Chapter 3 Flashcards
Fertilization
union of sperm and ovum to produce a zygote, also called conception
Zygote
one-celled organism resulting from fertilization – a zygote has 23 chromosomes from mother and 23 chromosomes from father = 46 in all
Ovulation
the rupture of a mature follicle and expulsion of the ovum
Cervix
the opening of the uterus
Assisted Reproductive Technologies (ART)
conception through artificial means; has a 23.6% success rate, very expensive
Dizygotic Twins
twins conceived by the union of two different ova (or a single ovum that has split) with two different sperm cells; also called fraternal twins; not more alike genetically than other siblings
Monozygotic Twins
Twins resulting from the division of a single zygote after fertilization; also called identical twins; genetically similar
Heredity
the genetic transmission of heritable characteristics from parents to offspring
Deoxyribonucleic Acid (DNA)
chemical that carries inherited instructions for the development of all cellular forms of life
Chromosomes
coils of DNA that consist of genes – every cell except sperm and ova has 23 pairs of chromosomes
Genes
small segments of DNA located in definite positions on particular chromosomes
Mutations
permanent alterations in genes or chromosomes that may produce harmful characteristics
X Chromosomes
chromosomes containing the genes for femaleness
Y Chromosomes
chromosomes containing the genes for maleness
Dominant Inheritance
hereditary characteristic that is expressed by an organism
Recessive Inheritance
hereditary characteristic that is carried by an organism that does not express or show it
Homozygous
possessing two identical alleles for a trait
Heterozygous
possessing differing alleles for a trait
Phenotype
observable characteristics of a person
Genotype
genetic makeup of a person, containing both expressed and unexpressed characteristics
Sex-linked Inheritance of Defects
pattern of inheritance in which certain characteristics carried on the X chromosome inherited from the mother are transmitted differently to her male and female offspring
Heritability
statistical estimate of contribution of heredity to individual differences in a specific trait within a given population
Reaction Range
potential variability, depending on environmental conditions, in the expression of a hereditary trait
Cephalocaudal Principle
the upper parts of the body develop before the lower parts of the trunk
Proximodistal Principle
The parts of the body near the center develop before the extremeties
Germinal Stage
first two weeks of prenatal developed, characterized by rapid cell division, blastocyst formation, and implantation in the wall of the uterus
Amniotic Sac
fluid-filled membrane that encases the developing baby, protecting it and giving it room to move
Placenta
organ that allows, oxygen, nourishment, and wastes to pass between mother and embryo
Umbilical Cord
Cord that connects the placenta to the baby and vice versa
Embryonic Stage
second stage of gestation (2-8 weeks), characterized by rapid growth and development of major body systems and organs
Trimester
a three-month period of pregnancy
Spontaneous Abortion
natural expulsion of the uterus of an embryo that cannot survive outside the womb; also called a miscarriage
Stillborn
term for a baby that is born dead after at least 20 weeks’ gestation
Fetal Stage
final stage of gestation (from 8 weeks to birth), characterized by increased differentiation of body parts and greatly enlarged body size
Ultrasound
prenatal medical prodecure 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
Teratogen
environmental agent, such as a virus, a drug, or radiation, that can interfere with normal prenatal development and cause developmental abnormalities
