Download Before you begin this in-class project, you will need the following

Before you begin this in-class project, you will need the following items which can be found
at your local dollar store/craft store:
 Pipe cleaners
 Colored plastic beads
Transcription and Translation Project
http://learn.genetics.utah.edu/
Transcription is a process in which genes, or segments of DNA which encode for mRNA and
ultimately a protein, are “turned on.” When this process of gene activation occurs, the
segment of double-stranded DNA containing the gene is unwound and “opened.” A protein
named RNA Polymerase II begins transcribing the DNA when it finds a start transcription
sequence, or TATAA box. Transcribe the gene below using the bottom strand as the template
strand.
(A in DNA  U in mRNA, C in DNA  G in mRNA, G in DNA C in mRNA, T in DNA  A in mRNA)
Before the mRNA exits the nucleus, 3 post-transcriptional modifications occur:
1. Introns (intragenic sequences) are spliced out of the mRNA
2. On the 5’ end of the mRNA, a 5’-methyl-guanosine cap is added
3. On the 3’ end of the mRNA, a poly-A tail is added
mRNAs are exported out of the nucleus and dock at the ribosomes that lie along the Rough
Endoplasmic Reticulum (RER) and are freely floating in the cytoplasm. The two subunits of the
ribosome clamp onto the end of the mRNA and begin scanning mRNA for a start translation
site, or AUG site
mRNA is translated into amino acids when read in groups of 3 nucleotides, or codons (see
universal codon chart in your book or on-line). Stop sequences are also encoded by either an
UGA, UAA, or an UAG. When a stop codon is encountered, the ribosome complex
disassociates and the polypeptide sequence is complete. The polypeptide then is folded into a
protein (Lodish, 2007).
Nucleus
DNA
5’ A T A T T C A T T A T G C C C A A A G G G T T T T A G C C 3’ Non-template
3’ T A T A A G T A A T A C G G G T T T C C C A A A A T C G G 5’ Template
Transcription
mRNA: 5’ ________________________________________________________3’
Translation
Protein : Amino-_______________________________________________________________________-COOH
Ribosomes
mRNA
Mutations are changes in the DNA sequence. Sometimes, the mutation leads to a change in
the resultant polypeptide sequence and sometimes it doesn’t. Some common mutations are:
a single nucleotide being converted into a wrong nucleotide, deletions of 1 or many
nucleotides, or insertions of 1 or many nucleotides.
For codon information, search for codon chart.
DELETION:
DNA
T deleted
ΔT
5’ A T A T T C A T T A T G C C C A A A G G G T T T
A G C C 3’
Non-template
3’ T A T A A G T A A T A C G G G T T T C C C A A A
T C G G 5’
Template
mRNA: 5’
3’
Protein: Amino-
- COOH
INSERTION:
DNA
T inserted
5’ A T A T T C A T T A T G C C C T A A A G G G T T T T A G C C 3’
Non-template
3’ T A T A A G T A A T A C G G G A T T T C C C A A A A T C G G 5’
Template
mRNA: 5’
3’
Protein: Amino-
-COOH
Below is a representation of the col1A gene  the α-helical protein found in NORMAL
COLLAGEN 1A protein.
Transcribe and translate its sequence:
DNA
5’ ATG GAA GGG AGT AAA GGC TAT GAC ACA GGT CGT TCG GGC GAT TAC GGG CGC TGA 3’ Non-temp.
3’ TAC CTT CCC TCA TTT CCG ATA CTG TGT CCA GCA AGC CCG CTA ATG CCC GCG ACT 5’ Template
mRNA: 5’
Protein: Amino-
3’
-COOH
Using colored beads and pipe cleaners, demonstrate the primary sequence of the COLLAGEN
1A sequence determined above. Use the legend below to determine which colored bead
represents which amino acid. Then, based upon your understanding of ionic interactions
(negatives and positives are attracted to each other), conform your primary sequence into its
appropriate secondary alpha-helical structure on to your pipe cleaner.
YELLOW BEADS = NON-POLAR, HYDROPHOBIC: Gly, Ala, Val, Leu, Ile, Pro, Phe, Tyr, Trp
GREEN BEADS = POLAR, UNCHARGED: Met, Ser, Thr, Cys, Asp, Glu
BLUE BEADS = POSITIVELY CHARGED: Lys, Arg, His
RED BEADS = NEGATIVELY CHARGED: Asp, Glu
Below is a representation of the col2A gene  the α-helical protein found in NORMAL
COLLAGEN 2A protein.
Transcribe and translate its sequence and conform the resultant primary sequence on to your pipe cleaner:
DNA
5’ ATG CGA GGG AGT GAG GGC ACG AAG GGA CAA GAG GGT CAC AGG GGG AGC GAA ATG 3’
3’ TAC GC T CCC TCA CTC CCG TGC TTC CCT GTT CTC CCA GTG TCC CCC TCG CTT TAC 5’ Template
mRNA: 5’
Protein: Amino-
3’
-COOH
Osteogenesis imperfecta: caused by a loss in or mutations in collagen (genes: col1A, col2A)
this disrupt collagen quaternary structure. It is often referred to as “brittle bone disease” as
individuals with the condition suffer from bones that break very easily. Their bones may also
be quite deformed (http://www.niams.nih.gov/Health_Info/Bone/Osteogenesis_Imperfecta).
Below is a mutated col1A gene  the mutated α-helical protein found in the mutated
COLLAGEN 1A protein associated with some forms of osteogenesis imperfecta.
Transcribe and translate its sequence and conform the resultant primary sequence on to your pipe cleaner:
DNA
5’ ATG GAA GGG AGT AAC
AGC
TTG TCG
TAT GAC ACA GGT CGT TCG GGC GAT TAC GGG CGC TGA 3’ Non-temp.
3’ TAC CTT CCC TCA
ATA CTG TGT CCA GCA AGC CCG CTA ATG CCC GCG ACT 5’ Template
mRNA: 5’
3’
Protein: Amino-
-COOH
* Notice the pattern of the beads has been altered in the mutant. This disrupts the α-helical
structure and impairs function of collagen!
Normal Collagen Quaternary
Structure
Mutated Collagen Quaternary Structure
resulting in Osteogenesis imperfecta
(Figure used from http://www.cell.com/cms/attachment/579430/4340625/gr1.jpg)
Critical Thinking Questions
1. What type of chemical bonds form in between amino acids in the primary structures of all proteins?
2. What type of chemical bonds form in between the negatively charged and positively charged amino acids
in collagen?
3. When the quaternary structure of collagen forms, the triple α-helix, what type of weak interactions
maintain its complex structure between the polar, hydrophilic amino acids between each protein chain?
4. Name and describe all the levels of protein structure that are ultimately affected by the mutation shown
causing osteogenesis imperfecta?
5. Which of these types of chemical interactions are disrupted by heat? By the addition of salt? By the
addition of hydrolases (enzymes that catalyze hydrolysis reactions)?
6. Besides bone, what other types of problems/system issues might someone with osteogenesis imperfecta
experience?