Chapter 3: Forming a New Life Flashcards by TRIZZA MAE ANGKE

Union of sperm and ovum to produce a zygote; also called conception .

fertilization

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One-celled organism resulting from
fertilization.

zygote

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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

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Twins resulting from the division of a single zygote after fertilization; also called identical twins ; they are genetically similar.

monozygotic twins

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The genetic transmission of heritable characteristics from parents to offspring

heredity

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Sequence of bases within the DNA molecule; governs the formation of proteins that determine the structure and functions of living cells.

genetic code

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Chemical that carries inherited instruc-
tions for the development of all cellular
forms of life.

deoxyribonucleic acid (DNA)

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Coils of DNA that consist of genes.

chromosomes

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Small segments of DNA located in definite positions on particular chromosomes; functional units of heredity.

genes

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Complete sequence of genes in the
human body.

human genome

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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

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Permanent alterations in genes or
chromosomes that may produce
harmful characteristics.

mutation

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In humans, the 22 pairs of chromo-
somes not related to sexual expression.

autosomes

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Pair of chromosomes that determines
sex: XX in the normal human female,
XY in the normal human male.

sex chromosomes

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Two or more alternative forms of a gene
that occupy the same position on
paired chromosomes and aff ect the
same trait.

alleles

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Possessing two identical alleles for a trait.

homozygous

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Possessing diff ering alleles for a trait.

heterozygous

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Pattern of inheritance in which a child
receives identical recessive alleles,
resulting in expression of a nondominant
trait.

recessive inheritance

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Pattern of inheritance in which, when a
child receives diff erent alleles, only the
dominant one is expressed.

dominant inheritance

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Pattern of inheritance in which multiple
genes at diff erent sites on chromo-
somes aff ect a complex trait

polygenic inheritance

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Observable characteristics of a person.

phenotype

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Genetic makeup of a person, containing
both expressed and unexpressed
characteristics.

genotype

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Combination of genetic and
environmental factors to produce
certain complex traits.

multifactorial transmission

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Mechanism that turns genes on or off
and determines functions of body cells.

epigenesis

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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)