Lecture 4- Genetics, Epigenetics, and Early Life Development Flashcards
Define Genome
1) The complete set of genetic material in organisms
2) all DNA sequences of an organism
Describe the features of DNA
1) Double helix
2) bade of base pairs A-T, G-C
3) nucleotides are the basic units of the DNA
Define gene
specific sequence of nucleotides that codes for a protein
Why are proteins important?
essential for all biological functions like building cells or regulating chemical reactions
What is dominant inheritance?
trait that observable in every generation
What is recessive inheritance?
trait that disappear in one generation, only to reappear in a subsequent one
How many chromosomes do humans have?
46
- autosomes- 22 pairs are same in both male and female
- sex chromosome differs
Define genotype
part of the genetic makeup of an individual which determines their characteristics e.g. eye colour
Define phenotype?
Set of observable characteristics of an individual resulting from the interaction of the genotype with the environment
What is monozygotic twin?
share 100% of DNA
What is a dizygotic twin?
share 50% of the gene
Why do we study twins?
As they share the same environment, comparing their similarities helps separate genetic and environmental factors
Define heritability
the proportion of phenotypic variation that can be explained by genetic variation
What did Polderman et al (2015) find?
1) meta-analysis find a 49% heritability between twins
What is Epigenetics?
- changes that do not alter the DNA sequence but affect how genes are expressed (environmental factors)
- influence of experience on gene expression
What is genetic inheritance?
1) traits inherited through rare DNA mutation
2) selection is slow- takes many generations to adapt to environmental changes
What is the difference in epigenetics compared to genetic inheritance?
1) changes do not alter the DNA sequence
2) changes influenced by environmental factors
- nutrition, stress, toxins
3) Faster adaptation
What does epigenetic change include?
1) DNA methylation
2) Histone modification
3) both regulate gene expression without altering DNA sequence
What is DNA methylation?
1) acts by turning genes off
2) methyl group can attach to DNA segments and decrease the access to these segments
3) Lead to long-term gene silencing
What is developmental plasticity?
one genotype can give rise to a range of different physiological or morphological states in response to various environmental conditions during development
What can modify an individuals Epigenome?
1) Nutritional status
2) Toxins
3) Stress
Define Teratogens
Environmental agents that may cause developmental deviation in the foetus
- drugs
- medication
- Parental health/ emotional state
What are the effects of teratogen?
abnormalities, mental impairments, emotional bond, and socioemotional impairments
What are the effects of maternal smoking during pregnancy?
1) increased hyperactivity
2) conduct disorder
3) Asthma
4) changes in DNA methylation in the placenta, foetal cord and pulmonary function during childhood
What are the effects of maternal alcohol consumption during pregnancy?
1) impaired growth
2) Stillbirth
3) Foetal alcohol spectrum disorder
What are the effects of both smoking and alcohol during pregnancy?
1) changes to DNA methylation in the cord blood of an infant
2) epigenetic changes are critical between prenatal environment and substance abuse risk in adolescence
