Transcription and Translation in Prokaryotes vs Eukaryotes

What is the primary function of mRNA?

To carry the genetic information from DNA to the ribosome for protein synthesis.

What role does rRNA play in the cell?

It forms part of the structure of ribosomes, which synthesize proteins.

What is the function of tRNA?

To deliver specific amino acids to the ribosome during protein synthesis.

What is the role of miRNA?

To regulate gene expression post-transcriptionally by silencing specific mRNAs.

What is transcription?

The process by which a sequence of DNA nucleotides is copied to RNA.

What is a major difference between prokaryotic and eukaryotic transcription?

Prokaryotes transcribe almost all their DNA, while eukaryotes do not transcribe most of their DNA.

What are the major steps of transcription?

Initiation, Elongation, Termination.

What is the role of RNA polymerase in transcription?

To synthesize RNA based on the DNA template.

What is the difference between the sense and antisense DNA strands?

The antisense strand is the template for RNA synthesis, while the sense strand has the same sequence as the RNA.

What is a polycistronic mRNA?

An mRNA that encodes multiple proteins, common in prokaryotes.

What is the lac operon?

A set of genes in E. coli that are involved in lactose metabolism, regulated together.

What are constitutive enzymes?

Enzymes that are synthesized at a constant rate and are involved in basic cellular functions.

What are inducible enzymes?

Enzymes whose synthesis depends on the cell's needs.

What is the role of sigma factors in prokaryotic transcription?

They enhance the binding of RNA polymerase to specific promoters.

What is the TATA box?

A DNA sequence that indicates where a genetic sequence can be read and decoded.

What is the role of Rho protein in transcription termination?

It helps dissociate the RNA polymerase complex from the DNA.

What are enhancers in eukaryotic transcription?

DNA sequences that significantly increase the effectiveness of promoters.

What is the difference in transcription between prokaryotes and eukaryotes?

Eukaryotes have multiple RNA polymerases and more complex control sequences.

Where does transcription occur in eukaryotic cells?

In the nucleus.

What is post-transcriptional modification?

The process by which RNA is modified after transcription, including capping, polyadenylation, and splicing.

What is the biological importance of post-translational modification of proteins?

It affects protein function, stability, localization, and activity.

What is the significance of transcription frequency?

It varies for different genes and is regulated based on cellular needs.

What is the primary difference in RNA polymerases between prokaryotes and eukaryotes?

Prokaryotes have one enzyme for all RNAs, while eukaryotes have three different enzymes for different classes of RNA.

What is the primary transcript?

The immediate product of transcription.

What modifications occur to RNAs after transcription?

Appending nucleotide sequences to 3' & 5' ends, removal of polynucleotide sequences, and modification of specific nucleotide residues.

What is the function of the Poly(A) tail?

It is a 250 nucleotide sequence added to the 3' end of mRNA for stability and regulation.

What are introns?

Nonexpressed intervening sequences that are excised from pre-mRNAs.

What are exons?

Expressed sequences of mRNA that are spliced together after intron excision.

What is antisense technology?

A method for the treatment of disease, exemplified by EXONDYS 51 (eteplirsen) injection.

What is RNA editing?

A mechanism that promotes diversity from a single transcript and allows tissue-specific control.

What is the role of tRNA in protein synthesis?

tRNA carries amino acids to ribosomes and translates mRNA codons into specific amino acids.

What specifies an amino acid in the genetic code?

A codon, which consists of three consecutive bases.

What are the initiation codons?

AUG (most frequent) and GUG.

What are the stop codons?

UAG, UAA, and UGA.

What is the difference between prokaryotic and eukaryotic ribosomes?

Eukaryotic ribosomes are larger and use Met as the initiating amino acid instead of fMet.

What are the three tRNA binding sites on the ribosome?

A (aminoacyl), P (peptidyl), and E (exit) sites.

What is the process of translation?

The synthesis of proteins from mRNA sequences, proceeding from N-terminus to C-terminus.

What is post-translational processing?

The modifications that proteins undergo after synthesis, including folding and covalent modifications.

What is the role of aminoacyl tRNA synthetases?

Enzymes that attach specific amino acids to their corresponding tRNA.

What is the significance of the degenerate genetic code?

It means that multiple codons can specify the same amino acid.

What is the function of mRNA?

mRNA carries genetic information from DNA to ribosomes for protein synthesis.

What is the role of release factors in translation?

They help terminate translation when the ribosome reaches a stop codon.

What modifications can occur during post-translational processing?

Phosphorylation, glycosylation, lipidation, proteolysis, and ubiquitination.

