8!!Eukaryotic Gene Transcription and Translation

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Questions and Answers

What is the primary function of transcription factors in eukaryotic transcription?

They bind to the RNA transcript to prevent degradation.

They catalyze the synthesis of RNA from DNA directly.

They assist in the folding of newly synthesized RNA strands.

They help to regulate gene expression by forming a complex with RNA polymerase II. (correct)

In eukaryotic cells, which of the following accurately describes RNA polymerase II?

It incorporates nucleotides into RNA without the need for a template strand.

It requires a complex of general transcription factors to initiate transcription. (correct)

It is the only type of RNA polymerase present in eukaryotes.

It synthesizes RNA in the 3’-to-5’ direction.

Which component of the eukaryotic transcription initiation complex is specifically responsible for recognizing the core promoter?

TFIE

TFIID (correct)

TFIIF

TFIIA

What direction is RNA synthesized during transcription in eukaryotic cells?

5’-to-3’ direction Signup and view all the answers

Which of the following best describes the role of TFIID in the transcription process?

It initiates the assembly of other transcription factors and RNA polymerase II. Signup and view all the answers

What is the primary role of the core promoter in eukaryotic transcription?

To host the binding site for RNA polymerase and basic transcription machinery Signup and view all the answers

Which of the following statements about the TATA box is correct?

It is the first core promoter motif identified and recognized by TBP Signup and view all the answers

What role does the Downstream Promoter Element (DPE) serve in eukaryotic transcription?

It is involved in the initiation of transcription by RNA polymerase II Signup and view all the answers

Which consensus sequence corresponds to the Initiator Element (INR)?

YYANWYY Signup and view all the answers

Which element is commonly flanked by the B recognition element (BRE) in human promoters?

TATA box Signup and view all the answers

What type of RNA polymerase is responsible for the transcription of all types of RNA in prokaryotes?

Single RNA polymerase Signup and view all the answers

Which transcription factor is essential at the core promoter for the initiation of transcription by RNA polymerase II?

TATA-binding protein (TBP) Signup and view all the answers

Which strand of DNA is used as the template for RNA synthesis?

The 3’-to-5’ strand Signup and view all the answers

What is the primary role of transcription factors in the transcription process?

To regulate gene expression and initiate transcription Signup and view all the answers

How many different RNA polymerases are present in eukaryotic cells?

Three Signup and view all the answers

What is the end product of transcription in eukaryotic cells?

Messenger RNA (mRNA) Signup and view all the answers

Which component is required during translation to synthesize proteins?

Ribosomal RNA (rRNA) Signup and view all the answers

Which of the following correctly distinguishes the sense and antisense strands of DNA?

The sense strand carries the information for RNA synthesis, the antisense strand does not. Signup and view all the answers

What is transcripted by RNA polymerase II during gene transcription?

Complementary RNA from a DNA template Signup and view all the answers

What is replaced in RNA during the process of transcription compared to DNA?

Thymine (T) → Uracil (U) Signup and view all the answers

Which statement correctly describes eukaryotic RNA polymerases?

There are three different RNA polymerases in eukaryotic cells. Signup and view all the answers

What is the role of transcription factors in eukaryotic transcription?

They regulate gene expression and form a pre-initiation complex. Signup and view all the answers

Which component specifically initiates the assembly of other transcription factors and RNA polymerase II?

TFIID Signup and view all the answers

In which direction is RNA synthesized during transcription?

5’-to-3’ direction Signup and view all the answers

What is the function of the TATA-binding protein (TBP) within TFIID?

It recognizes and binds to the promoter region. Signup and view all the answers

What is the approximate length of the promoter region in base pairs?

100–1000 base pairs long Signup and view all the answers

Which of the following elements is primarily recognized by the transcription factor TATA-binding protein?

TATA box Signup and view all the answers

What is the location of the Downstream promoter element (DPE) relative to the transcription start site?

Located about 28–32 nucleotides downstream Signup and view all the answers

Which consensus sequence is associated with the Initiator element (INR)?

YYANWYY Signup and view all the answers

In relation to the transcription start site (TSS), where is the core promoter generally found?

From about -40 to +40 base pairs Signup and view all the answers

Which molecule is required for the synthesis of proteins during translation?

Ribosomal RNA (rRNA) Signup and view all the answers

During transcription, what is replaced in RNA compared to DNA?

Thymine (T) is replaced by Uracil (U) Signup and view all the answers

What initiates transcription by binding to the promoter region of DNA?

RNA polymerase II Signup and view all the answers

What is the starting material required for translation?

Messenger RNA (mRNA) Signup and view all the answers

Which of the following statements accurately describes RNA polymerase in eukaryotic cells?

