Chapter Three - Forming a New Life

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Fertilization, the union of an ovum and a sperm, results in the formation of what?
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Terms in this set (97)
Fertilization, the union of an ovum and a sperm, results in the formation of what?
A One-Celled Zygote.
Following the formation of the one-celled zygote it then does what?
Duplicates itself by cell division.
Multiple births can occur by either:
The fertilization of two ova (or one ovum that has split) or by the splitting of one fertilized ovum.
Higher multiple births result from:
Either the fertilization of two ova (or one ovum that has split) or by the splitting of one fertilized ovum, or a combination of the two.
Twins that have different genetic makeups and may be of different sexes are called
Dizygotic (fraternal) Twins.
Do Monozygotic (identical) Twins typically have much the same or much different genetic makeups?
Much the same.
Fertilization
Union of sperm and ovum to produce a zygote, also called conception.
Zygote
One-celled organism resulting from fertilization.
Dizygotic Twins
Twins conceived by the union of two different ova (or a single ovum that has split) with two different sperm cells; also called fraternal twins; they are no more alike genetically than any other siblings.
Monozygotic Twins
Twins resulting from the division of a single zygote after fertilization; also called identical twins; they are genetically similar.
The basic functional units of heredity areThe genes.Genes are made ofDeoxyribonucleic acid (DNA).DNA carries what?The biochemical instructions, or genetic code, that governs the development of cell functions.The complete sequence of genes in the human body is called?The Human Genome.Deoxyribonucleic Acid (DNA)Chemical that carries inherited instructions for the development of all cellular forms of life.Genetic CodeSequence of bases within the DNA molecule; governs the formation of proteins that determine the structure and functions of living cells.ChromosomesCoils of DNA that consist of genesGenesSmall segments of DNA located in definite positions on particular chromosomes, functional units of heredity.Human GenomeComplete sequence of genes in the human body.MutationsPermanent alterations in genes or chromosomes that may produce harmful characteristics.At conception, each normal human being receives how many chromosomes from mom and how many from dad?23 chromosomes from mom and 23 from dad.What forms the 23 pairs of chromosomes?22 pairs of autosomes and 1 pair of sex chromosomes.A child who receives an X chromosome from each parent is genetically what?Female.A child who receives a Y chromosome from the dad is what?Male.The simplest patterns of genetic transmission are:Dominant and Recessive Inheritance.When a pair of alleles are the same, a person is what?Homozygous.When a pair of alleles are different, a person is what?Heterozygous.AutosomesIn humans, the 22 pair of chromosomes not related to sexual expression.Sex ChromosomesPair of chromosomes that determines sex: XX in the normal human female, XY in the normal human male.AllelesTwo or more alternative forms of a gene that occupy the same position on paired chromosomes and affect the same trait.HomozygousPossessing two identical alleles for a trait.HeterozygousPossessing differing alleles for a trait.Dominant InheritancePattern of inheritance in which, when a child receives different alleles, only the dominant one is expressed.Recessive InheritancePattern of inheritance in which a child receives identical recessive alleles, resulting in expression of a non dominant trait.Most normal human characteristics are the result of what?Polygenic or multifactorial transmission.Except for most monozygotic twins, each child inherits a what?Unique genotype.Dominant Inheritance and Multifactorial Transmission explain what?Why a person's phenotype does not always express the underlying genotype.The Epigenetic Framework controls what?The functions of particular genes.The Epigenetic framework is affected by what?Environmental factors.Polygenic InheritancePattern of inheritance in which multiple genes at different sites on chromosomes affect a complex trait.PhenotypeObservable characteristics of a person.GenotypeGenetic makeup of a person, containing both expressed and unexpressed characteristics.Multifactorial TransmissionCombination of genetic and environmental factors to produce certain complex traits.EpigenesisMechanism that turns genes on or off and determines functions of body cells.Birth defects and diseases may result from what?Simple dominant, recessive, or sex-linked inheritance, from mutations, or from genome imprinting.Chromosomal abnormalities can cause what?Birth defects.Incomplete DominancePattern of inheritance in which a child receives two different alleles, resulting in partial expression of a trait.Sex-linked InheritancePattern of inheritance in which certain characteristics carried on the X chromosome inherited from the mother are transmitted differently to her male and female offspring.Down SyndromeChromosomal disorder characterized by moderate-to-severe mental retardation and by such physical signs as a downward-sloping skin fold at the inner corners of the eyes. Also called Trisomy-21.Genetic CounselingClinical service that advises prospective parents of their probable risk of having children with hereditary defects.Research in behavioral genetics is based on what?The assumption that the relative influences of heredity and environment withing a population can be measured statistically.If heredity is an important influence on a trait, genetically close persons will be more similar or more different