1.How many water molecules are lost from the condensation
of 100 amino acids into a polypeptide?
2.Amino acids are connected via __________ bonds, which
occur between the carboxyl group of one amino acid and the
amino group of another.
3 . In how many different ways can the amino acids leucine,
glutamate, and glycine be arranged?
4 .A new drug is developed which selectively cleaves covalent
bonds between two sulfur atoms of non-adjacent amino acids
in a polypeptide chain. Which level of protein structure in
affected molecules would be most directly affected by the
drug?
5.Albumin is a large protein which circulates freely in human plasma. Another
type of protein, called aquaporins, act as a channel for water to enter and exit a
cell, and are located within the lipid bilayer of a cell’s plasma membrane. Based
on their physiological locations, how would the tertiary structure of these two
proteins mostly likely compare?(choose below)
a. Albumin has more of nonpolar core with nonpolar out layer while
aquaporins have a more polar core with polar outer layer.
b. Albumin has more of nonpolar core with polar outer later while
aquaporins have more polar core with nonpolar outer layer.
c. Albumin has more polar core with non polar outer layer while
aquaporins have a more of non polar core with polar outer layer
d. Albumin has more polar core with polar outer layer while aquaporins
have a more of non polar core with non polar outer layer
6.The major protein component of human hair is α-keratin.
Hair ‘straighteners’ are commonly used tools which use heat
to iron hair into temporarily lying flat and straight. What is
the best biological explanation for this phenomenon?(choose below)
a. Hair straitner denatures protein by disrupting the PH
b. Hair straitner disrupt hydrogen bonds in α-keratin
c. Hair stratner disrupt ionic bonds between α-keratin
molecules
d. Hair straitner disrupt disulphide bridges in α-keratin
7.A group of researchers isolate ‘Protein X’ from the wall of a human
stomach with the intent of learning how to synthesize stomach tissue
in the lab. Subsequently, they determine the exact sequence of amino
acids of the protein in its unfolded state, and create a functional
mRNA template to translate Protein X in vitro. They manage to
translate an exact copy of the polypeptide chain in the lab, but then
realize that it takes several days for the protein to fold into its final
tertiary structure. In vivo, they observe that several thousand copies
of Protein X are folded from polypeptide chains every minute. What
is NOT a plausible explanation for this difference in folding times?(choose below)
a. The in vitro study lacks key enzymes
b. The temperature in vitro is too low
c. The in vitro study lacks key tRNA molecule
d. The in vitro PH is too high
8.A certain genetic disorder prevents the production of
signalling molecules which direct the intracellular trafficking
of proteins. If the disease exclusively affects the signal which
directs proteins to the proteasome, what primary effect
would most likely be observed?(choose below).
a. Increased synthesis of proteins
b. Decreased degradation of proteins
c. Increased degradation of proteins
d. Decreased synthesis of proteins
9 .If the Golgi apparatus were damaged by an ingested toxin,
what aspect of protein synthesis would be most affected?(choose below)
a. Translation
b. Beta sheet formation
c. Protein glycosylation
d. Alpha helix formation
10 . A nonsense mutation has occurred in the DNA segment
which codes for “protein A”. After it has been transcribed and
translated, what is the most likely product formed from this
mutated region?(Choose below).
a. A small, truncated, nonfunctional “protein A”
b. A product that differs in only a single amino acid from
“protein A”
c. A product that differs in only a single base pair from “protein
A”, but with entirely different amino acids
d. A normally shaped, fully functional “protein A”
10 .Outline factors which does not affect pKa
value of an amino
acid
11. The following piece of double stranded DNA encodes a very
short peptide. In the space below, write the sequence of
mRNA that would be synthesized by RNA polymerase from
this piece of DNA if the bottom strand is the template. Then
write the protein sequence in one-letter code that would be
synthesized by the ribosome from that mRNA using the first
reading frame (use Genetic Code Table below).
i. 5’-ATGGCTGGGTGCTTTTAA-3’
ii. 3’ –TACCGACCCACGAAAATT-5
1. 99 water molecules would be lost from the condensation of 100 amino acids into a polypeptide.
2. Amino acids are connected via peptide bonds, which occur between the carboxyl group of one amino acid and the amino group of another.
