BIO 1001 Exam 4

Regions of DNA with tighter nucleosome packing (closed conformation) are less accessible to transcription factors, leading to lower gene expression. Conversely, open conformations allow for more gene expression.

The anticodon of the tRNA that carries tryptophan is 3'-ACC-5'. This sequence is complementary to the tryptophan codon on mRNA (5'-UGG-3').

RNA polymerase reads the template strand of DNA during transcription. This strand is complementary to the coding strand, which has the same sequence as the resulting mRNA (except for thymine replaced by uracil).

The figure shows an active lac operon, indicating high lactose and low glucose levels. The repressor is inactive (not bound to the operator), and the CAP-cAMP complex (activator) is bound to the promoter, promoting transcription of lac genes.

High glucose levels will inactivate the CAP-cAMP complex, thus reducing the expression of the lac operon. This occurs because glucose is the preferred energy source over lactose.

Alternative splicing can result in different mRNA transcripts from the same gene. In the example, the XLM1 gene has an exon included in skin cells but excluded in muscle cells. This means the XLM1 mRNA will be longer in skin cells and shorter in muscle cells. However, the DNA sequence of the gene itself remains unchanged.

The exposed codon in the A-site of the ribosome is 5'-GGA-3'. The anticodon of the tRNA that will bind to this codon is 3'-CCU-5'.

The final polypeptide sequence translated from the mRNA shown is Met-Gly-Pro-Leu-Ser-Gly. This sequence is determined by the order of codons on the mRNA and the corresponding amino acids.

An operon is a cluster of genes under the control of a single promoter. This allows for coordinated expression of these genes, often involved in a specific metabolic pathway.

Chromosomal translocation involves a segment of one chromosome breaking off and attaching to a different chromosome. This can lead to altered gene expression and potentially disease.

The RNA transcript would be 5'-UUACCCG-3'. This is because RNA polymerase uses the template strand to build the complementary mRNA, replacing thymine (T) with uracil (U).

A mutation deleting most of the operator sequence in the lac operon would result in constitutive (constant) expression of the operon, regardless of the presence of lactose. This occurs because the repressor can no longer bind to the operator to block transcription.

Mutations within introns are least likely to impact gene expression because introns are non-coding regions that are removed during splicing. Mutations in promoters, operators, splice sites, or translational regulatory elements are more consequential.

Scenario 1 depicts a repressor molecule engaging in negative control of gene regulation in a prokaryotic cell. The repressor binds to the operator, blocking RNA polymerase and thus inhibiting transcription.

A is a small effector molecule that binds to the activator protein, changing its conformation to allow it to bind to DNA and promote transcription. The activator functions in positive control of gene regulation.

The hypothesis is that proline acts as a small effector molecule, binding to a repressor protein. This binding activates the repressor, allowing it to bind to the operator and block transcription of the proline operon. This is a form of negative feedback regulation.

Mutation #1 is a missense mutation, resulting in a different amino acid being incorporated into the protein. This change can affect the protein's structure and function.

Mutation #2 is a nonsense mutation that introduces a premature stop codon. This results in a shorter protein than the wild type because translation terminates prematurely at the stop codon.

The correct order of eukaryotic transcription events is: III, I, IV. 1. Transcription factors bind to the promoter.2. The 5' cap is added.3. The poly-A tail is added.RNA polymerase II recognizes the start codon is not a step in eukaryotic transcription.

In prokaryotic cells, transcription and translation occur in the cytoplasm, and splicing doesn't happen. Prokaryotes lack a nucleus, so all steps occur in the same compartment.

The input of gene expression is DNA, and the final output is protein.

In eukaryotic cells, the small ribosomal subunit recognizes the 5' cap of the mRNA. It then scans the mRNA until it encounters the start codon, AUG, where translation initiation begins.

The mutation upstream of the VRN4 transcription start site likely affects an enhancer sequence. This sequence regulates gene expression by enhancing RNA polymerase binding and transcription. Deletion would result in reduced mRNA levels and thus lower VRN4 protein production.

A mutated KRAS gene with increased activity is classified as an oncogene. Oncogenes promote uncontrolled cell proliferation, contributing to cancer development.

Adding methyl groups to the core promoter region of a gene is associated with gene silencing, reducing transcription and ultimately protein production.

The mRNA transcript of the DNA strand is 5' AUGAAACAUUAAAUA 3'. This sequence mirrors the coding strand (except for thymine replaced by uracil), and represents the RNA molecule that will be translated.

The polypeptide sequence is Met-Lys-Leu. This is determined by the mRNA sequence and the genetic code.

The loss of the methionine (Met) aminoacyl-tRNA synthetase would prevent translation initiation. This is because tRNAmet must be charged with Met to recognize the start codon AUG, which is essential for initiating protein synthesis.

Ribosomes contain rRNA (ribosomal RNA), tRNA (transfer RNA), and proteins. They do not contain DNA, which is located in the nucleus of eukaryotic cells.

The mRNA transcript would be 5' UAC AUG AGU ACA CCA GCA AUC 3'. The coding strand and the mRNA have the same sequence, except for thymine (T) replaced by uracil (U) in the mRNA.

A nonsense mutation in the 5' end of the gene is most likely to produce the largest change in protein structure and function. This is because it results in premature termination of translation, producing a truncated and likely non-functional protein.

The trp operon is expressed in the absence of tryptophan with an inactive repressor. This means that when tryptophan levels are low, the repressor is unable to bind to the operator, allowing RNA polymerase to transcribe the operon and synthesize tryptophan.

It is possible to determine a person's hair color from the cheek cell DNA. Cheek cells contain the complete genome, including the genes that determine hair color.

When functioning normally, the chocolate tumor suppressor gene would stop the cell cycle when DNA damage is detected. This prevents cells with damaged DNA from replicating, thus reducing cancer risk.

Although polysome-synthesized proteins have the same primary structure, they can differ in length and amino acid sequence. This difference arises from differences in post-translational modifications and polypeptide processing.

Sigma factor plays a crucial role in the initiation of transcription in prokaryotes. It assists RNA polymerase in recognizing and binding to the promoter region on DNA. This process allows proper initiation of transcription of the coding region and terminator.

Stem-loop formation is essential for termination of transcription in prokaryotes. It is also vital for the structure and function of tRNA molecules.

Based on the data provided, the correct order of enzymes in the metabolic pathway is: Enzyme 1, Enzyme 4, Enzyme 3, Enzyme 2. This order is determined by the rescue results with different supplements.

If gene P has a mutation, the cell could be rescued when supplemented with E only. This indicates that Enzyme 2 is responsible for converting D to E.

Chromatin structure, the way DNA is packed in eukaryotic cells, plays a significant role in gene regulation. Prokaryotic DNA is not organized into chromatin, and therefore this factor is absent in prokaryotes.