Exam 4: Practice Exam Flashcards
(18 cards)
The process of error correction of mismatched bases carried out by DNA polymerases is called proofreading
True
A null mutation is a type of loss of function mutation.
True
Somatic mutations can be inherited.
False
Transposable elements can cause gene mutations.
True
Mismatch repair recognizes the unmethylated strand and repairs it.
True
Mutations that arise in nature, from no particular artificial agent, are called
spontaneous mutations
What term would be applied to a regulatory condition that occurs when protein is associated with a particular section of DNA and greatly reduces transcription?
Negative control
Which of the following is similar among enhancers, silencers, and insulators?
They all can function at larger distances away from a promoter.
Which of the following processes seems to be the most similar between eukaryotic and
prokaryotic genetic regulation?
transcriptional regulation
Which of the following is NOT considered a noncoding RNA?
mRNA
Allolactose can be described as a
inducer
Which of the following distinguishes eukaryotic focused promoters and dispersed promoters?
Focused promoters initiate transcription at a specific site and dispersed promoters allow for transcription to begin at a verity of downstream positions.
What is the difference between nonhomologous end joining (NHEJ) and homology directed repair (HDR)?
NHEJ: NHEJ is an error-prone repair mechanism. In NHEJ, the broken DNA ends are directly ligated together without the need for a template. This process often leads to the introduction of small insertions or deletions (indels) at the site of repair, which can result in mutations.
HDR: HDR, on the other hand, is a high-fidelity repair mechanism. It uses a template, typically a sister chromatid or a homologous chromosome, to guide the repair of the broken DNA strands. This template ensures accurate repair and maintains the original DNA sequence.
If every cell in a multicellular organism contains the same genome, why do different
cells, like muscle, skin, liver, and bone cells, have such different morphology and function?
While every cell in a multicellular organism has the same set of genes, not all genes are active or expressed in every cell. Cell differentiation involves the selective activation and repression of specific genes in response to signals from the cellular environment. This regulation is controlled by transcription factors, which bind to specific DNA sequences and either enhance or inhibit gene transcription. Modifications that are epigenetic like histone modification and DNA methylation play into this.
The following is a diagram of the lac operon in E. coli. Describe two different mutations that would result in maximal synthesis of the lac proteins (β-galactosidase, etc.) even in the absence of allolactose.
-The lac operon has an operator region (lacO) where the lac repressor protein binds to regulate transcription. A constitutive mutation in the lacO operator would result in a change that prevents or weakens the binding of the lac repressor, regardless of the presence of allolactose.
-Constitutive Mutation in the lacI Gene: The lacI gene encodes the lac repressor protein. A constitutive mutation in the lacI gene would result in a change in the repressor protein itself, making it unable to bind to allolactose or the operator.
A. In what type of regulatory system would a co-repressor function?
B. In what type of regulatory system would a co-activator function?
C. Describe a functional similarity between activators and repressors
A) Negative repressible?
B) Positive inducible?
c) Both activators and repressors are proteins involved in gene regulation that bind to the promoter region, either preventing or allowing DNA transcription through RNA Polymerase.
Describe 3 separate examples that demonstrate the role DNA structure plays in gene regulation.
-Chromatin and Histone Modification: The DNA molecule is packaged into a complex structure known as chromatin. Chromatin consists of DNA wrapped around histone proteins. The accessibility of genes within chromatin is influenced by the arrangement and modification of histones.
-DNA Methylation: Methylation makes certain nucleotides less available for transcription.
-Enhancer sequences are regulatory DNA sequences that, when bound by specific proteins called transcription factors, enhance the transcription of an associated gene. They can be located far away from the gene, but because DNA is folded and coiled in the nucleus, the enhancer may actually be located near the transcription start site in the folded state.
Briefly describe the processing of micro RNAs and how they contribute to gene regulation.
-micro RNA gene
-transcription
-nuclease cleavage
-transport to cytoplasm
-dicer cleaves precursor of miRNA
-single strands of miRNA act within RITS
The binding of miRNAs to target mRNAs results in the fine-tuning of gene expression. Multiple miRNAs can target a single mRNA, and a single miRNA can regulate the expression of multiple genes.
