Chapter 3: Genetic Bases of Child Development

how many sperm does male ejaculation contain?

300-500 million

how many chromosomes does a gamete (sex cell) contain?

23

meiosis

cell division that results in gametes with 23 chromosomes

mitosis

cell division resulting in exact copies of cells

ectogenesis

fertilization of an egg outside the uterus

in-vitro fertilization

mixing egg and sperm and planting fertilized eggs inside mother

why does in-vitro fertilization result in an increased likelihood of twins or triplets?

because higher chance that more than 1 egg can attach to uterus

autosomes

first 22 pairs of chromosomes

which chromosome determines the sex of the child?

23 (sperm determines the sex)

DNA

molecule made up of chemical components; code for genes

gene

group of nucleotide bases that generate production of biological building blocks

alleles

specific forms of gene

heterozygous

different

homozygous

same

genotype

complete set of genes

phenotype

physical, behavioural, psychological features (all the characteristics we actually see)

dominant gene

chemical instructions are always followed

recessive gene

instructions are ignored when a dominant allele is present but expressed in the presence of another recessive allele

incomplete dominance

aspects of both heterozygous alleles are expressed; no one allele dominates

endogamy

tendency to preferentially mate with people of the same social/cultural group

clinical variation

geographical genetic variation

polygenic inheritance

contribution of many genes to a person's phenotypic expression

monozygotic twins

identical twins; single fertilized egg that splits into two

dizygotic twins

fraternal twins; two separate eggs fertilized by two separate sperm

what are the 3 strong areas of genetic influence?

intelligence, psychopathy, and personality

why are so few disorders associated with dominant alleles?

because if it is dominant then anyone who has an allele for it shows the condition and natural selection wouldn't allow for it (likely wouldn't live long enough)

what is an exception disease that is dominant and is able to persist?

Huntington's disease

why is Huntington's disease able to persist as a dominant allele?

because it isn't expressed until later in the lifespan

abnormal chromosomes

development is disrupted with extra, missing, or damaged chromosomes

which chromosome is effected in down syndrome?

extra 21st chromosome

mainstreaming

educational program to prepare children with developmental disabilities for school

abnormal sex chromosomes

disorders associated with atypical numbers of X and Y chromosomes

reaction range

extent to which full genetic expression can occur based on the limits of the environment

types of nature/nurture relationships

#NAME?

passive gene-environment relation

parents provide early environment for young children; infants are passive because they are not making active choices to control anything (it is all under parents' control)

evocative gene-environment relation

evoking or prompting people to respond in a certain way (taking a more active role in environment because enriched environment is encouraging certain things)

active gene-environment relation

individuals actively seek environments related to their genetic makeup; niche-picking, develops over childhood