An Introduction to Heredity

         Offspring acquire genes from parents by inheriting chromosomes
         Like begets like, more or less: a comparison of asexual and sexual
         reproduction

    The Role of Meiosis in Sexual Life Cycles

         Fertilization and meiosis alternate in sexual life cycles
         Meiosis reduces chromosome number from diploid to haploid: a closer look

    Origins of Genetic Variation

         Sexual life cycles produce genetic variation among offspring
         Evolutionary adaptation depends on a population's genetic variation
 

Chapter  13
heredity - the transmission of traits from one generation to the next.
variation - offsprings differ somewhat in appearance from parents and siblings.
genetics - the scientific study of heredity and hereditary variation.
gene pool - the total aggregate of genes in a population at any one time.
asexual reproduction - a type of reproduction involving only one parent that produces genetically identical offspring by budding or by the division of a single cell or the entire organism into two or more parts.
clone - a lineage of genetically identical individuals.
sexual reproduction - a type of reproduction in which two parents give rise to offspring that have unique combinations of genes inherited from the gametes of the two parents.
life cycle - the entire sequence of stages in the life of an organisms, from the adults of one generation to the adults of the next.
Somatic cell (soh-MAT-ik) - any cell in a multicellular organism except a sperm or egg cell.
karyotype (KAR-ee-oh-type) - a method of organizing the chromosomes of a cell in relation to number, size, and type.
homologous chromosomes (home-OL-uh-gus) - chromosome pairs of the same length, centromere position, and staining pattern that possess genes for the same traits at corresponding loci. One homologous chromosome is inherited from the organism's father, the other from the mother.
sex chromosomes - the pair of chromosomes responsible for determining the sex of an individual.
autosome (AW-tuh-some) - a chromosome that is not directly involved in determining sex, as opposed to the sex chromosomes.
gamete (GAM-eet) - a haploid egg or sperm cell; gametes unite during sexual reproduction to produce a diploid zygote.
haploid cell (HAP-loid) -a  cell containing only one set of chromosomes (n).
fertilization - the union of haploid gametes to produce a diploid zygote.
zygote - the diploid product of the union of haploid gametes in conception; a fertilized egg.
diploid cell (DIP-loyd) - a cell containing two sets of chromosomes (2n), one set inherited from each parent.
meiosis (my-OH-sis) - a two-stage type of cell division in sexually reproducing organisms that results in gametes with half the chromosome number of the original cell.
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.
sporophyte - the multicellular diploid form in organisms undergoing alternation of generations that results from a union of gametes and that meiotically produces haploid spores that grow into the gametophyte generation.
gametophyte (guh-MEE-toh-fite) - the multicellular haploid form in organisms undergoing alternation of generations, which mitotically produces haploid gametes that unite and grow into the sporophyte generation.
meiosis I - first division of cells
meiosis II - second meiotic division that separates sister chromatids and is virtually identical in mechanism to mitosis.
synapsis - the pairing of replicated homologous chromosomes during prophase I of meiosis.
tetrad -
chiasma (KY-as-muh) (plural, chiasmata) - the X-shaped, microscopically visible region representing homologous chromatids that have exchanged genetic material through crossing over during meiosis.
crossing over - the reciprocal exchange of genetic material between nonsister chromatids during synapsis of meiosis I.
 
 

    Gregor Mendel's Discoveries

         Mendel brought an experimental and quantitative approach to genetics:
         science as a process
         By the law of segregation, the two alleles for a character are packaged into
         separate gametes
         By the law of independent assortment, each pair of alleles segregates into
         gametes independently
         Mendelian inheritance reflects rules of probability
         Mendel discovered the particulate behavior of genes: a review

    Extending Mendelian Genetics

         The relationship between genotype and phenotype is rarely simple

    Mendelian Inheritance in Humans

         Pedigree analysis reveals Mendelian patterns in human inheritance
         Many human disorders follow Mendelian patterns of inheritance
         Technology is providing new tools for genetic testing and counseling

