biology genetics unit - ms. rozema's classes · 2019-02-27 · 2 | p a g e lesson 4 student...
TRANSCRIPT
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Name: __________________________________________________________ Hour: __________ Teacher: ROZEMA
Biology
Genetics Unit
[Packet-2] What do we know so far?
Video Observations:
DMD Research & Background Information:
Muscles:
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Lesson 4 Student Activity Sheets: Why don’t people with DMD make dystrophin?
PART 1: Gene Expression Proteins are complex molecules made up of subunits called amino acids. There are 20 different amino acids and the
different combinations of these is what makes one protein different from the next. There can be hundreds or thousands of
individual amino acids in a protein. This amino acid sequence determines a protein’s structure and function. Proteins can perform a lot of different functions: some proteins provide structure to an organism, some act as chemical
messengers and allow different parts of the body to communicate, some proteins help with chemical reactions like
digestion, and some proteins play a role in your immune system. Proteins are made through a process called gene expression (sometimes referred to as protein synthesis). Gene expression
has two major parts: transcription and translation. All cells have DNA in them. Recall from your previous science classes
that DNA is the “code” for all of the traits an organism has. All of your DNA is contained inside each cell’s nucleus. A
section of DNA that codes for a specific trait is called a gene. A gene actually contains the code for one specific protein.
Cells read the section of DNA and make a molecule that is very similar to DNA, called RNA. The process of making
RNA from DNA is called transcription. The special type of RNA made in transcription is called mRNA. The lower case
“m” stands for messenger. Messenger RNA then leaves a cell’s nucleus and travels to another part of the cell called the
ribosome. A ribosome then reads the mRNA and makes a chain of amino acids that will then fold into the specific protein.
Making a chain of amino acids from mRNA is called translation.
Checking for Understanding: 1. Work with the person next to you to draw a picture of how you think gene expression (or protein synthesis) works.
Label the parts of your picture using words from the reading above.
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PART 2: Analogies 2. Work with a partner or alone to create another analogy about protein synthesis.
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MAKING SENSE: 3. Explain what you know about protein synthesis.
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PART 3: Dystrophin and DMD
There is a section of your DNA that scientists have isolated that contains the instructions for how to make dystrophin.
Scientists refer to this section of your DNA as the DMD gene. DMD stands for Duchenne Muscular Dystrophy. DMD is
the largest known human gene. There is more than one kind of muscular dystrophy. We have spent most of our time
discussing Duchenne’s. In this case, the DNA of a person with Duchenne’s does not code for the protein dystrophin at all.
This means that people with DMD do not make any dystrophin. Another type of muscular dystrophy is called Becker’s. In
this case, the DNA codes for some dystrophin or an incomplete version of the dystrophin. People with Becker’s MD have
some dystrophin so their muscles deteriorate more slowly, meaning they have normal muscle function for more of their
lives. 6. Compare and contrast the dystrophin in Duchenne’s, Becker’s and healthy muscle:
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PART 4: Protein Synthesis Simulation
PROCEDURE: Answer the questions as you go through the computer simulation. http://genes.inquiry-hub.net/
INVESTIGATION 1: Lactase 7. What do you notice about the DNA?
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8. What happens when you push “Transcribe”?
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9. What happens when you push “Release”?
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10. What happens when you push “Translate”?
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11. What happens when you push “Release”?
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12. Write down the sequence of amino acids in the original protein.
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13. Create 1 deletion mutation and follow the steps you used before.
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14. Write down the sequence of amino acids in the new protein.
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15. How is this protein different from the original protein made?
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BUILDING UNDERSTANDINGS: 16. Describe in your own words the process of gene expression (DNA → RNA → proteins)
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INVESTIGATION 2: DMD
17. Using the simulation, test different types and numbers of mutations in the DMD gene. Record your results in the table
below.
Type of
mutation
Number of
Mutations
Number of Changed Amino Acids
in Protein
Results (functional protein- yes
or no?)
MAKING SENSE: 18. What happens when DNA is mutated? Be sure to link DNA to proteins in your answer.
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PART 5: Mutations Background Information
Mutations are changes in the DNA of an organism. These mutations can be harmful, helpful or neutral (not having any
impact on the organism at all.) There are three types of mutations-insertion, deletion and substitution. Substitution mutations occur when a single base pair is substituted for the correct base. For example, if a section of DNA
is ATTCG, the mutated strand could be ATTGG. Insertion mutations occur when one or more base pairs is added (inserted) to a DNA sequence. For example, if a section
of DNA is ATTCG, the mutated strand could be ATATCG. Deletion mutations occur when one or more base pairs are omitted from a DNA sequence. For example, if a section of
DNA is ATTCG, the mutated strand could be ATCG. Mutations can happen for several reasons. A. DNA fails to copy accurately. Most of the mutations that we think of are "naturally-occurring." For example,
when a cell divides, it makes a copy of its DNA — and sometimes the copy is not quite perfect. That small difference
from the original DNA sequence is a mutation.
B. Mutations can be caused by environmental factors such as Ultraviolet Radiation (UV), X-rays and smoking
tobacco. Examples of diseases caused by environmental factors resulting in mutations would be skin and lung cancer.
C. A mutation can be inherited if it exists in a sperm or egg cell. Examples of common inherited mutations cause
Cystic Fibrosis, Huntington's and Hemophilia.
19. Summarize what you learned from the reading to answer the question- What causes mutations?
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CONCLUSIONS: 20. For people with Duchenne’s muscular dystrophy, how must their DNA be different from a person who does not have
DMD? Justify your answer with observations from this simulation.
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21. How does the structural change of the DMD protein affect its function?
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What did we learn / figure out in this packet sequence?
What new research questions can we ask, to continue to help us better discover and
figure out DMD?
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Below is our INITIAL CLASS MODEL we created.
Can we add anything new, or edit anything to improve it?? Show below!