L3: Behavioural Genetics

Lamarck suggested

evolution through use vs disuse

Darwin suggested

evolution through natural selection for survival

Mendelian genetics

how inherible traits are passed down from parents to offspring

dichotomous traits

do not occur in combination - brown vs white seeds

true breeding lines

inherited members always produce offspring with the same trait

alleles

alternate forms of the same gene

homozygous

trait with 2 identical alleles

heterozygous

trait with 2 different alleles

dominant trait

displayed in either the homo or hetero condition

recessive traits

only displayed in homozygous condition

phenotype

observable traits

genotype

genetic makeup

gene

segment of DNA encoding specific proteins

DNA

double helix of nucleotide bases, ATGC - adenine + thymine, guanine + cytosine

histones

spools which DNA winds around

chromatin

package of DNA + histones

chromosome

DNA is further packaged to form

how many chromosomes we have

23 matched pairs, 22 autosomes + 1 sex pair (female XX male XY)

RNA (ribonucleic acid)

created when gene segment of DNA unwinds

transcription

copying genetic information from DNA to RNA

translation

ribosome creating proteins according to MRNA

enhancers/promoters

DNA part determining if structural genes initiate protein synthesis

transcription factors

proteins binding to DNA - influence extent of gene expression

2 types of cell division

mitosis and meiosis

mitosis

chromosomes doubling then splitting

meiosis

creation of gametes with ½ full set of chromosomes

polygenic

single phenotypic trait is controlled by multiple genes

pleiotropic

1 gene influences multiple phenotypic traits

animal studies have found

genes can pass behavioural traits onto next generation but environment is crucial, gxe effect

epigenetics

study of changes in gene expression without changing genetic code

DNA methylation changes with experiences

epigenetic research in humans

PKU - homozygotes lack enzyme

MAOA gene

genome

pre existing genetic risk factors

epigenome

enviornmental triggers

research of intergenerational transmission of memories

cherry blossom smell and electric shock in mice - offspring can be conditioned to be fearful

PTSD + childhood trauma had more epigenetic changes than only PTSD

Epigenetic research on twins

MZ twins get different epigenetic marks throughout lifespan

MZ twins obtain epigenetic marks at higher concordance rate than DZ twins