Question 1

Which type of chemical bond is primarily responsible for the mechanical strength and stability of hair fibers?

Accepted Answer

Disulfide bonds

Question 2

A patient’s DNA sequence for insulin has a mutation that changes the codon GAG to GAA. What type of mutation is this, and what is its likely effect?

Accepted Answer

Silent mutation; no change in amino acid

Question 3

Which of the following treatments is most likely to permanently reshape hair by altering its internal chemical structure?

Accepted Answer

Perming solutions that break and reform disulfide bonds

Question 4

A mutation in the DNA sequence changes the codon UGU (cysteine) to UGA. What is the consequence of this mutation?

Accepted Answer

It introduces a stop codon (nonsense mutation)

Question 5

Which environmental factor is most likely to cause hair to return to its natural curl pattern after heat styling?

Accepted Answer

Humidity and water

Question 6

Given the following DNA sequence: $5'-GTC GGA GCT CTC TAC GTC TGC TGG GGA GGA GGC GGC TGC TAC ACC AGC ACC-3'$, what is the corresponding mRNA sequence?

Accepted Answer

$5'-CAG CCU CGA GAG AUG CAG ACG ACC CCU CCU CCG CCG ACG AUG UGG UCG-3'$

Question 7

Which of the following best explains why hair from individuals of East Asian descent tends to be straighter and thicker compared to hair from individuals of European descent?

Accepted Answer

Differences in the shape and arrangement of disulfide bonds

Question 8

A patient’s insulin protein sequence has a substitution that changes a hydrophobic amino acid to a hydrophilic one. What is the most likely effect on the protein’s tertiary structure?

Accepted Answer

The protein may misfold or lose function due to altered interactions

Question 9

Which of the following DNA mutations would NOT result in a change in the amino acid sequence of the protein?

Accepted Answer

AAGGCCGGAUGGCGGCAAU

Question 10

Which of the following is the correct sequence of events in transcription and translation?

Accepted Answer

DNA unwinding → mRNA synthesis → tRNA brings amino acids → protein synthesis

Question 11

A sickle cell mutation changes the normal hemoglobin DNA sequence from GAG to GTG. What is the effect of this mutation at the protein level?

Accepted Answer

Glutamic acid is replaced by valine

Question 12

Which of the following best describes a frameshift mutation?

Accepted Answer

A mutation caused by insertion or deletion of nucleotides that alters the reading frame

Question 13

Why do perming solutions have a more lasting effect on hair structure than hydrogen bonds?

Accepted Answer

Disulfide bonds are covalent and require chemical treatment to break and reform

Question 14

Which of the following is a real-world consequence of a nonsense mutation in the insulin gene?

Accepted Answer

Insulin protein is truncated and likely nonfunctional

Question 15

A DNA sequence is mutated such that an extra nucleotide is inserted. What is the most likely outcome for the resulting protein?

Accepted Answer

The protein will have a frameshift and likely be nonfunctional

Question 16

Which of the following best explains why hair is more resistant to breakage after treatment with products that repair disulfide bonds?

Accepted Answer

Disulfide bonds are stronger than hydrogen bonds and restore mechanical strength

Question 17

Which of the following codons is a stop codon in mRNA translation?

Accepted Answer

$UAA$

Question 18

A patient’s hair is found to be highly porous after repeated chemical treatments. What is the most likely explanation for this observation?

Accepted Answer

Disulfide bonds have been broken, reducing hair strength

Question 19

Which of the following is the correct order of steps for determining the amino acid sequence from a DNA template strand?

Accepted Answer

Transcribe DNA to mRNA, then translate mRNA to protein

Question 20

Which of the following is a plausible reason why hair from South Asian populations often shows intermediate follicle shapes and curl patterns?

Accepted Answer

Intermediate arrangement of disulfide bonds

Protein Structure, Genetic Mutations, and Hair Texture: General Biology Study Notes

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