Chapter 17 - Transcription, RNA Processing, and Translation

These flashcards cover key concepts of transcription, RNA processing, and translation as outlined in Chapter 17 of the Biological Science textbook.

Transcription

The process of synthesizing RNA from a DNA template.

RNA polymerase

An enzyme that synthesizes RNA by using ribonucleoside triphosphates (NTPs) as substrates.

Template strand

The strand of DNA that is used as a guide for RNA synthesis.

Coding strand

The DNA strand that has the same sequence as the synthesized mRNA, with T replaced by U.

Holoenzyme

A complex of RNA polymerase and sigma factor that initiates transcription.

Promoter

A DNA sequence that signals the start site for RNA synthesis.

Sigma protein

A protein that binds to RNA polymerase to form a holoenzyme and recognizes the promoter.

-10 box

A conserved sequence (TATAAT) in bacterial promoters that plays a role in transcription initiation.

-35 box

A sequence in bacterial promoters (TTGACA) that is recognized by the sigma factor.

Transcription bubble

A localized unwinding of the DNA helix that occurs during transcription.

Elongation

The phase of transcription where RNA polymerase adds nucleotides to the growing RNA strand.

Termination

The process by which RNA polymerase stops transcription and releases the RNA molecule.

Transcription-termination signal

A sequence in DNA that codes for RNA that forms a hairpin structure, triggering termination.

Hairpin structure

A secondary structure in RNA that signals the completion of transcription.

Eukaryotic transcription

The process of RNA synthesis in eukaryotes, which involves multiple RNA polymerases.

General transcription factors

Proteins that assist RNA polymerase in recognizing promoters in eukaryotic transcription.

Poly(A) signal

A sequence in eukaryotic transcription that leads to the addition of a poly(A) tail.

Primary transcript

The initial RNA product synthesized from DNA, which must undergo processing.

RNA processing

The modifications made to the primary transcript to produce a mature mRNA.

Introns

Noncoding sequences in a gene that are removed during RNA processing.

Exons

Coding sequences that remain in the mature mRNA after processing.

Splicing

The process of removing introns from the primary RNA transcript.

Spliceosome

The complex that catalyzes the splicing of introns from pre-mRNA.

snRNPs (small nuclear ribonucleoproteins)

Molecular complexes composed of snRNAs and proteins that play a role in RNA splicing.

Lariat

A loop structure formed during the splicing of introns.

Cap

A modified guanine nucleotide added to the 5' end of mRNA for stability and ribosome binding.

Poly(A) tail

A stretch of adenine nucleotides added to the 3' end of mRNA to protect it from degradation.

Untranslated regions (UTRs)

Segments of mRNA that are not translated into protein, located at the 5' and 3' ends.

Ribonucleoside triphosphates (NTPs)

The building blocks used by RNA polymerase to synthesize RNA.

3' end

The terminal end of an RNA molecule where nucleotides are added during elongation.

RNA processing events

The modifications required to convert the primary RNA transcript into mature mRNA.

5' cap importance

It facilitates binding to ribosomes and protects mRNA from degradation.

RNA polymerase types in eukaryotes

Three distinct types of RNA polymerases: I, II, and III.

Template-directed synthesis

The process by which RNA polymerases synthesize RNA by using a DNA template.

Direction of transcription

Transcription proceeds in the 5' to 3' direction.

Bacterial transcription initiation

Begins when RNA polymerase binds to the promoter with the help of sigma protein.

Transcription termination in bacteria

Occurs when RNA polymerase encounters a termination signal that forms a hairpin.

mRNA

Messenger RNA; the RNA copy of a gene that encodes for a protein.

Eukaryotic versus prokaryotic transcription

Eukaryotic transcription involves additional processing, while prokaryotic is direct.

Transcription location in eukaryotes

Transcription occurs in the nucleus, while translation occurs in the cytoplasm.

RNA processing timeline

Occurs after transcription and before translation in eukaryotic cells.

snRNA

Small nuclear RNA involved in the splicing process.

Transcription factors

Proteins that help induce the transcription of specific genes.

holoenzyme function

To initiate transcription by recognizing promoter sequences.

Transcription mechanism

Involves unwinding DNA, forming a bubble, and synthesizing RNA.

Sigma factor function

Guides RNA polymerase to the correct promoter sequence for initiation.

Promoter recognition

The process where RNA polymerase and sigma interact with specific DNA sequences.

Direction of RNA polymerase movement

Determined by the orientation of the promoter on the DNA.

Transcription bubble components

Includes the template strand of DNA and the newly synthesized RNA.

Process of adding a cap to mRNA

Involves the addition of a guanine nucleotide to the 5' end.

Purpose of the poly(A) tail

To enhance stability and facilitate export from the nucleus.

RNA splicing purpose

To generate multiple mRNA variants from a single gene.

Role of ribonucleoproteins

Assist in the splicing process and form the spliceosome.

Transcription elongation mechanism

RNA polymerase synthesizes RNA in a continuous manner.

Importance of the TATA box

A key element in eukaryotic promoters that assists in transcription initiation.

RNA synthesis process

Includes initiation, elongation, and termination phases.

Eukaryotic mRNA modifications

Include capping, polyadenylation, and splicing.

Key outcome of splicing

Production of a continuous coding sequence in mature mRNA.

Function of the transcription bubble

Facilitates access to the template DNA strand by RNA polymerase.

Lariat structure function

Facilitates the splicing of introns out of the RNA molecule.

Diversity of RNA processing

Allows for alternative splicing and varied protein products.

3’ untranslated region (UTR) role

Containts regulatory elements that influence translation.

Cap structure effect

Increases mRNA stability and assists in ribosome recognition.

RNA polymerase I

Synthesizes rRNA in eukaryotic cells.

RNA polymerase II

Synthesizes mRNA in eukaryotic cells.

RNA polymerase III

Synthesizes tRNA and other small RNAs in eukaryotic cells.

Concept of alternative splicing

The process by which different combinations of exons are joined together.

TATA box functional significance

It helps position RNA polymerase for the start of transcription.

Role of enhancers

Increase transcription levels of associated genes.

Effects of introns on gene expression

Introns can regulate gene expression and alternative splicing.

Transcription factors in eukaryotes

Proteins needed for the binding of RNA polymerase to DNA.

Templates for transcription

Only one strand of DNA serves as a template for RNA synthesis.

Types of nucleotides used in RNA

Are ribonucleoside triphosphates, specifically ATP, CTP, GTP, and UTP.

Significance of 7-methylguanylate cap

Protects mRNA from degradation and is recognized by the ribosome.

The splicing catalyzing structure

Formed by a complex of snRNPs known as spliceosome.

Importance of base-pairing

Ensures the accuracy of nucleotide sequence during transcription.

Polyadenylation function

Aids in the termination of transcription and stability of mRNA.

nucleotide addition during elongation

Nucleotides are continuously added to the growing RNA strand.

Template directionality in transcription

RNA polymerase synthesizes RNA from 5' to 3' end.

Transcription initiation phase

Begins when RNA polymerase binds to a promoter with the help of sigma.

Mechanism of transcription termination

Involves the formation of a hairpin structure to disassociate RNA polymerase.

RNA processing difference in eukaryotes

Initial transcripts require extensive processing before they can be translated.

Understanding of intron/exon relationship

Only exons are present in mature mRNA after splicing.

Formation of mRNA from pre-mRNA

Requires transcription, capping, polyadenylation, and splicing.