Chapter  14
Character - a heritable feature that varies among individuals.
Trait - each variant for a character.
True-breeding - when two individuals breed, their offspring are of the same variety (some plants).
Hybridization - the crossing of two varieties.
monohybrid cross - a breeding experiment that uses parental varieties differing in a single character.
P generation -
F1 generation - the first filial or hybrid offspring in a genetic cross-fertilization.
F2 generation - offspring resulting from interbreeding of the hybrid F1 generation.
allele (uh-LEEL) - an alternative form of a gene.
dominant allele - in a heterozygote, the allele that is fully expressed in the phenotype.
recessive allele - in a heterozygote, the allele that is completely masked in the phenotype.
law of segregation - Mendel's first law, stating that allele pairs separate during gamete formation, and then randomly re-form pairs during the fusion of gametes at fertilization.
homozygous (HOME-oh-ZY-gus) - having two identical alleles for a given trait.
heterozygous (HET-ur-oh-ZY-gus) - having two different alleles for a given trait.
Phenotype (FEE-nuh-type) - the physical and physiological traits of an organism.
genotype (JEE-noh-type) - the genetic makeup of an organism.
dihybrid cross (DY-HY-brid) - a breeding experiment in which parental varieties differing in two traits are mated.
law of independent assortment - Mendel's second law, stating that each allele pair segregates independently during gamete formation; applies when genes for two traits are located on different pairs of homologous chromosomes.
incomplete dominance - a type of inheritance in which F1 hybrids have an appearance that is intermediate between the phenotypes of the parental varieties.
codominance - a phenotypic situation in which both alleles are expressed in the heterozygote.
pleiotropy (PLY-eh-troh-pee) -  the ability of a single gene to have multiple effects.
epistasis - a phenomenon in which one gene alters the expression of another gene that is independently inherited.
quantitative character - a heritable feature in a population that varies continuously as a result of environmental influences and the additive effect of two or more genes (polygenic inheritance).
polygenic inheritance (POL-ee-JEN-ik) - an additive effect of two or more gene loci on a single phenotypic character.
norm of reaction - the range of phenotypic possibilities for a single genotype, as influenced by the environment.
Multifactorial -
Pedigree - a family tree describing the occurrence of heritable characters in parents and offspring across as many generations as possible.
Carrier -
Cystic fibrosis -
Tay Sachs -
Sickcle cell disease -
Huntingston’s disease -
amniocentesis (AM-nee-oh-sen-TEE-sis) - a technique for determining genetic abnormalities in a fetus by the presence of certain chemicals ordefective fetal cells in the amniotic fluid, obtained by aspiration from a needle inserted into the uterus.
chorionic villus sampling (CVS) (KOR-ee-on-ik VILL-us) - a technique for diagnosing genetic and congenital defects while the fetus is in the uterus. A small sample of the fetal portion of the placenta is removed and analyzed.
 
 

    Relating Mendelism to Chromosomes

         Mendelian inheritance has its physical basis in the behavior of
         chromosomes during sexual life cycles
         Morgan traced a gene to a specific chromosome: science as a process
         Linked genes tend to be inherited together because they are located on the
         same chromosome
         Independent assortment of chromosomes and crossing over produce genetic
         recombinants
         Geneticists can use recombination data to map a chromosome's genetic
         loci

    Sex Chromosomes

         The chromosomal basis of sex varies with the organism
         Sex-linked genes have unique patterns of inheritance

    Errors and Exceptions in Chromosomal Inheritance

         Alterations of chromosome number or structure cause some genetic
         disorders
         The phenotypic effects of some genes depend on whether they were
         inherited from the mother or the father (imprinting)
         Extranuclear genes exhibit a non-Mendelian pattern of inheritance

