1.
addition rule: the rule of probability of any one of two or more mutually exclusive events occurring can be determined by adding their individual probabilites
2.
alleles (1st part of Mendel's model): alternative versions of a gene; account for variations in inherited characters
3.
alleles of that gene (2nd part of Mendel's model): for each character, an organism inherits two copies of a gene, one from each parent
4.
alternation of generations: a life cycle in which there is both a multicellular diploid form, the sporophyte, and a multicellular haploid form, the gametophyte; characteristic of plants and some algae
5.
amniocentesis: a technique associated with prenatal diagnosis in which amniotic fluid is obtained by aspiration from a needle inserted into the uterus; the fluid and the fetal cells are analyzed
6.
asexual reproduction: a single individual is the sole parent and passes copies of all its genes to its offspring without the fusion of gametes
7.
autosomes: a chromosome that is not directly involved in determining sex; not a sex chromosome
8.
blending hypothesis: the idea that genetic material contributed by the two parents mixes in a manner analogous to the way blue and yellow paints blend to make green
9.
carrier: an individual that is heterozygous for a disorder or disease that could transmit the recessive allele to their offspring
10.
character: an observable heritable feature that varies among individuals (ex: color of the flower)
11.
chiasmata: the x-shaped region where crossing over has occurred earlier in prophase I between non-sister chromatids
12.
chorionic villus sampling (CVS): a technique associated with prenatal diagnosis in which a small sample of the fetal portion of the placenta is removed by insertion of a narrow tube through the cervix into the uterus and suctions
13.
clone: a group of genetically identical individuals
14.
codominance: two alleles each affect the phenotype in separate, distinguishable ways (ex: AB blood type=A and B carbohydrates on surface of blood cell)
15.
complete dominance: one allele in a pair showed dominance over the other
16.
consanguineous mating: a man and woman closely related mating; offspring more prone to disorders (ex: Jews or of Jewish descent have higher risks of having tay-sachs disease)
17.
crossing over: the exchange of genetic material between non-sister chromatids during prophase I of meiosis
18.
cystic fibrosis: genetic disorder caused by a recessive allele for a chloride channel protein; characterized by an excessive secretion of mucus and consequent vulnerability to infection, fatal if untreated
19.
dihybrid: heterozygous for two characters being followed in the cross (ex: YyRr)
20.
diploid cell: any cell with two chromosome sets (human: 2n=46)
21.
dominant allele (3rd part of Mendel's model): determines the organism's appearance
22.
epistasis: the phenotypic expression of a gene at one locus alters that of a gene at a second locus (ex: Ee-pigment deposition and Bb-codes for color; without pigment deposition no color can be shown)
23.
f1 generation: first filial generation; the hybrid offspring from the p generation
24.
f2 generation: second filial generation; the offspring from the f1 hybrids that were allowed to self polinate
25.
fertilization: the union of haploid gametes to form a diploid zygote
26.
fetoscopy: a needle thin tube containing a viewing scope and light is inserted into the uterus
27.
gametes: reproductive cells; a haploid reproductive cell such as an egg or sperm; gametes unite during sexual reproduction to produce a diploid zygote
28.
genes: a discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA endowed by parents
29.
genetics: the scientific study of heredity and hereditary variation
30.
genotype: an organism's genetic makeup
31.
germ cells: gametes develop form specialized cells in the gonads (ovaries and testes)
32.
haploid cell: gametes contain a single set of chromosomes (human: n=23)
33.
heredity: the transmission of traits from one generation to the next
34.
heterozygous: two different alleles for a character or gene
35.
homologous chromosomes or homologs: two chromosomes composing a pair have the same length, centromere position, and staining pattern
36.
homologous pairs at the metaphase plate: during metaphase I chromosomes are positioned at metaphase plate as pairs of homologs rather than individual chromosomes like in metaphase of mitosis
37.
homozygous: a pair of identical alleles for a character or gene
38.
huntington's disease: a degenerative disease caused by a lethal dominant allele that has no obvious phenotypic effect until between the ages of 35-45 and is deadly within 10-20 yrs; characterized by uncontrollable body movements and degeneration of nervous system
39.
hybridization: the mating, or crossing of two true breeding varieties
40.
incomplete dominance: neither allele is completely dominant, phenotype is a blend between the two parental varieties (ex: red snapdragon and white snapdragon= pink snapdragon)
41.
karyotype: a display of the chromosome pairs of a cell arranged by size and shape
42.
