.::Vocabulary of Concepts of Ch.11 Patterns of Inheritance::.

allele	One of two or more molecular forms of a gene that arise by mutation and code for different versions of the same trait.
codominance	In heterozygotes, simultaneous expression of a pair of nonidentical alleles that specify different phenotypes.
continuous variation	Of a population, a more or less continuous range of small differences in a given trait among its individuals.
dihybrid cross	An intercross between two F1 heterozygotes that are identical for two gene loci; the dihybrids are offspring of parents that bred true for different versions of two traits.
epistasis	Interaction among the products of two or more gene pairs.
F1	The offspring of an initial genetic cross.
F2	The offspring of parents who are the first filial generation from a genetic cross.
gene	Unit of information for a heritable trait, passed from parents to offspring.
genotype	Genetic constitution of an individual; a single gene pair or the sum total of an individual's genes.
heterozygous	Having a pair of nonidentical alleles at a gene locus (that is, on a pair of homologous chromosomes).
homozygous dominant	Having a pair of dominant alleles at a gene locus (on a pair of homologous chromosomes).
homozygous recessive	Having a pair of recessive alleles at a gene locus (on a pair of homologous chromosomes).
hybrid offspring	Of a genetic cross, offspring having a pair of nonidentical alleles for a trait.
incomplete dominance	Condition in which one allele of a pair is not fully dominant; a heterozygous phenotype somewhere between both homozygous phenotypes emerges.
independent assortment	Mendelian theory that by the end of meiosis, each pair of homologous chromosomes (and linked genes on each one) are sorted before shipment to gametes independently of how the other pairs were sorted. Later modified to account for the disruptive effect of crossing over on linkages.
monohybrid cross	Intercross between two F1 heterozygotes that are identical for one gene locus; offspring of two parents that breed true for different forms of a trait.
multiple allele system	Three or more slightly different molecular forms of a gene that occur among individuals of a population.
phenotype	Observable trait or traits of an individual that arise from gene interactions and gene-environment interactions.
pleiotropy	Positive or negative effects on two or more traits owing to expression of alleles at a single gene locus. Effects may or may not emerge at the same time.
probability	The chance that each outcome of a given event will occur is proportional to the number of ways the outcome can be reached.
Punnett-square method	Construction of a simple diagram as a way to predict probable outcomes of a genetic cross.
segregation	Mendelian theory. Sexually reproducing organisms inherit pairs of genes (on pairs of homologous chromosomes), the two genes of each pair are separated from each other at meiosis, and they end up in separate gametes.
testcross	Experimental cross to determine whether an individual of unknown genotype that shows dominance for a trait is either homozygous dominant or heterozygous.
true-breeding lineage	Of sexually reproducing species, a lineage in which only one version of a trait appears over the generations in all parents and their offspring

Ilustrations

allele:

codominance:

continuous variation:

dihybrid cross:

epistasis:

f1:

f2:

gene:

genotype:

heterozygous:

homozygous dominant:

homozygous recessive:

incomplete dominance:

independent assorment:

monohybrid cross:

multiple allele system:

phenotype:

pleitropy:

probability:

punnet square method:

segregation:

testcross:

true breeding lineage:

.::Vocabulary of Concepts of Ch.12: Human Genetics::.

