Transcript Topic 3- Cells

Topic 3- Cells
&
Tools Used in the Lab
What is the difference between a
theory and a law?
Theory- Not definite
or proven, but is
backed by
scientific
evidence.
Law- Definite,
proven and is
supported by
scientific
evidence.
Cell Theory: (3 parts)
All living things are composed of cells.
• 1. Cells are the basic unit of structure.
• 2. Cells are the basic unit of function.
• 3. Cells come from pre-existing cells
MITOSIS
Levels of Organization
• Organelle: part of the cell
• Cell: basic unit of living things
• Tissue: made of a group of cells
• Organ: made of several tissues
• Organ System: composed of a group of organs
• Organism: a living thing
Levels of Organization
Cell Models: An Interactive Animation
Animal Cell
Plant Cell
Cell Organelles (Parts of the Cell)
Organelles Common to BOTH Animal &
Plant Cells:
1. Cell/Plasma Membrane:
• 1. surrounds all cells
• 2. regulates what goes into and out of the cell semipermeable
The Cell Membrane is labled A in
both pictures
2. Nucleus: (contains DNA/RNA)
• Controls the functions of the cell. It has a
membrane of its own (nuclear membrane).
[Brain]
Letter B - Nucleus
3. Nucleolus:
• Found within the nucleus. Allows
RNA to enter the cell.
Dark circle w/in B - nucleolus
4. Cytoplasm:
• Jelly-like fluid containing other organelles
• It moves in a circular motion- CYCLOSIS.
5. Endoplasmic Reticulum E.R. :
• Channels - Aids in transport.
• Can be smooth or rough
• Rough- contains Ribosomes
Letter B - is the Endoplasmic Reticulum
6. Ribosomes:
• Site of protein synthesis. Can be free or
attached to the E.R.
Letter C - Ribosomes
7. Mitochondria:
• Site of cellular respiration 
ATP=ENERGY.
[Powerhouse]
8. Golgi Bodies/Apparatus/Complex:
• Stacks of flattened tubes that
package wastes in the cell.
[Garbage Men]
9. Vacuoles: STORAGE
• Holds water or food. LARGE in a
plant cell. small in an animal cell.
[Storage Bin]
Letter A - Vacuole
Vacuole
Organelles only in ANIMAL
CELLS:
• Lysosomes: Digests food or old, worn out
parts of the cell. “Suicide Sacs”
• Centrioles: Aids in cell division. Come in
pairs.
Organelles only in PLANT
CELLS:
•
•
Chloroplasts: Contains chlorophyll traps light and
allows plants to make food  PHOTOSYNTHESIS
Cell Wall: Non-living structure that supports and
protects the cell. Composed of cellulose.
Letter C – Cell Wall
Letter B – Chloroplasts - Photosynthesis
Tools & Techniques Used In the Lab:
Microscopes
•Image is upside down & backwards.
•If you need to center a specimen,
move the slide in the opposite direction.
Types of Microscopes
Compound Light Microscope:
• 2 sets of lenses (ocular &
objective)
• Specimens must be thin &
transparent
Compound Microscope
Total Magnification
• Eye piece x
Objective lens = Total Magnification
Calculating Total Magnification
What is the total
magnification under low
power?
10 * 15 = 150x
What is the total
magnification under high
power?
10 * 45 = 450x
Focusing:
•
•
•
•
•
•
Put slide on stage
Turn to low power obj.
Use coarse adj. knob to focus
Turn to high power
Use fine adj. knob to focus
* Never use coarse adj. knob under high
power  you could crack the slide
Microscope MeasurementThe unit of measurement used with the
microscope is the micron (um).
1mm=1,000 um
1. When converting
mm  um
• Move decimal point
3 places to the
RIGHT
• 5mm=5,000 um
2. When converting
um  mm
• Move decimal point
3 places to the
LEFT
• 9,000um=9mm
Which neuron is the longest?
How long is one cell in Micrometers?
In um, approximately how long is the paramecium?
Field of ViewWhen you look in the ocular, it is the
view you see.
• HIGH POWER FOV is 4x
smaller than low power
FOV.
• You will see less cells, but
more detail.
• High power is darker than
low power.



LOW POWER FOV is 4x
LARGER than high
power FOV.
You will see more cells,
but less detail.
Low power is brighter
than high power.
Field of View (FOV)
Microscope Measurements:
• Q: If you can see 20
cells under low power
FOV, how many will
you see under high
power FOV?
• LOW POWER 
HIGH POWER ( / 4)
• 20 / 4 = 5 cells under
High power
• Q. If you can see 2
cells under high power
FOV, how many will
you see under low
power FOV?
• HIGH POWER 
LOW POWER (X 4)
• 2 x 4 = 8 cells under
Low power
More Tools & Techniques Used in the
Lab:
1. Stereomicroscope/ Binocular / Dissecting
Microscope:
 2 eyepieces
 look at opaque objects
2. Electron Microscope
- uses beams of electrons and magnets
- specimens thin and dead
- view inside mitochondria or ribosomes
- extremely powerful
Microdissection Instruments:
• Dissection of cells
• Can be used to transplant a nucleus from one cell
to another
Stains:
• Makes organelles more visible
• Iodine- yellow stain
• Methylene Blue (vital/living) - blue stain
Centrifuge:
• Spins contents at a high speed
• Separates contents by density
• Heaviest- bottom Lightest- top
Chromatography:
• Separates pigments/colors at different rates
Gel Electrophoresis:
• Used to separate substances that have an electrical
charge
• Substance is cut using an enzyme
• Substances are placed into wells located at the top of
the gel
• Substances separated based on their size and charge
• Small particles travel further through the gel, large
particles do not
• Can be used to separate fragments of DNA
Gel electrophoresis