SBI3U
Module 3b: Gene Expression
Student Learning Goals
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
I can describe what the central dogma of genetics is
I can describe what the information in DNA is used for
I can describe why DNA is encased in the nucleus and doesn’t leave
I can describe the form in which genetic information leaves the nucleus
I can describe the role of ER and golgi in gene expression
I can describe what a codon is and its role in gene expression
I can describe what redundancy in the genetic code is and how it acts to protect the
integrity of genetic information
I can name and describe the purposes of the various types of RNA
I can describe similarities and differences between DNA and RNA
I can list and describe the various steps of protein synthesis
I can describe the role each of the following have in protein synthesis:
 RNA Polymerase
Promoter
 DNA
RNA Nucleotides (U, A, G, C)
 Terminator Sequence
7-methyl guanosine triphosphate (cap)
 Poly-A-Polymerase
Tail
 Intron
Exon
 Spliceosomes
Ribosomes
 tRNA
mRNA
 rRNA
Anticodon
 Codon
Start codon
 A site
P site
 Amino acid
Stop codon
I can describe how the directionality of DNA and RNA is used during transcription
and translation
I can translate and transcribe a sequence of DNA
I can describe the experimental procedures used by Garrod, Beadle, Tatum and
Ingram as well as their contributions to genetics
I can describe how a series of genes can control a metabolic pathway and what
happens to that pathway when one or several of those genes mutate
I can describe how prokaryotes and eukaryotes differ in terms of their usage of
introns and exons
I can describe the unique characteristics that the promoter region has versus the
other portions of a gene
I can list the anticodons for a gene
I can list and describe all the “omes”
I can describe the process by which non-coding DNA controls coding DNA
U I can describe the biotechnological applications that have resulted from a greater
understanding of non-coding DNA’s role inside the cell
V I can describe reasons why DNA expression must be controlled
W I can describe the mechanisms of the trp operon and lac operon as well the ways in
which they differ
X I can model the process of gene expression (protein synthesis) and the mechanisms
of the trp/lac operons
Y I can describe the forms of gene regulation
Z I can describe what a mutation is and how they are created
AA I can list, describe and identify the various types of mutations
Expected Assessments
 Test
 Quizzes
 Poster

Work to Be Done
1. Do the following to get an understanding of protein synthesis and gene expression:
1.1. Watch the first wiki video for “Protein Synthesis: Overall Process” and answer
the following questions:
1.1.1. How is the process represented in the video machine-like?
1.1.2. What are the 2 general phases of protein synthesis?
1.1.3. What is accomplished in the first phase?
1.1.4. What is accomplished in the second phase?
1.2. Watch the second and third videos for “Protein Synthesis: Overall Process”
with the handout “Overview of Transcription and Translation” in front of you.
1.3. Read pg. 237-241
1.4. Take down or read the notes “Central Dogma”, “Genetic Code”, and “RNA”
and watch the fourth video for “Protein Synthesis: Overall Process”
1.5. Answer the following questions using the above work:
1.5.1. What is the central dogma of genetics?
1.5.2. Why is DNA stored in the nucleus and not allowed to leave?
1.5.3. What is information in DNA used for?
1.5.4. In what form is genetic information able to leave the nucleus safely?
1.5.5. What purpose do the ER and golgi have in gene expression?
1.5.6. What is a codon?
1.5.7. Your note says that there is redundancy in the genetic code? Provide a
specific example of this using the codon chart on pg. 240.
1.5.8. What amino acid is coded by the start codon?
1.5.9. How do the 3 forms of RNA differ in terms of their purpose?
1.5.10. How does RNA and DNA differ?
1.5.11. Q10-11, 13 on pg. 241.
Watch the 1st wiki video for “Transcription”
Read pg. 242-244.
Watch the 2nd wiki video for “Trancription”
Read or take down the note “Protein Synthesis”
Watch the 3rd wiki video for “Transciption”
Use the handout “Transcription Flow Chart Key Words” and pg. 242-244 to
create a flow chart that describes step-by-step how an mRNA transcript is
created inside of the nucleus.
