Transcript Chapter 4 Cells

The Microscope
or light source
The Microscope
• Scientist use microscopes to reveal details that
otherwise might be difficult or impossible to see
– Biologist use them to study organisms and their
parts
Simple Microscope
• The simple microscope is a single lens
microscope is used to produce an
enlarged image.
Compound Microscope
• Compound Microscope- shines light through
specimen and has at least two lenses to magnify
an image.
The Development of Light Microscopes
Compound light microscopes can
magnify objects up to 2,000 times.
The Microscope
• Magnification- the increase of an object’s
apparent size
• Power of magnification is the degree of
enlargement (how many times will the object be
multiplied?)
• Power of magnification = ocular (eyepiece) lens X
magnification of objective lens
The Microscope
• Resolution- the ability of the microscope
to deliver a clear image
**the higher the magnification the lower the
resolution
Development of Electron
Microscopes
 The electron microscope was invented in the 1940s.
 This microscope uses
a beam of electrons to
magnify structures..
Transmission Electron
Microscope (TEM)
• Transmission Electron Microscope (TEM)-
– a beam of electrons must pass through a very
thinly sliced specimen.
– Has great resolution of internal structures
– Can magnify objects up to 500,000 times.
The transmission electron microscope
(TEM) allows scientists to study the
structures contained within a cell.
Scanning Electron
Microscopes (SEM)
• Scanning Electron Microscope– passes beams of electrons over (scans the
surface of) the specimen’s surface and
provides a 3D image
– Can be magnified up to 100,000 times.
SEM Pictures
Compound Light
Microscope
1. beams of light
Electron Microscopes
beams of electrons
2. glass lenses
electromagnetic lenses
view on a florescent
3. view through ocular
screen or photographic
lenses
plate
can only view dead
4. can view living things things
5. 2000X
500,000X
Father of Microscopy
 Anton Van
Leeuwenhoek (16321723)
 Leeuwenhoek is known to have
made over 500 "microscopes," of
which fewer than ten have
survived to the present day.
These typically magnified
between 20 to 30 times.
 He discovered blood cells, and
was the first to see living sperm
Chapter 4 Cells
What is a cell?
• A cell is the smallest unit of life that
can carry on all the functions of life.
Who first discovered cells?
• Robert Hooke first
discovered cells in 1665
• He was an English scientist
that looked at a cork oak tree
with an early light
microscope; they reminded
him of the rooms or “cells”
where monks lived.
Who first observed
living cells?
• Anton van Leeuwenhoek in
1673
• He viewed pond water
organisms and called them
“Wee beasties”. We now
call them protists.
What are the three parts of
the cell theory?
1. All living things are made of cells
2. Cells are the basic units of
structure & function in all organisms.
3. Cells come only from the
reproduction of existing cells.
What shapes do cells come in?
• Cells come in a variety of shapes and their
shapes usually reflect their function.
• Examples:
(we will do the chart together)
How big or small are cells?
-Cells are measure in micrometers(µm)
-Most cells are only 10-50µm in
diameter.
-The smallest cell is bacteria
-The largest cell is ostrich egg
-The longest cell is nerve cell in a
giraffe’s leg
How big or small are cells?
How big can cells get?
• The size of a cell is limited by the
relationship of the cell’s outer surface
area to it’s volume
– (Surface area to volume ratio)
Surface Area
• A two-dimensional measurement of the
size of the surface of an object
Volume
• The amount of three dimensional space
occupied by an object.
SA to Volume Ratio
• As cells grow, their volume increases
much more than their surface area!
• The limited surface area would not
allow materials to enter or leave the
cell quickly enough to meet the cell’s
needs.
Surface Area to Volume
• What would happen if you fried the
whole potato instead of making French
fries?
What are the three main parts?
1. Cell Membrane- semi or selectively
permeable. It controls which substances
pass in and out of the cell. Made up of a
phospholipid bilayer.
2. Nucleus- contains the hereditary
information (DNA) and directs most of
the cell’s activities.
3. Cytoplasm- the region between the
cell’s nucleus and the cell membrane,
which contains the organelles and the
cytosol (jelly-like substance)
What are the two types of
cells?
• Eukaryote - cells that have a nucleus and
membrane-bound organelles.
• Examples: plant and animal cells
• Prokaryote cells that do not have a
nucleus and membrane-bound organelles.
• Examples:bacteria
How do plant and animal cells
differ?
PLANT
• Cell wall
• Central vacuole
• Chloroplast
• No lysosomes
ANIMAL
• No cell wall
• No central vacuole
• No chloroplast
• Lysosomes
What is the difference between
unicellular and multicellular
organisms?
• Unicellular- one cell can carry out all the
functions of life.
Example: bacteria, paramecium,
amoeba
• Multicellular – organisms composed of
many cells that are specialized to carry
out specific jobs (Cell Specialization)
– Therefore the cells depend upon other cells for
survival (Cell Interdependence)
What are the levels of
structural organization in
multicellular organisms?
1. Atom and molecule
2. Macromolecules
3. Organelles
4. Cell
5. Tissue
6. Organ
7. Organ System
8. Organism
Pictures
More pictures
Tissue
Organ
Organ
Organ Systems
Cells Product
• All cells must generate protein
(monomer: amino acid)
• Cells make protein through a process
called protein synthesis.
Cells Product
• Transcription: the process of making a
copy of DNA into mRNA. This occurs in
the nucleus
• Translation: the process of translating
mRNA to tRNA into an amino acid
chain.