Chapter 2: From Conception to Birth – Flashcards
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zygote
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single cell that is formed from the fusing of two gametes, a sperm and an ovum
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DNA (deoxyribonucleic acid)
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the molecule that contains the chemical instructions for cells to manufacture various proteins
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chromosome
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one of the 46 molecules of DNA that almost every cell of the human body contains
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gene
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small section of a chromosome; basic unit for the transmission of heredity > consists of a string of chemicals that provide instructions for the cell to manufacture certain proteins > humans have 20,000 - 23,000
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gamete
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reproductive cell (sperm or ovum) that contains only 23 chromosomes - each person can produce 2^23 gametes (8,388,608)
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allele
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two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome ex. gene apoE4 makes a person more susceptible to AIDS, heart disease, and Alzheimer's than gene apoE2
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polymorphic
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genes with various/multiple alleles
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genotype
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an organism's entire genetic inheritance, or genetic potential
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phenotype
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observable characteristics of a person, including appearance, personality, intelligence, and all other apparent traits
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genome
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complete set of genes for a certain species
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additive genes
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multiple genes that contribute to the phenotype
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dominant-recessive pattern (non-additive)
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interaction of a pair of genes in such a way that the phenotype reveals the influence of one (the dominant gene) more than that of the other ( the recessive gene)
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carrier
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a person who had inherited a recessive gene that is not expressed in the phenotype - the recessive gene is carried on the genotype
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X-linked recessive inheritance
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gene carried on the X chromosome > if a male inherits an X-linked recessive trait, he expresses that trait because the Y chromosome has no counteracting gene > females are more likely to be carriers of X-linked traits, but are less likely to express them
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epigenetics
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study of changes in organisms caused by modification of gene expression rather than alteration of the genetic code itself
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1. What is the relationship between DNA, chromosomes, and genes?
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All living things are composed of cells that promote growth and sustain life according to the instructions in their molecules of DNA > each molecule of DNA is called a CHROMOSOME > chromosomes contain units of instructions called GENES, with each gene located on a particular chromosome
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2. Why is it said that your parents could have given you millions of different siblings?
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When a sperm and ovum combine to make a zygote, they create a cell in which the genes on one of 8 million possible sperm interact with one of the 8 million possible ova from the mother - they can combine in an astronomical number of unique ways
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3. What surprises came form the Human Genome Project?
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Humans have between 18,000 and 23,000 genes (not 100,000+ as previously believed), which is even fewer than dogs and mice - it is not always clear where one gene begins and ends - any two people of different ethnicity, gender, or age share 99.5% of their genetic code
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4. How is the sex of a zygote determined?
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combination of two possible chromosomes 23 (XX) = girl (XY) = boy
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5. Monozygotic twins, dizygotic twins, and nontwin siblings
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monozygotic twins: originate from one zygote; have identical genetic makeup and share a prenatal environment dizygotic twins: originate from two fertilized ova; share a prenatal environment nontwin siblings: zygotes that share the same parents, but no the same genetic material or prenatal environment
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6. How could a child inherit a disease neither parent has
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One or more parent can be a CARRIER for that disease; although the disease does not appear in either parent's phenotype, the gene is passed on to half of their children
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7. How is diabetes both genetic and not genetic
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Although people inherit genes that put them at risk for type 2 diabetes, their lifestyle (being fat and not exercising) activates their genetic risk ; epigenetic changes can make diabetes irreversible
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germinal period
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first two weeks of a pregnancy ; characterized by rapid cell division and the beginning of cell differentiation - about 60% of all zygotes do not grow or implant properly and therefore do not survive this stage - few women will even realize that they were pregnant
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embryonic period
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third through eighth week of pregnancy ; basic body structure, including internal organs, but not sex organs form - about 20% of all embryos are aborted spontaneously (early miscarriage), mostly due to a chromosomal abnormality
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fetal period