1.12. Watch the remaining 2 videos for “Transcription” with your flow chart in front
of you and check to see if it is correct. The last video, in particular, will help
you visualize the ways in which the mRNA is modified once it is created.
Answer the following questions:
1.12.1. What is unique about the chemical characteristics of the promoter
compared to other parts of a gene? What might be the advantage of this?
1.12.2. In what direction is the mRNA constructed?
1.12.3. What part of the gene does not get copied when making the mRNA?
1.12.4. What stops transcription of the gene?
1.12.5. What is the difference between an intron and exon?
1.12.6. How do prokaryotes and eukaryotes differ with respect to introns/exons?
1.12.7. What happens to a protein if the introns are not removed from the mRNA
transcript?
1.13. Watch the 1st wiki video for “Translation”
1.14. Read pg. 250-253
1.15. Watch the 2nd wiki video for “Translation”
1.16. Use the handout “Translation Flow Chart Key Words” and pg. 250-253 to
create a flow chart that describes step-by-step how the information in an mRNA
transcript is decoded to produce a protein.
1.17. Watch the 3rd and 4th wiki videos for “Translation” and follow along with your
flow to chart to see if it is accurate. Answer the following questions:
1.17.1. What is the wobble hypothesis? How does it help ensure the integrity of
gene expression?
1.17.2. What are the sizes of the two ribosome pieces that clamp down on the
mRNA?
1.17.3. In which direction is the mRNA read by ribosomes?
1.17.4. Why is the P site of a ribosome given the designation “P”?
1.17.5. Why is the A site of a ribosome given the designation “A”?
1.17.6. Is tRNA single-stranded or double-stranded? What intermolecular force
holds it in its cloverleaf shape? What causes it to have hairpin turns at
three ends?
1.17.7. What ensures the correct amino acid is placed in the correct position of the
growing polypeptide as it is being built?
1.17.8. List all the possible anticodons for the amino acid ‘phe’ using the codon
chart on pg. 240.
1.6.
1.7.
1.8.
1.9.
1.10.
1.11.
1.18. Do the handouts “Synthesis of a Protein: A Simulation Activity” and
“Additional Lab Exercise: Amino Acid Sequence in a Protein.” Check your
answers with the completed copies on the wiki once you are done.
2. Do the following to get an understanding of how genes control metabolic pathways:
2.1. Read pg. 234-236 and answer the following questions.
2.1.1. Based on figures 2-4, what would you define a metabolic pathway as?
2.1.2. List one example of a metabolic pathway that we have studied this year.
2.1.3. What is the relationship between genetic information found in genes and
biochemical pathways?
2.1.4. Look at “Garrod’s Hypothesis” and describe what normally happens to
alkapton in individuals who do not have alkaptonuria.
2.1.5. Describe what happens to alkapton in individuals who do have alkaptonuria.
2.1.6. Why does this occur if a gene is mutated?
2.1.7. What was Garrod’s hypothesis? What did he likely observe that helped him
form this hypothesis?
2.2. Watch the 2nd wiki video for “Scientists Contributions to Genetics: Beadle and
Tatum”
2.3. Use pg. 234-235, the above video and the handout “Beadle and Tatum” to
answer the following questions:
2.3.1. Describe Beadle and Tatum’s experiment.
2.3.2. Look at the handout. If mutant strain 1 is placed on minimal nutrient
medium it won’t grow. What additional nutrient could it be given to ensure
it grows?
2.3.3. Explain why mutant strain 3 won’t grow on minimal nutrient medium but
will grow when also given argino-succinate. Why does citrulline
accumulate in this particular mutant?
2.3.4. What is proven if a mutated strain won’t grow on the minimal medium but
will grow if given an additional amino acid nutrient?
