Term
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Definition
| Union of sperm and ovum to produce a zygote; also called conception |
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Term
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Definition
| one- celled organism resulting from fertilization |
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Term
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Definition
| Twins conceived by the union of two different ova (or a single ovum that has split) with two different sperm cells. (Fraternal twins) No more alike genetically than any other sibling. |
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Term
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Definition
| Twins resulting from the division of a single zygote after fertilization. (Identical twins) They are genetically similar. |
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Term
DNA
(deoxyribonucleic acid) |
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Definition
| Chemical that carries inherited instructions for the development of all cellular forms of life. |
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Term
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Definition
| Sequence of bases within the DNA molecule; governs the formation of proteins that determines the structure and functions of living cells. |
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Term
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Definition
| Coils of DNA that consist of genes. |
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Term
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Definition
| Small segments of DNA located in definite positions on particular chromosomes; functional units of heredity. |
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Term
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Definition
| Complete sequence of genes in the human body. |
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Term
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Definition
| In the humans, the 22 pairs of chromosomes not related to sexual expression. |
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Term
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Definition
| Pair of chromosomes that determines sex: XX in the normal human female, XY in the normal human male. |
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Term
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Definition
| Two or more alternative forms of a gene that occupy the same position on paired chromosomes and affect the same trait. |
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Term
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Definition
| Possessing two identicle alleles for a trait |
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Term
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Definition
| Possessing differing alleles for a trait. |
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Term
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Definition
| Pattern of inheritance in which, when a child recieves different alleles, only the dominant one is expressed. |
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Term
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Definition
| Pattern of inheritance in which a child recieves identicle recessive alleles, resulting in expression of a nondominant trait. |
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Term
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Definition
| Pattern of inheritance in which multiple genes at different sites on chromosomes affect a complex trait. |
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Term
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Definition
| Permanent alterations in genes or chromosomes that may produce harmful characterisics. |
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Term
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Definition
| Observable characteristics of a person. |
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Term
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Definition
| Genetic makeup of a person, containing both expressed and unexpressed characteristics. |
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Term
| Multifactorial Transmission |
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Definition
| Combination of genetic and environmental factors to produce certain complex traits. |
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Term
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Definition
| Mechanism that turns genes on or off and determines functions of body cells. |
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Term
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Definition
| Pattern of inheritance in which a child recieves two different alleles, resulting in partial expression of a trait. |
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Term
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Definition
| Pattern of inheritance in which certain characteristics carried on the X chromosome inherited from the mother are transmitted differently to her male and female offspring. |
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Term
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Definition
| Chromosomal disorder characterized by moderate-to-severe mental retardation and by such physical signs as downward-sloping skin fold at the inner corners of the eyes. |
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Term
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Definition
| Clinical service that advises prospective parents of their probable risk of having children with hereditary defects. |
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Term
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Definition
| Quantitiative study of relative heredity and environmental influences on behavior. |
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Term
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Definition
| Statistical estimate of contribution of heredity to individual differences in a specific trait within a given population. |
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Term
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Definition
| Term describing tendency of twins to share the same trait or disorder. |
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Term
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Definition
| Potential variability, depending on environmental conditions, in the expression of a heredity trait. |
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Term
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Definition
| Limitation on varience of expression of certain inherited characteristics. |
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Term
| Genotype- Environment Interaction |
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Definition
| The portion of phenotype variation that results from the reactions of genetically different individuals to similar environmental conditions. |
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Term
| Genotype-Environment Correlation |
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Definition
| Tendency of certain genetic and environmental influences to reinforce each other; may be passive, reactive (evocative), or active. Also called genotype- environment covariance. |
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Term
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Definition
| Tendency of a person, especially after early childhood, to seek out environments compatible with his or her genotype. |
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Term
| Nonshared Environmental Effects |
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Definition
| The unique environmentin which each child grows up, consisting of distinctive influences or influences that affect one child differently than another. |
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Term
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Definition
| Extreme overweight in relation to age, sex, height and body type. |
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Term
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Definition
| Characteristic disposition, or style of approaching and reacting to situations. |
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Term
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Definition
| Mental disorder marked by loss of contact with reality; symptoms include hallucinations and delusions. |
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Term
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Definition
| Period of development between conception and birth. |
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Term
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Definition
| Age of an unborn baby, usually dated from the first day of an expectant mother's last menstrual cycle. |
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Term
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Definition
| First 2 weeks of prenantal development, characterized by rapid cell division, blastocyst formation, and implantation in the wall of the uterus |
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Term
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Definition
| Second stage of gestation (2-8 weeks) Characterizedby rapid growth and development of major body systems and organs. |
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Term
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Definition
| Natural expulsion from the uterus of an embryo that cannot survive outside the womb (miscarriage) |
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Term
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Definition
| Final stage of gestation (from 8 weeks to birth), characterized by increased differentiation of body parts and greatly enlarged body size. |
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Term
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Definition
| Prenantal medical procedure using high-frequency sound waves to detect the outline of a fetus and it's movements, so as to determine whether a pregnancy is progressing normally. |
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Term
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Definition
| Capable of causing birth defects. |
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Term
Fetal Alcohol Syndrome
(FAS) |
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Definition
| Combination of mental, motor, and developmental abnormalities affecting the offspring of some women who drink heavily during pregnancy. |
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Term
AIDS
(Acquired Immune Deficiency Syndrome) |
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Definition
| Viral disease that undermines effective functioning of the immune system. |
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Term
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Definition
| Physical or psychological demands on a person or organism. |
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