15. Gene Expression

Steps of Transcription

DNA Transcription Made EASY | Part 2: Elongation

RNA and Transcription

In a particular bacterial species, temperature-sensitive conditional mutations cause expression of a wild-type phenotype at one growth temperature and a mutant phenotype at another—typically higher—temperature. Imagine that when a bacterial cell carrying such a mutation is shifted from low to high growth temperatures, RNA polymerases in the process of elongation complete transcription normally, but no new transcripts can be started. The mutation in this strain most likely affects:
a. the terminator sequence
b. the start codon
c. sigma
d. one of the polypeptides of the core RNA polymerase

Animation: Elongation of the RNA Strand

Cannot proofread using a 3'-to-5' exonuclease activity.

Polymerizes nucleotides in a 5'-to-3' direction.

Which of the following properties is NOT shared by RNA polymerase and DNA polymerase?

The nucleotide shown here is called cordycepin triphosphate. It is a natural product of a fungus that is used in traditional medicines. If cordycepin triphosphate is added to a cell-free transcription reaction, the nucleotide is added onto the growing RNA chain but then no more nucleotides can be added. Examine the structure of cordycepin and explain why it ends transcription. <img class="fr-dib" src="https://lightcat-files.s3.amazonaws.com/problem_images/eb52db8315e15f8d-1677289684312.jpg" style="width: 300px;">

DNA Transcription Made EASY | Part 1: Initiation 🐣

Transcription

Why is it important for plants to exclude certain ions? Summarize the difference between active and passive exclusion mechanisms.

DNA Transcription Made EASY | Part 3: Termination

No. This is where sister chromatids are attached.

No. Introns are removed when mRNA is modified.

No. This is the start codon of translation.

Consider where RNA polymerase attaches.

One strand of a DNA molecule has the following sequence: 3&prime;-AGTACAAACTATCCACCGTC-5&prime;. In order for that strand to be transcribed, there would have to be a specific recognition sequence, called a(n) __________, to the left of the DNA sequence indicated.

Eating even a single death cap mushroom (Amanita phalloides) can be fatal due to a compound called αα-amanitin, a toxin that inhibits transcription.What would you predict to be the immediate outcome of adding αα-amanitin to a cell?
a. reduced DNA synthesis
b. reduced production of one or more types of RNA
c. reduced binding of tRNAs to anticodons
d. reduced rate of translocation of ribosomes translating mRNA

The mRNA detaches from the RNA polymerase as the RNA polymerase leaves the DNA strand.

RNA polymerase attaches to the DNA at the promoter sequence of the gene.

A ribosome attaches to the initiation codon of a completed mRNA strand.

RNA polymerase moves along the template strand of the DNA creating an mRNA strand.

What happens during the initiation step of DNA transcription?

Prokaryotic Transcription Initiation and Elongation

In eukaryotic cells, transcription cannot begin until
a. the two DNA strands have completely separated and exposed the promoter.
b. several transcription factors have bound to the promoter.
c. the 5′ caps are removed from the mRNA.
d. the DNA introns are removed from the template.

3) Termination of Transcription

α-Amanitin inhibits transcription by binding inside an RNA polymerase to a region other than the active site that catalyzes addition of a nucleotide to the RNA chain. Based on the model of RNA polymerase shown in Figure 17.3, predict how the toxin might function to inhibit transcription. <img data-fr-image-pasted="true" class="fr-dib fr-uploading" src="blob:https://admin3.clutchprep.com/345f5af8-63ce-4753-8f81-fb924a31b8dc" style="width: 300px;">

Transcription in eukaryotes requires which of the following molecules in addition to RNA polymerase?

The RNA polymerase enzyme binds to                   , initiating transcription.
a. amino acids;
b. tRNA;
c. the promoter sequence;
d. the ribosome

1) Initiation of Transcription

The RNA polymerase moves along the DNA in the 5' to the 3' direction.

The 3' end of the RNA molecule is produced first.

The RNA polymerase must first bind to a promoter sequence.

Transcription is always initiated at a "start codon".

During transcription of DNA to RNA:

1) Elongation of Transcription

A Level Biology Revision "Transcription"

Why are proton pumps in root-hair plasma membranes important?
a. They pump protons into cells, generating a membrane potential (voltage).
b. They allow toxins to be concentrated in vacuoles, so the toxins do not poison enzymes in the cytoplasm.
c. They set up an electrochemical gradient that makes it possible for roots to absorb cations and anions.
d. They set up the membrane voltage required for action potentials to occur.

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Introduction to Types of RNA

Central Dogma

Genetic Code

Steps of Translation

Introduction to Transcription

Review of Transcription vs. Translation

Introduction to Translation

Mutations

Eukaryotic RNA Processing and Splicing

Post-Translational Modification

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