Transcription and Translation in Eukaryotic Cells

Questions and Answers

In eukaryotic cells, transcription cannot begin until:

Several transcription factors have bound to the promoter. (correct)

The two DNA strands have completely separated and exposed the promoter.

DNA nucleases have isolated the transcription unit.

The DNA introns are removed from the template.

The 5' caps are removed from the mRNA.

Which of the following is not true of a codon?

It is the basic unit of the genetic code.

It consists of three nucleotides.

It never codes for more than one amino acid.

It may code for the same amino acid as another codon.

It extends from one end of a tRNA molecule. (correct)

The anticodon of a particular tRNA molecule is:

The part of tRNA that bonds to a specific amino acid.

Changeable, depending on the amino acid that attaches to the tRNA.

Complementary to the corresponding triplet in rRNA.

Complementary to the corresponding mRNA codon. (correct)

Catalytic, making the tRNA a ribozyme.

Which of the following is not true of RNA processing?

Exons are cut out before mRNA leaves the nucleus. Signup and view all the answers

Which component is not directly involved in translation?

DNA Signup and view all the answers

Which of the following mutations would be most likely to have a harmful effect on an organism?

A single nucleotide insertion downstream of, and close to, the start of the coding sequence Signup and view all the answers

Study Notes

Transcription in Eukaryotic Cells

Transcription initiation requires several transcription factors to bind to the promoter before RNA polymerase can attach and start transcribing DNA.

Codons

Codons consist of three nucleotides and are fundamental units of the genetic code, determining specific amino acids during protein synthesis.
Multiple codons can code for the same amino acid, highlighting the redundancy in the genetic code.
A codon does not extend from the tRNA molecule, which carries the anticodon.

tRNA and Anticodons

The anticodon of tRNA is complementary to the corresponding mRNA codon, ensuring accurate translation of the genetic code.
This complementary pairing is crucial for the correct incorporation of amino acids during protein synthesis.

RNA Processing

In RNA processing, exons are not cut out; instead, introns are removed while exons are spliced together to form mature mRNA.
Nucleotide modifications, such as the addition of a 5' cap and poly-A tail, occur at both ends of the RNA molecule.
Ribozymes and spliceosomes play critical roles in facilitating RNA splicing.

Components of Translation

Translation involves mRNA, tRNA, ribosomes, and GTP, whereas DNA is not directly involved in the translation process.

Effects of Mutations

A single nucleotide insertion near the start of the coding sequence is most likely to have harmful effects due to potential frameshift mutations that alter the reading frame, affecting protein synthesis.
Other mutations like nucleotide substitutions and deletions may not have as severe consequences, especially if they occur in non-coding regions or have no impact on the protein function.

Description

Explore the intricate processes of transcription and translation in eukaryotic cells. This quiz covers key aspects such as codons, tRNA, and RNA processing, enhancing your understanding of genetic code and protein synthesis. Test your knowledge on these fundamental concepts of molecular biology.