Chapter 3 Flashcards
single cell formed from the union of 2 gametes, a sperm & an ovum
zygote
reproductive cell; that is, a sperm or ovum that can produce a new individual if it combines w/ a gamete from the other sex to make a zygote
gamete
chemical composition of the molecules that contain the genes, which are the chemical instructions for cells to manufacture various proteins
DNA
one of the 46 molecules of DNA (in 23 pairs) that virtually each cell of the human body contains & that, together, contain all of the genes. other species have more of fewer chromosomes
chromosome
small section of a chromosome; the basic unit for the transmission of heredity. a gene consists of a string of chemicals that provide instructions for the cell to manufacture certain proteins
gene
a variation that makes a gene different in some way from other genes for the same characteristics. many genes never vary; others have several possible alleles
allele
the full set of genes that are the instructions to make an individual member of a certain species
genome
an organisms entire genetic inheritance, or genetic potential
genotype
chromosome pair that, in humans, determines sex. the other 22 pairs are autosomes, inherited equally by males & females
23RD pair
a 23rd chromosome pair that insists of two x-shaped chromosomes, one each from the mother & the father. XX a zygotes become females
XX
a 23RD chromosome pair that consists of an x-shaped chromosome from the mother & a y-shaped chromosome from the father. XY zygotes become males
XY
cells from which any other specialized type of cell can form
stem cells
twins who originate from one zygote that splits part very early in development. (also called identical twins) other monozygotic mult. births (such as triplets & quadruplets) can occur as well
monozygotic (MZ) twins
twins who are formed when 2 separate ora are fertilized by 2 separate sperm at roughly the same time (fraternal twins)
dizygotic (DZ) twins
general term for the techniques designed to help infertile couples conceive & then sustain a pregnancy
assisted reproductive technology (ART)
fertilization that takes place outside a woman’s body (as in a glass lab dish) the procedure involves mixing sperm w/ ova that have been surgically removed from the woman’s ovary. if a zygote is produced, it is inserted into a woman’s uterus, where it may implant & develop into a baby
in vitro fertilization (INF)
observable characteristics of a person, including appearance, personality, intelligence, & all other traits
phenotype
a condition in which a person has 47 chromosomes instead of the usual 46, w/ 3 rather than 2 chromosomes at the 21st site. people w/ Down Syndrome typically have distinctive characteristics, including unusual facial features, Hearst abnormalities, & language difficulties
down syndrome
consultation & testing by trained experts that enable individuals to learn about their genetic heritage, including harmful conditions that they might pass along to any children they may conceive
genetic counseling