Chapter  15
*Chromosome theory of inheritence
wild type An individual with the normal phenotype.
*Mutant phenotype
Sex linked gene Genes located on one sex chromosome but not the other.
Linked gene Genes that are located on the same chromosome.
genetic recombination The general term for the production of offspring that combine traits of the two parents.genomic imprinting The parental effect on gene expression. Identical alleles may have different effects on offspring, depending on whether they arrive in the zygote via the ovum or via the sperm.
Parental types
recombinant An offspring whose phenotype differs from that of the parents.
*Genetic map
*Linkage map
*Cytological maps
*Duchenne muscular dystropy
*Hemophilia
Barr body The dense object lying along the inside of the nuclear envelope in female mammalian cells, representing the one inactivated X chromosome.
nondisjunction An accident of meiosis or mitosis, in which both members of a pair of homologous chromosomes or both sister chromatids fail to move apart properly.
aneuploidy (AN-yoo-ploy-dee) A chromosomal aberration in which certain chromosomes are present in extra copies or are deficient in number.
*Trisomic
*Monosomic
polyploidy (POL-ee-ploid-ee) A chromosomal alteration in which the organism possesses more than two complete chromosome sets.
duplication An aberration in chromosome structure resulting from an error in meiosis or mutagens; duplication of a portion of a chromosome resulting from fusion with a fragment from a homologous chromosome.
inversion An aberration in chromosome structure resulting from an error in meiosis or from mutagens; reattachment in a reverse orientation of a chromosomal fragment to the chromosome from which the fragment originated.
translocation (1) An aberration in chromosome structure resulting from an error in meiosis or from mutagens; attachment of a chromosomal fragment to a nonhomologous chromosome. (2) During protein synthesis, the third stage in the elongation cycle when the RNA carrying the growing polypeptide moves from the A site to the P site on the ribosome. (3) The transport via phloem of food in a plant.
Down syndrome A human genetic disease resulting from having an extra chromosome 21, characterized by mental retardation and heart and respiratory defects.
genomic imprinting The parental effect on gene expression. Identical alleles may have different effects on offspring, depending on whether they arrive in the zygote via the ovum or via the sperm.
fragile X syndrome A hereditary mental disorder, partially explained by genomic imprinting and the addition of nucleotides to a triplet repeat at the end of an X chromosome.

    DNA as the Genetic Material

         The search for the genetic material led to DNA: science as a process
         Watson and Crick discovered the double helix by building models to
         conform to X-ray data: science as a process

    DNA Replication and Repair

         During DNA replication, base pairing enables existing DNA strands to serve
         as templates for new complementary strands
         A large team of enzymes and other proteins carries out DNA replication
         Enzymes proofread DNA during its replication and repair damage in existing
         DNA
         The ends of DNA molecules pose a special problem

Chapter  16
transformation (1) The conversion of a normal animal cell to a cancerous cell. (2) A phenomenon in which external genetic material is assimilated  by a cell.
*Bacteriophages
phage (fage) A virus that infects bacteria; also called a bacteriophage.
double helix The form of native DNA, referring to its two adjacent polynucleotide strands wound into a spiral shape.
*Semiconservative model
*Origin of replication
replication fork A Y-shaped point on a replicating DNA molecule where new strands are growing.
DNA polymerase An enzyme that catalyzes the elongation of new DNA at a replication fork in the 5'(3' direction by the addition of nucleotides to the existing chain.
leading strand The new continuous complementary DNA strand synthesized along the template strand in the mandatory 5' ( 3' direction.
lagging strand A discontinuously synthesized DNA strand that elongates in a direction away from the replication fork.
DNA ligase (LY-gaze) A linking enzyme essential for DNA replication; catalyzes the covalent bonding of the 3' end of a new DNA fragment to the 5' end of a growing chain.
*Helicase
*Single strand binding protein
*Mismatch repair
*Nuclease
*Excision repair
telomere The end of a chromosome. Repetitive DNA sequences at telomeres help conserve chromosome tips. temperate deciduous forest A biome located throughout midlatitude regions where there is sufficient moisture to support the growth of large, broad-leaf deciduous trees.
*telomerase

    The Connection Between Genes and Proteins

         The study of metabolic defects provided evidence that genes specify
         proteins: science as a process
         Transcription and translation are the two main processes linking gene to
         protein: an overview
         In the genetic code, nucleotide triplets specify amino acids
         The genetic code must have evolved very early in the history of life

    The Synthesis and Processing of RNA

         Transcription is the DNA-directed synthesis of RNA: a closer look
         Eukaryotic cells modify RNA after transcription

    The Synthesis of Protein

         Translation is the RNA-directed synthesis of a polypeptide: a closer look
         Signal peptides target some eukaryotic polypeptides to specific destinations
         in the cell
         RNA plays multiple roles in the cell: a review
         Point mutations can affect protein structure and function
         What is a gene?: revisiting the question

