Lecture on DNA Mutations and Gene Regulation

These flashcards cover key concepts and definitions related to DNA mutations, gene regulation, and methods like CRISPR used in genetic engineering.

What defines a transition mutation in DNA sequences?

A substitution where one purine is replaced with another purine or one pyrimidine with another pyrimidine.

What type of mutation creates a premature stop codon?

A nonsense mutation that creates a premature stop codon.

What type of mutation alters a codon without changing the amino acid sequence?

A silent mutation where the amino acid remains the same.

Which mutation type occurs more frequently due to involving chemically similar bases?

Transition mutations because they involve chemically similar bases.

What describes a loss-of-function mutation that completely disables a gene?

Amorphic mutation, with complete loss of function.

Which mutations are passed on to offspring?

Germline mutations found in egg or sperm cells.

Which compound can act as a base analog mimicking thymine?

5-Bromouracil, which can mimic thymine in DNA.

What genetic process results in the duplication of chromosomal regions?

Ectopic recombination, involving misaligned chromosomes.

What type of DNA damage is caused by UV light?

Pyrimidine dimers, which create covalent links between bases.

Which class of mobile genetic elements does not contain transposase and relies on reverse transcription?

Class 1 transposable elements, which replicate via RNA.

What is the main difference between missense and nonsense mutations?

A missense mutation changes the amino acid, while a nonsense mutation creates a stop codon.

How can drugs mitigate the effects of a nonsense mutation?

By making the ribosome less sensitive to premature stop codons.

What type of mutation involves insertion or deletion of nucleotides affecting reading frame?

Frameshift mutation, which alters the reading frame.

What type of mutation adds a novel function to a gene?

Neomorphic mutation that adds a novel function.

What is the most common single-nucleotide change in spontaneous mutations?

Deamination of cytosine to uracil.

What is the principal method by which prokaryotic cells regulate gene expression?

By controlling the initiation of transcription.

What region allows activator proteins to enhance transcription?

Enhancer region that interacts with transcription factors.

What type of molecule requires a specific receptor to exert effects on gene expression?

Hormone.

Which mechanism prevents gene transcription during gene silencing?

DNA methylation of cytosine residues.

What is the role of the 5' cap added to mRNA?

Protects the mRNA from degradation by nucleases.

Where do tissue-specific transcription factors bind for gene expression?

Proximal promoter regions near the transcription start site.

Which nitrogenous base is often affected during DNA methylation?

Cytosine, through methylation at CpG sites.

What is the term for one X chromosome in females being randomly inactivated?

Lyonization.

What is the relationship between histone acetylation and gene expression regulation?

Acetylation generally leads to gene activation while methylation leads to repression.

What is associated with the gene expression pattern in the yellow agouti mouse model?

Lower levels of methylated genes, leading to increased gene expression.

Which statement about epigenetic marks in early embryos is true?

Imprinted genes retain epigenetic tags.

Who is responsible for recognizing and cutting the target DNA sequence in CRISPR?

Cas9 protein.

What small DNA sequence is necessary for Cas9 protein binding?

PAM (Protospacer Adjacent Motif).

Which repair mechanism causes small insertions or deletions at a DNA cut site?

Non-homologous end joining.

Why are gene drives designed to bias inheritance?

To ensure the edited gene is passed to most or all offspring.

Which component is NOT necessary in the core CRISPR-Cas9 system?

Green Fluorescent protein.

What is an example of positive eugenics?

Encouraging individuals with desirable traits to have more children.

What is the best definition of human eugenics?

A set of beliefs and practices aimed at improving the genetic quality of a human population.