Eukaryotes possess three distinct RNA polymerases. Signup and view all the answers

What is the role of general transcription factors in the transcription process?

They are necessary for RNA polymerase II to begin transcription. Signup and view all the answers

What does the TFIID complex specifically recognize in the transcription initiation process?

The promoter region of DNA. Signup and view all the answers

Which part of the DNA strand is referred to as the template strand during RNA synthesis?

The strand that is complementary to the RNA produced. Signup and view all the answers

Which of the following best describes the function of transcription factors in eukaryotic cells?

They regulate gene expression and initiate transcription. Signup and view all the answers

Study Notes

Eukaryotic Gene Transcription and Translation

Eukaryotic gene transcription and translation is a complex process occurring in the nucleus and cytoplasm respectively
This involves multiple steps, including DNA transcription into RNA (messenger RNA, mRNA), mRNA processing, and translation of mRNA into protein in the ribosomes

Molecular Mechanisms of Disease

The diagram shows a eukaryotic cell with various organelles including: the nucleus, endoplasmic reticulum (rough and smooth), cytoskeleton, mitochondria, and ribosomes
Components found in the nucleus include chromatin, nuclear pore, nuclear envelope, nucleolus, and glycogen granules
Cytoskeleton components include microtubules, microfilaments, intermediate filaments, and also microvilli, centrosome, and centriole
Other organelles identified in the cell include: plasma membrane, secretory vesicles, lysosome, peroxisome
Flagellum and Cillum are components of the cell

Transcription

Transcription is the synthesis of messenger RNA (mRNA) from a DNA template in the nucleus
Starting materials include DNA as the template, and required machinery such as RNA polymerase II and transcription factors
End product: messenger RNA (mRNA) after processing

Translation

Translation is the synthesis of proteins in the cytoplasm, using information encoded by messenger RNA (mRNA)
Starting materials include mRNA, required machinery such as ribosomal RNA (rRNA), ribosomal proteins, and transfer RNA (tRNAs)
End product: polypeptide

Sense vs Antisense DNA Strands

The coding strand (sense strand) has the same sequence as the mRNA, except thymine is replaced by uracil
The template strand (antisense strand) dictates the sequence of the mRNA during transcription

Transcription - Both Strands Encode Genes

DNA has 3.6 x 10⁴ base pairs
Both DNA strands are transcribed although only one strand serves as a template for the first mRNA sequence being created

Transcription - RNA Polymerase

RNA polymerase binds to DNA, initiates transcription at a promoter region, and incorporates nucleotides into a complementary RNA strand from the template strand
Eukaryotes have three slightly different RNA Polymerases (I, II, III) that handle different types of RNA
- RNA polymerase I is responsible for most ribosomal RNA
- RNA polymerase II is responsible for mRNA transcripts
- RNA polymerase III is involved in producing tRNA and 5S rRNA

Eukaryote Transcription - Core Promoter

The core promoter is the site on DNA where RNA polymerase binds before initiating transcription
Key elements include: -TATA box -Initiator element (INR) -Proximal promoter element -Downstream promoter element (DPE)
These elements are within about 250 base pairs of the transcription start site.

Eukaryote Transcription - Enhancer Regions

These regions can be upstream (up to 50,000 base pairs) or downstream of the start site
Enhancers enhance the rate of transcription by binding transcription factors that interact with the pre-initiation complex of the promoter region of a gene.

Eukaryote Transcription - Pre-Initiation Complex (PIC)

A complex of approximately 100 proteins necessary for transcription of protein-coding genes in eukaryotes
Components include:
- TFIID
- RNA polymerase II
- TFIIB
- TFIIA

Eukaryote Transcription - Elongation

Extension of the RNA transcript using the DNA template by RNA Polymerase II
RNA polymerase incorporates 20-50 nucleotides into the RNA molecule per second
The region of unwound DNA is ~13 bp wide and is called the transcription bubble
During elongation, the transcription bubble moves along the DNA, unwinding and rewinding it as needed, relieved by topoisomerases

Eukaryote Transcription - Termination

In eukaryotes, there is no well-defined sequence for termination
Termination in eukaryotes is often associated with polyadenylation signal sequence (PAS) often appearing as AAUAAA
This region of RNA determines the ultimate length of the mRNA by processing steps, followed by addition of Adenosines at the 3' end -> polyadenylation
The AAUAAA sequence is found well past the end of coding region leading to the poly-A tail

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Description

This quiz focuses on the intricacies of eukaryotic gene transcription and translation, outlining the processes that occur in the nucleus and cytoplasm. Participants will explore key components involved in transcription, mRNA processing, and translation into proteins. Gain a deeper understanding of cellular mechanisms and organelles involved in these fundamental biological processes.