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Questions and Answers
What distinguishes a germ-line mutation from a somatic mutation?
What distinguishes a germ-line mutation from a somatic mutation?
- Germ-line mutations only occur in non-coding regions.
- Germ-line mutations affect only the tissue in which they occur.
- Germ-line mutations can be passed to offspring, while somatic mutations cannot. (correct)
- Germ-line mutations are more common than somatic mutations.
Which of the following statements about frame shift mutations is true?
Which of the following statements about frame shift mutations is true?
- Frame shift mutations involve the insertion or deletion of one or more nucleotides. (correct)
- Frame shift mutations always occur in coding sequences only.
- Frame shift mutations lead to silent mutations in all cases.
- Frame shift mutations do not affect proteins produced by the gene.
What is the primary consequence of a mutation occurring within a promoter region?
What is the primary consequence of a mutation occurring within a promoter region?
- It has no effect on gene expression.
- It may alter the transcription rate of the associated gene. (correct)
- It will prevent any protein from being produced by the gene.
- It will always lead to a harmful mutation.
Which type of mutation is typically associated with providing variation necessary for natural selection?
Which type of mutation is typically associated with providing variation necessary for natural selection?
In the context of cancer development, which factor is most critical in influencing whether a mutation leads to tumor formation?
In the context of cancer development, which factor is most critical in influencing whether a mutation leads to tumor formation?
Flashcards
Mutation
Mutation
A heritable change in the DNA sequence, essential for evolution. Mutations can be harmful, beneficial, or silent.
Base Substitution
Base Substitution
A type of mutation where one DNA base is replaced with another.
Frame Shift
Frame Shift
A type of mutation where the reading frame of the DNA sequence is altered, changing the amino acid sequence.
Germ-line mutation
Germ-line mutation
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Somatic mutation
Somatic mutation
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Study Notes
Mutation, DNA Repair, Cancer
- Mutations are heritable changes in DNA sequence, fundamental to evolution
- Mutations are sources of variation for natural selection, potentially harmful, beneficial, or silent
- Types of mutations include base substitutions (e.g., changing one nucleotide for another) and frame shifts (shifting the reading frame of the DNA)
- Consequence of point mutations can be silent (no change in polypeptide), missense (changes one amino acid), nonsense (shortens polypeptide) or frameshift (different amino acid sequence)
- Mutations outside coding sequences can alter transcription rate by affecting promoters, potentially enhancing or inhibiting transcription
- Germ-line mutations occur in gametes (sperm or egg) and are heritable; somatic mutations occur in body cells and are not heritable
- Mutations often result from spontaneous errors during DNA replication or exposure to mutagens
- Spontaneous mutations can include errors in DNA replication, reactive metabolic products, changes in nucleotide structure, and transposons
- Induced mutations arise from chemical agents (e.g., benzo(a)pyrene) or physical agents (e.g., UV light, X-rays) that damage DNA
- DNA repair mechanisms exist to detect and correct mutations minimizing damage
- Direct repair corrects incorrect structures directly; base excision and nucleotide excision repair remove abnormal parts of the strand; mismatch repair repairs base pair mismatches
- Cancer is a disease of multicellular organisms characterized by uncontrolled cell division
- Cancers originate from a single cell that mutates and grows abnormally
- A tumor is an overgrowth of cells, potentially benign or malignant
- Oncogenes are mutated genes for cell growth signaling proteins, leading to permanent activation of cell division pathways
- Proto-oncogenes are normal cell division control genes that can become oncogenes if mutated
- Tumor suppressor genes are inhibitors of cell division, preventing uncontrolled proliferation; mutations in these genes can interfere with cell division control leading to cancer
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