CHAPTER TWO: Genetic Bases of Child Development Flashcards
Genotype
Individuals particular set of genes, inherited from each parent
Phenotype
directly observable characteristics, which represent the combined effects of their genotype and environmental influences
- physical, behavioural and psychological features
chromosomes
thread-like structures in the nucleus contain genetic material
- most cells have 46
-have 23 pairs of chromosones
(eggs and sperm are gametes)
alleles
a specific form of a gene, one variant of the gene
dominant vs recessive
Dominant trait: shows up in both cases
Recessive trait: show up when alleles are homozygous only
homozygous
conditions in which the alleles in the pair of chromosomes are the
same - (BB or bb)
- If the alleles from both parents are alike, their child is homozygous for that trait
heterozygous
conditions in which the alleles in the pair of chromosomes are
different (Bb)
- if a child receives a different allele from each parent, they are heterozygous for that trait
polygenic traits
- multiply determined traits (intelligence, personality)
- creates spectrum of outcomes
heritability
an estimate of the proportion of trait variability in a population that is determined by genetic differences
- ex: heritability of height = 90%
twin studies
a researcher might compare sets of identical twins raised in the same family with fraternal twins raised in the same family
- flaw is that parents and others may treat identical twins more similarly than they treat fraternal
adoption studies
determine if adopted children are more similar on certain traits to their adoptive parents and siblings (with whom they share an environment) or their birth parents and siblings (with whom they share genes)
monozygotic vs dizygotic twins
monozygotic twin: identical twins; single fertilized eggs split in two ( 100% genetic relatedness)
dizygotic twins – fraternal twins; two eggs fertilized at the same time by two separate sperm ( 50% genetic relatedness)
relationship of intelligence scores in twins:
- higher in identical twins
- IQ scores of identical twins raised apart still have strong positive correlation
- genes and environment also play an influence
conception method: test tube baby (louise brown 1978)
- Born in England, Brown was the world’s first ‘test-tube baby’
- conceived in laboratory dish
in virto fertalization (IVF)
technique of fertilizing eggs by mixing sperm and egg
together in a laboratory dish and then placing a few of these fertilized eggs in the
mother’s uterus
- sperm and eggs usually from parents but sometimes a donor
- expensive procedure
sex chromosome
the 23rd pair; determines sex of the child
- Egg always carries X chromosome, and sperm carries an X or Y
o XX = female
o XY = male
deoxyribonucleic acid (DNA)
biochemical basis of heredity, a molecule made up of 4 nucleotides
- Each chromosome consists of one molecule of DNA
gene
a group of nucleotide bases that provide a specific set of biochemical instructions
sickle cell trait
a disorder in which individuals show signs of mild anemia only
when seriously deprived of oxygen
- incomplete dominance can affect red blood cells
- when an individual has both dominant and recessive
down syndrome
genetic disorder caused by extra 21st chromosome that results in intellectual defect
- extra chromosome usually by egg
- eyes, head, neck, mental and developmental lag
Klinefelters syndrome
- XXY
- 1 in 500-1000 male births
- Tall, small testicles, sterile, below normal intelligence, passive
Turners Syndrome
X
- 1 in 2500-5000 female births
- short, limited development of secondary sex characteristics, problems
perceiving spatial relations
behavioural genetics
branch of genetics that deals with inheritance of behavioural and psychological traits
CRISPR (Clustered regularly interspaced short palindromic repeats)
technique used to edit genes
- genetic material to be deleted and replaced by other DNA
- has many ethical issues
psychological characteristics affected by heredity
number of letter sounds that children knew
- correlation 0.68 for identical twins and 0.53 for fraternal twins
· measure of ability to resist temptation
o correlation 0.38 identical twins and 0.16 for fraternal twins
· aggressive play with peers
o correlation of 0.55 identical twins and 0.16 fraternal twins
· identical twins are more alike than fraternal twins
Phenylketonuria (PKU)
occurs only when children inherit a particular recessive
gene on chromosome 12 from both parents
- lack enzyme that breaks down phenylalanine (amino acid)
- leads to delayed mental development
reaction range
our environment interacts with the genes to determine where in that range we will fall.
epigenesis
interplay between genes and multiple levels of the environment (from
cells to culture) that drives development
methylation
process by which experience alters expression of DNA, where genetic code is preserved but gene is silenced by methyl molecule
niche picking
deliberately seeking environments that fit one’s heredity
- ex. extroverted children seeking out company of other children like themselves
