Chapter 2 Flashcards
Zygote
The single cell that is formed from the fusing of 2 gametes, a sperm and an ovum
Deoxyribonucleic Acid (DNA)
The molecule that contains the chemical instructions for cells to manufacture various proteins
Chromosome
One of the 46 molecules of DNA (in 23 pairs) that each cell of the human body contains and that, together, contain all the genes. Other species have more or fewer chromosomes.
Gene
A 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.
Gamete
A reproductive cell; that is, a sperm or an ovum that can produce a new individual if it combines with a gamete from the other sex to form a zygote.
Allele
Any of the possible forms in which a gene for a particular trait can occur.
Each variation is a single-nucleotide polymorphism (SNP)
Polymorphic
Means “many forms”
Genotype
An organism’s entire genetic inheritance, or genetic potential
Phenotype
The observable characteristics of a personal, including appearance, personality, intelligence, and all other traits
Genome
The full set of genes that are in the instructions to make an individual member of a certain species
How many human genes are there?
20,000 to 23,000
XX
A 23rd chromosome pair that consists of 2 X shaped chromosomes, one each from the mother and the father. XX zygotes become females.
XY
A 23rd chromosome pair that consists of an X shaped chromosome from the mother and a Y shaped chromosome from the father. XY zygotes become males.
What gene does the Y chromosome has that is responsible for developing male organs and the production of certain fetal hormones?
the SRY gene
Monozygotic (Identical) Twins
Twins who originate from one zygote that splits apart very early in development
Incomplete splits create conjoined twins
Dizygotic (Fraternal) Twins
Twins who are formed when 2 separate ova are fertilized by 2 separate sperm at roughly the same time.
Are women who have had dizygotic twins likely to have another set?
Yes because ovulating more than one ova a month is genetic, so both she and her future daughters are likely to have more sets of dizygotic twins
Polygenic
Affected by many genes
Multifactorial
Influenced by many factors
Additive Gene
A gene that adds something to some aspect of the phenotype. Its contribution depends on additions from other genes, which may come from either the same or the other parent.
ex: height, hair curliness, skin color
Nonadditive Genes
Genes which do not contribute equal shares
Dominant-Recessive Pattern
The interaction of a pair of alleles in such a way that the phenotype reveals the influence of one allele (the dominant gene) more than that of the other (the recessive gene)
Carrier
A person whose genotype includes a gene that isn’t expressed in the phenotype. Such an unexpressed gene occurs in half the carrier’s gametes and thus is passed on to half of the carrier’s children, who will most likely be carriers, too. Generally, the characteristic appears in the phenotype only when such a gene is inherited from both parents.
X-Linked
A gene carried on the X chromosome. If a male inherits an X-linked recessive gene from his mother, he expresses that trait because the Y from his father has no counteracting gene. Females are more likely to be carriers of X-linked traits but are less likely to express them.
Germinal Period
The first 2 weeks of prenatal development after conception, characterized by rapid cell division and the beginning of cell differentiation.
