Developmental Psychology – Chapter 3 – Biology and Behavior (pp.91-126)
Nature and Nurture
19th Century, in England, Francis Galton talent runs in families, because very close
relatves of an eminent man were more likely to be high achievers than were less close
relatves
John Stuart Mill Galton´s subjects were similar in eminence because auf environmental
factors (e.g. economic well-being, social status, educaton, etc.)
Gregor Mendel (19th Century) observed distnct paaerns of inheritance in pea plants and
thereby established the modern understanding of how characteristcs are transmiaed from
parent to ofspring
James Watson, Francis Crick, Rosalind Franklin (1950s) much deeper understanding of
how genetc infuences operate through the identicaton of the structure of the DN , the
basic component of heredity transmission
Genome – the complete set of an organism´s genes – has been mapped, of myriad species of
plants and animals (in 2015, genomes have been sequenced of over 250 animal species)
lead to innovatons in gene synthesis a method for producing DN
in 2016 human genome project
Revelatons
Current estmate of 19.000 protein-coding genes, is far fewer than previous
estmates ranging from 35.000-100.000 genes
Most of these genes are possessed by all living things and are devoted in decreasing
order
Development results from the close and contnual interplay of nature and nurture –
genes and experience
Genetc and Environmental Factors
Genotype – the genetc material an individual inherits
Phenotype – the observable expression of the genotype, including both body
characteristcs and behavior
Environment – every aspect of an individual and his/her surroundings other than
genes
1. Parent´s Genotype-Child´s Genotype
This relaton involves the transmission of genetc material – chromosomes and
genes – from parent to ofspring
Chromosomes – molecules of DN that transmit genetc informatonn made up of
twisted strands of DN
, DNA (Deoxyribonucleic acid) – molecules that carry all the biochemical
instructons involved in the formaton and functoning of an organism
These instructons are packaged in genes – sectons of chromosomes that are the
basic unit of heredity in all living things (each gene segment of DN coding for
a speciic protein)
Genes make up only 2% of the human genomen rest is “junk DN ” important in
infuencing transmission by regulatng the actvity of protein-coding genes
Human Heredity
excepton sex cells (gemetes/germ cells) only 23 chromosomes due to cell
division (meiosis)
each chromosome pair carries genes of the same type, sequences of DN that are
relevant to the same traits
Sex Determinatin
sex chromosomes – the chromosomes (X and Y) that determine an individual´s
gender
female 2x X chromosome division of gametes results in all eggs having X
male half X, half Y father determines the sex
a gene on the Y chromosome encodes the protein that triggers the prenatal
formaton of tests by actvatng genes or other chromosomes testosterone
Diversity and Individuality
mutaton – a change in the secton of DN (random, spontaneous errors or caused by
environmental factors)
o if occurring in germ cells origin of many inherited diseases, disorders
o some mutatons provide the basis for evoluton making individuals more
viable
randim assirtment of chromosomes in the formaton of egg and sperm (223 or 8.4
million possible combinatons of chromosomes)
crossing over – the process by which secton of the DN switch from one
chromosome to the othern crossing over promotes variability among individuals
geneti Transmissiin if Disirders
dominant-recessive paaerns
o e.g. sickle cell anemia (recessive gene disorder), both harmful (if exhibitng
efect) and beneicial (if carrier)
polygenic inheritance combinaton of genes lead to heritable traits, such as human
disorders
sex-linked inheritance some single-gene disorders are more common in men,
because women can balance deicits out by having two X chromosomes
chromosomal anomalies errors in germ cell-division, resultng in a zygote having
either more or fewer complement of chromosomes (e.g. Down-syndrome)
gene anomalies e.g. Williams Syndrome (25 genes on chromosome 7)
Regulator-Gene Defects (controlling expression of other genes)
Unidentied genetc basis e.g. dyslexia highly heritable reading disability that
probably stems from a variety of gene-based conditons
2. Child´s Genotype-Child´s Phenotype
Endophenotypes – intermediate phenotypes, including the brain and nervous
systems, that do not involve overt behavior
Gene expressiin: Develipmental ihanges
Nature and Nurture
19th Century, in England, Francis Galton talent runs in families, because very close
relatves of an eminent man were more likely to be high achievers than were less close
relatves
John Stuart Mill Galton´s subjects were similar in eminence because auf environmental
factors (e.g. economic well-being, social status, educaton, etc.)
