Cesarean Delivery
Chromosomes
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
-those that are expressed
Down Syndrome
a disorder produced by the presence of an extra chromosome on the 21st pair; once referred to as mongolism
Embryonic Stage
2 weeks - 8 weeks
-organism firmly secures to uterus and called an embryo
-development of major organs and basic anatomy
Three Layers:
Ectoderm: form skin, hair, teeth, sense organs, brain, spinal cord
Endoderm: inner layer forms digestive system, liver, pancreas, respiratory system
Mesoderm: sandwiched between other two and forms muscles, bones, blood, circulatory system
Fetal Stage
8 weeks- birth
Fragile X Syndrome
A disorder produced by injury to a gene on the X chromosome, producing mild to moderate mental retardation
-most common form of inherited mental retardation in males and a significant cause in females
Genes
the basic unit of genetic information
Genetic Counseling
the discipline that focuses on helping people deal with issues relating to inherited disorders
Genotype
underlying combination of genetic material present (but not outwardly visible) in an organism
Germinal Stage
Fertilization- 2 weeks
Heterozygous
inheriting from parents different forms of a gene for a given trait
-allele contains different forms of genes from parents
Homozygous
inheriting from parents similar genes for a given trait
-allele contains similar genes from each parent
Infertility
15% of couples; inability to conceive after 12 to 18 months
-maternal infertility influenced by age; hormone imbalance, damaged fallopian tubes or uterus, stress, abuse of alcohol or drugs
-Paternal infertility influenced by illicit drugs, tobacco, STDs
Solutions?
-artificial insemination
-in vitro fertilization
-surrogate mother
Klinefelter’s Syndrome
A disorder resulting from the presence of an extra X chromosome that produces underdeveloped genitals, extreme height, and enlarged breasts
-chromosome disorder in males. People with this condition are born with at least one extra X chromosome
Low-birthweight infants
weigh less than 2500 grams (around 5 1/2 pounds at birth
Monozygotic Twins
twins who are genetically identical
Multifactorial Transmission
many traits determined by combination of both genetic and environmental factors; genotype provides particular range within which a phenotype may achieve expression; in many cases the environment determines the way in which a particular genotype will be expressed as a phenotype
ex: people with a genotype that permits them to gain weight easily may never be slim, no matter how much they diet
Phenotype
the observable trait; the trait that actually is seen
Postmature infants
2 weeks or more overdue
Preterm infants
or premature infants , are born prior to 38 weeks after conception
Recessive Trait
a trait within an organism that is present, but is not expressed
-those that are NOT expressed
Sickle-cell Anemia
inherited disease in which the red blood cells, normally disc-shaped, become crescent shaped