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Levels of Organization in Biology
Atom
Organism
Molecule
Population
Cell
Tissue
Community
Organ
Ecosystem
ECOLOGY
System
Biosphere
Characteristics of Life
1) Cellular Organization
2) Uses Energy—metabolism (nutrition, transport,
respiration, excretion, synthesis)
3) Reproduction
4) Requires Water
5) Respond to the Environment
6) Uses DNA as genetic material
7) Development
8) Evolves
Systems
• All levels of life have systems of related parts
that interact to form a whole.
• Have inputs and outputs
• Have boundaries
Examples of Systems
Systems in Biology
• Systems can be as small as atoms and
molecules to as big as the universe.
– Systems have boundaries
• E.g. Human skin that surrounds and holds together our
internal organs.
– Systems have inputs and outputs
• matter and energy coming into and of the system
boundaries
Use the following format for all your
lab write ups!
1) Start with a
problem statement:
• Question based on
observation that will
be answered in the
experiment. You write
it in the form of a
question
“What is the
effect of
MV on RV?”
Ex: Does air contain a life force that
causes spontaneous generation or
are there other organisms in the air
that cannot be seen?
2) Formulate a Hypothesis:
• If (manipulated variable)…
then (responding
variable)… because
(relevant explanation).
OR
• IF (the manipulated variable)
IS (describe how you change
it), THEN (the responding
variable) WILL (describe the
effect) BECAUSE … (give a
reason for your prediction).
He predicted that…
Microorganisms carried in the air caused
growth of organisms
Ex: If a sterilized broth is exposed
to air through a swan neck flask,
then it will remain free of
microorganisms because swan
neck will capture any
microorganisms that are carried in
the air.
3) Identify the
variables:
• Manipulated: The
variable that is
changed
• Responding: The
variable that is
measured due to
the change
Ex:
Manipulated: exposure to air
Responding: growth of
organisms in broth
Control (fixed) variables: variables
that do not change
• At least three CONTROLLED
VARIABLES are required, but more
may be necessary. The controlled
variables you list must be relevant to
your investigation. You need to
control for all variables that may
reasonably affect the outcome of the
investigation. Materials used and
measurement techniques are NOT
controlled variables (they are validity
measures). While materials and
techniques must be consistent, a true
variable is something that could
directly influence the responding
variable, not just how it is measured.
Ex:
Temperature at which flasks are
stored
Time that flasks are allowed to sit
Amount of light that flasks are
exposed to
4) Identify the
Groups:
NEW!!
• Experimental group- set-up that
has the MV
• Control group- set-up with no
MV
**Needs to be included in the
procedure
Experimental group:
sterilized broth in
broken flask, sterilized
broth in swan neck flask
Control group: sterilized
broth in sealed swan
neck flask.
7) Data Collection:
• Record data accurately and neatly
• Includes both qualitative and
quantitative
• Data table must include appropriate
units, headings and DESCRIPTIVE title
• Averages included when trails are
indicated
• See sample data table
Descriptive title
Responding Variable
(+ unit of measurement):
Manipulated Variable
(+ unit of measurement):
Trials
Levels of MV
#1
#2
#3
Average of Trials
This table can be made using MS Word, MS Excel or by hand.
Data Tables drawn by hand:
•Use a ruler.
•Neat and legible.
•Make it big enough that I can read it!
8) Data Analysis:
•Process data in a meaningful way
•Look for patterns and trends
•Graph and or mathematical calculations
Graph: See example…..
•Variables listed with units of measurement
•Even increments on both X and Y axis
•Ruler used whenever hand drawn for all straight
lines
TITLE
Describes what you are
studying
Y-AXIS
Responding
Variable & Unit of
Measurement
NEATNESS
•Ruler is used for lines on
the graph
•Ruler is used for the X
and Y axis lines
•Legible handwriting
X-AXIS
Manipulated Variable &
Unit of Measurement
KEY
Identifies
different sets of
data found in
your graph
(should be colorcoded)
9) Develop Conclusions:
4 parts
•State whether your hypothesis is “supported” or “not
supported”
•Evidence that your hypothesis is supported or not supported….