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ninth week until birth (about 38 - 40 weeks) ; fetus grows in size and matures in functioning - about 5% of all fetuses are aborted spontaneously before viability (22 weeks) and are defined as "stillborn" when born dead after 22 weeks; this is more common in poorer nations
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birth
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only about 31% of all zygotes become living newborn babies - only about 3% of all conceptions after the age of 40 result in live births
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Beginning of pregnancy
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-begins at conception (fertilization of the ova by the sperm) - cannot be confirmed until implantation of the zygote to the uterine wall (6-12 days after conception) - many obstetricians date the onset of pregnancy from the date of the woman's last menstrual period (LMP)
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Gestational time (length of pregnancy)
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Full-term pregnancies last 266 days - about 38 weeks - if calculated by LMP, pregnancy lasts about 40 weeks
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Trimesters
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first trimester: months 1-3 second trimester: months 4-6 third trimester: months 7-9
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Due date
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assigned/estimated date of birth based on woman's LMP - only 5% of babies are born on this date babies born 3 weeks before this date or two weeks after are considered "full term" or "on time" - babies born before this date are "preterm" and babies born after are "post-term"
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stem cells
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cells that have the potential to develop into many different cell types
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omnipotent/totipotent stem cells
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can form ALL cell types in a body, including extraembryonic (placental) cells - embryonic cells within the first few cell divisions
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pluripotent stem cells
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can give rise to all of the cell types in the body - embryonic stem cells
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multipotent stem cells
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can develop into a limited number of different cell types - ex. adult stem cells and cord blood stem cells
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implantation
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about a week after conception, the outer cells form a shell that will become the PLACENTA - these cells must embed themselves into the lining of the uterus ; about 50% of natural conceptions do not successfully implant
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embryo (weeks 3-8)
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cells begin to take a shape - the embryo - begins when a thin line (primitive streak) appears down the center of the cell mass ; neural tube, CNS 4 weeks: embryo is 3mm long and has a head; minuscule blood vessel (heart) begins to pump 5 weeks: arms and legs start to emerge ; upper arms, forearms, palms, and webbed fingers grow ; legs, knees, feet, and webbed toes - 52 days: fingers separate - 54 days: toes separate 7 weeks: embryo is about 2cm long; eyes, nose, digestive system, and some toes have developed 8 weeks: emberyo weighs 1 gram and is 1 inch long; has all organs (except sex organs) ; moves frequently (150 mph) but movement is random and imperceptible to the woman
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ultrasound
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high frequency sound; waves bounce back when they hit tissues of differing densities ; waves are translated into an image of internal organs or of the fetus
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sonogram
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image produced by an ultrasound
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fetus
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9 weeks: sex organs develop - male fetuses experience a rush of testosterone, affecting the brain 3 months: fetus weighs 3 oz, is 3 inches long (3 months/3 ounces/3 inches)
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age of viability
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age past the time of conception (about 22 weeks) at which a fetus can survive outside of the mother's womb (with specialized medical care)
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average prenatal weights
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8 weeks - end of embryonic period: 1/30 oz (1 gram) 13 weeks - end of first trimester: 3 oz (85 g) 22-25 weeks - age of viability: 20-32 oz (565-900 g) 26-28 weeks - end of second trimester: 2-3 lbs (900-1,400 g) 35 weeks - end of preterm period: 5.5 lbs (2,500 g) 38 weeks - full term: 7.5 lbs (3,400 g)
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Apgar scale
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acronym for the assessment of newborn health (5 vital signs) 1. Appearance (color) 2. Pulse (heart rate) 3. Grimace (cry) 4. Activity (muscle tone) 5. Respiration (breathing)
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cesarean section (c-section)
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surgical birth in which incisions through the mother's abdomen and uterus allow the fetus to be removed quickly instead of being delivered through the vagina - increase medical complications after birth and reduce breast-feeding - raise rate of childhood obesity because they lack beneficial but bacteria
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doula
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a woman who helps with the birth process, including massage during birth and help with breast-feeding - beneficial for immigrant, low-income, or single women who may be intimidated by large hospitals or docto5rs
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Brazelton Neonatal Behavioral Assessment Scale (NBAS)
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test often administered to newborns that measures responsiveness and records 46 behaviors, including 20 reflexes
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reflex
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unlearned, involuntary action or movement in response to a particular stimulus ; occurs without conscious throught
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postpartum depression
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8-15% of women experience a sense of inadequacy and sadness (baby blues to postpartum psychosis)
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couvade
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paternal experiences of pregnancy and birth (weight gain and indigestion during pregnancy and pain during labor)
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8. What major event occurs to end the germinal period?