Chapter  17
auxotroph (AWK-soh-trohf) A nutritional mutant that is unable to synthesize and that cannot grow on media lacking certain essential molecules normally synthesized by wild-type strains of the same species.
One gene- one polypeptide hypothesis
transcription The transfer of information from a DNA molecule into an RNA molecule.
messenger RNA (mRNA) A type of RNA synthesized from DNA in the genetic material that attaches to ribosomes in the cytoplasm and specifies the primary structure of a protein.
RNA processing Modification of RNA before it leaves the nucleus, a process unique to eukaryotes.
*Primary transcription
triplet code A set of three-nucleotide-long words that specify the amino acids for polypeptide chains.
codon (KOH-don) A three-nucleotide sequence of DNA or mRNA that specifies a particular amino acid or termination signal; the basic unit of the genetic code.
*Reading frame
RNA polymerase (pul-IM-ur-ase) An enzyme that links together the growing chain of ribonucleotides during transcription.
*Transcription unit
*Promoter
transcription factor A regulatory protein that binds to DNA and stimulates transcription of specific genes.
*Transcription initiation complex
*TATA box
terminator A special sequence of nucleotides in DNA that marks the end of a gene; it signals RNA polymerase to release the newly made RNA molecule, which then departs from the gene.
5'cap During RNA processing, an "attach here" sign for small ribosomal subunits; at the 5' end of an mRNA molecule, the cap helps inhibit degradation and enhances translation.
poly-A tail During RNA processing, a nucleotide complex at the 3' end of an mRNA molecule that helps inhibit degradation and enhances translation.
RNA splicing The removal of noncoding portions of the RNA molecule after initial synthesis.
intron (IN-tron) The noncoding, intervening sequence of a coding region (exon) in eukaryotic genes.
exon The coding region of a eukaryotic gene that is expressed. Exons are separated from each other by introns.
spliceosome (SPLY-see-oh-some) A complex assembly that interacts with the ends of an RNA intron in splicing RNA; releases an intron and joins two adjacent exons.
ribosome A cell organelle constructed in the nucleolus, consisting of two subunits and functioning as the site of protein synthesis in the cytoplasm.
domain A taxonomic category above the kingdom level; the three domains are archaebacteria, eubacteria, and eukaryotes.
transfer RNA (tRNA) An RNA molecule that functions as an interpreter between nucleic acid and protein language by picking up specific  amino acids and recognizing the appropriate codons in the mRNA.
Anticodon (AN-tee-CO-don) A specialized base triplet on one end of a tRNA molecule that recognizes a particular complementary codon on an mRNA molecule.
Wobble A violation of the base-pairing rules in that third nucleotide (5' end) of a tRNA anticodon can form hydrogen bonds with more than one kind of base in the third position (3' end) of a codon.
*Aminoacyl tRNA sythetase
transfer RNA (tRNA) An RNA molecule that functions as an interpreter between nucleic acid and protein language by picking up specific amino acids and recognizing the appropriate codons in the mRNA.

P site Peptidyl-tRNA site; the binding site on a ribosome that holds the tRNA carrying a growing polypeptide chain.
A site Aminoacyl-tRNA site; the binding site on a ribosome that holds the tRNA carrying the next amino acid to be added to a growing
*polypeptide chain.
*E site
*Initiation
*Elongation
*Termination
polyribosome (POL-ee-RY-boh-some) An aggregation of several ribosomes attached to one messenger RNA molecule.
population A group of individuals of one species that live in a particular geographic area.
*Signal peptide
*Sign recognition particle (SRP)
mutation (myoo-TAY-shun) A rare change in the DNA of genes that ultimately creates genetic diversity.

