Chapter 1 - Introduction: The Scientific Study of Life
NEW AIM: How is all life united?
Topic 8
Scientific Inquiry and Skills
Chapter 1 - Introduction: The Scientific Study of Life
AIM: What is Science?
What is Science ?
The process we use to know something
Chapter 1 - Introduction: The Scientific Study of Life
AIM: What is Science?
How do we do science?
We use the scientific method
Chapter 1 - Introduction: The Scientific Study of Life
AIM: What is Science?
Fig. 1.3A
Chapter 1 - Introduction: The Scientific Study of Life
AIM: What is Science?
Fig. 1.3A
Chapter 1 - Introduction: The Scientific Study of Life
AIM: What is Science?
Fig. 1.3A
Chapter 1 - Introduction: The Scientific Study of Life
AIM: What is Science?
Inference
A conclusion you make based on observations
Chapter 1 - Introduction: The Scientific Study of Life
AIM: How is all life united?
Let’s do an experimental design question
Things to keep in mind:
1. Question in bullets should be answered in bullets
and you should only be answering what the bullet
asks.
2. A hypothesis is NOT and IF/THEN. It is a statement
that answers your question like: The plants getting
fertilizer will grow taller. NOT if the plants get
fertilizer then they will grow taller.
3. The independent variable is the one you alter (it
starts with the letter “I”. It is not fertilizer, it is the
AMOUNT OF fertilizer. – goes on x axis of graph
4. The dependent variable is what you
measure…height, mass, color, etc… - goes on y axis
of graph
5. Make sure you use a placebo (sugar pill) if you are
treating HUMAN subject only.
Chapter 1 - Introduction: The Scientific Study of Life
AIM: How is all life united?
Let’s do an experimental design question
Things to keep in mind:
6. If they are asking what is wrong with an
experiment…
Always look for sample size, for a control group, and
look if it was repeatable.
7. If they ask how to make the experiment more
valid
Increase sample size, repeat experiment
Chapter 1 - Introduction: The Scientific Study of Life
AIM: How is all life united?
Laboratory skills
There are 1000 micrometers (um) in 1 mm
How many micrometers in 2.3 mm?
2300um
Chapter 4 - A Tour of the Cell
AIM: The practical microscope…
Laboratory skills
Field of view with mm ruler
What is the width of this organism?
Estimate the field of view at 1.5mm and estimate that 3 organisms fit
across it. Therefore the organism is around 0.5mm or 500um.
Chapter 4 - A Tour of the Cell
AIM: The practical microscope…
Laboratory skills
Field of view with mm ruler
What is the width of this cell?
Estimate the field of view at 1.5mm and estimate that 4 cells fit across it.
Therefore the organism is around 1.5/4 or 0.375mm or 375um.
Chapter 4 - A Tour of the Cell
AIM: The practical microscope…
Laboratory skills
Low Power
High Power
Remember that as magnification increases, FOV decreases
Chapter 4 - A Tour of the Cell
AIM: The practical microscope…
Laboratory skills
Remember that magnification is ocular times objective lens and know
the parts.
Chapter 4 - A Tour of the Cell
AIM: The practical microscope…
Under the microscope, the object you are looking at will be rotated by
180 degrees…
Chapter 4 - A Tour of the Cell
AIM: The practical microscope…
Laboratory skills
Measuring Liquid Volume:
Use a graduated cylinder and read the bottom of the meniscus.
Chapter 12 - DNA Technology and the Human Genome
AIM: What are some other tools of DNA technology?
Laboratory skills
Gel Electrophoresis
This technique allows one to not only indirectly view the DNA, but also to separate
and view the DNA fragments.
Fig. 12.10
Chapter 12 - DNA Technology and the Human Genome
AIM: What are some other tools of DNA technology?
Gel Electrophoresis
Gel (like jell-o)
The gel is made of either agarose or polyacrylamide. It has tiny, microscopic pores
that DNA can fit through.
Fig. 12.10
Chapter 12 - DNA Technology and the Human Genome
AIM: What are some other tools of DNA technology?
Gel Electrophoresis
Gel (like jell-o)
The DNA sample is loaded in the wells at the top of the gel. One sample per well.
Fig. 12.10
Chapter 12 - DNA Technology and the Human Genome
AIM: What are some other tools of DNA technology?
Gel Electrophoresis
Electricity (electrons flow
from top of gel by the
samples to the bottom of
the gel)
Electricity is then run through the gel. Why do you think the negative end is on the
sample side and the positive end is on the other end of the gel?
