Download CLARK LAP Wednesday March 26 2014 STRAWBERRY DNA

Sara Sterling
Nativity School of Worcester
Seventh Grade Science
Period 6: 1:15- 2:01pm
Wednesday, March 26, 2014
Clark University Master of Arts in Teaching Program
Learning Activity Plan
I. Content: Describe what it is you will teach. What is the content?
The purpose of today’s lesson is to discuss the applications of DNA
extraction and analysis. Students will complete the first part of a lab in which
they extract DNA from frozen strawberries. The lab will involve a precise
procedure and students will need to follow the directions correctly in order to
yield the most DNA. Students will listen to a video about DNA finger printing
and gel electrophoresis. Students should identify that in order for DNA to be
extracted, proteins must breakdown the
II. Learning Goals: Describe what specifically students will know and be able to do after
the experience of this class.
 Identify where DNA is located in a cell, synthesize cell theory and the
location of DNA to evaluate the statement “DNA unites us all”
 Compare and contrast prokaryotic and eukaryotic cells
 Describe an organelle and identify several organelles in an eukaryotic cell
 Synthesize information from the lesson by answering reading check
questions
III. Rationale: Explain how the content and learning goal(s) relate to your Curriculum
Unit Plan learning goals.
The venn diagram is designed to help students review the differences between
prokaryotic and eukaryotic cells. The cell rap is designed to hook students into
the next reading, the students heard it last year and I think they will enjoy
singing along to the tune. The reading is similar to the previous reading, in
that it is a dense text divided into subsections. The cards are designed to be a
personalized way to interact with the text. It should not take the students very
long to write down the points, and it will help them to fill in the graphic
organizer. I have given the students a graphic organizer to help them
understand the main ideas about different organelles. I have modeled the first
line on the organizer to show students my expectations. The cards are
designed to be a personalized way to interact with the text. It should not take
the students very long to write down the points, and it will help them to fill in
the graphic organizer. By completing two passes of the same reading, I hope
students will absorb more of the material. I hope that this lesson will meet the
needs of my audio-visual learners and visual learners.
IV. Assessment: Describe how you and your students will know they have reached your
learning goals.
 Students will fill out a venn diagram in order to compare prokaryotic and
eukaryotic cells



Students will be able to read a complex text for a main idea and will use a
graphic organizer to organize their information.
Students will read for a specific task, write their answers on a card, and share
out their organelle on their card with the class.
Students will synthesize the lesson information in the form of summary
questions for the chapter.
V. Personalization and equity: Describe how you will provide for individual student
strengths and needs. How will you and your lesson consider the needs of each student
and scaffold learning? How specifically will ELL students and students with learning
disabilities gain access and will be supported?
I will incorporate visuals including note sheets and a Youtube video. Students will be able to
collaborate with their peers to draw conclusions and make connections. Students will be engaged in
the decoder challenge as they race their partner to complete the strand of DNA. The class will then
select a representative to make a strand for me to solve. All students will have the opportunity to be
involved in the lesson. The homework assignment allows for student choice and is designed to
increase student investment in the activity. The homework assignment is the third time students will be
using the reading to complete an activity. The assignment should help the lower students read
critically and absorb more material.
VI. Activity description and agenda
Duration
What the students
will be doing
Watching the video
about DNA
What I will be doing
Rationale
Playing the
http://www.youtube.com/watch?
v=zwibgNGe4aY
“What is DNA?”
1:20 to 1:25
Fill out note sheet
from the video.
Think, Pair, Share.
1:25 to 1:35
Go over HW
questions: p.89 #1-8
Notes: Make a
timeline for the
discovery of DNA
1:35 to 1:40
Think Pair Share:
Explain what is meant
by the statement
“DNA unites all
organisms” (p.89 #8)
Complete the
Decoding Challenge
-Students will have to
write the opposing
sequence for a strand
of DNA.
-Teacher guided for
round 1
-Round 2, one partner
Highlight key ideas from the
video: location of DNA,
structure of DNA, and Function
of DNA.
