W6: Genetics, epigenetics and development Flashcards
What is a genotype and what is the genotype contained in? (3)
Genotype is the genetic makeup of an individual
It is contained in the 23 pairs of chromosomes
The chromosomes are made up of pairs of alleles (e.g, genetic variants) provided by the parents
Genotype ≠ you example
- Could inherit a gene for blue eyes but brown eyes because brown eyes is a dominant gene
- Carry gene for blue yes but don’t express it
- Have genetics that do not reflect who you are
These epigenetic are: (2)
the influence of enviroment on gene expression
It alters the structure of DNA
What is phenotype? - (2)
- Observable expression of genetics
- e.g., appearance, alcohol tolerance, metabolism
Dominant alleles vs recessive traits (2)
Dominant alleles (e.g brown eyes) override recessive alleles (e.g blue eyes)
Recessive traits only appear when the recessive gene inherited from each parent (need to copies of the recessive allele)
What are chromosomes? (2)
Thread-like structures inside the nucleus of cells
Chromosomes contains genes that are blueprints or instructions for building proteins
Human cells usually contain ___ pairs of chromosomes
23 pairs of chromosomes
22 pairs of chromosomes look
the same in males and females
23rd pair of chromosomes differ
between males and females (X vs Y) - dicates their sex
What is the 23rd pair of chromosomes in males? (sex chromosome)
XY (mismatched pair)
What is sex chromosome in female? (23rd pair of chromosome)
XX - Matched pair
What is epigenetics? (the study of…) -
The study of genetic changes caused by external mechanisms
Epignetics
Genetic change (physiological adaptations) may be due to external mechanisms like… (3)
- Nurtiton
- Stress
- Toxins
These genetic changes (physiological adaptations) are not always (2)
adaptive changes
Epigenetics is often maladaptive
Epigenetics are often involved in various disorders (6)
- Alzheimer’s disease
- Depression
- Schizophrenia
- Multiple sclerosis
- Stress response
- Cancer
Methylation is the process which
Underlies epigenetics
Methylation
What is a methyl group?
Molecules which contain 1 carbon atoms and 3 hydrogen atoms
The methyl group attaches to the DNA segments which are located on the chromosome and serves as
Act as “switches” which activates (ON) or represses gene expression (OF)
Early development - Epigenetics
Sources as to early development having long-impacts on health (3)
Fetal Origins Hypothesis
Developmental plasticity
Early birth weight
Intergenerational transmission
Fetal Origins Hypothesis (3)
- Role of nutrition and malnutrition in healthy fetal development
- Undernutrition during fetal development and infancy changes the body’s structure, physiology, and metabolism
- This may lead to coronary heart disease, stroke, cancer, diabetes and other issues later in adult life
Developmental plasticity (2)
- One genotype can lead to a range of physiological states in response to environments during development
- Epigenetics!
Birthweight is a predictor of heart disease (3)
Decreased chance for heart disease with increased birthweight
This is replicated in Europe, North America, and India
Assumed to be the result of slow fetal growth
Intergenerational transmission (2)
Enduring epigenetic changes transmitted to offspring
Epigenetic changes occurring in the fetus can be passed on to later generations, affecting their descendants
Intergenerational transmission
Examples
Not supposed to be smoking or drinking while pregnant
Intergenerational transmission is that (2)
If you are smoking drinking or doing anything that has toxins that harm your body, this can be passed down to offspring
E.g. nurtiton/stress you have experienced can be passed down
Stress and intergenerational transmission (3)
Offspring of Holocaust survivors at greater risk for the development of PTSD, depression, and anxiety
Women with PTSD from trauma during pregnancy give birth to at-risk offspring
- Third trimester is more sensitive period for these effects
The theory that underlies the epigenetic process
Theory of early epigenetic processes
Theory of early epigenetic process
Early experience of prolonged stress and early life adversities activate the stress hormone system
may program the system toward a lifelong alteration (genetic change) of the hormonal response to minor stressors - since assume stress would reoccur
Theory of early epigenetic processes
Early experience of prolonged stress and early life adversities activate the stress hormone system and may program the system toward a lifelong alteration (genetic change) of the hormonal response to minor stressors
(2)
HPA axis is more sensitive to stressors because of epigenetic changes (methyl group attaching to DNA and changing how HPA axis functions on molecular level)
Greater release of cortisol
- Increased blood pressure
- Likelhood of Heart disease and anxiety
Early environmental experiences have a lasting impact on a child’s later success in school and life generally
Evidence
Vocabulary predictable at 18 months based on family education and income
Adverse living circumstances impair development in first 24-36 months and the greater adversity, the greater the
odds of developmental delay
Risk factors for the development
Maltreated children who are exposed up to 6 adverse experiences face a 90-100% likelihood of having one or more
delays in their cognitive, language, or emotional development (Barth et al., 2008).
Risk factors for the development
Adults who recall having 7 or 8 adverse experiences in childhood are 3 times more likely to have
cardiovascular disease as an adult (Dong et al., 2004)
Physiological adaptations in genes due to epigenetics can be due to (6)
- Nutrition (Environment) - Fetal Origin Hypothesis
- Birthweight predictor of heart disease
- Toxins and intergenerational transmission - pregnancy
- Stress and intergenerational transmission
- Adverse living circumstances
- Maltreated children (environment)