Gregor Mendel (19th Century) observed distnct paaerns of inheritance in pea plants and
thereby established the modern understanding of how characteristcs are transmiaed from
parent to ofspring
James Watson, Francis Crick, Rosalind Franklin (1950s) much deeper understanding of
how genetc infuences operate through the identicaton of the structure of the DN , the
basic component of heredity transmission
Genome – the complete set of an organism´s genes – has been mapped, of myriad species of
plants and animals (in 2015, genomes have been sequenced of over 250 animal species)
lead to innovatons in gene synthesis a method for producing DN
in 2016 human genome project
Revelatons
Current estmate of 19.000 protein-coding genes, is far fewer than previous
estmates ranging from 35.000-100.000 genes
Most of these genes are possessed by all living things and are devoted in decreasing
order
Development results from the close and contnual interplay of nature and nurture –
genes and experience
Genetc and Environmental Factors
Genotype – the genetc material an individual inherits
Phenotype – the observable expression of the genotype, including both body
characteristcs and behavior
Environment – every aspect of an individual and his/her surroundings other than
genes
1. Parent´s Genotype-Child´s Genotype
This relaton involves the transmission of genetc material – chromosomes and
genes – from parent to ofspring
Chromosomes – molecules of DN that transmit genetc informatonn made up of
twisted strands of DN
, DNA (Deoxyribonucleic acid) – molecules that carry all the biochemical
instructons involved in the formaton and functoning of an organism
These instructons are packaged in genes – sectons of chromosomes that are the
basic unit of heredity in all living things (each gene segment of DN coding for
a speciic protein)
Genes make up only 2% of the human genomen rest is “junk DN ” important in
infuencing transmission by regulatng the actvity of protein-coding genes
Human Heredity
excepton sex cells (gemetes/germ cells) only 23 chromosomes due to cell
division (meiosis)
each chromosome pair carries genes of the same type, sequences of DN that are
relevant to the same traits
Sex Determinatin
sex chromosomes – the chromosomes (X and Y) that determine an individual´s
gender
female 2x X chromosome division of gametes results in all eggs having X
male half X, half Y father determines the sex
a gene on the Y chromosome encodes the protein that triggers the prenatal
formaton of tests by actvatng genes or other chromosomes testosterone
Diversity and Individuality
mutaton – a change in the secton of DN (random, spontaneous errors or caused by
environmental factors)
o if occurring in germ cells origin of many inherited diseases, disorders
o some mutatons provide the basis for evoluton making individuals more
viable
randim assirtment of chromosomes in the formaton of egg and sperm (223 or 8.4
million possible combinatons of chromosomes)
crossing over – the process by which secton of the DN switch from one
chromosome to the othern crossing over promotes variability among individuals
geneti Transmissiin if Disirders
dominant-recessive paaerns
o e.g. sickle cell anemia (recessive gene disorder), both harmful (if exhibitng
efect) and beneicial (if carrier)
polygenic inheritance combinaton of genes lead to heritable traits, such as human
disorders
sex-linked inheritance some single-gene disorders are more common in men,
because women can balance deicits out by having two X chromosomes
chromosomal anomalies errors in germ cell-division, resultng in a zygote having
either more or fewer complement of chromosomes (e.g. Down-syndrome)
gene anomalies e.g. Williams Syndrome (25 genes on chromosome 7)
Regulator-Gene Defects (controlling expression of other genes)
Unidentied genetc basis e.g. dyslexia highly heritable reading disability that
probably stems from a variety of gene-based conditons
2. Child´s Genotype-Child´s Phenotype
Endophenotypes – intermediate phenotypes, including the brain and nervous
systems, that do not involve overt behavior
Gene expressiin: Develipmental ihanges