Highlight the key ideas
including bases, nucleotides, 3
scientists,
http://www.dnai.org/timeline/
and Math skills (p.89 #5—
Chargaff’s Rule)
Listening to students responses:
“DNA is found in the cells of all
organisms, therefore DNA
unites us all”
Extension
information for
students to show
WHERE we find
DNA in a cell
Engage the students
with a collaborative
discussion.
1:15 to 1:20
1:45 to 1:55
Circulate to monitor student
accuracy and student behavior.
Co-teacher
responsibility
Monitor student
behavior
Monitor student
behavior
Formative
assessment.
Monitor student
behavior
Formative
assessment.
Monitor student
behavior
Reinforce base pair
connections.
Help struggling
students, monitor
student behavior
1:55 to 2:00
will write a strand of
DNA their partner
must complete the
second strand
-Final Round one
student will create a
strand of DNA for me
to solve
Exit Ticket
Write HW down in
Agenda Book
VII.
Collect Exit tickets
Explain HW: Menu option for
the reading—Graphic organizer
or (DNA structure, DNA
function, DNA scientists, DNA
base pairs) Outline of key ideas
from the reading, or Brochure
(with a labeled drawing for a
strand of DNA, description of 3
scientists, and drawing of the 4
nucleotides)
Summative
Assessment
Monitor student
behavior
List the Massachusetts Learning Standards this lesson addresses.
LS2 Recognize that all organisms are composed of cells, and that many organisms are singlecelled. In these single celled organisms, one cell must carry out all the basic functions of life
LS3 Compare and contrast plant and animal cells, including major organelles (cell
membrane, cell wall, nucleus, cytoplasm, chloroplasts, mitochondria, vacuole)
VIII.
Reflection
a. In light of all areas of planning, but especially in terms of your stated purpose and
learning goals, in what ways was the activity(ies) successful? How do you know? In
what ways was it not successful? How might the activity be planned differently
another time?
b. What did you learn from the experience of this lesson that will inform your next
LAP?
Key
concepts
DNA
Genome
Genes
Extraction
Laboratory
techniques
Introduction
Have you ever wondered how scientists
extract DNA from an organism? All living organisms have DNA,
which is short for deoxyribonucleic acid; it is basically the
blueprint for everything that happens inside an organism’s
cells. Overall, DNA tells an organism how to develop and
function, and is so important that this complex compound is
found in virtually every one of its cells. In this activity you’ll
make your own DNA extraction kit from household chemicals
and use it to separate DNA from
strawberries. Background
Whether you’re a human,
rat, tomato or bacterium, each of your cells will have DNA
inside of it (with some rare exceptions, such as mature red
blood cells in humans). Each cell has an entire copy of the same
set of instructions, and this set is called the genome. Scientists
study DNA for many reasons: They can figure out how the
instructions stored in DNA help your body to function properly.
They can use DNA to make new medicines or genetically modify
crops to be resistant to insects. They can solve who is a suspect
of a crime, and can even use ancient DNA to reconstruct
evolutionary histories!
To get the DNA from a cell, scientists typically rely on one of
many DNA extraction kits available from biotechnology
companies. During a DNA extraction, a detergent will cause the
cell to pop open, or lyse, so that the DNA is released into
solution. Then alcohol added to the solution causes the DNA to
precipitate out. In this activity, strawberries will be used
because each strawberry cell has eight copies of the genome,
giving them a lot of DNA per cell. (Most organisms only have
one genome copy per cell.)
Materials
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Rubbing alcohol
Measuring cup
Measuring spoons
Salt
Water
Dishwashing liquid (for hand-washing dishes)
Glass or small bowl
Cheesecloth
Funnel
Tall drinking glass
Three strawberries
Resealable plastic sandwich bag
Small glass jar (such as a spice or baby food jar)
Bamboo skewer, available at most grocery stores. (If you use a baby
food or short spice jar, you could substitute a toothpick for the
skewer.)