Embryonic Period
The stage of prenatal development from approximately the 3rd through 8th week after conception, during which the basic forms of all body structures, including internal organs, develop
Fetal Period
The stage of prenatal development from the 9th week after conception until birth, during which the fetus grows in size and matures in functioning
Preterm
Born more than 3 weeks before the due date
Post-term
Born more than 2 weeks after the due date
Stem Cells
Cells from which any other specialized type of cell can form
Implantation
The process, beginning about 10 days after conception, in which the developing organism burrows into the tissue lining the uterus, where it can be nourished and protected as it continues to develop
Placenta
The organ that surrounds and protects the developing organism
Embryo
Name for the developing human organism from about the 3rd through 8th week after conception
Primitive Streak
Thin line that appears down the middle of the embryo at about day 14. It will become the neural tube around the 22nd day and eventually develop into the central nervous system, brain, and spinal column
Fetus
Name for a developing human organism from the start of the 9th week after conception until birth
Ultrasound (Sonogram)
An image of a fetus (or an internal organ) produced by using high frequency sound waves
Neurogenesis
Development of new neurons
Synaptogenesis
Development of new synapses
Age of Viability
The age (at about 22 weeks after conception) at which a fetus may survive outside the uterus is specialized medical care is available
Oxytocin
Hormone that prepares fetus for delivery and starts labor
Apgar Scale
A quick assessment of the newborn’s body functioning. The baby’s heart rate, respiratory effort, muscle tone, color, and reflexes are given a score of 0, 1, or 2 twice- at one minute and 5 minutes after birth- and each time the total of all 5 scores is compared with the ideal score of 10 (which is rarely attained, aim for 7)
Cesarean Section (C-Section)
A surgical birth, in which incisions through the mom’s abdomen and uterus allow the fetus to be removed quickly, instead of being delivered through the vagina
Epidural
An injection in a particular part of the spine to alleviate labor pain
Induced Labor
Starting, speeding, or strengthening labor with a drug
Doula
A woman who helps with the birth process. Doulas are trained to offer support to new mothers, including massage and suggestion for breastfeeding positions
Brazelton Neonatal Behavioral Assessment Scale (NBAS)
A test often administered to newborns that measures responsiveness and records 46 behaviors, including 20 reflexes
Reflex
An unlearned, involuntary action or movement in response to a stimulus. A reflex occurs without conscious thought
What are the 3 types of newborn reflexes?
- Reflexes that maintain oxygen supply
- Reflexes that maintain constant body temperature
- Reflexes that manage feeding
Couvade
Symptoms of pregnancy and birth experienced by fathers
Postpartum Depression
The sadness and inadequacy felt by some new mothers in the days and weeks after giving birth
Mild postpartum depression is called…
Baby Blues
The most severe postpartum depression is called…
Postpartum psychosis
What can be the first sign of postpartum depression?
The mother is very euphoric after giving birth
Parent-Infant Bond
The strong, loving connection that forms as parents hold, examine, and feed their newborn
Kangaroo-Care
A childcare technique in which a new mother holds the baby between her breasts, like a kangaroo that carriers her immature newborn in a pouch on her abdomen
Down Syndrome (Trisomy-21)
A condition in which a person has 47 chromosomes instead of the usual 46, with 3 rather than 2 chromosomes at the 21st position. People with Down Syndrome typically have distinctive characteristics, including unusual facial features (thick tongue, round face, slanted eyes), heart abnormalities, and language difficulties
Teratogen
Any agent or condition, including viruses, drugs, and chemicals, that can impair prenatal development, resulting in birth defects or complications
Behavioral Teratogen
Agents and conditions that can harm the prenatal brain, impairing the future child’s intellectual and emotional functioning
Cerebral Palsy
A disorder that results from damage to the brain’s motor centers. People with cerebral palsy have difficulty with muscle control, so their speech and/or body movements are impaired
Anoxia
A lack of oxygen that, if prolonged, can cause brain damage or death
Threshold Effect
A situation in which a certain teratogen is relatively harmless in small doses but becomes harmful once exposure reaches a certain level (the threshold)
Fetal Alcohol Syndrome (FAS)
A cluster of birth defects, including abnormal facial characteristics, slow physical growth, and intellectual disabilities, that may occur in the child of a woman who drinks alcohol while pregnant
Spina Bifida
Neural-tube defect where the tail of the spine isn’t enclosed properly
Anencephaly
Neural-tube defect where part of the brain is missing
Low Birth Weight (LBW)
A body weight at birth of less than 5.5 pounds (2,500 grams)
Very Low Birth Weight (VLBW)
A body weight at birth of less than 3 pounds 5 ounces (1,500 grams)
Extremely Low Birth Weight (ELBW)
A body weight at birth of less than 2 pounds 3 ounces (1,000 grams)
Small for Gestational Age (SGA)
Having a body weight at birth that is significantly lower than expected, given the time since conception.
ex: a 5 pound (2,265 gram) newborn is SGA if born on time, but isn’t SGA if born 2 months early.
Hispanic Paradox
The surprising discovery that, although socioeconomic status usually correlates with poor health, this isn’t true for Hispanics in the US.
ex: when compared with the US average LBW rate, Hispanic newborns are less often of LBW
Heritability
A statistic that indicates what percentage of the variation in a particular trait within a particular population, in a particular context and era, can be traced to genes.