2.3.5. What is the one gene-one enzyme hypothesis?
2.3.6. How did Beadle and Tatum’s experiment support this hypothesis?
2.3.7. Fill in the chart on the handout “Q5 (pg. 236)” to answer this same question.
2.3.8. Answer Q6 on pg. 236.
3. Do the following to get an understanding of non-coding DNA:
3.1. Watch the wiki videos 1-3 for “Non-Coding DNA and Gene Control”
3.2. Read or take down the note “Non-Coding DNA and Gene Control”
3.3. Watch the remaining two video for “Non-Coding DNA and Gene Control” with
the handout “Non-Coding DNA” in your hand so you can follow along with the
steps
3.4. Answer the following questions:
3.4.1. Look at the “omes” from your note. Why do you think the number of
proteins that make up the proteome is much greater than the number of coding
genes in the exome? Does this contradict the “one gene, one protein”
hypothesis that was formulated by Beadle, Tatum, and Ingram?
3.4.2. Based on the videos you watched and the content of the note, should noncoding DNA (introns) be called ‘junk DNA’ or leftovers from evolution?
Why or why not/
3.4.3. Each mRNA made from transcription has a UTR or untranslated region. In
what sense is it “untranslated”?
3.4.4. Overall, what is the purpose of introns or non-coding DNA?
3.4.5. Why are the miR’s referred to a being “micro”?
3.4.6. What part of protein synthesis or gene expression is stopped by the miR’s or
siRNA’s?
3.4.7. In the second step of the process, a miR folds over and forms a short hairpin.
In what other form of RNA have we seen hairpins in the RNA?
3.4.8. Why is the miR also called shRNA or dsRNA once it folds over on itself?
3.4.9. How is the attachment of RISC to the UTR of an mRNA transcript like a
boot that is put on a car by police? Why does the attachment of RISC stop
translation of an mRNA transcript into a protein?
3.4.10. What sort of treatment options have been opened up by the discovery of
interfering RNA?
3.5. Watch the wiki videos for HIV under the heading “Non-Coding DNA and Gene
Control.” Re-read the portion of the note on HIV Therapy. Answer the
following questions:
3.5.1. What role do white blood cell membrane proteins play in an HIV infection?
3.5.2. What would happen to HIV reproduction if those proteins weren’t in white
blood cell membranes?
3.5.3. How can RNA interference be used to potentially treat or cure HIV
infection?
4. Do the following to get an understanding of how gene expression is controlled:
4.1. Watch the wiki videos under the heading “Control of Gene Expression: Gene
Regulation”
4.2. Take down the first 2 portions of the note “Control of Gene Expression” with
the sub-headings “Why control gene expression?” and “Prokaryotes.” Answer
the following questions:
4.2.1. In what ways is the control of gene expression necessary for cell efficiency?
4.2.2. How is it possible that a brain cell and a white blood cell look and function
differently even though they contain the same DNA?
4.3. Watch the 1st wiki video for the “trp Operon”
4.4. Read pg. 256-257 on the trp operon. Answer the following questions:
4.4.1. Based on fig. 2 (pg. 256) and fig. 3 (pg. 257) what are the 3 parts of an
operon?
4.4.2. What is the general purpose of the trp operon?
4.5. Watch the 2nd wiki video for the “trp Operon”
4.6. Read or take down the portion of the note “Control of Gene Expression” that
has the flow chart for the trp operon. Using the above videos, pg. 256-257 and
the flow chart to create a plastercine model that you can use to demonstrate to
your teacher how the trp operon works.
4.7. Watch the 1st wiki video for the “lac operon”
4.8. Read pg. 255-256 on the lac operon. Answer the following question:
4.8.1. What is the general purpose of the lac operon?
4.9. Watch the 2nd wiki video for the “lac operon”
4.10. Read or take down the portion of the note “Control of Gene Expression” that
has the flow chart for the lac operon. Using the above videos, pg. 255-256 and
the flow chart to create a plastercine model that you can use to demonstrate to
your teacher how the lac operon works.
4.11. Read or take down the portion of the note “Control of Gene Expression” that
describes gene expression in eukaryotes.
5. Do the following to get an understanding of mutations:
5.1. Read pg. 259-263.
5.2. Watch the wiki videos for “Mutations”
5.3. Read or take down the note for “Mutations”
5.4. Do the handout “Mutations” using the codon chart on pg. 240 and pg. 259-263.
5.5. Do Q2-3, 6-7 on pg. 263.