Disorders and defects are often product of recessive alleles.
Phenylketonuria (PKU) is a common defect (1 in 8000).
If both parents have recessive alleles = 1 in 4 children.
PKU is lack of enzymes that neutralizes phenylalanine (proteins) found in:
Chapter 2: Overview
The Birth Experience
The Newborn Infant
Results from the union of two gametes, the egg and the sperm
Gametes produced through specialized cell division, meiosis:
Each has only hal
Genes instruct the production of protein crucial for
DNA can duplicate itself mitosis. This allows a single celled ovum to
become a many-celled adult.
Largely control the continuous switching on and off of genes that
At 32 weeks gestation, the fetus decreases
responses to repeated or continued stimulation, a
simple form of learning called habituation
Newborn infants have been shown to recognize
Newborns also prefer smells, tastes, and
The Family Study
The mainstay of modern behavioral genetics research
A trait of interest is measured among groups of people who vary in
Correlations for traits measured for individuals who
Type of Studies
Males and females just as likely to inherit recessive disorders.
BUT, when harmful allele is carried in the X chromosome, X-linked
Females dominant X suppresses recessive X.
Males more likely affected: their sex ch
Some Environmental Hazards to Fetus or Newborn
Maternal alcoholism can lead to fetal alcohol syndrome (FAS), which is
associated with mental retardation, facial deformity, and other problems
Cigarette smoking during pregnancy is li
The Newborn Infant
Interacting with the Environment
State: The infants level of arousal and engagement in the environment
Ranges from deep sleep to intense activity
Is an important influence in the newborns exploration of the world
Six States of Arousa
Boy or Girl?
Every pair of chromosomes can be distinguished.
22 match (autosomes): Longest = 1, shortest = 22.
The 23rd consists of sex chromosomes (M=XY, F=XX)
Does an X or Y bearing chromosome fertilize the ovum?
A gene on the Y chromosome encodes the p
The Role of Hormones
Hormones play a crucial role in sexual differentiation
All human fetuses can develop either male or female genitalia, depending
on the presence or absence of testosterone
One of the many ways in which the fetus acts as an instigator
Directly observable physical and behavioral characteristics
are phenotypes determined by genes and environment.
The genotype is the genetic makeup of the individual (from
parents and species).
Parents genetic contribution to the childs genotype