What is the role of transcription factors in eukaryotic transcription?

They are necessary for RNA polymerase to bind to promoter sequences.

What is the role of the ribosome in protein synthesis?

It serves as the site where mRNA is translated into a polypeptide chain.

What happens to proteins after they are synthesized?

They may undergo modifications to become biologically active.

What are the main differences between DNA and RNA?

RNA is made of ribonucleotides, while DNA is made of deoxyribonucleotides. RNA contains Uracil (U) instead of Thymine (T) found in DNA.

What is the process of transcription?

Transcription is the process by which RNA is synthesized from a DNA template.

What are the key molecules involved in transcription?

Key molecules include RNA polymerase, transcription factors, and nucleotides.

How do the proteins involved in transcription differ from those in DNA replication?

The proteins involved in transcription are specific to RNA synthesis, while those in DNA replication are specific to DNA synthesis.

What modifications occur to transcription products before they become mRNA?

Transcription products undergo capping, polyadenylation, and splicing to become mature mRNA.

What is the role of mRNA in translation?

mRNA serves as the template for synthesizing proteins during translation.

What are the roles of molecular machines in translation?

Molecular machines such as ribosomes, tRNA, and various initiation, elongation, and termination factors facilitate the translation of mRNA into proteins.

What is the sugar component of RNA?

The sugar component of RNA is ribose.

What base pairs with Adenine (A) in RNA?

Uracil (U) pairs with Adenine (A) in RNA.

What is the significance of the differences between DNA and RNA?

The differences in structure and function between DNA and RNA are crucial for their roles in genetic information storage and protein synthesis.

What is the primary function of RNA in relation to DNA?

RNA serves as a template for protein synthesis, transcribing genetic information from DNA.

What is the structure difference between RNA and DNA?

RNA is smaller than DNA and exists as a single strand.

What is transcription?

Transcription is the synthesis of RNA from a DNA template.

Which enzyme facilitates RNA synthesis?

RNA polymerase.

How does RNA polymerase differ from DNA polymerase?

RNA polymerase can initiate RNA synthesis without a primer and is less accurate than DNA polymerase.

What are general transcription factors?

Proteins required for RNA polymerase II to initiate transcription by binding to promoter regions.

What is a promoter in the context of transcription?

A promoter is a DNA sequence near the transcription start point that signals where transcription should begin.

What is the TATA box?

A crucial DNA sequence in eukaryotic promoters that helps initiate transcription.

What is the role of spliceosomes in RNA processing?

Spliceosomes remove introns from pre-mRNA and join exons together.

What is the difference between introns and exons?

Introns are non-coding sequences that are removed, while exons are coding sequences that are expressed.

What is alternative splicing?

A process that allows pre-mRNA to be spliced in different ways to produce diverse proteins from a single gene.

What is the purpose of the 5' cap in mRNA?

The 5' cap protects mRNA from degradation and aids in translation initiation.

What is the 3'-poly-A tail?

A chain of adenine nucleotides added to the 3' end of mRNA that stabilizes it and facilitates its exit from the nucleus.

What is a codon?

A codon is a sequence of three nucleotides in mRNA that specifies an amino acid.

What is the start codon and its significance?

The start codon is AUG, which signals the beginning of translation and codes for methionine.

What role do tRNA molecules play in translation?

tRNA molecules match amino acids to codons in mRNA.

What is the function of aminoacyl-tRNA synthetases, or tRNA charging?

They attach amino acids to their corresponding tRNA molecules.

What are the three binding sites of a ribosome?

A (accepting), P (peptidyl), and E (empty) sites.

What initiates translation?

The initiator tRNA carrying methionine binds to the small subunit of the ribosome.

What is termination in translation?

Termination occurs when a stop codon is reached, and release factors facilitate the release of the polypeptide chain.

What is the role of release factors in translation termination?

Release factors bind to the ribosome at the stop codon and promote the release of the newly synthesized polypeptide.

How does RNA processing affect the final mRNA product?

Covalent modifications and splicing convert pre-mRNA into mature mRNA ready for translation.

What is the significance of proofreading mechanisms in RNA and DNA polymerases?

Both enzymes have mechanisms to correct errors, but RNA polymerase is less accurate than DNA polymerase.

What is the role of gene regulatory proteins in transcription?

They bind to specific DNA sequences to enhance or repress gene expression.

What is the function of chromatin modifying enzymes in transcription?

They alter chromatin structure to facilitate or inhibit access to DNA for transcription.

What is the significance of the consensus sequences at the RNA polymerase II start site?

They help in the binding of transcription factors and RNA polymerase, ensuring accurate transcription initiation.