Childhood Test 2 Review Flashcards
Identical twins
siblings conceived fom one egg; after conception, the fertilized egg splits in half, with each half having the same genetic material; aslo called monozygotic twins
fraternal twins
siblings conceived when two eggs are fertilized at the same time; also called izygotic twins
chromosomes
a grouop of 20K to 25K genes arranged in a long string
deoxyribonucleic acid
DNA; the molecule that ocntains genetic information
gene
a section of DNA that contains the genetic code for inherited characteristics
mitosis
the process by which chromosomes make copies of themselves before cell dividion takes place
gamate
reproductive cells that contain 23 chromosomes apiece; a sex cell, either a sperm or an egg
sperm
male sex cel
ovum
a matrue egg, or female sex cell
meiosis
the process of cell division that produces the gamtes, or sex cells, each containing 23 chromosomes
zygote
a fertilized ovum, during the first 2 weeks after conception
callele
a variant of a gnee; alleles usually come in pairs one located on each of a pair of chromosomes
homozygous
having two matching alleles for a particular characteristic
heterozygous
having two different alleles for aparticular hcaracterisitc
dominant-recessive inheritance
pattern of inheritance that reveals the haraccteristic of the recessive gene only if no dominant gene is presented in the organism
codominant
pattern of inheritance that invovles the join action of many gnes, often I nconjuction with environmental factors
polygenic inheritance
process of inheritance that invovles the inpupt of many genes in order to control te expression of a single characteristic
x-linked inheritance
pattern of inheritance in which a recessive gene is carreid on the x chromosome and is thus expresse mainly in males
hemophelia
inherited x-linked disorder in which blood fails to clot nomrally; occurs cheifly in males
mutation
change or alteration in a gene
phenylketonuria (PKU)
Genetic disorder that causes daage to the central nervous system if not diagnosed at birth and controlled with a special diet, this is inherited when both recessive alleles are obtained
sickle cell anemia
genetic disoder in which red blood cells become sticky and shaped like crescent moons os sickles; the affected blood cells have trouble passing thorugh small blood vessels, thereby causing blood clots to occur, and mostly occurs when both alleles are inherited.
Fragile X syndrom
an x-linked genetic fisorder that is a common cause of mental retardation. Causes a change in a specific gene that causes a small amount of FMRP to be produced which is crucial for the functionoing of the central nervous system.
Down Syndrom
a chromosomal disroder in which 21st chromosome pair has a extra chroomsome attached to it; causes hsort stature, low muscle tone,, heart problems, and mental retardation; also known as trisomy 21.