Mutation, DNA Repair, and Cancer

A collection of flashcards summarizing key concepts from the lecture on mutation, DNA repair, and cancer.

What is a mutation?

A heritable change in the genetic material, a permanent change in the nucleotide sequence of DNA.

What are the two categories of mutations?

Spontaneous mutations and induced mutations.

What is a base-pair substitution?

A mutation that alters a single nucleotide; it can lead to silent, missense, or nonsense mutations.

What is a frameshift mutation?

A mutation caused by the insertion or deletion of nucleotides that alters the reading frame of codons.

What are chromosomal mutations?

Mutations that affect large segments of DNA and include deletion, duplication, inversion, and translocation.

How do mutations occur?

Mutations can be spontaneous or induced by environmental factors.

What is a mutagen?

A chemical or physical agent that interacts with DNA to cause mutations.

How is a carcinogen different than a mutagen?

All carcinogens are mutagens, but not all mutagens cause cancer; carcinogens specifically lead to cancer.

What are oncogenes?

Genes that, when mutated, have the ability to promote cell division and growth.

What is the function of tumor-suppressor genes?

Genes that inhibit cell division and promote DNA repair; their loss can contribute to cancer.

What role do the Ras and p53 genes play in cancer?

Mutations in Ras can lead to overactive cell growth, while p53 helps regulate the cell cycle and prevent cancerous growth.

What is a point mutation?

A mutation that affects only one or a small number of nucleotides in a gene.

What is a silent mutation?

A base substitution that does not change the amino acid sequence of the resulting protein.

What is a missense mutation?

A mutation that leads to a single amino acid change in the resulting protein.

What is a nonsense mutation?

A mutation that converts an amino acid codon into a stop codon, leading to premature termination of translation.

What is a frameshift effect?

The alteration of the reading frame of codons, leading to different and often nonfunctional proteins.

What is DNA repair?

Mechanisms by which cells recognize and correct damage to DNA.

What is nucleotide excision repair?

A repair mechanism that removes and replaces damaged DNA segments.

What is the significance of transposons in mutations?

Transposons can insert into genes, potentially disrupting gene function and causing mutations.

What types of mutations can lead to genetic diseases?

Mutations that occur in coding sequences, such as deletions, point mutations, and frameshift mutations.

What is the relationship between lifespan and cancer risk?

The longer we live, the more likely we are to accumulate mutations that can lead to cancer.

What are some common causes of induced mutations?

Chemical agents like nicotine, physical agents like UV light, and certain viruses.

How do genetic changes contribute to cancer progression?

An accumulation of mutations in oncogenes and tumor-suppressor genes lead to malignant transformation.