Use concrete data. Use range of data when available
•Errors/improvements (realistic)
•Modifications to the procedure
Reminders:
•NO ABBREVIATIONS
•Include all the parts indicated in the directions
•Metric, metric, metric……
Review of Microscopy
or Turret
Magnification:
Ocular (Eyepiece): 10X
or Turret
Objectives:
•
•
•
•
Low Power: 4X
Medium Power: 10X
High Power: 40X
Highest Power: 100X
Total Magnification:
Total Magnification =Ocular X Objective
Low Power:
10 X 4 = 40X total mag
Medium Power:
10 X 10 = 100X total mag
High Power:
10 X 40 = 400X total mag
Highest Power:
10 X 100 = 1000X total mag
DO NOT ADD!!!!
or Turret
Lighting the FOV:
• The lower the power, the lighter the FOV (easier to see image).
• The higher the power, the darker the FOV (harder to see image).
– DIAPHRAGM (adjusts the amount of light):
Disc underneath the stage that
contains holes of different sizes.
Dial to a larger hole to let in
more light.
or Turret
Diaphragm
Field of View (FOV):
Field of View (FOV):
• The lower the power, the more FOV you see. (More area is
magnified less)
• The higher the power, the less FOV you see. (Less area is
magnified more)
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10x
15X
20X
30X
40X
Lighting the FOV:
• The lower the power, the lighter the FOV (easier to see image).
• The higher the power, the darker the FOV (harder to see image).
– DIAPHRAGM (adjusts the amount of light):
Disc underneath the stage that
contains holes of different sizes.
Dial to a larger hole to let in
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more light.
or Turret
Diaphragm
How to make a wet mount slide preparation
1.
2.
3.
4.
5.
Take out a clear, clean slide.
Place 2 drops of water on the middle of the slide.
Carefully place specimen in the middle of water.
Gently lower cover slip onto water drops.
Repeat if the following happens…
A.
B.
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Water seeps out sides of cover slips
Wick away extra water seeping out by placing a piece of paper
towel right next to cover slip. Hold there until all the water is
gone from outside of cover slip.
Air pockets under cover slip
Redo.
Modern Microscopes
• Some of the light microscopes here are capable of
1000x magnification.
– That is about the limit of a light microscope’s magnification
without losing clarity (called Resolving Power).
• Due to the width of visible light’s wavelength
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• The electron microscope was introduced in the 1950s
and uses the wavelength of electrons to increase the
resolving power by 100x.
– Approx. 100,000x magnification!!
– Cell Biology advanced rapidly as cellular organelles were clearly
seen for the first time.
A few limitations of electron
microscopes
• Specimen must be
placed in a vacuum and
is typically coated with a
conductive metal like
gold. Consequently you
can’t look at living
specimens under electron
microscopes.
•All images produced are
black and white, so you
can’t distinguish colors.
Pictures are usually
colored in digitally later.
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It all started with an invention….
• The first microscope
– Sacharias Jansen,
1595, Middleburg,
Holland
– It launched great
leaps in Astronomy
and Biology.
– Some of the first great
observations with it
were made by6
傠Њ
Robert Hooke (1635-1703)
– Designed
microscopes
– Discovered and
documented
the first “cells” in 1665
• Named them after the
cells in
which a monk sleeps.
From: http://www.ucmp.berkeley.edu/history/hooke.html
Antony van Leeuwenhoek
(1632-1723)
A tradesman from Holland
who became fascinated with
Hooke’s book
Discovered bacteria, protists,
sperm cells, blood cells,
nematodes, etc.
Became an expert lens grinder
and made over 500 simple
microscopes
Acute eyesight and lens
grinding skill let him build
microscopes that were capable
of 200X magnification
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Cell Theory
1838 Mattias Schleiden stated
that all plant tissues consisted of
cells
1839 Theodore Schwann stated
that all animal tissues consisted of
cells
Each conjectured that there was a
nucleus
1858 Rudolf Virchow combined
the two ideas and added that all
cells come from pre-existing cells,
formulating the Cell Theory
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Rudolf Virchow
Cell Theory
• All living things are
composed of one or more
cells
• In organisms, cells are the
basic units of structure and
function.
• All cells are produced only
from existing cells.