abortion:	Premature, spontaneous or induced expulsion of the embryo or fetus from uterus.
aneuploidy:	Having one extra or one less chromosome relative to the parental chromosome number.
autosome:	Any chromosome of a type that is the same in males and females of the species.
crossing over:	At prophase I of meiosis, an interaction in which non-sister chromatids of a pair of homologous chromosomes break at corresponding sites and exchange segments; genetic recombination is the result.
deletion:	At cytological level, loss of a segment from a chromosome. At molecular level, loss of one to a few base pairs from a DNA molecule.
disease:	Outcome of infection when defenses aren't mobilized fast enough and a pathogen's activities interfere with normal body functions.
double-blind study:	Different investigators independently collect, then compare data.
duplication:	Gene sequence repeated several to many hundreds or thousands of times. Even normal chromosomes have such sequences.
genetic abnormality:	A rare or less common version of a heritable trait.
genetic disorder:	Any inherited condition that causes mild to severe medical problems.
genetic recombination:	Result of any process that puts new genetic information into a DNA molecule (e.g., by crossing over).
homologous chromosome:	Of cells with a diploid chromosome number, one of a pair of chromosomes identical in size, shape, and gene sequence, and that interact at meiosis. Nonidentical sex chromosomes (e.g., X and Y) also interact as homologues during meiosis.
in-vitro fertilization:	Conception outside the body (''in glass'' petri dishes or test tubes).
independent assortment:	Mendelian theory that by the end of meiosis, each pair of homologous chromosomes (and linked genes on each one) are sorted before shipment to gametes independently of how the other pairs were sorted. Later modified to account for the disruptive effect of crossing over on linkages.
inversion:	Part of a chromosome that became oriented in reverse, with no molecular loss.
karyotype:	Preparation of metaphase chromosomes sorted by length, centromere location, other defining features.
linkage group:	All genes on a chromosome.
mosaicism:	Cells of same type express genes differently, so phenotypic differences emerge in same type of tissue. E.g., occurs by X chromosome inactivation in female mammals; also by nondisjunction in any cell after fertilization (only descendants of altered cell inherit the abnormal chromosome number).
Non-disjunction:	Failure of sister chromatids or a pair of homologous chromosomes to separate during meiosis or mitosis. Daughter cells end up with too many or too few chromosomes.
polyploidy:	Having three or more of each type of chromosome in the nucleus of a eukaryotic cell at interphase.
reciprocal cross:	A paired cross. In the first cross, one parent displays the trait of interest. In the second, the other parent displays it.
sex chromosome:	A chromosome with genes that affect sexual traits. Depending on the species, somatic cells have one or two sex chromosomes of the same or different type (e.g., in mammals, XX females, XY males).
syndrome:	A set of symptoms that may not individually be a telling clue but collectively characterize a genetic disorder or disease.
translocation:	Of cells, movement of a stretch of DNA to a new chromosomal location with no molecular loss. Of vascular plants, distribution of organic compounds by way of phloem.
X chromosome:	A type of sex chromosome. An XX mammalian embryo becomes female; an XY pairing causes it to develop into a male.
Y chromosome:	A type of sex chromosome. An XX mammalian embryo becomes female; an XY pairing causes it to develop into a male.

.::Vocabulary of Concepts of Ch.13 and 14. DNA::.

1.      adenine:              A purine; a nitrogen-containing base in certain nucleotides. Base pairs with thymine in DNA.

2.       bacteriophage:  Category of viruses that infect bacterial cells.

3.       cloning: Making a genetically identical copy of DNA or of an organism.

4.       cytosine:              Pyrimidine; one of the nitrogen-containing bases in nucleotides.

5.       deoxyribonucleic acid (DNA):     Of cells and many viruses, the molecule of inheritance. H bonds join its two helically twisted nucleotide strands, one of which has instructions (in its base sequence) for synthesizing all of the enzymes and other proteins required to build and maintain cells.

6.       DNA ligase:         Enzyme that seals new base-pairings during DNA replication.

7.       DNA polymerase:            Enzyme of replication and repair that assembles a new strand of DNA on a parent DNA template.

8.       DNA repair:         Enzyme-mediated process that fixes small-scale alterations in a DNA strand by restoring the original base sequence.

9.       DNA replication:               Any process by which a cell duplicates its DNA molecules before dividing.

10.   guanine:               Nitrogen-containing base in one of four nucleotide monomers of DNA or RNA.

11.   nucleotide:         Small organic compound with deoxyribose (a five-carbon sugar), a nitrogenous base, and a phosphate group. Monomer for adenosine phosphates, nucleotide coenzymes, and nucleic acids.

12.   thymine:              A nitrogen-containing base; one of the nucleotides in DNA (not in RNA).

13.   x-ray diffraction image: Pattern that forms on film exposed to x-rays that have been directed at a molecule; reveals positions of atoms, not the molecular structure.

14.   anticodon:           Series of three nucleotide bases in tRNA; can base-pair with an mRNA codon.

15.   base sequence:                Sequential order of bases in a DNA or RNA strand.

16.   base-pair substitution:  One amino acid has replaced another during protein synthesis.

17.   carcinogen:         Any substance or agent that can trigger cancer.

18.   codon:   One of 64 possible base triplets in an mRNA strand. A code word for an amino acid in a polypeptide chain; a few codons also act as START or STOP signals for translation.

19.   deletion:              At cytological level, loss of a segment from a chromosome. At molecular level, loss of one to a few base pairs from a DNA molecule.

20.   exon:     One of the base sequences of an mRNA transcript that will become translated.

21.   gene mutation: A small-scale change in the nucleotide sequence of a DNA molecule.

22.   genetic code:     The correspondence between nucleotide triplets in DNA (then mRNA) and specific sequences of amino acids in a polypeptide chain; the basic language of protein synthesis in cells.

23.   insertion:             Insertion of one to a few bases into a DNA strand. Also, a movable attachment of muscle to bone.

24.   intron:   A noncoding portion of a pre-mRNA transcript; excised before translation.

25.   ionizing radiation:            High-energy wavelengths.

26.   mRNA (messenger RNA):            A single strand of ribonucleotides transcribed from DNA, then translated into a polypeptide chain. The only RNA encoding protein-building instructions.

27.   mutation rate:   Of a gene locus, the probability that a spontaneous mutation will occur during or between DNA replication cycles.