3. The amino acids leucine, glutamate, and glycine can be arranged in 6 different ways (LLL, LLG, LGL, GLG, GLL, GGL).
4. The tertiary structure of affected molecules would be most directly affected by the drug.
5. b. Albumin has more of a nonpolar core with a polar outer layer while aquaporins have a more polar core with a nonpolar outer layer.
6. d. Hair straighteners disrupt disulphide bridges in α-keratin.
7. c. The in vitro study lacks key tRNA molecule.
8. b. Decreased degradation of proteins.
9. c. Protein glycosylation would be most affected.
10. a. A small, truncated, nonfunctional "protein A" would most likely be formed from the mutated region.
11. i. 5'-AUGGCUGGGUGCUUUUAA-3' ii. Met-Leu-Gly-Cys-Phe.
If DNA cannot leave the nucleus how can it get the instructions out to make the protein needed to survive?
DNA is transcribed into messenger RNA (mRNA) in the nucleus through a process called transcription. The mRNA molecule then carries the genetic information from the DNA out of the nucleus and into the cytoplasm of the cell. There, the mRNA molecule is used as a template to synthesize a protein through a process called translation, which occurs on ribosomes in the cytoplasm. In summary, the information encoded in the DNA is transcribed into mRNA in the nucleus and then translated into a protein in the cytoplasm.
1. In the condensation of 100 amino acids into a polypeptide, 99 water molecules would be lost. This is because each peptide bond formation involves the removal of one water molecule.
2. Amino acids are connected via peptide bonds, which occur between the carboxyl group (-COOH) of one amino acid and the amino group (-NH2) of another.
3. The amino acids leucine, glutamate, and glycine can be arranged in 6 different ways. This can be calculated by finding the permutations of these 3 amino acids, which is 3 factorial (3!) = 3 x 2 x 1 = 6.
4. The drug that selectively cleaves covalent bonds between two sulfur atoms of non-adjacent amino acids in a polypeptide chain would most directly affect the tertiary structure of the affected molecules. Tertiary structure is defined by the overall folding and three-dimensional arrangement of the polypeptide chain.
5. The tertiary structures of albumin and aquaporins would likely differ based on their physiological locations. Albumin, being a freely circulating protein in plasma, is primarily hydrophobic (nonpolar) in the core with a hydrophilic (polar) outer layer. On the other hand, aquaporins, which act as water channels within the lipid bilayer of the plasma membrane, have a hydrophilic (polar) core and a hydrophobic (nonpolar) outer layer. Therefore, the correct answer would be option b: Albumin has more of a nonpolar core with a polar outer layer, while aquaporins have a more polar core with a nonpolar outer layer.
6. The best biological explanation for hair straighteners temporarily straightening hair is that they disrupt the disulfide bridges in α-keratin. Disulfide bridges are covalent bonds formed between sulfur atoms in different cysteine residues of α-keratin. By applying heat, the hair straightener breaks these disulfide bonds, allowing the protein structure of α-keratin in hair to be temporarily altered, resulting in straightening.
7. The most plausible explanation for the difference in folding times between in vitro and in vivo synthesis of Protein X is that the in vitro study lacks key chaperone proteins or enzymes that assist in the proper folding of proteins. Chaperone proteins help facilitate protein folding and prevent misfolding or aggregation. Therefore, option a is the correct answer.
8. If the disease exclusively affects the signal that directs proteins to the proteasome, the primary effect would most likely be decreased degradation of proteins. Proteasomes are responsible for degrading proteins that are marked for destruction. If the signaling molecules directing proteins to the proteasome are affected, then there would be a decrease in the targeting and degradation of proteins.
9. If the Golgi apparatus were damaged by an ingested toxin, the aspect of protein synthesis that would be most affected is protein glycosylation. The Golgi apparatus is responsible for modifying and sorting proteins, including the addition of carbohydrate chains in the process known as glycosylation.
10. A nonsense mutation in the DNA segment that codes for "protein A" would most likely result in the synthesis of a small, truncated, nonfunctional "protein A". A nonsense mutation introduces a premature stop codon in the DNA sequence, resulting in the termination of translation before a full-length functional protein can be synthesized.
11. Based on the given DNA sequence (bottom strand as the template), the corresponding mRNA sequence would be: 5'-AUGGCUGGGUGCUUUUAA-3'. Using the genetic code table, the protein sequence synthesized from this mRNA in the first reading frame would be: Methionine-Glycine-Trp-Leu-Phe.