law of independent assortment: Mendel's second law; states that each pair of alleles segregates or assorts independently of each other pair during gamete formation
43.
law of segregation (4th part of Mendel's model): Mendel's first law; stating that the two alleles in a pair segregate into different gametes during gamete formation
44.
life cycle: the generation-to-generation sequence of stages in the reproductive history of an organism, from conception to production of its own offspring
45.
locus: a gene's specific location along the length of a chromosome
46.
meiosis: a cell division in sexually reproducing organisms consisting of two rounds of cell division but only one round of DNA replication; results in cells with half the number of chromosome sets as the original cell
47.
meiosis I: the first division of a two stage process of cell division in sexually reproducing organisms; aka reductional division
48.
meiosis II: the second division of a two stage process of cell division in sexually reproducing organisms; aka equational division
49.
monohybrid: heterozygous for one particular character being followed in the cross (ex: Aa)
50.
multifactorial: many factors both genetic and environment influence phenotype
51.
multifactorial disorders: a genetic component plus a significant environmental influence (ex: heart disease, diabetes, cancer, alcoholism, certain mental illnesses like schizophrenia and bipolar)
52.
multiple alleles: multiple alleles exist for a single gene (ex: ABO blood type)
53.
multiplication rule: the rule of probability of two or more independent events occurring together can be determined by multiplying their individual probabilites
54.
norm of reaction: the range of phenotypes produced by a single genotype, due to environmental influences (ex: hydrangea flower color varies on environment)
55.
p generation: parental generation or the true breeding parents
56.
particulate hypothesis of inheritance: parents pass on discrete heritable units (genes) that retain their separate identities in offspring; like playing cards that can be shuffled and passed along after generation
57.
pedigree: a diagram of a family tree with conventional symbols, showing the occurrence of heritable characters in parents and offspring over multiple generations
58.
phenotype: an organism's appearance or observable traits
59.
phenylketonuria (PKU): a recessively inherited disorder that causes the inability to properly metabolize phenylalanine which can accumulate to toxic levels in the blood causing severe intellectual disability (mental retardation)
60.
pleitrophy: the ability of a single gene to have multiple effects (ex: cystic fibrosis and sickle cell disease)
61.
polygenic inheritance: an additive effect of two or more genes on a single phenotypic character
62.
punnett square: a diagrammatic device for predicting the allele composition of offspring from a cross between individuals of known genetic makeup
63.
quantitative characters: a heritable character that varies continuously over a range rather than in an either-or fashion
64.
recessive allele (3rd part of Mendel's model): has no noticeably effect on the organism's appearance
65.
recombinant chromosomes: a chromosome created when crossing over combines DNA from two parents into a single chromosome
66.
separation of homologs: during anaphase I duplicated chromosomes of each homologous pair move toward opposite poles, but sister chromatids remain attached unlike anaphase of mitosis the sister chromatids separate
67.
sex chromosomes: a chromosome responsible for determining the sex of an individual; X and Y
68.
sexual reproduction: two parents give rise to offspring that have unique combinations of genes inherited from the two parents via gametes
69.
sickle cell disease: most common among african descent; recessive inherited blood disease in which a single nucleotide change in the hemoglobin protein of RBCs causes an abnormal variety causing symptoms like clog small vessels, physical weakness, pain, organ damage, and paralysis
70.
somatic cell: all cells of the body except the gametes and their precursors
71.
synapsis: the pairing and physical connection of duplicated homologous chromosomes during prophase I of meiosis
72.
synapsis and crossing over: during prophase I duplicated homologs pair up and form the synaptonemal complex between them holds them in synapsis then follows crossing over
73.
tay-sachs disease: a genetic disease caused by a recessive allele for a dysfunctional enzyme, leading to accumulation of certain lipids in the brain; causes seizures, blindness, and degeneration of motor and mental performance usually show after a few months after birth followed by death in a few years
74.
testcross: breeding an organism of unknown genotype with a recessive homozygote to reveal the unknown genotype of an organism
75.
trait: one of two or more detectable variants in a genetic character
76.
true breeding: referring to organisms that produce offspring of the same variety over many generations of self-pollination
77.
ultrasound: imaging technique to examine a fetus directly for major anatomical abnormalities; reflected sound waves are used to produce an image
78.
variation: differences between members of the same species
79.
zygote: a fertilized egg; is diploid since contains one set of maternal and paternal chromosomes
