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Gene Regulation
How does your body know when
to make proteins?
Unit 5 – Chapter 12-5
Gene Regulation Terms
• RNA polymerase – The enzyme used
to transcribe a gene.
• lac Operon – Section of DNA
containing binding sites for the
promoter, operator, and the lactase
gene.
Gene Regulation Terms
• Lactase – The enzyme used to break
down the sugar in milk
• Lactose – The sugar found in milk
Gene Regulation Terms
• Repressor Protein – Prevents RNA
polymerase from making the mRNA
strand
• Operator – Section of the DNA the
repressor binds to.
• Promoter – Section of the DNA that
RNA polymerase binds to
No Lactose Present:
RNA Polymerase
Repressor protein
• Is lactase made? WHY?
• NO, because the repressor protein is
blocking RNA polymerase from copying
the gene for lactase
With Lactose Present:
• What happens to the repressor when lactose
is present?
• Lactose fits into the active site of the repressor
protein, which causes it to release from the
operator. RNA polymerase can copy the gene.
Lactose present: mRNA is made
mRNA strand that
will be translated to
make Lactase.
No Lactose Present:
RNA Polymerase
Repressor protein
• What will happen after all the lactose is
broken down?
• The repressor protein will grab onto the
operator stopping the production of
lactase.
lac Operon from Dolan DNA
Learning Center
• http://teachercenter.insidecancer.org/p/920
Eukaryote and Prokaryote Gene
Regulation:
Operons generally are not found in
1. ___________
eukaryotes
2. Most eukaryotic genes are controlled
Individually
___________ and have __________
Regulatory
sequences that are much more Complex
______
than those of the lac operon.
Eukaryote and Prokaryote Gene
Regulation:
3. A typical feature in a eukaryotic cell is
the presence of a gene sequence about
30 base pairs long with a sequence of
TATATA
TATAAA This
___________
or ___________.
sequence is found directly before the
RNA Polymerase
starting point for __________________.
This region is known as the TATA
_______
Box
Eukaryote and Prokaryote Gene
Regulation:
4. What does the TATA box do?
•
Helps position the RNA polymerase by
“marking” the spot just before where
transcription will take place.
5. How do enhancer sequences affect gene
regulation?
•
Allow proteins to bind to DNA opening
up tightly packed chromatin so genes
can be copied. Also, some use repressor
proteins to prevent transcription.
Regulation and Development:
1. What are hox genes?
Genes that control
organ and tissue
development in
various parts of the
embryo.
Determines organism’s
basic body plan.
Regulation and Development
2. How important are hox genes?
If they are mixed up, an
animal’s body plan will
be mixed up; In the
wrong order.
Regulation and Development
3. What example does the book give as a
possilbe mutation for Drosophila is the hox
gees are mutated?
Repeat in hox genes: Double
Winged Drosophila
Regulation and Development
Side
4. Hox genes are located _______by
Side in a single cluster, arranged in the
______
Exact order in which they are
_________
expressed in the body.
5. Draw:
Amoeba Sisters
• https://www.youtube.com/watch?v=h_1QL
dtF8d0