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10-12 days after conception, implantation occurs, in which the developing organism burrows into the tissues that lines the uterus where it will be nourished - the shapeless cell mass takes shape and become an embryo
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9. What body parts develop during the embryonic period?
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the CNS and facial features begin to form upper arm, forearm, palms, webbed fingers legs, knees, feet, webbed toes
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10. What crucial developments occur about halfway through the fetal period
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months 4-6 is the period of the greatest brain growth - it increases about 6 times in size; develops new neurons/synapses and divides into hemispheres - CNS begins to regulate basic body functions (breathing and sucking)
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11. What does the Apgar scale measure?
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Appearance Pulse Grimace Activity Respiration
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12. Advantages and disadvantages of cesarean sections?
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+ usually safe for the mother and baby when the head is too large for the pelvis; can plan when to give birth - increase post-birth complications and reduce breast-feeding - children have double the rate of childhood obesity due to a lack of beneficial bacteria in the guts of babies delivered surgically
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13. In what ways do doulas support women before, during, and after giving birth?
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use time contractions, massage the mother, provide encouragement, help couples decide when to leave home for the hospital, help breastfeed
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14. What in the newborn's appearance and behavior helps with parental bonding>
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big hairless head, tiny toes/hands/feet cause new parents to swoon and feel protective newborns stare, cry, stop crying, and cuddle in the first hours of life, which aid in bonding
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15. How do fathers experience pregnancy and birth?
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Many fathers experience biological symptoms of pregnancy and birth along with the mother (weight gain, indegestion and pain during pregnancy) > known as couvade
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16. What are the signs of postpartum depression
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new mother might seem euphoric after birth - unable to sleep/stop talking, or keep from worrying following this high, she might "crash" and have trouble caring for her newborn because she is overwhelmed by sadness and feelings on inadequacy
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17. In the LAST trimester of pregnancy, the fetus' weight increases:
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by more than a factor of 2
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Down syndrome (trisomy 21)
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condition in which a person has 47 chromosomes instead of the usual 46 - with 3 chromosomes (instead of 2) in the 21st position - often have a distinctive appearance: think tongue, round face, slanted eyes, hearing problems, heart abnormalities, muscle weakness, and are short
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fragile X syndrome
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genetic condition caused by more than 200 repititions of one gene (involves the X chromosome) that causes slow cognitive development
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teratogen
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anything (drugs, viruses, pollutants, malnutrition, stress, etc - that can impair prenatal development, increasing the risk of prenatal abnormalities and birth complications
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behavioral teratogens
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agents and conditions that can harm the prenatal brain, impairing the future child's intellectual and emotional functioning
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critical period
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First days and weeks are critical for body formation. Final months are important for body weight. Health during the entire fetal period is important for brain development
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threshold effect
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situation in which a certain teratogen is relatively harmless in small doses but becomes harmful ones exposure reaches a certain level
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fetal alchohol syndrome (FAS)
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a cluster of birth defectws (including abnormal facial characteristics, slow physical growth, and intellectual disabilities) that may occur in the child of a woman who drinks alcohol while pregnant
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maternal genes on the prenatal environment
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one allele results in loww levels of folic acid in the mother's bloodstream ; this deficiency, via the placenta, affects the embryo, which may develop neural tube defects (spina bifida - tail of the spine is not enclosed properly or anencephaly - part of the brain is missing)
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cerebral palsy
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disorder that results from damage to the brain's motor centers > incurs difficulty with muscle control - impaired speech and/or body movement
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anoxia
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a lack of oxygen that, if prolonged, can cause brain damage or death
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false positives
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result of a lab test (blood, urine, sonogram) that suggests an abnormality that is not present
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low birthweight (LBW)
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a body weight at birth of less than 5.5 lbs (2,500 g)
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very low birth weight (VLBW)
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a body weight at birth of less than 3 lbs, 5 oz (1,500 g)
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extremely low birth weight (ELBW)
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a body weight at birth of less than 2 lbs, 3 oz (1,000g)
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preterm birth