Preparation
• Chill the rubbing alcohol in the freezer. (You’ll need it later.)
• Mix one half teaspoon of salt, one third cup of water and one
tablespoon of dishwashing liquid in a glass or small bowl. Set
the mixture aside. This is your extraction liquid. Why do you
think there is detergent in the extraction liquid?
• Completely line the funnel with cheesecloth. Insert the funnel tube
into the tall drinking glass (not the glass with the extraction
liquid in it).
• Remove and discard the green tops from the strawberries.
Procedure
• Put the strawberries into a resealable plastic sandwich bag and push
out all of the extra air. Seal the bag tightly.
• With your fingers, squeeze and smash the strawberries for two
minutes. How do the smashed strawberries look?
• Add three tablespoons of the extraction liquid you prepared to the
strawberries in the bag. Push out all of the extra air and reseal
the bag. How do you think the detergent and salt will affect the
strawberry cells?
• Squeeze the strawberry mixture with your fingers for one minute.
How do the smashed strawberries look now?
• Pour the strawberry mixture from the bag into the funnel. Let it drip
through the cheesecloth and into the tall glass until there is very
little liquid left in the funnel (only wet pulp remains). How does
the filtered strawberry liquid look?
• Pour the filtered strawberry liquid from the tall glass into the small
glass jar so that the jar is one quarter full.
• Measure out one half cup of cold rubbing alcohol.
• Tilt the jar and very slowly pour the alcohol down its side. Pour
until the alcohol has formed approximately a one-inch-deep
layer on top of the strawberry liquid. You may not need all of
the one half cup of alcohol to form the one-inch layer. Do not let
the strawberry liquid and alcohol mix.
• Study the mixture inside of the jar. The strawberry DNA will appear
as gooey clear/white stringy stuff. Do you see anything in the
jar that might be strawberry DNA? If so, where in the jar is it?
• Dip the bamboo skewer into the jar where the strawberry liquid and
alcohol layers meet and then pull up the skewer. Did you see
anything stick to the skewer that might be DNA? Can you spool
any DNA onto the skewer?
• Extra: You can try using this DNA extraction activity on lots of
other things. Grab some oatmeal or kiwis from the kitchen and
try it again! Which foods give you the most DNA?
• Extra: If you have access to a milligram scale (called a balance),
you can measure how much DNA you get (called a yield). Just
weigh your clean bamboo skewer and then weigh the skewer
again after you have used it to fish out as much DNA as you
could from your strawberry DNA extraction. Subtract the initial
weight of the skewer from its weight with the DNA to get your
final yield of DNA. What was the weight of your DNA yield?
• Extra: Try to tweak different variables in this activity to see how
you could change your strawberry DNA yield. For example, you
could try starting with different amounts of strawberries, using
different detergents or different DNA sources (such as oatmeal
or kiwis). Which conditions give you the best DNA yield?
Observations and results
Were you able to see DNA in
the small jar when you added the cold rubbing alcohol? Was the
DNA mostly in the layer with the alcohol and between the
layers of alcohol and strawberry liquid?
When you added the salt and detergent mixture to the smashed
strawberries, the detergent helped lyse (pop open) the
strawberry cells, releasing the DNA into solution, whereas the
salt helped create an environment where the different DNA
strands could gather and clump, making it easier for you to see
them. (When you added the salt and detergent mixture, you
probably mostly just saw more bubbles form in the bag because
of the detergent.) After you added the cold rubbing alcohol to
the filtered strawberry liquid, the alcohol should have
precipitated the DNA out of the liquid while the rest of the
liquid remained in solution. You should have seen the
white/clear gooey DNA strands in the alcohol layer as well as
between the two layers. A single strand of DNA is extremely
tiny, too tiny to see with the naked eye, but because the DNA
clumped in this activity you were able to see just how much of it
three strawberries have when all of their octoploid cells are
combined! (“Octoploid” means they have eight genomes.)