Q: Which of the following sequences represents the correct flow of genetic information according to the central dogma?

$$\text{DNA} \rightarrow \text{RNA} \rightarrow \text{Protein}$$

Question 1

Beadle and Tatum’s experiments with Neurospora crassa demonstrated that genes specify the production of specific enzymes. Which of the following best summarizes their findings?

Accepted Answer

Each gene codes for a single enzyme, supporting the one gene–one enzyme hypothesis.

Question 2

Which of the following statements about the central dogma of molecular biology is correct?

Accepted Answer

DNA is transcribed into RNA, which is then translated into protein.

Question 3

In eukaryotic cells, what is the primary function of the 5′ cap and poly-A tail added to pre-mRNA?

Accepted Answer

They facilitate the export of mRNA from the nucleus, protect mRNA from degradation, and help ribosomes attach to the 5′ end.

Question 4

A mutation in the gene encoding Enzyme B in the arginine biosynthesis pathway of Neurospora crassa would most likely result in which phenotype?

Accepted Answer

The mutant can grow only if provided with citrulline or arginine.

Question 5

Which of the following best describes the difference between transcription in prokaryotes and eukaryotes?

Accepted Answer

In prokaryotes, translation can begin before transcription is finished, while in eukaryotes, transcription and translation are separated by the nuclear envelope.

Question 6

Which of the following is true regarding the genetic code?

Accepted Answer

It is redundant, with multiple codons specifying the same amino acid.

Question 7

A point mutation changes a codon from UAU to UAA. What is the most likely consequence of this mutation?

Accepted Answer

A nonsense mutation resulting in premature termination of translation.

Question 8

Which enzyme is responsible for attaching the correct amino acid to its corresponding tRNA molecule?

Accepted Answer

Aminoacyl-tRNA synthetase

Question 9

During translation, which site on the ribosome holds the tRNA carrying the growing polypeptide chain?

Accepted Answer

P site

Question 10

Alternative RNA splicing allows eukaryotic cells to:

Accepted Answer

Produce multiple polypeptides from a single gene by including or excluding different exons.

Question 11

Which of the following best explains why a frameshift mutation is often more damaging than a point mutation?

Accepted Answer

Frameshift mutations change the reading frame, potentially altering every amino acid downstream of the mutation.

Question 12

Which of the following is NOT a function of the spliceosome?

Accepted Answer

Adding the poly-A tail to mRNA

Question 13

A patient is diagnosed with sickle-cell anemia, which is caused by a single nucleotide substitution in the β-globin gene. What type of mutation is this?

Accepted Answer

Missense mutation

Question 14

Which of the following sequences represents the correct flow of genetic information according to the central dogma?

Accepted Answer

$$	ext{DNA} ightarrow 	ext{RNA} ightarrow 	ext{Protein}$$

Question 15

Which of the following best describes the role of ribozymes?

Accepted Answer

They are RNA molecules that function as enzymes, such as in RNA splicing.

Question 16

A mutation changes the codon GAA (which codes for glutamic acid) to GAG (which also codes for glutamic acid). What type of mutation is this?

Accepted Answer

Silent mutation

Question 17

Which of the following is a direct result of RNA processing in eukaryotes?

Accepted Answer

The addition of a 5′ cap and a poly-A tail to the pre-mRNA.

Question 18

Which of the following statements about codons is correct?

Accepted Answer

Each codon specifies either an amino acid or a stop signal during translation.

Question 19

Which of the following best explains why proteins synthesized by bound ribosomes are often secreted from the cell?

Accepted Answer

Bound ribosomes synthesize proteins that enter the endomembrane system, allowing for secretion.

Gene Expression: From Gene to Protein

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