Describe Transcription Process - Biology

What is an intron?

A noncoding RNA segment removed from pre-mRNA. Non-coding sequences removed during RNA processing.
Which base in RNA pairs with adenine ( $A$ ) on the DNA template during transcription?

Uracil ( $U$ ). RNA contains uracil instead of thymine found in DNA.
Which base in RNA pairs with cytosine ( $C$ ) on the DNA template during transcription?

Guanine ( $G$ ). Standard Watson-Crick base pairing rule for transcription.
What is transcription in the context of gene expression and protein synthesis?

Synthesis of RNA from a DNA template by RNA polymerase. First step of gene expression, creating RNA copy of DNA.
What is the role of transcription in protein synthesis?

It produces mRNA that carries coding information to ribosomes. Links DNA genetic code to protein synthesis machinery.
What is the main function of the poly- $A$ tail on eukaryotic mRNA?

Increases mRNA stability and aids nuclear export. Prevents degradation and facilitates nuclear export of mRNA.
Which codon is the typical start codon on mRNA?

AUG. Universal start signal for protein synthesis initiation.
What is the main function of the $5'$ cap on eukaryotic mRNA?

Protects mRNA and helps ribosome binding for translation. Essential for mRNA stability and efficient translation initiation.
Choose the DNA template triplet that would transcribe into mRNA codon $5'\text{-}AUG\text{-}3'$ .

$3'\text{-}TAC\text{-}5'$ . Template strand runs antiparallel to transcribed mRNA.
Which complex performs pre-mRNA splicing in eukaryotes?

The spliceosome. Ribonucleoprotein complex that catalyzes intron removal.
In which direction does RNA polymerase read the DNA template strand?

In the $3'\rightarrow 5'$ direction. Template is read in opposite direction to RNA synthesis.
What is the role of a promoter in transcription?

DNA site where RNA polymerase binds to start transcription. Initiates transcription by providing binding site for polymerase.
Choose the mRNA sequence transcribed from DNA template $3'\text{-}TAC\text{-}5'$ .

$5'\text{-}AUG\text{-}3'$ . RNA sequence complementary to template with $U$ replacing $T$ .
Where does transcription occur in eukaryotic cells?

In the nucleus. Eukaryotic DNA is compartmentalized in nucleus for transcription.
Which molecule binds the promoter first in eukaryotes to help recruit RNA polymerase II?

General transcription factors. Required proteins that assemble at promoter before RNA polymerase.
What happens during transcription termination?

RNA polymerase stops and releases the RNA transcript. Final phase ending transcription and releasing RNA product.
What is RNA processing in eukaryotes?

Modification of pre-mRNA to produce mature mRNA. Post-transcriptional modifications prepare RNA for translation.
What is the function of tRNA in relation to an mRNA transcript?

It matches anticodons to codons and delivers amino acids. Transfer RNA bridges mRNA codons with specific amino acids.
Which DNA strand has the same base sequence as the RNA transcript (except $T$ vs $U$ )?

Coding (non-template) strand. Has identical sequence to RNA except thymine replaces uracil.
How does alternative splicing affect protein synthesis?

It allows one gene to produce multiple protein variants. Increases protein diversity from limited number of genes.
What modification is added to the $5'$ end of eukaryotic pre-mRNA?

A $5'$ cap (modified guanine nucleotide). Protective modification enhancing mRNA stability and function.
What is RNA splicing?

Removal of introns and joining of exons in pre-mRNA. Processing step that removes introns from pre-mRNA.
What happens during transcription elongation?

RNA polymerase adds ribonucleotides to extend the RNA strand. Second phase where RNA chain grows by nucleotide addition.
Which base in RNA pairs with guanine ( $G$ ) on the DNA template during transcription?

Cytosine ( $C$ ). Standard Watson-Crick base pairing rule for transcription.
Identify the correct mRNA base added opposite a DNA template base $G$ .

C. Complementary base pairing during RNA synthesis.
What is the primary product of transcription for a protein-coding gene in prokaryotes?

mRNA. Prokaryotes lack RNA processing, making mature mRNA directly.
What is the template strand of DNA in transcription?

The DNA strand read by RNA polymerase to build complementary RNA. Serves as the blueprint for RNA sequence synthesis.
Which RNA type directly serves as the template for translation?

mRNA. Messenger RNA carries genetic information to translation sites.
Where does transcription occur in prokaryotic cells?

In the cytoplasm (nucleoid region). Prokaryotes lack nucleus, so transcription occurs in cytoplasm.
What is a codon in the context of an mRNA transcript?

A three-nucleotide mRNA sequence that specifies an amino acid or stop. Basic unit of genetic code determining amino acid sequence.
Identify the correct mRNA base added opposite a DNA template base $A$ .

U. RNA uses uracil instead of thymine for adenine pairing.
What is the function of rRNA in relation to an mRNA transcript?

It forms ribosomes and catalyzes peptide bond formation. Ribosomal RNA provides structure and catalytic function for translation.
What is an exon?

A coding RNA segment retained in mature mRNA. Protein-coding sequences that remain in mature mRNA.
What are the three main stages of transcription?

Initiation, elongation, termination. Three sequential phases of the transcription process.
What is alternative splicing?

Producing different mRNAs by joining exons in different combinations. Process creating multiple mRNA variants from single gene.
Which base in RNA pairs with thymine ( $T$ ) on the DNA template during transcription?

Adenine ( $A$ ). Standard Watson-Crick base pairing rule for transcription.
What modification is added to the $3'$ end of eukaryotic pre-mRNA?

A poly- $A$ tail. Adenine nucleotides added to protect and stabilize mRNA.
Which enzyme catalyzes RNA synthesis during transcription?

RNA polymerase. Key enzyme that reads DNA and builds complementary RNA strand.
Which statement best distinguishes transcription from translation?

Transcription makes RNA from DNA; translation makes protein from mRNA. Transcription and translation are distinct molecular processes.
Identify the correct mRNA base added opposite a DNA template base $C$ .

G. Watson-Crick base pairing rules for transcription.
What is the primary product of transcription for a protein-coding gene in eukaryotes?

Pre-mRNA (primary RNA transcript). Eukaryotes produce unprocessed RNA that requires modification.
Which codons function as stop codons on mRNA?

UAA, UAG, UGA. Three codons that signal termination of protein synthesis.
Identify the correct mRNA base added opposite a DNA template base $T$ .

A. Complementary base pairing during transcription process.
What is a transcription terminator (termination signal)?

A DNA sequence that causes transcription to stop. Specific DNA sequence signaling end of transcription.
Which amino acid is specified by the start codon AUG?

Methionine. First amino acid incorporated into all proteins.
Which RNA polymerase transcribes most mRNA genes in eukaryotic cells?

RNA polymerase II. Specific polymerase for protein-coding genes in eukaryotes.
What happens during transcription initiation?

RNA polymerase binds promoter and begins RNA synthesis. First phase establishes transcription machinery at promoter.
In which direction does RNA polymerase synthesize RNA?

In the $5'\rightarrow 3'$ direction. RNA is always synthesized from $5'$ to $3'$ end.
Identify the correct direction for RNA synthesis: $3'\rightarrow 5'$ or $5'\rightarrow 3'$ ?

$5'\rightarrow 3'$ . RNA polymerase always synthesizes RNA in this direction.
Which option best describes how prokaryotes link transcription and translation?

They can occur simultaneously in the cytoplasm. Prokaryotic coupling allows immediate translation of nascent mRNA.

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