point mutation A change in the chromosome at a single nucleotide within a gene.
*Substitution
base-pair substitution A point mutation; the replacement of one nucleotide and its partner from the complementary DNA strand by another pair of nucleotides.
missense mutation The most common type of mutation involving a base-pair substitution within a gene that changes a codon, but the new codon makes sense in that it still codes for an amino acid.
nonsense mutation A mutation that changes an amino acid codon to one of the three stop codons, resulting in a shorter and usually
nonfunctional protein.
deletion (1) A deficiency in a chromosome resulting from the loss of a fragment through breakage. (2) A mutational loss of a nucleotide from a gene.
Frameshift mutation
mutagen (MYOOT-uh-jen) A chemical or physical agent that interacts with DNA and causes a mutation.
*Ames test
 
 

    The Genetics of Viruses

         Researchers discovered viruses by studying a plant disease: science as a
         process
         A virus is a genome enclosed in a protective coat
         Viruses can reproduce only within a host cell: an overview
         Phages reproduce using lytic or lysogenic cycles
         Animal viruses are diverse in their modes of infection and replication
         Plant viruses are serious agricultural pests
         Viroids and prions are infectious agents even simpler than viruses
         Viruses may have evolved from other mobile genetic elements

    The Genetics of Bacteria

         The short generation span of bacteria facilitates their evolutionary adaptation
         to changing environments
         Genetic recombination produces new bacterial strains
         The control of gene expression enables individual bacteria to adjust their
         metabolism to environmental change

Chapter  18
capsid The protein shell that encloses the viral genome; rod-shaped, polyhedral, or more completely shaped.
*Viral envelopes
*Bacteriophages
phage (fage) A virus that infects bacteria; also called a bacteriophage.
*Host range
lytic cycle (LIT-ik) A type of viral replication cycle resulting in the release of new phages by death or lysis of the host cell.
lysogenic cycle A type of viral replication cycle in which the viral genome becomes incorporated into the bacterial host chromosome as a prophage.
temperate virus A virus that can reproduce without killing the host.
prophage (PRO-fage) A phage genome that has been inserted into a specific site on the bacterial chromosome.
*Viral envelope
*Provirus
retrovirus (REH-troh-VY-rus) An RNA virus that reproduces by transcribing its RNA into DNA and then inserting the DNA into a cellular chromosome; an important class of cancer-causing viruses.
reverse transcriptase (trans-KRIP-tase) An enzyme encoded by some RNA viruses that uses RNA as a template for DNA synthesis.
HIV (human immunodeficiency virus) The infectious agent that causes AIDS; HIV is an RNA retrovirus.
AIDS (acquired immunodeficiency syndrome) The name of the late stages of HIV infection; defined by a specified reduction of T cells and the appearance of characteristic secondary infections.
vaccine A harmless variant or derivative of a pathogen that stimulates a host's immune system to mount defenses against the pathogen.
viroid (VY-roid) A plant pathogen composed of molecules of naked RNA only several hundred nucleotides long.
prion An infectious form of protein that may increase in number by converting related proteins to more prions.
nucleoid region The region in a prokaryotic cell consisting of a concentrated mass of DNA.
transformation (1) The conversion of a normal animal cell to a cancerous cell. (2) A phenomenon in which external genetic material is assimilated  by a cell.
*Transduction
conjugation (KON-joo-GAY-shun) A recombination mechanism that results in the transfer of genetic material between two bacterial cells that are temporarily joined.
plasmid (PLAZ-mid) A small ring of DNA that carries accessory genes separate from those of a bacterial chromosome.
F plasmid The fertility factor in bacteria, a plasmid that confers the ability to form pili for conjugation and associated functions required for the transfer of DNA from donor to recipient.
R plasmid A bacterial plasmid whose resistance to certain antibiotics poses serious medical problems.
transposon (trans-POH-son) A transposable genetic element; a mobile segment of DNA that serves as an agent of genetic change.
insertion sequence The simplest kind of a transposon, consisting of inserted repeats of DNA flanking a gene for transposase, the enzyme that catalyzes genetic transposition.
Composite transposons
*Operator
operon (OP-ur-on) A unit of genetic function common in bacteria and phages, consisting of regulated clusters of genes with related functions.
repressor A protein that suppresses the expression of prophage or operon genes.
*Regulatory gene
*Coreprssor
*Cyclic amp
*cAMP receptor protein
 

