Chapter 3: Biological Foundations, Prenatal Development, and Birth Flashcards
phenotype
directly observable characteristics that result from one’s genotype
genotype
the complex blend of genetic information that determines our species and influences all our unique characteristics
chromosomes
rodlike structures which store and transmit genetic information
DNA (deoxyribonucleic acid)
structures that compose chromosomes; a long double-stranded molecule that looks like a twisted ladder. Each rung of the ladder consists of a pair of chemical substances called bases.
gene
a segment of DNA along the length of the chromosome
mitosis
The process of cell duplication, in which each new cell receives an exact copy of the original chromosomes
gametes
Sex cells, or sperm and ova, which contain half as many chromosomes as regular body cells.
meiosis
The process of cell division through which gametes are formed and in which the number of chromosomes in each cell is halved.
zygote
The newly fertilized cell formed by the union of sperm and ovum at conception.
crossing over
During meiosis, the exchange of genes between chromosomes next to each other.
autosomes
The 22 matching chromosome pairs in each human cell.
sex chromosomes
The twenty-third pair of chromosomes, called XX in females and XY in males, which determines the sex of the child.
identical (monozygotic) twins
Twins that result when a zygote, during early cell duplication, separates into two clusters of cells with the same genetic makeup. Distinguished from fraternal, or dizygotic, twins.
fraternal (dizygotic) twins
Twins resulting from the release and fertilization
of two ova. Genetically, they are no more alike than ordinary siblings. Distinguished from identical, or monozygotic, twins.
allele
each of two or more of the same gene located at the same place on the chromosomes
homozygous
Having two identical alleles at the same place on a pair of chromosomes. Distinguished from heterozygous.
heterozygous
Having two different alleles at the same place on a pair of chromosomes. Distinguished from homozygous.
dominant–recessive inheritance
A pattern of inheritance in which, under heterozygous conditions, the influence of only one allele is apparent.
carriers
A heterozygous individual who can pass a recessive trait to his or her offspring.
modifier genes
Genes that enhance or dilute the effects of other genes.
incomplete dominance
A pattern of inheritance in which both alleles are expressed in the phenotype, resulting in a combined trait, or one that is intermediate between the two.
x-linked inheritance
A pattern of inheritance in which a recessive gene is carried on the X chromosome, so that males are more likely than females to be affected.
genomic imprinting
A pattern of inheritance in which alleles are imprinted, or chemically marked, in such a way that one pair member is activated, regardless of its makeup.
mutation
A sudden but permanent change in a segment of DNA.
polygenic inheritance
A pattern of inheritance in which many genes deter-
mine a characteristic that varies on a continuum among people.
genetic counseling
A communication process designed to help couples
assess their chances of giving birth to a baby with a hereditary disorder and choose the best course of action in view of risks and family goals.
prenatal diagnostic methods
Medical procedures that permit detection of developmental problems before birth.
amnion
The inner membrane that encloses the prenatal organism in amniotic fluid, which helps keep temperature constant and provides a cushion
against jolts caused by the mother’s movement.
chorion
The outer membrane that forms a protective covering around the prenatal organism. It sends out tiny hairlike villi, from which the placenta begins to develop.
placenta
The organ that permits exchange of nutrients and waste products between the bloodstreams of the mother and the embryo, while also preventing the mother’s and embryo’s blood from mixing directly.
umbilical cord
The long cord connecting the prenatal organism to the placenta that delivers nutrients and removes waste products.
embryo
The prenatal organism from 2 to 8 weeks after conception—the period when the groundwork is laid for all body structures and internal organs.
fetus
The prenatal organism from the ninth week to the end of pregnancy— the period in which body structures are completed and dramatic growth in size occurs.
vernix
A white, cheeselike substance covering the fetus, preventing the skin from chapping due to constant exposure to amniotic fluid.
lanugo
White, downy hair that covers the entire body of the fetus, helping the vernix stick to the skin.
age of viability
The age at which a fetus born early first has a chance of
survival, occurring sometime between 22 and 26 weeks.
teratogen
Any environmental agent that causes damage during the prenatal period.
fetal alcohol spectrum disorder (FASD)
A range of physical, mental, and behavioral outcomes caused by prenatal alcohol exposure.
fetal alcohol syndrome (FAS)
The most severe form of fetal alcohol specrum disorder, distinguished by slow physical growth, facial abnormalities, and brain injury; usually affects children whose mothers drank heavily throughout pregnancy. Distinguished from partial fetal alcohol syndrome (p-FAS) and alcohol-related neurodevelopmental disorder (ARND).
partial fetal alcohol syndrome (p-FAS)
A form of fetal alcohol spectrum disorder characterized by facial abnormalities and brain injury but less severe than fetal alcohol syndrome; usually seen in children whose mothers drank alcohol in smaller quantities during pregnancy. Distinguished from fetal alcohol syndrome (FAS) and alcohol-related neurodevelopmental disorder (ARND).
alcohol related neurodevelopmental disorder (ARND)
The least severe form of fetal alcohol spectrum disorder, involving brain injury but with typical physical growth and absence of facial abnormalities. Distinguished from fetal alcohol syndrome (FAS) and partial fetal alcohol syndrome
(p-FAS).
natural (prepared) childbirth
A group of techniques aimed at reducing pain and medical intervention and making childbirth as rewarding an experience as possible. Typically includes classes that provide information about the birth process, relaxation and breathing techniques to counteract the pain of uterine contractions, and a labor coach who provides encouragement and affection.
breech position
A position of the baby in the uterus that would cause the buttocks or feet to be delivered first.
Rh factor incompatibility
A condition that arises when the Rh protein is present in the fetus’s blood but not in the mother’s, causing the mother to build up antibodies. If these enter the fetus’s system, they destroy red blood cells, reducing the oxygen supply to organs and tissues.
preterm infants
Infants born several weeks or more before their due date.
small-for-date-infants
Infants whose birth weight is below their expected weight considering the length of the pregnancy.
infant mortality
The number of deaths in the first year of life per 1,000 live births
neonatal mortality
The number of deaths within the first month of life per 1,000 live births.
behavioral genetics
A field devoted to uncovering the contributions of nature and nurture to the diversity of human traits and abilities.
heritability estimates
A measure of the extent to which individual differences in complex traits, such as intelligence or personality in a specific population, are due to genetic factors.
kinship studies
Studies comparing the characteristics of family members to estimate the importance of heredity in complex human characteristics.
gene-environment interaction
The idea that individuals’ genetic makeup influences their responsiveness to qualities of the environment
canalization
The tendency of heredity to restrict the development of some characteristics to just one or a few outcomes.
gene-environment correlation
The idea that heredity influences the environments to which individuals are exposed.
niche-picking
A type of genetic–environmental correlation in which individuals actively choose environments that complement their heredity.
epigenesis
Development resulting from ongoing, bidirectional exchanges between heredity and all levels of the environment.
