CHAPTER TWO: Genetic Bases of Child Development

Question 1

Genotype

Answer 1

Individuals particular set of genes, inherited from each parent

Question 2

Phenotype

Answer 2

directly observable characteristics, which represent the combined effects of their genotype and environmental influences
- physical, behavioural and psychological features

Question 3

chromosomes

Answer 3

thread-like structures in the nucleus contain genetic material
- most cells have 46
-have 23 pairs of chromosones
(eggs and sperm are gametes)

Question 4

alleles

Answer 4

a specific form of a gene, one variant of the gene

Question 5

dominant vs recessive

Answer 5

Dominant trait: shows up in both cases
Recessive trait: show up when alleles are homozygous only

Question 6

homozygous

Answer 6

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

Question 7

heterozygous

Answer 7

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

Question 8

polygenic traits

Answer 8

• multiply determined traits (intelligence, personality)
• creates spectrum of outcomes

Question 9

heritability

Answer 9

an estimate of the proportion of trait variability in a population that is determined by genetic differences
- ex: heritability of height = 90%

Question 10

twin studies

Answer 10

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

Question 11

adoption studies

Answer 11

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)

Question 12

monozygotic vs dizygotic twins

Answer 12

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)

Question 13

relationship of intelligence scores in twins:

Answer 13

• higher in identical twins
• IQ scores of identical twins raised apart still have strong positive correlation
• genes and environment also play an influence

Question 14

conception method: test tube baby (louise brown 1978)

Answer 14

• Born in England, Brown was the world’s first ‘test-tube baby’
• conceived in laboratory dish

Question 15

in virto fertalization (IVF)

Answer 15

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

Question 16

sex chromosome

Answer 16

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

Question 17

deoxyribonucleic acid (DNA)

Answer 17

biochemical basis of heredity, a molecule made up of 4 nucleotides
- Each chromosome consists of one molecule of DNA

Question 18

gene

Answer 18

a group of nucleotide bases that provide a specific set of biochemical instructions

Question 19

sickle cell trait

Answer 19

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

Question 20

down syndrome

Answer 20

genetic disorder caused by extra 21st chromosome that results in intellectual defect
- extra chromosome usually by egg
- eyes, head, neck, mental and developmental lag

Question 21

Klinefelters syndrome

Answer 21

• XXY
• 1 in 500-1000 male births
• Tall, small testicles, sterile, below normal intelligence, passive

Question 22

Turners Syndrome

Answer 22

X
- 1 in 2500-5000 female births
- short, limited development of secondary sex characteristics, problems
perceiving spatial relations

Question 23

behavioural genetics

Answer 23

branch of genetics that deals with inheritance of behavioural and psychological traits

Question 24

CRISPR (Clustered regularly interspaced short palindromic repeats)

Answer 24

technique used to edit genes
- genetic material to be deleted and replaced by other DNA
- has many ethical issues

Question 25

psychological characteristics affected by heredity

Answer 25

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

Question 26

Phenylketonuria (PKU)

Answer 26

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

Question 27

reaction range

Answer 27

our environment interacts with the genes to determine where in that range we will fall.

Question 28

epigenesis

Answer 28

interplay between genes and multiple levels of the environment (from
cells to culture) that drives development

Question 29

methylation

Answer 29

process by which experience alters expression of DNA, where genetic code is preserved but gene is silenced by methyl molecule

Question 30

niche picking

Answer 30

deliberately seeking environments that fit one’s heredity
- ex. extroverted children seeking out company of other children like themselves