Chapter 6 Genetics, Conception, and Fetal Development VOCAB Flashcards
Alleles
An alternate form of a gene.
Aneuploidy
An abnormal number of chromosomes.
Cephalocaudal
Progression from head to toe (head-to-rump)
Chromosomes
Threadlike packages of genes and other DNA in the nucleus of a cell.
Diploid
Having a pair of chromosomes (46, or 23 pairs, in humans) that represents one copy of every chromosome from each parent; the number of chromosomes normally present in body cells other than gametes.
Euploid cell
A cell with the correct or normal number of chromosomes within the cell.
Gamete
Reproductive cell; in the female an ovum and in the male a spermatozoon.
Genotype
Genetic makeup of an individual.
Haploid
Having one copy of a chromosome from each pair (23 in humans, or half the diploid number). Gametes normally have a haploid number of chromosomes.
Hematopoiesis
Production of blood cells; normally occurs in the bone marrow but may occur in extramedullary sites.
Heterozygous
Having two different alleles for a genetic trait.
Homologous
pairing at meiosis and having the same structural features and pattern of genes.
Homozygous
Having two identical alleles for a genetic trait.
Human genome
The complete set of genetic instructions in the nucleus of each human cell.
Hydramnios
Excessive volume of amniotic fluid (more than 2000 ml at term). Also called polyhydramnios.
Karyotype
A picture of a cell’s chromosomes, arranged from largest to smallest pairs.
Lanugo
Fine, soft hair covering the fetus.
Meiosis
Reduction cell division in gametes that halves the number of chromosomes in each cell.
Mitosis
Cell division in body cells other than the gametes.
Monosomy
Presence of only one of a chromosome pair in every body cell.
Multiple-marker screening
Analysis of maternal serum for abnormal levels of alpha-fetoprotein, human chorionic gonadotropin, and estriols that may predict chromosomal abnormalities of the fetus; often called triple-screen or quad screen.
Addition of tests such as inhibin A have improved accuracy of the results, leading to alternate names for the package of tests.
Mutation
Change in a gene that usually affects its function. Mutations may be in either the gametes or the somatic cells.
Nuchal cord
Umbilical cord around the fetal neck.
Oligohydramnios
Abnormally light or reduced menstruation.
Oogenesis
Formation of gametes (ova) in the female.
Phenotype
The outward expression of one’s genetic makeup.
Polyploidy
Having additional full sets of chromosomes
Pseudomenstruation
Vaginal bleeding in the newborn, resulting from withdrawal of placental hormones.
Sex chromosomes
The X or Y chromosome. Females have two X chromosomes; males have one X and one Y chromosome.
Somatic cells
Body cells other than the gametes, or germ cells.
Spermatogenesis
Formation of male gametes (sperm) in the testes.
Translocation
Attachment of all or part of a chromosome to another chromosome.
Trisomy
Presence of three copies of a chromosome in each body cell.
Vernix caseosa
Thick, white substance that protects the skin of the fetus.
Zygote
Cell formed by union of an ovum and sperm.
