CH 3 Summary Flashcards
gametes are produced through; other cells reproduce through
meiosis; mitosis
when do the sperm’s and egg’s chromosomes merge?
conception
types and amounts of chromosomes in the 46
22 pairs of autosomes; 1 pair of sex chromosomes
each chromosome is a molecule of what
DNA
DNA is made up of _________ _______ organized in a structure that resembles a ________ __________
nucleotide pairs; spiral staircase
2 DNA nucleotide pairs
adenine-thymine and guanine-cytosine
gene
section of DNA that provides biochemical instructions
genotype
all of a person’s genes
phenotype
physical, behavioral and psychological characteristics that develop when the genotype is exposed to a specific environment
alleles
different forms of the same gene
homozygous gene
has the same allele on a pair of chromosomes
heterozygous gene
has different alleles on a pair of chromosomes
incomplete dominance
person is heterozygous for that gene but the phenotype shows a mix b/w the dominant and recessive phenos
polygenic inheritance
phenotype reflects combined activity of many distinct genes
which 2 phenotypes often involve polygenic inheritance
behavioral and psychological
how has polygenic inheritance traditionally been studied?
studying twins and adopted children, and identifying DNA markers
nonshared environmental influences
family environments affect each child in the fam differently
most inherited disorders are carried by _______ alleles
recessive
some inherited disorders
sickle-cell disease, albinism, cystic fibrosis, PKU, Tay-Sachs disease
why are inherited disorders rarely carried by dominant alleles
individuals with these disorders often don’t live long enough to have children (except Huntington’s disease)
what happens to most fertilized eggs that don’t have 46 chromosomes after conception
they’re aborted spontaneously; except for Down syndrome (extra 21st chromosome)
why are disorders of the sex chromosomes more common that autosome disorders
bc sex chromosomes contain less genetic material than autosomes
sex chromosome disorders
Klinefelter’s syndrome, XYY complement, Turner’s syndrome, XXX syndrome
do genes directly affect behavior
no
how do genes indirectly affect behavior
increase the odds that a child will behave in a particular way
the impact of a gene on behavior depends on what
the environment that the genetic instructions are carried out in
passive gene-environment relation
parents pass on genotypes to their kids and provide much of the early environment for their young kids
evocative gene-environment relation
occurs during development as the child’s genotype evokes responses from the environment
active gene-environment relation
common in older children and adolescents because old individuals actively seek environments suited to their genotype
reaction range
extent to which full genetic expression can occur depending on the limits imposed by the environment
what explains that one genotype can lead to different phenotypes
reaction range