in that trait?Similar.Family studies, adoption studies, and studies of twins enable researches to measure what?The heritability of specific traits.Concepts that describe ways in which heredity and environment work together are (5):Reaction Range, Canalization, Genotype-environment interaction, genotype-environment correlation (or covariance), and niche-picking.Siblings tend to be more different than alike in what?Intelligence and personality.According to some behavioral geneticists, heredity accounts for most of the similarity or difference?Similarity.According to some behavioral geneticists, nonshared environmental effects account for most of the similarity or difference?Difference.Behavioral GeneticsQuantitative study of relative hereditary and environmental influences on behavior.HeritabilityStatistical estimate of contribution of heredity to individual differences in a specific trait within a given population.ConcordantTerm describing tendency of twins to share the same trait or disorder.Reaction RangePotential variability, depending on environmental conditions, in the expression of a hereditary trait.CanalizationLimitation on variance of expression of certain inherited characteristics.Genotype-environment InteractionThe portion of phenotypic variation that results from the reactions of genetically different individuals to similar environmental conditions.Genotype-Environment CorrelationTendency of certain genetic and environmental influences to reinforce each other, may be passive, reactive (evocative) or active. Also called genotype-environment covariance.Niche-PickingTendency of a person, especially after early childhood, to seek out environments compatible with his or her genotype.Nonshared Environmental EffectsThe unique environment in which each child grows up, consisting of distinctive influences or influences that affect one child differently than another.Obesity, longevity, intelligence, temperment, and other aspects of personality are influenced by what?Both heredity and environment.A highly heritable neurological disorder that also is environmentally influenced is?Schizophrenia.ObesityExtreme overweight in relation to age, sex, height, and body type as defined by having a body mass index at or above the 95th percentile.TemperamentCharacteristic disposition, or style of approaching and reacting to situations.SchizophreniaMental disorder marked by loss of contact with reality; symptoms include hallucinations and delusions.What are the 3 stages of gestation that prenatal development occur in?Germinal, Embryonic, and Fetal Stages.What often happens to severely defective embryos in the first trimester of pregnancy?Spontaneously aborted.As fetuses grow they:move less, but more vigorously.Swallowing amniotic fluid stimulates what for the fetuses?Taste and smell.Fetuses seem able to:Hear, exercise sensory discrimination, learn, and remember.GestationPeriod of development between conception and birth.Gestational AgeAge of an unborn baby, usually dated from the first day of an expectant mother's last period.Germinal StageFirst two weeks of prenatal development, characterized by rapid cell division, blastocyst formations, and implantation in the well of the uterus.ImplantationThe attachment of the blastocyst to the uterine wall at about day 6.Embryonic StageSecond stage of gestation (2 to 8 weeks), characterized by rapid growth and development of major body systems and organs.Spontaneous AbortionNatural expulsion from the uterus of an embryo that cannot survive outside the womb; also called miscarriage.Fetal StageFinal stage of gestation (from 8 weeks to birth), characterized by increased differentiation of body parts and greatly enlarged body size.UltrasoundPrenatal medical procedure using high-frequency sound waves to detect the outline of a fetus and its movements, so as to determine whether a pregnancy is progressing normally.The developing organism can be greatly affected by?It's prenatal environment.The likelihood of a birth defect may depend on?The timing and intensity of an environmental event and its interaction with genetic factors.Important environmental influences involving the mother include:Nutrition, smoking, intake of alcohol or other drugs, transmission of maternal illnesses or infections, maternal stress, anxiety, or depression, maternal age and physical activity, and external environmental hazards (ex. chemicals and radiation).External influences can also affect what?The fathers sperm.TeratogenEnvironmental agent, such as a virus, a drug, or radiation, that can interfere with normal prenatal development and cause developmental abnormalities.Fetal Alcohol Syndrome (FAS)Combination of mental, motor, and developmental abnormalities affecting the offspring of some women who drink heavily during pregnancy.Acquired Immune Deficiency Syndrome (AIDS)Viral disease that undermines effective functioning of the immune system.StressPhysical or psychological demands on a person or organism.What can be used to determine whether an unborn baby is developing normally?Ultrasound, sonoembryology amniocentesis, chorionic villus sampling, fetoscopy, preimplantation genetic diagnosis, umbilical cord sampling, and maternal blood tests.Early, high quality prenatal care can lead to detection of what?Defects and disorders and, may help reduce maternal and infant death, low birth weight, and other birth complications.Racial/Ethnic disparities in prenatal care may be a factor in disparities in what?Low birth weight and perinatal death.Preconception care for every woman of childbearing age would reduce what?unintended pregnancies.Preconception care for every woman of childbearing age would increase what?Chances of good pregnancy outcomes.