Gene Expression and Epigenetics Flashcards
What is gene expression?
Gene expression is the process where the genetic code in DNA directs protein synthesis. Some genes are inactive in certain cells, while others are active.
What determines the phenotypic traits of an organism?
Homologous chromosomes carry gene pairs that determine phenotypic traits, with each gene variant called an allele.
How do mutations contribute to genetic diversity?
Mutations create different alleles, leading to genetic variation. This means two organisms may have a similar phenotype but different genotypes.
Can identical genotypes lead to different phenotypes?
Yes, environmental factors such as temperature, sunlight, and diet can influence phenotype despite having the same genotype.
What is epigenetics?
Epigenetics is the study of how the environment influences gene expression without changing the DNA sequence.
What are the two main types of epigenetic modifications?
- DNA Methylation – Addition of methyl groups to cytosine bases, silencing genes.
- Histone Acetylation – Loosening chromatin structure to activate gene expression.
Can epigenetic changes be inherited?
Yes, epigenetic tags can be passed from parents to offspring through sperm and egg cells.
Give an example of how epigenetics affects identical twins.
Identical twins have the same DNA but may develop different physical traits and health conditions due to different environmental exposures.
How is gene expression regulated?
Gene expression is regulated by transcription factors that either activate or repress transcription.
What is the role of transcription factors?
• Activators bind to DNA and increase transcription.
• Repressors bind to DNA and block transcription.
What is the role of the promoter sequence?
The promoter is a region where RNA polymerase binds to initiate transcription.
How does DNA methylation affect gene expression?
Methylation of cytosine bases inhibits RNA polymerase from binding, preventing transcription.
How does histone acetylation influence gene expression?
Acetylation loosens chromatin, making DNA accessible for transcription, whereas deacetylation condenses it, silencing genes.
What happens when histone proteins are methylated?
Methylation can either activate or repress gene expression, depending on the specific histone and number of methyl groups added.
What are some molecules that regulate translation?
- Micro-RNA (miRNA) – Binds to mRNA, preventing translation.
- Small Interfering RNA (siRNA) – Binds to mRNA and promotes degradation.
- Long Non-Coding RNA (lncRNA) – Can inhibit miRNA, allowing translation.
What environmental factors influence gene expression?
• Temperature (e.g., Himalayan rabbit fur changes with temperature)
• Sunlight (e.g., melanin production in humans)
• Diet & Lifestyle (e.g., nutrient intake affects gene regulation)
• Chemical Exposure (e.g., BPA, arsenic, illicit drugs)
• Trauma & Stress (e.g., epigenetic markers inherited from trauma survivors)
How can epigenetic changes contribute to disease?
Changes in methylation patterns can disrupt normal gene regulation, leading to diseases such as cancer, cardiovascular disease, and autoimmune disorders.
How is cancer linked to epigenetics?
Uncontrolled cell division occurs when epigenetic changes silence tumor suppressor genes or activate oncogenes.
What is cell differentiation?
The process where identical cells become specialized in function and structure due to gene regulation.
What are pluripotent and multipotent stem cells?
• Pluripotent – Can develop into any cell type.
• Multipotent – Can develop into only a limited number of cell types.
Why are epigenetic markers important in differentiation?
They ensure that once a cell becomes specialized, it remains that way through mitosis.
How does epigenetics explain differences in clones?
While clones share identical DNA, environmental influences create epigenetic differences, leading to variation in traits.
How is gene expression controlled in therapeutic cloning?
Scientists manipulate gene expression in stem cells to differentiate them into specific tissue types for medical use.
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