    The Structure of Chromatin

         Chromatin structure is based on successive levels of DNA packing

    Genome Organization at the DNA Level

         Repetitive DNA and other noncoding sequences account for much of a
         eukaryotic genome
         Gene families have evolved by duplication of ancestral genes
         Gene amplification, loss, or rearrangement can alter a cell's genome

    The Control of Gene Expression

         Each cell of a multicellular eukaryote expresses only a small fraction of its
         genes
         The control of gene expression can occur at any step in the pathway from
         gene to functional protein: an overview
         Chromatin modifications affect the availability of genes for transcription
         Transcription initiation is controlled by proteins that interact with DNA and
         with each other
         Posttranscriptional mechanisms play supporting roles in the control of gene
         expression

    The Molecular Biology of Cancer

         Cancer results from genetic changes that affect the cell cycle
         Oncogene proteins and faulty tumor-suppressor proteins interfere with
         normal signaling pathways
         Multiple mutations underlie the development of cancer

Chapter  19
Histones(HISS-tone) A small protein with a high proportion of positively charged amino acids that binds to the negatively charged DNA and plays a key role in its folding into chromatin.
Nucleosome (NOO-klee-oh-some) The basic, beadlike unit of DNA packaging in eukaryotes, consisting of a segment of DNA wound around a protein core composed of two copies of each of four types of histone. nucleus (1) An atom's central core, containing protons and neutrons. (2) The chromosome-containing organelle of a eukaryotic cell. (3) A cluster of neurons.
*Receptive DNA
*Satellite DNA
*Alu elements
Multigene family A collection of genes with similar or identical sequences, presumably of common origin.
*Pseudogenes
Gene amplification The selective synthesis of DNA, which results in multiple copies of a single gene, thereby enhancing expression.
Transposons (trans-POH-son) A transposable genetic element; a mobile segment of DNA that serves as an agent of genetic change.
Immunoglobulin genes (Ig) (IM-myoo-noh-GLOB-yoo-lin) One of the class of proteins comprising the antibodies.
Differentiation The structural and functional divergence of cells as they become specialized during a multicellular organism's development; dependent on the control of gene expression.
DNA methylation The addition of methyl groups (CH3) to bases of DNA after DNA synthesis; may serve as a long-term control of gene expression.
*Genomic imprinting
*Histone acetylation
*Control elements
Enhancers A DNA sequence that recognizes certain transcription factors that can stimulate transcription of nearby genes.
environmental grain An ecological term for the effect of spatial variation, or patchiness, relative to the size and behavior of an organism.
*DNA binding domain
*Alternative splicing
*Proteasomes
Proto-oncogenes (PRO-toh-ONK-oh-jeen) A normal cellular gene corresponding to an oncogene; a gene with a potential to cause cancer, but that requires some alteration to become an oncogene.
Tumor suppressor genes A gene whose protein products inhibit cell division, thereby preventing uncontrolled cell growth (cancer).
*Ras gene
*P53 gene
 

    DNA Cloning

         DNA technology makes it possible to clone genes for basic research and
         commercial applications: an overview
         Restriction enzymes are used to make recombinant DNA
         Genes can be cloned in recombinant DNA vectors: a closer look
         Cloned genes are stored in DNA libraries
         The polymerase chain reaction (PCR) clones DNA entirely in vitro

    Analysis of Cloned DNA

         Restriction fragment analysis detects DNA differences that affect restriction
         sites
         Entire genomes can be mapped at the DNA level

    Practical Applications of DNA Technology

         DNA technology is reshaping medicine and the pharmaceutical industry
         DNA technology offers forensic, environmental, and agricultural applications
         DNA technology raises important safety and ethical questions
Chapte 20
Recombinant DNA A technique in which gene segments from different sources are recombined in vitro and transferred into cells, where the DNA may be expressed.
*Genetic engineering
Biotechnology The industrial use of living organisms or their components to improve human health and food production.