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1858
Prokaryotic vs Eukaryotic Cells
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Prokaryotic Cells (Bacteria)
•Prokaryotic Cells
– primitive, ‘before kernal’
- NO NUCLEUS
– Lack internal membranes (no
“membrane-bound” organelles)
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– Genetic material: single,
circular DNA molecule suspended
in the cytoplasm
•Ex. Bacteria
(such as Anthrax or E. coli)
–Microscopic, single-celled
organisms
Unicellular (one) vs.
Multicellular (many)
Unicellular: Single-Celled
• Most common forms of life
on Earth.
• Carry out all functions of
Life.
– Bacteria
– Amoeba
– Paramecium
Unicellular (one) vs.
Multicellular (many)
Multicellular
• Larger organisms.
• Different cells have
specialized functions,
together making a
complete organism.
– Human
– Spider
– Jellyfish
• Visit a “Tour of the Cell” at:
video
Cell Membrane: “Security
Gate”
• Surrounds the cell
• Controls movement of
materials into and out of cell
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Nucleus:
– Controls the functions of the
cell (the brain)
– Includes the following:
• Nuclear Envelope (Membrane):
Controls movement into and
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out of the nucleus
• Nuclear Pore: holes where
movement takes place
Nucleus:
• Nucleolus: Dark area
inside nucleus, believed
to be for making RNA
and ribosomes
• Chromatin: Genetic
Material (DNA) which is
organized into
structures called
chromosomes during
cell division.
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Cytoplasm:
• remainder of the contents of
the cell consisting of:
– Cytosol:liquid
environment
– Cytoskeleton: network of
protein fibers that
supports the shape of the
cell and anchors its
organelles and serves as a
“track” for them to move
on. Crisscrosses the
cytoplasm
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Mitochondria: “Powerhouse”
• Provides energy for cell.
– Converts food to usable energy for cell.
• Have their own ribosomes and DNA.
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Golgi Apparatus (Complex): “packaging and
distributing center”
• Stack of membrane-enclosed spaces.
• Process/Sorts/Packages protein/lipids for distribution within the cell and
export out of the cell.
• Proteins/lipids come from endoplasmic reticulum.
Endoplasmic
Reticulum (ER):
• (Highway) Set of
channels…aids in movement
of molecules inside the cell.
• Rough ER:
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– Ribosomes found on surface.
• Smooth ER:
– No ribosomes on surface.
Ribosome (4d):
• (Factory) Makes proteins and is found in the cytosol or on the
ER.
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Vacuole: “Storage Tanks”
• Fluid filled sack.
• Stores water, food
molecules, ions and
enzymes.
• Animal cells contain many
small vacuoles.
• Plant cells contain a large
central vacuole…we will be
talking about this more
later…
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Lysosomes: “Suicide Sacs/Recycling Centers”
•
•
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•
•
Carry enzymes to destroy cellular
waste.
– Break down damaged/worn out
cell parts.
Engulf/digest targeted molecules
– Defend cell from invading
bacteria/viruses
Once thought to be only in animal
cells, but exist minimally in plant
cells.
Membrane protects cell from
enzymes.
Plant Cell
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Plant Cells:
contain all of the previous organelles (except centrioles) as
well as:
Cell Wall:
• Gives cells shape and
support and provides
protection.
• Found in algae, fungi and
most bacteria too.
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Plant Cells:
contain all of the previous organelles (except centrioles) as
well as:
Chloroplast: (green)
• Changes sun’s energy into
food.
• Also in green algae.
Plant Cells:
contain all of the previous organelles (except centrioles) as
well as:
Central Water Vacuole:
• Single, large water filled
vacuole in the middle of the
cell.
• Strengthen cells and
provide support for plant.
• Contains toxins to harm
plant predators, waste
products and pigment for
color (petals).
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Animal Cell
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Animal Cells
contain all of the previous organelles plus:
Centrioles: 2 cylindrical organelles (together called a
centrosome)
• Formed by hollow protein fibers called microtubules (part of the
cytoskeleton)
• Produce microtubules that aid in첀Б
moving chromosomes during cell
division.
• Found in animals and algae only
but not in all animal cells.
Video tour of cell