Module 02.01 Prenatal Development Flashcards
zygote
the new cell formed by the process of fertilization
genes
the basic unit of genetic understanding
DNA molecules
the substance that genes are composed of that determines the nature of every cell in the body and how it will function
chromosomes
rod-shaped portions of the DNA that are organized into 23 pairs
gametes
(sex cells: ova and sperm) are formed in the adult body via meiosis
monozygotic twins
twins who are genetically identical
dizygotic twins
twins who are produced when two separate ova are fertilized by two separate sperm at roughly the same time
dominant trait
the one trait that is expressed when two competing traits are present
recessive trait
a trait within an organism that is present but not expressed
genotype
the underlying combination of genetic material present (but not outwardly visible) in an organism
phenotype
an observable trait; the trait that is actually seen
allele
genes governing traits that may take alternate forms (e.g. hair or eye color)
homozygous
inheriting similar genes for a given trait from both parents
heterozygous
inheriting different forms of a gene for a given trait from each parent
phenylketonuria (PKU)
an inherited disorder in which a child is unable to make use of phenylalanine, an essential amino acid present in proteins found in milk and other foods
polygenic inheritance
inheritance in which a combination of multiple pairs of genes is responsible for the production of a particular trait
reaction range
the potential degree of variability in the expression of a trait as a result of environmental conditions
X-linked genes
genes that are considered recessive and located only on the X chromosome (e.g. hemophilia, and red-green color blindness) [thereby affecting males more than females]
behavioral genetics
the study of the effects of heredity on behavior
Down syndrome
(previously mongolism) a disorder produced by the presence of an extra chromosome on the 21st pair
fragile X syndrome
a disorder produced by injury to a gene on the X chromosome, producing mild to moderate intellectual disability
sickle-cell anemia
a blood disorder that gets its name from the shape of the red blood cells
Tay-Sachs disease
a disorder that produces blindness and muscle degeneration before death; there is no treatment
Klinefelter’s syndrome
a disorder resulting from the presence of an extra X chromosome that produces underdeveloped genitals, extreme height, and enlarged breasts
Turner’s syndrome
a genetic disorder characterized by a missing or partially missing second X chromosome
genetic counseling
the discipline that focuses on helping people deal with issues relating to inherited disorders
karyotype
a chart containing enlarged photos of each of the chromosomes
ultrasound sonography
a process in which high-frequency sound waves scan the mother’s womb to produce an image of the unborn baby, who size and shape can then be assessed
amniocentesis
the process of identifying genetic defects by examining a small sample of fetal cells drawn by a needle inserted into the amniotic fluid surrounding the unborn fetus
chorionic villus sampling (CVS)
a test used to find genetic defects that involves taking samples of hairlike material that surrounds the embryo
germ line therapy
cells with defective genes are taken from an embryo, repaired, and replaced
