Reticulum
• Has ribosomes all over its surface.
• Involved in the production of proteins
Lesson Overview
Life Is Cellular
Cell Structure
•Smooth Endoplasmic Reticulum
• NO ribosomes on its surface.
»Production of membrane lipids.
»Detoxification of chemicals.
Lesson Overview
Life Is Cellular
Cell Structure
Golgi Apparatus
• Appears as a stack of flattened
membranes.
• Modifies, packages, and ships proteins
and lipids around the cell or out of the
cell.
Lesson Overview
Life Is Cellular
Cell Structure
• From the Golgi apparatus, proteins or lipids
are “shipped” to their final destination
inside or outside the cell.
Lesson Overview
Life Is Cellular
Cell Structure
Mitochondria
• The power plant of the cell.
• Converts chemical energy stored in food
(glucose) into useable energy!
Lesson Overview
Life Is Cellular
Cell Structure
Chloroplasts
• Captures light energy and converts it
into food (glucose).
• Only in plant cells!
• Photosynthesis
Lesson Overview
Life Is Cellular
Cell Structure
Cytoskeleton
• Tough and flexible framework that
supports the cell.
• Made of protein
• Plays a role in cell division.
CellCell
Structure
Wall
Cell Wall
• Outer-most layer of plant cells
• Protects, supports, and maintains the
shape of plant cells.
– Made of cellulose, pectin and lignin
Lesson Overview
Life Is Cellular
Cell Structure
Cell Membrane
What is the function of the cell membrane?
• It is the cell’s gate keeper!!
• Regulates what enters and leaves the
cell.
• The cell membrane is Selectively
Permeable
• Some substances can cross the
membrane easily, while others cannot!
Lesson Overview
Cell Membrane
Life Is Cellular
• Cell membranes are made of double-layer
of Phospholipids.
• Called the phospholipid bilayer.
• This makes the membrane a strong and
flexible barrier between the cell and its
surroundings.
Lesson Overview
Life Is Cellular
The Properties of Lipids
Phospholipid Review
• Fatty acid portions of such a lipid are
hydrophobic, or “water-hating”
• The opposite end of the molecule is
hydrophilic, or “water-loving.”
Lesson Overview
Life Is Cellular
The Properties of Lipids
• The hydrophobic fatty acid “tails” cluster
together
• The hydrophilic “heads” are attracted to
water.
• A lipid bilayer is the result.
Lesson Overview
Life Is Cellular
The Fluid Mosaic Model
• There are also carbohydrates and
proteins embedded in the membrane.
• The membrane contains several different
molecules, but remains flexible (Like a
liquid)
Cell Structure
Special Structures on some cell membranes
 Cilia - Movement or to moves materials
across the cell surface.
 Flagellum - propel the cell.
Cilia
Flagella
Slide 3.18
Cilia vs. Flagella Movement