Lecture 16 - Genetics, epigenetics, brain and behaviour Flashcards
(25 cards)
How is human DNA organised within cells?
DNA is packaged into 46 chromosomes in somatic cells (23 pairs: 22 autosomes and 1 pair of sex chromosomes)
What is a gene?
A gene is a stretch of DNA that encodes a functional molecule, such as a protein or RNA
What are single nucleotide polymorphisms (SNPs)?
SNPs are variations at a single base pair in DNA, occurring approximately once every 300 base pairs
What are copy number variants (CNVs)?
CNVs are larger DNA segments that are duplicated or deleted, leading to variations in the number of copies of a particular gene
What is gene expression?
Gene expression is the process by which information from a gene is used to synthesise functional gene products like proteins
Do all cells express the same genes?
No, while all cells contain the same DNA, gene expression varies by cell type and over time, leads to different functions
How does alternative splicing affect proteins?
Alternative splicing allows a single gene to produce multiple protein variants by rearranging exons during mRNA processing
What percentage of human genes are expressed in the brain?
Approximately 82-84% of human genes are expressed in the brain to some extent
What is epigenetics?
Epigenetics involves heritable changes in gene expression that do not alter the DNA sequence, often through chemical modifications
How do histone modificato=ions influence gene expression?
Chemical modifications like acetylation and methylation of histone proteins can either promote or repress gene expression by altering DNA accessibility
What is DNA methylation?
DNA methylation involves adding a methyl group to DNA, typically suppressing gene expression when ocurring at gene promoters
Are epigenetic changes permanent?
No, epigenetic modifications are dynamic and can be influenced by environmental factors, making them reversible
How can environmental factors affect gene expression?
Factors like diet, stress, toxins, and drugs can lead to epigenetic modifications, altering gene expression patterns
What did Dolinoy et al. (2006) discover about maternal diet and offspring phenotype?
They found that a maternal diet rich i genistein led to increasedDNA methylation at the agouti gene in mice, resulting in offspring with brown coats and reduced obesity risk
Can epigenetic changes be inherited?
Yes, some epigenetic modifications can be passed to offspring, influencing their gene expression and behaviour
How does parental experience affect offspring behaviour in mice?
Studies have shown that parental experiences, like exposure to certain odors paired with shocks, can lead to epigenetic changes in sperm, affecting offspring’s sensitivity to those odors
What is a gene-environment interaction (GXE)?
It’s when the effect of an environmental exposure on behaviour or health is influenced by an individuals genetic makeup
What did Caspi et al. (2003) find regarding the 5-HTT gene and depression?
Individuals with the short allele of the 5-TT gene exhibited more depression symptoms in response to stressful life events compared to those with the long allele
Has the 5-HTT gene-depression link been consistently replicated
Subsequent studies have had mixed results, with some failing to replicate the interaction, suggesting the need for more comprehensive research
What are polygenic risk scores?
They are numerical estimates of an individual’s genetic predisposition to a trait, calculated by summing the effects of multiple genetic variants
Do identical twins have identical epigenetic profiles?
No, while they start with similar epigenetic marks, environmental differences over time can lead to divergent epigenentic patterns
What did Fraga et al. (2005) observe in monozygotic twins?
They found that older twins had more differences in DNA methylation and histone acetylation compared to younger twins, correlating with phrenotypic differences
How do genetics and the environment shape behaviour?
Behaviour is influenced by the interaction of genetic makeup, environmental exposures, and chance effects, all modulated through mechanisms like gene expression and epigenetics
Why is understanding epigenetics important in psychology?
Epigenetics provides insight into how environmental factors can have lasting effects on gene expression, potentially influencing behaviour and mental health across generations
