G-9: Protein Folding = (10 pts.)
G-19: Mutating your protein = (10 pts.)
And, you may use it on a genetics re-test / final exam for G-1 through G-8!
Due: Tues/Weds 5/26-27/15
***Copy the things in bold, and follow the instructions in italics. Do not write the instructions on your paper!***
The function of a protein is ultimately determined by the sequence of bases (Adenine, Thymine, Cytosine, and
Guanine) that make up the “coding strand” of a DNA molecule.
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Describe in 2-3 sentences the process of DNA Replication, including where it occurs and how nucleotides
(A, T, C, G) pair up.
Write out (and label) your coding DNA and template DNA strands for your protein
Describe in 2-3 sentences the process of Transcription, including where it occurs, which DNA strand
(coding or template) is used, and how the DNA nucleotides (A, T, C, G) are paired with the RNA
nucleotides (A, U, C, G)
Write out (and label) your template DNA and RNA strands for your protein
Describe in 2-3 sentences the process of Translation, including where it occurs, & what codons are.
Write out (and label) your RNA strand and the amino acid sequence for your protein. Make sure it’s easy
to see the RNA triplets that correspond to each amino acid, and color code the amino acids.
Color your amino acids based on properties
Summarize what chemical properties each of the colors represent and how they interact (see protein
folding rules). You can skip any colors that you do not actually have in your amino acid sequence.
Describe in detailed sentences how you folded your protein model
The structure (shape) of a protein is what determines its function.
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Explain in complete sentences what kind of protein you have and what its function is (see back).
(optional) Draw or insert a picture of your (color-coded) folded protein (in or near the cell membrane)
Even small changes in the coding DNA could affect the function of a protein!
Some mutations won’t affect the protein at all.
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Give an example of a substitution in the coding DNA causing a silent mutation in your protein
Just show the mutated coding DNA (highlight the change) and the mutated amino acids (color-coded)
Some mutations could cause a protein to stop functioning properly.
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Give an example of a substitution in the coding DNA causing a nonsense mutation in your protein
Just show the mutated coding DNA (highlight the change) and the mutated amino acids (color-coded)
And some mutations might even give a protein an entirely new function!
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Give an example of an insertion or deletion in the coding DNA causing a frameshift mutation in your
protein
Just show the mutated coding DNA (highlight the change) and the mutated amino acids (color-coded)
Types of mutations
Silent
Mutation does not change the amino acid sequence
Nonsense
Mutation changes an amino acid into an early STOP
Frameshift
Insertion or deletion of 1 or 2 nucleotides changes all of the amino acids thereafter by shifting the
“reading frame” for the remaining codons. This shift could also create early or late STOP codons.
Amino acid properties:
(Yellow): Hydrophobic amino acids:
[start], M, A, G, I, L, F, W, Y, V
(Green): Positively charged amino acids:
R, H, K
(Red): Negatively charged amino acids:
D, E
(Blue): Hydrophilic amino acids:
S, T, N, Q, P
(Purple): Amino acids that make disulfide bonds:
C
Protein Folding Rules
1) If you have at least 2 cysteines (C) in your protein, make sure they
are bonded together (use a paperclip)
2) Amino acids with opposite charges (+/-) will attract (they like
being close together), and amino acids with the same charge (+/+ or
-/-) will repel (push away from each other)
3) Charged & hydrophillic amino acids like being in water (either
inside the cell 's cytoplasm or outside of the cell)
4) Hydrophobic amino acids will like being either in the cell
membrane (the middle of the cell membrane is also hydrophobic) or
together, hiding in the middle of the charged & hydrophillic amino
acids so they don't have to touch water.
Protein Function Examples:
(Choose one of the example functions based on the shape of your protein)
Protein fully in the membrane (hydrophobic outside, hydrophilic inside):
Channel (“transport protein”) p.87 or “membrane receptor” (p.84)
Protein attached to the membrane by hydrophobic end, with hydrophilic end sticking out of (or into) the cell.
Receptor (p.84) or cell identity tag (p.82)
Protein floating in the cytoplasm (hydrophobic outside, hydrophilic inside):
Enzyme (p.55), or signal molecule (“ligand” in p.84)
If you need help, see Mr. Warren…
- Wednesday
5/13/15 and 5/27/15
After school in the library
(until 4:30pm)
- Thursday 5/14/15 (Detention!)
After school in B216 (until 4:30pm)
(You don’t need to have a
detention in order to come in for
help, but you can serve one while
you’re at it).
- By appointment
- Via message/e-mail