Chapter 3: Forming a New Life Flashcards
Union of sperm and ovum to produce a zygote; also called conception .
fertilization
One-celled organism resulting from
fertilization.
zygote
Twins conceived by the union of two
diff erent ova (or a single ovum that has
split) with two diff erent sperm cells; also
called fraternal twins ; they are no more
alike genetically than any other siblings.
dizygotic twins
Twins resulting from the division of a single zygote after fertilization; also called identical twins ; they are genetically similar.
monozygotic twins
The genetic transmission of heritable characteristics from parents to offspring
heredity
Sequence of bases within the DNA molecule; governs the formation of proteins that determine the structure and functions of living cells.
genetic code
Chemical that carries inherited instruc-
tions for the development of all cellular
forms of life.
deoxyribonucleic acid (DNA)
Coils of DNA that consist of genes.
chromosomes
Small segments of DNA located in definite positions on particular chromosomes; functional units of heredity.
genes
Complete sequence of genes in the
human body.
human genome
A process by which the non–sex cells divide in half over and over again, the DNA
replicates itself, so that each newly
formed cell has the same DNA structure as all the others.
mitosis
Permanent alterations in genes or
chromosomes that may produce
harmful characteristics.
mutation
In humans, the 22 pairs of chromo-
somes not related to sexual expression.
autosomes
Pair of chromosomes that determines
sex: XX in the normal human female,
XY in the normal human male.
sex chromosomes
Two or more alternative forms of a gene
that occupy the same position on
paired chromosomes and aff ect the
same trait.
alleles
Possessing two identical alleles for a trait.
homozygous
Possessing diff ering alleles for a trait.
heterozygous
Pattern of inheritance in which a child
receives identical recessive alleles,
resulting in expression of a nondominant
trait.
recessive inheritance
Pattern of inheritance in which, when a
child receives diff erent alleles, only the
dominant one is expressed.
dominant inheritance
Pattern of inheritance in which multiple
genes at diff erent sites on chromo-
somes aff ect a complex trait
polygenic inheritance
Observable characteristics of a person.
phenotype
Genetic makeup of a person, containing
both expressed and unexpressed
characteristics.
genotype
Combination of genetic and
environmental factors to produce
certain complex traits.
multifactorial transmission
Mechanism that turns genes on or off
and determines functions of body cells.
epigenesis
Pattern of inheritance in which a child
receives two diff erent alleles, resulting
in partial expression of a trait.
incomplete dominance
Pattern of inheritance in which certain
characteristics carried on the X
chromosome inherited from the mother
are transmitted differently to her male
and female off spring.
sex-linked inheritance
Chromosomal disorder characterized by
moderate-to-severe mental retardation
and by such physical signs as a downward-
sloping skin fold at the inner corners of
the eyes. Also called trisomy-21.
Down syndrome
Quantitative study of relative hereditary and environmental infl uences on behavior.
behavioral genetics
Clinical service that advises prospective
parents of their probable risk of having
children with hereditary defects.
genetic counseling
Statistical estimate of contribution of heredity to individual differences in a specific trait within a given population.
heritability
Term describing tendency of twins to
share the same trait or disorder.
concordant
Potential variability, depending on
environmental conditions, in the
expression of a hereditary trait.
reaction range
Limitation on variance of expression of
certain inherited characteristics.
canalization
The portion of phenotypic variation that
results from the reactions of genetically
different individuals to similar
environmental conditions.
genotype-environment interaction
Tendency of certain genetic and environmental influences to reinforce each other; may be passive, reactive (evocative), or active.
genotype-environment correlation
Children with differing genetic makeups
evoke different reactions from others.
Reactive, or evocative, correlations
Parents, who provide the genes that predispose a child toward a trait, also tend to provide an environment that encourages the development of that trait.
Passive correlations
As children get older and have more freedom to choose their
own activities and environments, they actively select or create experiences
consistent with their genetic tendencies.
Active correlations
Tendency of a person, especially after
early childhood, to seek out environments compatible with his or her
genotype.
niche-picking
The unique environment in which each child grows up, consisting of distinctive infl uences or infl uences that affect one child diff erently than another.
nonshared environmental effects
Characteristic disposition, or style of
approaching and reacting to situations.
temperament
Extreme overweight in relation to age,
sex, height, and body type as defined
by having a body mass index at or
above the 95th percentile.
obesity
Mental disorder marked by loss of
contact with reality; symptoms include
hallucinations and delusions.
schizophrenia
Period of development between
conception and birth.
gestation
What are the stages of prenatal development?
germinal, embryonic, and fetal
First 2 weeks of prenatal development,
characterized by rapid cell division,
blastocyst formation, and implantation
in the wall of the uterus.
germinal stage
The attachment of the blastocyst to the
uterine wall, occurring at about day 6.
implantation
Second stage of gestation (2 to
8 weeks), characterized by rapid growth
and development of major body
systems and organs.
embryonic stage
Natural expulsion from the uterus of an
embryo that cannot survive outside the
womb; also called miscarriage
spontaneous abortion
Final stage of gestation (from 8 weeks
to birth), characterized by increased
diff erentiation of body parts and greatly
enlarged body size.
fetal stage
Prenatal medical procedure using
high-frequency sound waves to detect
the outline of a fetus and its movements,
so as to determine whether a pregnancy
is progressing normally.
ultrasound
Environmental agent, such as a virus, a
drug, or radiation, that can interfere with
normal prenatal development and
cause developmental abnormalities.
teratogen
What are the ENVIRONMENTAL INFLUENCES: MATERNAL FACTORS
- Nutrition and Maternal Weight
- Malnutrition
- Physical Activity and Strenuous Work
- Drug Intake
- Maternal Illnesses
- Maternal Anxiety, Stress, and Depression
- Maternal Age
- Outside Environmental Hazards
Viral disease that undermines eff ective
functioning of the immune system.
acquired immune deficiency syndrome (AIDS)
Combination of mental, motor, and
developmental abnormalities aff ecting
the off spring of some women who drink
heavily during pregnancy.
fetal alcohol syndrome (FAS)
Physical or psychological demands on a
person or organism.
stress
Tiny viewing scope is inserted
in woman’s abdomen to view
embryo or fetus.
Can assist in diagnosis of
non chromosomal genetic
disorders.
Embryoscopy,
fetoscopy
What are the Prenatal Assessment Techniques
- Ultrasound (sonogram), sonoembryology
- Embryoscopy, fetoscopy
- Amniocentesis
- Chorionic villus sampling (CVS)
- Preimplantation genetic diagnosis
- Umbilical cord sampling
- Maternal blood test
High-frequency sound waves
directed at the mother’s
abdomen produce a picture
of fetus in uterus.
Ultrasound
(sonogram),
sonoembryology
Sample of amniotic fl uid is
withdrawn under guidance of
ultrasound and analyzed.
Most commonly used
procedure to obtain fetal cells
for testing.
Amniocentesis
Tissues from hairlike chorionic
villi (projections of membrane
surrounding fetus) are
removed from placenta and
analyzed.
Chorionic villus sampling (CVS)
After in vitro fertilization, a
sample cell is removed from
the blastocyst and analyzed.
Preimplantation genetic diagnosis
A sample of the prospective
mother’s blood is tested for
alpha fetoprotein.
Maternal blood test
Needle guided by ultrasound
is inserted into blood vessels
of umbilical cord.
Umbilical cord sampling (cordocentesis, or fetal blood sampling)
