6 - Genetic influences

Question 1

Central Dogma for genetics

Answer 1

DNA contains code for making proteins. Translated into mRNA which leaves the nucleus. Ribosome reads sequences and assembles amino acids to make protein.

Question 2

Makeup of human genes

Answer 2

Genome with 20-30,000 protein-coding genes. Only 1.5% of DNA encodes proteins (exons), rest is introns, regulation, unknown function, etc.

Question 3

Genetic variability

Answer 3

Genetic polymorphism - occurrence in same population of two or more alleles at one locus. Variability can occur exons, introns, anywhere. Sometimes with functional differences, sometimes with none. May be single nucleotides or larger regions.

Question 4

Epigenetics

Answer 4

Histones and methy markers. Tails on histones affected by surroundings. DNA wraps around helix, making it less readable. Methyl markers affect readability by repressing genes.

Question 5

Epigenetic differences induced by experience

Answer 5

Random and environmental factors (hormones, stress, toxins, lifestyle) lead to altered patterns of epigenetic gene regulation. Twins for example are more epigenetically divergent when old.

Question 6

3 classic behavioral genetic approaches

Answer 6

1. Adoption studies
2. Twin studies, identical or fraternal.
3. Heritability - calculate variance in a trait due to genetic factors as opposed to envrionmental or other.

Question 7

Issues with heritability studies

Answer 7

Misinterprets how genes encode proteins that shape developmental processes but are constantly interacting with the environment. It can make you think that one or the other are not important when they both are.

Question 8

Single genes associated to social behaviors

Answer 8

Aside from genetic/medical disorders like Turner’s syndrome and Fragile X, not really found. Not likely that large variation in a trait can be accounted for by 1 gene. Less power to detect gene-gene interactions. Unreplicable.

Question 9

2 ways to attempt to find single genes related to social behaviors

Answer 9

Bottom-up approaches, Candidate gene approaches.

Question 10

Bottom-up approaches

Answer 10

Collect data and analyze to find relevant patterns. Not starting out with preconceived ideas about which gene is relevant to development

Question 11

Candidate gene approaches

Answer 11

Studies using a priori knowledge of genes that may be important to a specific development pattern. However, not easily replicable really. Hypothesis driven.

Question 12

Gene-gene interactions

Answer 12

Genes interact in netwroks and pathways. Some synergistically and additively, others antagonistically and neutrally.

Question 13

Gene-environment interactions

Answer 13

Association between genotype & phenotype may only hold true in certain environment. Example: monkeys with short allele of 5-HTT gene show problems if they are growing up if they are peer reared. MAOA and violence for examine

Question 14

MAOA

Answer 14

Monoamine oxidase A metabolizes dopamine, norepinephrine, serotonin. One polymorphism has been related to conduct disorder. Violence if child is mistreated. However possible that it cannot be extrapolated between ethnic groups as Maori have a unique haplotype.

Question 15

Meta-analyses

Answer 15

Studies that statistically aggregate and analyze all published findings with respect to an independent variable predicting a dependent.

Question 16

Gene effects on environment experienced

Answer 16

Passive gene-environment association - genes affect caregiver behavior. Active gene-environment association - individuals seek out environments they are predisposed to like. Evocative gene-environment association - children affect the way others react to them.