Fig. 12.10
DNA is negative because the phosphates are negative. The
negative electrons moving down push (repel) the DNA down with
Chapter 12 - DNA Technology and the Human Genome
AIM: What are some other tools of DNA technology?
Gel Electrophoresis
Which will move faster through the micro-porous gel, the longer DNA fragments or
the shorter DNA fragments?
The small fragments (fewer nucleotides) will move more easily through the gel and
hence go faster than the large ones. Therefore, gel electrophoresis separates DNA
Chapter 12 - DNA Technology and the Human Genome
AIM: What are some other tools of DNA technology?
Gel Electrophoresis
This is all great, but we still can’t physically see the DNA…
Fig. 12.10
Chapter 12 - DNA Technology and the Human Genome
AIM: What are some other tools of DNA technology?
Gel Electrophoresis
The gel is soaked with a a compound called ethidium bromide, which sticks to DNA
and lights up when you hit the gel with UV light…
Fig. 12.10
Chapter 12 - DNA Technology and the Human Genome
How can we use bacteria to manipulate DNA and protein?
Restriction enzymes
1. molecular DNA scissors (enzymes that cut DNA)
2. Different restriction enzymes cut different sequences of DNA.
3. Scientists have isolated hundreds of different restriction enzymes from many different
bacteria – EcoRI, BamHI, NcoI, etc…
Chapter 12 - DNA Technology and the Human Genome
How can we use bacteria to manipulate DNA and protein?
Restriction enzymes
Ex. The restriction enzyme EcoRI cuts at GAATTC
Fig. 12.4
Chapter 12 - DNA Technology and the Human Genome
How can we use bacteria to manipulate DNA and protein?
Restriction enzymes
Ex. EcoRI
EcoRI
Chapter 12 - DNA Technology and the Human Genome
AIM: What are some other tools of DNA technology?
Different people have different restriction
sites in their DNA due to mutations (see
left).
Draw what the gel would look like for the
restriction digest of the criminal and the
suspect.
Section of the DNA from
the crime scene
Section of the same DNA
segment from the suspect.
Chapter 12 - DNA Technology and the Human Genome
AIM: What are some other tools of DNA technology?
Criminal’s
DNA fingerprint
Suspect’s
DNA fingerprint
Suspect did not do it!!
criminal
suspect
Fig. 12.11A
Chapter 12 - DNA Technology and the Human Genome
AIM: What are some other tools of DNA technology?
Can also be used to detect disease,
determine paternity, or analyze general
genetic relatedness as more closely related
individuals will have more similar band
patterns (similar size fragments).
Chapter 12 - DNA Technology and the Human Genome
AIM: What are some other tools of DNA technology?
Review:
1. Digest DNA with restriction enzymes
2. Run restriction fragments on a gel
(gel electrophoresis) – shorter ones go
further
3. Compare fragments
Relationships and Biodiversity
State Lab
Laboratory skills
Remember Paper chromatography?
- Analytical technique for separating and identifying mixtures based on their attraction to
the paper or the solvent running up the paper
Relationships and Biodiversity
State Lab
How does Paper chromatography work?
The solvent (water in this case) will wick (travel) up the paper. The solvent will eventually make its way
to the sample absorbed on the paper (which must be above the water level).
The molecules in the sample will have different attractions for the paper and the solvent (water):
If the affinity is high for the solvent, the molecule will move quickly up the paper with the solvent. If
the molecule has a high affinity for the paper, it will stick to the paper and resist movement and only
move slowly up the paper thereby separating the different molecules.
Relationships and Biodiversity
State Lab
Station 4 - Paper Chromatography to Separate Plant Pigments
1. Take four strips of chromatography paper and try to straighten them the best you
can by curling them in the opposite direction and putting a slight crease down the
center (see example setup on the bench).
2. Draw a line 2 cm from the bottom of each of the four chromatography papers.
Use a pencil to label the top edge of the chromatography paper either Bc (Botanus
curus), X, Y, or Z (look at Figure 2 in the lab manual).
Relationships and Biodiversity
State Lab
Station 4 - Paper Chromatography to Separate Plant Pigments
3. Add about 1cm of water to each beaker.
4. Place two drops of plant extract from Botanus curus just above the pencil
line as shown in Figure 2.
5. Place the paper into the water and allow the water to move up the paper.
Repeat steps 4 and 5 for the other samples.
Pigment Sample MUST BE above the water level or the
pigment will just diffuse into the water!!!!!!
Chapter 4 - A Tour of the Cell
AIM: The practical microscope…
Laboratory skills
Dichotomous keys
Chapter 4 - A Tour of the Cell
AIM: The practical microscope…
Four State Labs