Topic 8A: Mutations and Gene Expression Flashcards
What is a mutation?
A mutation is a random change in DNA which may result in genetic variants.
What are the different types of mutations?
Mutations can be classified as point mutations (changes in a single base pair):
~insertion (adding bases), ~deletion (removing bases) ~frame-shift mutations (altering the reading frame of the gene).
What is a silent mutation?
A silent mutation is a mutation that does not change the amino acid sequence of a protein, often due to the redundancy of the genetic code.
What is a nonsense mutation?
A type of mutation that changes a codon to a stop codon, resulting in the premature termination of protein synthesis.
How do mutations lead to cancer?
Mutations in specific genes (e.g., proto-oncogenes and tumor suppressor genes) can lead to uncontrolled cell division, causing the formation of tumors and cancer.
What are oncogenes?
Oncogenes are mutated or overexpressed versions of normal genes (proto-oncogenes) that promote cell division, potentially leading to cancer.
What are tumor suppressor genes?
genes that normally regulate cell division and prevent tumor formation. Mutations in these genes can result in the loss of cell cycle control and cancer development.
What is metastasis?
The process by which cancer cells spread from the original (primary) tumor to other parts of the body, forming secondary tumors.
How can mutations affect the cell cycle?
Mutations can disrupt the normal regulation of the cell cycle, leading to uncontrolled cell division and potentially cancerous growth.
How do you interpret cancer data such as tumor growth rates?
often used to assess:
~The aggressiveness of the cancer
~Effectiveness of treatments and prognosis.
~Statistical analyses like survival rates or changes in tumor size over time help in understanding the progression of the disease.
How can genetic screening help in cancer diagnosis?
Genetic screening can identify mutations or genetic predispositions that increase the risk of cancer, allowing for earlier detection and personalised treatment strategies.
What are stem cells?
Stem cells are undifferentiated cells that have the potential to differentiate into various cell types. They play a role in growth, repair, and regeneration of tissues.
What is the difference between embryonic stem cells and adult stem cells?
Embryonic stem cells are pluripotent, meaning they can differentiate into almost any cell type, while adult stem cells are multipotent, meaning they can differentiate into a more limited range of cell types.
What are the potential uses of stem cells in medicine?
Stem cells can be used for regenerative medicine, such as repairing damaged tissues, treating degenerative diseases, and in stem cell therapies for conditions like Parkinson’s disease and spinal cord injury.
How is transcription regulated in eukaryotic cells?
Transcription is regulated through promoters, enhancers, repressors, and transcription factors, which control the binding of RNA polymerase and the initiation of transcription.
What role do transcription factors play in gene expression?
Transcription factors are proteins that bind to specific DNA sequences near the gene to either promote or inhibit transcription, thus regulating gene expression.
How does translation control gene expression?
Translation is controlled by the availability of mRNA, ribosomes, and tRNAs. Post-translational modifications can also affect protein function and activity.
What is epigenetics?
Epigenetics refers to changes in gene expression that do not involve alterations to the underlying DNA sequence, such as DNA methylation and histone modification.
What is DNA methylation and how does it affect gene expression?
DNA methylation involves the addition of methyl groups to DNA, typically at cytosine bases, which can silence gene expression by preventing transcription factors from binding to the DNA.
What are histone modifications and how do they regulate gene expression?
Histone modifications, such as acetylation and methylation, alter the structure of histones, affecting how tightly DNA is wound around them. This can either enhance or repress gene expression by influencing access to the DNA.
How can you evaluate data on phenotypes?
Phenotypic data can be evaluated by analyzing how traits are inherited, understanding environmental influences, and using statistical methods to identify patterns of variation in a population.
What is penetrance in genetics?
Penetrance refers to the proportion of individuals with a particular genotype who exhibit the expected phenotype. It can be influenced by environmental factors, mutations, and genetic interactions.
What is expressivity in genetics?
Expressivity refers to the degree or severity of a phenotype in individuals with the same genotype, which can vary due to genetic, environmental, or epigenetic factors.
Mutation
A change in the DNA sequence that can lead to alterations in the genetic code and potentially affect the organism’s phenotype.
Oncogene
A mutated or overexpressed version of a normal gene that drives cell division and can lead to cancer.
Tumor Suppressor Gene
A gene that normally inhibits cell division and prevents tumor formation, whose mutation can lead to cancer.
Metastasis
The spread of cancer cells from the original tumor to other parts of the body, forming secondary tumors.
Stem Cells
Undifferentiated cells that can differentiate into various specialized cell types and are essential for tissue repair and regeneration.
Epigenetics
The study of changes in gene expression that do not involve changes to the DNA sequence, such as DNA methylation and histone modification.
Transcription Factors
Proteins that regulate gene expression by binding to specific DNA sequences to promote or inhibit transcription.
DNA Methylation
The addition of methyl groups to DNA, typically at cytosine bases, which can silence gene expression.
Histone Modification
The addition or removal of chemical groups to histone proteins that affects chromatin structure and regulates gene expression
Penetrance
The proportion of individuals with a particular genotype who exhibit the expected phenotype.
Expressivity
The degree or severity of a phenotype in individuals with the same genotype, influenced by genetic and environmental factors.