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birth that occurs at 35 weeks or fewer after the date of conception
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small for gestational age (SGA) or small-for-dates
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having a body weight at birth that is significantly lower than expected, given the time since conception
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immigrant paradox
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immigrants tend to be healthier than U.S.-born residents of the same ethnicity - first evident among Mexican-Americans
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heritability
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statistic that indicates what percentage of the variation in a trait within a population, in a particular context and era can be traced to genes
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the presence of three rather than two chromosomes at a particular location
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trisomy refers to
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down syndrome
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Alaina is pregnant and has undergone prenatal testing. The initial tests raised some red flags, and a subsequent DNA test confirmed that the fetus does in fact have three copies of chromosome 21, or:
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increase greatly
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Yuko is a 32-year-old woman in Kyoto, Japan. She has accepted a job in San Jose, California, and is preparing to immigrate to the United States. In the United States, Yuko's alcohol consumption will most likely:
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none
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Ann gave birth 37 weeks after conception. Her baby weighed 6 pounds, 1 ounce. Ann's baby was _____ birthweight. low very low extremely low or none
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very low birth weight
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Birth weight that is less than 3 pounds 5 ounces
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extremely low birth weight
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birth weight that is less than 2 pounds 3 ounces
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low birth weight
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birth weight that is 5 1/2 pounds or less
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down syndrome
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Helena is 40 years old and has just conceived her first child. Her age at conception means that she has a GREATER risk of having a fetus with:
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nature and nuture
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Heritability statistics reflect:
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teratogens
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Six-year-old Austin is hyperactive and has been tested for ADHD. A school psychologist suggests that Austin's hyperactivity might reflect the influence of some prenatal substance that did not affect his physical development, but instead influenced the development of his brain. Austin might be showing the effects of behavioral _____ that his mother ingested while he was in the womb. teratogens couvades trisomies anoxias
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longitudinal
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A researcher selects a sample of children with two myopic parents. She assess the children over a 10-year period, when they are 6, 8, 10, 12, 14, and 16 years old. Because the same participants are tracked for an extended period, the researcher's study exemplifies a(n) ______ design. longitudinal experimental cross-sectional correlational
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cerebral palsy
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Melanie, who is 18 years old, continued drinking alcohol and smoking cigarettes during her pregnancy. When she gave birth at 34 weeks, her daughter weighed 4 pounds. Now 9 months old, her daughter is not sitting up by herself and is showing signs of other motor control difficulties. She may have: Please choose the correct answer from the following choices, and then select the submit answer button. fragile X syndrome. cerebral palsy. Huntington disease. anoxia.
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low
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Belinda gave birth 36 weeks after conception. Her baby weighed 5 pounds, 2 ounces. Belinda's baby was _____ birthweight. Please choose the correct answer from the following choices, and then select the submit answer button. extremely low very low low
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16 year old donna
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Who is MOST likely to give birth to a low-birthweight child? Please choose the correct answer from the following choices, and then select the submit answer button. 25-year-old May Ling, who gained 25 pounds during her pregnancy 21-year-old Janice, who was herself a low-birthweight baby 30-year-old Maria, who has already given birth to four children 16-year-old Donna, who diets frequently despite being underweight
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Dr. Chan recognizes a link between reduced hours spent in daylight and rising rates of myopia.
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Dr. Chan has diagnosed 8-year-old Hsu with myopia (nearsightedness). He recommends that Hsu should spend more time playing outside in the sun. Why would Dr. Chan make this recommendation? Please choose the correct answer from the following choices, and then select the submit answer button. Dr. Chan does not want to prescribe glasses for Hsu. Dr. Chan recognizes a link between reduced hours spent in daylight and rising rates of myopia. There is no reason for Dr. Chan to make this recommendation. Dr. Chan thinks that Hsu needs more vitamin A to slow down the progression of myopia.
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being low birth weight
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Jillian is 22 years old and pregnant, on food stamps, and often skips meals. Her baby may be at an increased risk of: Please choose the correct answer from the following choices, and then select the submit answer button. being low-birthweight. having Down syndrome. being high-birthweight. experiencing anoxia.
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huntington disease
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a disease caused by a repitition on a single gene, not an extra chromosome.
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cystic fibrosis
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A genetic disorder that is present at birth and affects both the respiratory and digestive systems.
