HONORS BIOLOGY 2A
Online Investigation: Molecular Genetics
Purpose: To investigate the relation of form and function regarding the principal aspects of the central
dogma: replication, transcription and translation. In addition, we will investigate the specific influence of
mutation on form and functional relationships regarding enzymes and genetic disease. Answer the
following questions in order in your lab notebook, using complete sentences and specific detail.
Section One: The Central Dogma
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Open the link to the University of Utah Genetics Site and take the Virtual Tour of The Basics as
a review of DNA, mitosis, proteins and inheritance. View the sections up through “What Is A
Protein”
Direct Link: http://gslc.genetics.utah.edu/units/basics/tour/
1.
Based upon what you have seen in these segments, what does the central dogma say about
the relationship of proteins, genes and DNA?
2.
How would you explain the disease of sickle cell anemia in terms of the molecular genetics
of hemoglobin proteins?
Next open the link to The Washington Post: Library of Life and answer the following question:
Direct Link: http://www.washingtonpost.com/wp-srv/health/images/genes/genome.htm
3.
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Why are there two sets of chromosomes in each cell if all the “instructions” are encoded on
one set? How does this contribute to the variety of expressed proteins within our species?
Open the following link to learn about the relationship between the central dogma and stem
cells. Direct Link: http://learn.genetics.utah.edu/content/tech/stemcells/sctypes/
Within this section, click on the activities “What is a stem cell niche?” and “Blood Cell Niche”
4.
Based upon your knowledge of DNA, transcription and translation, why can stem cells be
differentiated into any type of cell in the body?
5.
What is the relationship between niche cells, stem cells and the process known as
differentiation?
6.
Explain the steps involved in the transformation of a stem cell into a red blood corpuscle.
Include the actions of the niche cells and the genetic basis of this transformation
Section Two: Gene Composition
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Open the link to Nova Online: Cracking The Code and answer the following questions about the
different parts of genes:
Direct Link: http://www.pbs.org/wgbh/nova/genome/expl_01_onoff.html
7.
Why is a promoter region (i.e. on/off switch) necessary in complex eukaryotic organisms?
8.
The human genome is comprised of at least 3.2 billion nucleotides. The genome of
Drosophila melogaster, the common fruit fly, contains a mere 182 million nucleotides.
Nevertheless, scientists claim that we share 61% genetic similarity to fruit flies. How does
the concept of introns within genes explain this similarity (in light of such apparent
difference)?
9.
How does the concept of Ancient code exemplify the theme of continuity within change?
10. How does the concept of single nucleotide polymorphisms (SNP’s) explain the theme of unity
within diversity?
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Open the link below to learn about exon splicing.
Direct Link: http://bcs.whfreeman.com/thelifewire/content/chp14/1402001.html
In the past, the central dogma of biology stated that every gene coded for one specific protein.
There are 250,000+ proteins present in Homo sapiens, a collection of proteins called the
proteome. Currently, the Human Genome Project suggests that there are only 19,599 proteincoding genes.
11. What does the information above seem to suggest about the relationship between genes
and proteins? How might this be explained with the concept of exon splicing?
12. What is the relationship between snRNPs, spliceosomes and pre-mRNA?
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Open the link below to practice the translation of the edited mRNA transcript into a protein
Direct Link: http://learn.genetics.utah.edu/content/begin/dna/transcribe/
13. Write out the completed sequence of translated amino acids for this section
14. How does the variety of stop codons compare with the variety of start codons?
Section Three: Causes of Mutation
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Return to the link from The Washington Post: Library of Life and access the section entitled
“amino acids” question:
Direct Link: http://www.washingtonpost.com/wp-srv/health/images/genes/genome.htm
15. What is the fundamental difference between a point mutation and a frameshift mutation?
16. Why don’t point mutations in the third position of the codon always cause a change in the
amino acid sequence? Reference the matrix from the previous link to answer this question.
17. Usually, a frameshift mutation has a greater impact on the protein. However, how might a
point mutation in the promoter region (go back to the NOVA link from section two if you
don’t remember the function of a promoter) have an equally significant impact on the
expression of a gene?
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Open the following link and answer questions about the genetic basis of disease.
Direct Link: http://learn.genetics.utah.edu/content/begin/dna/neurofibromin/
Access the “Test Neurofibromin Activity” link. Combine the different forms of neurofibromin
with the RAS protein and observe the rate of cell division.
18. What is the role of the RAS protein in the cell?
19. Compare and contrast the different mutant forms of neurofibromin with the rates of cell
division?
20. Why do the results above suggest difficulty in finding a definitive cure for all individuals
afflicted with neurofibromatosis?