Gene cloning The formation by a bacterium, carrying foreign genes in a recombinant plasmid, of a clone of identical cells containing the replicated foreign genes.
Restriction enzymes A degradative enzyme that recognizes and cuts up DNA (including that of certain phages) that is foreign to a cell.
Restriction site A specific sequence on a DNA strand that is recognized as a "cut site" by a restriction enzyme.
*Sticky end
*DNA ligase
Cloning vector An agent used to transfer DNA in genetic engineering, such as a plasmid that moves recombinant DNA from a test tube back into a cell, or a virus that transfers recombinant DNA by infection.
*Isolation
*Insertion
*Introduction
*Cloning
*Identification
*Nucleic acid hybridization
*Nucleic probe
Denaturation A process in which a protein unravels and loses its native conformation, thereby becoming biologically inactive. Denaturation occurs under extreme conditions of pH, salt concentration, and temperature.
*Expression vector
Complementary DNA (cDNA) DNA that is identical to a native DNA containing a gene of interest, except that the cDNA lacks noncoding regions (introns) because it is synthesized in the laboratory using mRNA templates.
*Artificial chromosomes
*Genomic library
Polymerase chain reaction (PCR) A technique for amplifying DNA in vitro by incubating with special primers, DNA polymerase molecules and ucleotides.
Gel electrophoresis (JELL eh-LEK-troh-for-EE-sis) The separation of nucleic acids or proteins, on the basis of their size and electrical charge, by measuring their rate of movement through an electrical field in a gel.
Southern blotting A hybridization technique that enables researchers to determine the presence of certain nucleotide sequences in a sample of DNA.
Restiction fragment length polymorphism (RFLPs) Differences in DNA sequence on homologous chromosomes that result in different patterns of restriction fragment lengths (DNA segments resulting from treatment with restriction enzymes); useful as genetic markers for making linkage maps.
*In situ hybridization
Human genome project An international collaborative effort to map and sequence the DNA of entire human genomes.
*Genetic linkage mapping
*Physical mapping
*Chromosome walking
*DNA sequencing
 

    From Single Cell to Multicellular Organism

         Embryonic development involves cell division, cell differentiation, and
         morphogenesis
         Researchers study development in model organisms
         to identify general principles: science as a process

    Differential Gene Expression

         Different types of cells in an organism have the same DNA
         Different cell types make different proteins, usually as a result of
         transcriptional regulation
         Transcriptional regulation is directed by maternal molecules in the
         cytoplasm and signals from other cells

    Genetic and Cellular Mechanisms of Pattern Formation

         Genetic analysis of Drosophila reveals how genes control development: an
         overview
         Gradients of maternal molecules in the early embryo control axis formation
         A cascade of gene activations sets up the segmentation pattern in
         Drosophila: a closer look
         Homeotic genes direct the identity of body parts
         Homeobox genes have been highly conserved in evolution
         Neighboring cells instruct other cells to form particular structures: cell
         signaling and induction in the nematode
         Plant development depends on cell signaling and transcriptional regulation:
         science as a process
 

Chapter  21
differentiation The structural and functional divergence of cells as they become specialized during a multicellular organism's  development; dependent on the control of gene expression.
morphogenesis The development of body shape and organization during ontogeny.
apical meristems (AY-pik-ul MARE-eh-stem) Embryonic plant tissue in the tips of roots and in the buds of shoots that supplies cells for the plant
to grow in length.
*model organism
*cell lineage
totipotency The ability of embryonic cells to retain the potential to form all parts of the animal.
determination The progressive restriction of developmental potential, causing the possible fate of each cell to become more limited as the embryo develops.
*cytoplasmic determinants
pattern formation The ordering of cells into specific three-dimensional structures, an essential part of shaping an organism and its individual  parts during development.
positional information Signals, to which genes regulating development respond, indicating a cell's location relative to other cells in an embryonic structure.
*embryonic lethals
*maternal effect genes
*egg-polarity genes
morphogens A substance, such as bicoid protein, that provides positional information in the form of a concentration gradient along an embryonic axis.
*segmentation genes
*gap genes
*pair-rule genes
*segment-polarity genes
homeotic genes (HOME-ee-OT-ik) Genes that control the overall body plan of animals by controlling the developmental fate of groups of cells.
homeobox Specific sequences of DNA that regulate patterns of differentiation during the development of an organism.
*apoptosis
*chimeras
organ-identity gene A plant gene in which a mutation causes a floral organ to develop in the wrong location.