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Rett syndrome
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Neurodevelopment of child (girl, as boys die in utero) fails between age 1-4, with poor head growth -X linked
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more or fewer than 46 chromosomes.
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Chromosomal abnormalities occur when the zygote's cells have: Please choose the correct answer from the following choices, and then select the submit answer button. 23 pairs of chromosomes. gametes with 23 chromosomes. 46 chromosomes, with damage to at least four. more or fewer than 46 chromosomes.
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cerebral palsy
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a disease marked by difficulties with movement
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anoxia
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deprivation of oxygen
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Couvades
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refers to pregnancy symptoms experienced by men.
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unlike; dominant
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____ most other genetic disorders, Huntington disease is a _____ disorder. Please choose the correct answer from the following choices, and then select the submit answer button. Like; dominant Unlike; dominant Like; recessive Unlike; recessive
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very low
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Bonnie gave birth 36 weeks after conception. Her baby weighed 3 pounds, 4 ounces. Bonnie's baby was _____ birthweight. Please choose the correct answer from the following choices, and then select the submit answer button. extremely low low very low none of these
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underweight
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Lily has always been considered thin, and she only gained 12 pounds in the last six months of her pregnancy. Her baby will likely be _____ at birth. Please choose the correct answer from the following choices, and then select the submit answer button. extremely low birthweight underweight of appropriate weight preterm
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more likely to have effects on brain development than on physical development.
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When it is consumed later in pregnancy, alcohol is a behavioral teratogen. This means that, as compared to its consumption earlier in pregnancy, alcohol consumed later in pregnancy is: Please choose the correct answer from the following choices, and then select the submit answer button. likely to have less severe effects. more likely to have effects on physical development than on brain development. likely to have more severe effects. more likely to have effects on brain development than on physical development.
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keeping alc out of their home until their children are cognitively more mature
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Cecil and Georgia both have parents who were alcoholics. Knowing that alcoholism can be influenced by genetics, they can help their two children to fight this genetic tendency by: Please choose the correct answer from the following choices, and then select the submit answer button. ignoring the issue completely. giving them alcohol from a very young age. keeping them isolated to limit peer exposure. keeping alcohol out of their home until their children are cognitively more mature.
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epigenetics
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Dr. Dubois conducts twin and family studies in different cultures to explore environmental factors influence the expression of genetic tendencies toward alcoholism. Recall the textbook's discussion of nature and nurture in Chapter 1. Dr. Dubois specializes in an emerging field called: Please choose the correct answer from the following choices, and then select the submit answer button. genetics. life-span development. epigenetics. meta-analysis.
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suffered several months of prenatal malnutirtion
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At birth, Clarence was classified as small for gestational age. It is likely that Clarence: Please choose the correct answer from the following choices, and then select the submit answer button. suffered several months of prenatal malnutrition. was born in a rural hospital. was born in a large city hospital. comes from a family with a history of such births.
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both SGA and LBW
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Kareem was born 36 weeks after conception. He weighed 5 pounds, 3 ounces. Kareem was: Please choose the correct answer from the following choices, and then select the submit answer button. LBW, but not SGA. neither LBW nor SGA. SGA, but not LBW. both SGA and LBW.
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psychological
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Greg has been an alcoholic for many years, despite numerous attempts to stop drinking. His father calls him weak, immoral, and a failure, and thinks that he can "cure" Greg by punishing him for his drinking. However, his father may be a bit hypocritical since Greg's inherited biochemistry and _____ traits, such as a tendency toward anger, have most likely made him more vulnerable to alcoholism. Please choose the correct answer from the following choices, and then select the submit answer button. moral intellectual adult psychological
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polygenic
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affected by many genes
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multifactoral
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influenced by many factors
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punnett square
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A chart that shows all the possible combinations of alleles that can result from a genetic cross
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thalassemia
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is an inherited blood disorder in which the body makes an abnormal form of hemoglobin.
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Recessive
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most gene disorders are recessive/dominant
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genetic vulnerability
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Some zygotes carry genes that make them vulnerable. Male fetuses are more vulnerable to teratogens than female ones. Neural-tube defects are more common in certain ethnic groups (e.g., Irish, English, and Egyptian).
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1. germinal 2. embryonic 3. fetal
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3 main periods of prenatal development
