Chapter Two: Biological Foundations Flashcards
chromosomes
threadlike structures in the nuclei of cells that contain genetic material
autosomes
first 22 pairs of chromosomes
sex chromosomes
23rd pair of chromosomes; these determine the sex of the child
deoxyribonucleic acid (DNA)
molecule composed of four nucleotide bases that is the biochemical basis of heredity
gene
group of nucleotide bases that proves a specific set of biochemical instructions
alleles
variations of genes
sickle-cell trait
disorder in which individuals show signs of mild anemia only when they are seriously deprived of oxygen; occurs in individuals who have one dominant allele for normal blood cells and one recessive sickle-cell allele
phenylketonuria (PKU)
inherited disorder in which the infant lacks a liver enzyme
Huntington’s disease
progressive and fatal type of dementia caused by dominant alleles
behavioral genetics
the branch of genetics that studies the inheritance of behavioral and psychological traits
polygenic inheritance
when phenotypes are the result of the combined activity of many separate genes
The first 22 pairs of chromosomes are called ______.
autosomes
_______ reflects the combined activity of a number of distinct genes.
polygenic inheritance
Individuals with ______ have an extra 21st chromosome, usually inherited by the mother.
Down Syndrome (“trisomy 21”)
in vitro fertilization
process by which sperm and egg are mixed in a petri dish to create a zygote, which is then placed in a woman’s uterus
zygote
fertilized egg
germ disc
small cluster of cells near the center of the zygote that will eventually develop into a baby
embryo
term given to the zygote once it is completely embedded in the uterine wall
ectoderm
outer layer of embryo, which will become the hair, the other later of skin, and the nervous system
mesoderm
middle layer of the embryo which becomes the muscles, bones, and circulatory system
endoderm
inner layer of the embryo, which becomes the lungs and the digestive system
amnion
inner sac which the developing child rests
cephalocaudal principle
a principle of physical growth that states that structures nearest the head develop first
proximodistal principle
principle of physical growth that starts structures nearest the center of the body develop first
period of the fetus
longest period of prenatal development, extending from the 9th until the 38th week after conception
cerebral cortex
wrinkled surface to the brain that regulates many functions that are distinctly human
vernix
substance that protects fetus’s skin during development
The period of the zygote ends _____.
at 2 weeks after conception (when zygote is completely implanted into the wall of the uterus)
Body structures and internal organs are created during the period of the ______.
embryo
______ is called the age of viability because this is when most of the systems function well enough to support life.
22-28 weeks
In the last few months of prenatal development, the fetus has regular periods of activity and _____, which are the first signs of fetal behavior
the eyes and ears respond to stimulation
teratogen
an agent that causes abnormal prenatal development
ultrasound
prenatal diagnostic technique that uses sound waves to generate an image of the fetus
amniocentesis
prenatal diagnostic technique that uses a syringe to withdraw a sample of amniotic fluid through a mother’s abdomen
chorionic villus sampling (CVS)
prenatal diagnostic technique that involves taking a sample of tissue from the chorion
General risk factors in pregnancy include a woman’s nutrition, ____, and her age.
prolonged stress
______ are some of the most dangerous teratogens because a pregnant woman is often unaware of their presence.
environmental hazards
During the period of the zygote, exposure to a teratogen typically results in _________.
spontaneous abortion of the fertilized egg
Two techniques are used to determine whether a fetus has a hereditary disorder are amniocentesis and _________.
chorionic villus sampling (CVS)
hypoxia
a birth complication in which umbilical blood flow is disrupted and the infant does not receive adequate oxygen
cesarean section
surgical removal of the infant from the uterus through an incision made in the mother’s abdomen
low birth weight
newborns who weigh less than 5 pounds
very low birth weight
newborns who weigh less than 3 pounds
extremely low birth weight
newborns who weigh less than 2 pounds
infant mortality
the number of infants out of 1,000 births who die before their first birthday
In the third stage of labor the _____ is delivered.
placenta
Two problems with using anesthesia during labor are that a woman can’t use her abdominal muscles to help push the baby down the birth canal and ___________.
the pain-relieving medication crosses the placenta and affects the baby
Home delivery is safe when a pregnant woman is healthy, has had a problem-free pregnancy, expects to have a problem-free delivery, and ________.
when trained health professionals are present to deliver the baby
When the supply of oxygen to the fetus is disrupted because the umbillical cord is squeezed shut, _____ results.
hypoxia
Genotype
Person’s hereditary makeup
Phenotype
Physical, behavioral, and psychological features that result from the interaction between one’s genes and the environment
Homozygous
Alleles in a pair of chromosomes are the same
Heterozygous
Alleles in a pair of chromosomes differ from each other
Dominant
Form of an allele whose chemical instructions are followed
Recessive
Allele whose instructions are ignored in the presence of a dominant allele
Incomplete Dominance
Situation in which one allele does not dominate another completely
Monozygotic Twins
Identical twins
Single fertilized egg splits to form 2 individuals
Dizygotic Twins
Fraternal twins
2 separate eggs are fertilized
Heritability Coefficient
Measure (derived from a correlation coefficient) of the extent to which a trait or characteristic is inherited
Niche-Picking
Process of deliberately seeking environments that are compatible with one’s genetic makeup
Non-shared Environmental Influences
Forces w/in a family that make siblings different from one another
Prenatal Development
Many changes that turn a fertilized egg into a newborn human
Eugenics
Effort to improve the human species by letting only people whose characteristics are valued by a society mate and pass along their genes
Implantation
Step in which the zygote burrows into the uterine wall and establishes connections with a woman’s blood vessels
Placenta
Structure through which nutrients and wastes are exchanged between the mother and the developing child
Amniotic Fluid
Fluid that surrounds the fetus
Umbilical Fluid
Structure containing veins and arteries that connects the developing child to the placenta
Age of Viability
Age at which a fetus can survive because most of its bodily systems function adequately; typically at 7 months after conception
Spina Bifida
Disorder in which the embryo’s neural tube does not close properly
Stress
Physical and psychological responses to threatening or challenging conditions
Fetal Alcohol Spectrum Disorder (FASD)
Disorder affecting babies whose mothers consumed large amounts of alcohol while they were pregnant
Fetal Medicine
Field of medicine concerned with treating prenatal problems before birth
Crowning
Appearance of the top of the baby’s head during labor
How many stages of labor are there?
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