Genetics

any molecule that is recognized as foreign by an organism and that therefore stimulates the production of specific protein molecules called antibodies.

a protein molecule that recognizes and binds to the foreign substance introduced into the organism as part of the immune response to remove the foreign antigen from the body.

the recessive allele is phenotypically expressed only when it is homozygous

(also referred to as semidominance or partial dominance) the phenotype of the heterozygote lies in the range between the phenotypes of individuals that are homozygous for either allele involved.

the heterozygote exhibits the phenotypes of both homozygotes.

the condition where one copy of a gene in a diploid organism is sufficient to give a normal phenotype.

an allele that results in the death of an organism

genes that, when mutated, can result in a lethal phenotype

both homozygotes and heterozygotes for that allele show the lethal phenotype

homozygotes for that allele have the lethal phenotype

the degree to which a penetrant gene or genotype is phenotypically expressed in an individual

genes that are autosomes affect a particular phenotype that appears in one sex, but not the other

traits often are controlled by autosomal genes. such traits appear in both sexes, but either the frequency of occurrence in the two sexes is different or the relationship between genotype and phenotype is different.

the range of potential phenotypes that a single genotype could develop if exposed to a range of environmental conditions

the phenomenon in which a phenotype of the offspring is determined not by the genotype of the offspring but by the nuclear genotype of the mother, with no influence by the paternal nuclear genome.

which determines whether two independently isolated mutants with the same phenotype have mutations in the same or different genes.

the interaction between alleles of two or more genes to control a single phenotype

A/- b/b and a/a b/b individuals have the same phenotype, which results in a phenotypic ratio in the F2 of 9:3:4

A/- B/- and A/- b/b individuals have the same phenotype, so the phenotypic ratio in the F2 is 12:3:1

a/a is epistatic to B and b, and b/b is epistatic to A and a.

A is epistatic to B and b, and B is epistatic to A and a.

when a modifier gene shifts the phenotype associated with a mutant allele of another gene toward the phenotype associated with the wild-type allele of that gene

the pattern of inheritance shown by extranuclear genes

• 1. ratios typical of Mendelian segregation are not found, because meiosis-based Mendelian segregation is not involved.
• 2. in multicellular eukaryotes, the results of reciprocal crosses involving extranuclear genes are not the same as reciprocal crosses involving nuclear genes, because meiosis-based Mendelian segregation is not involved.
• 3. extranuclear genes cannot be mapped to the chromosomes in the nucleus
• 4. extranuclear inheritance is not affected by substituting a nucleus with a different genotype.

all progeny have the phenotype of only one parent.

the phenotype of the mother is inherited exclusively

individuals that have a mixture of mutant and normal mitochondria

another name for a mutation or variant that gives a distinguishable phenotype

nonparental combinations of linked alleles

cytologically detectable visible changes in the chromosomes that make it possible to distinguish the chromosomes and, hence, the results of crossing-over under the microscope.

the pairing of alleles to match each other (w+ m+ and w m)

each homolog carries the wild-type allele of one gene and the mutant allele of the other gene (w+ m and w m+)

the presence of one crossover interferes with the formation of another crossover nearby

• the expressed extent of interference
• observed double crossover frequency/expected double crossover frequency

mathematical formulas that define the relationship between map distance and recombination frequency.

used to analyze pedigrees for possible linkage between two loci

simplest set of chemicals needed for the organism to grow and survive

supplies vitamins and amino acids and all kinds of substances that might be expected to be essential metabolites and whose biosynthesis might be interfered with by mutation.

strains of bacteria that are unable to synthesize essential nutrients

a bacterial strain that is wild type and thus can synthesize all essential nutrients

a process in which there is a unidirectional transfer of genetic information through direct cellular contact between a donor bacterial cell and a recipient bacterial cell.

recipients that have incorporated a piece of donor DNA into their chromosomes

the unidirectional transfer of extracellular DNA into cells, resulting in a phenotypic chance in the recipient.

a region of DNA with different sequence information on two strands

a process by which bacteriophages transfer genes from one bacterium to another

the detailed genetic mapping of sites within a gene

to find out whether two different mutants belonged to the same gene.

variations from the normal (wild type) condition in chromosome structure or chromosome number

expression of a recessive trait, caused by the absence of a dominant allele

a chromosomal mutation that results in the doubling of a segment of a chromosome

a chromosomal mutation that retults when a segment of a chromosome is excised and then reintegrated at an orientation 180 degrees fromt the original orientation

does not include the centromere

includes the centromere

when one recombinant chromatid becomes stretched across the cell as the two centromeres begin to migrate in anaphase

a chromosome with two centromeres

a chromosomal mutation in which there is a change in position of chromosome segments and the gene sequences they contain to different location in the genome

a gene that, in normal cells, controls the normal proliferation of cells

a gene that encodes a protein which plays a role in the transition from a differentiated cell to a tumor cell with an uncontrolled pattern of growth.

a change in the phenotypic expression of one or more genes as a result of a change in position in the genome

a meiotically or mitotically heritable change in gene expression that does not involve a change in the DNA sequence of the affected genes.

when an organism or a cell has one complete set of chromosomes or an exact multiple of complete sets

chromosome mutations resulting in variations in the number of chromosome sets occur in nature

involves a loss of one homologous chromosome pair (2N-2)

involves a loss of a single chromosome (2N-1)

involves a single extra chromosome, the cell has three copies of a particular chromosome and two copies of all other chromosomes. (2N+1)

involves an extra chromosome pair, there are four copies of one particular chromosome and two copies of all other chromosomes (2N+2)

occurs when there are three copies of chromosome 21.

a different sort of chromosomal mutation called centric fusion which produces three copies of the long arm of chromosome 21.

produces Patau syndrome

produces Edwards syndrome

genes whose activity is controlled in response to the needs of a cell or organism

genes are always active in growing cells

the regulatory substance that brings about gene induction

the phenomenon of producing a gene product in response to an inducer

a class of small molecules that help control the expression of many regulated genes

an enzyme that breaks down lactose into galactose and glucose, as well as catalyzing the isomerization of lactose to allolactose, a compound that is important in regulating expression of the lac operon.

a protein, found in the e. coli cytoplasmic membrane, actively transports lactose in the cell.

an enzyme that transfers an acetyl group from acetyl-CoA to beta glactosides.

one single mRNA molecule with three clustered genes

a gene or DNA sequence that controls only genes located on the same contiguous piece of DNA.

when two genes are located on different DNA molecules

a cluster of genes, the expressions of which are regulated together by operator repressor protein interaction, plus the operator region itself and the promoter.

a dimer of two identical polypeptides that binds to the CAP site along with cAMP (this makes the CAP-cAMP complex that is the positive-regulator molecule), which is upstream of the site where RNA polymerase binds to the promoter, CAP then recruits RNA polymerase to the promoter and transcription is initiated.

the product of trpR, which is basically an inactive repressor that alone cannot bind to the operator.

what terminates short transcripts

these bind to the promoter and recruit RNA polymerase II. only a low, basal level of transcription occurs with only general transcription factors.

stimilate transcription initiation

a large multiprotein complex that does not bind directly to DNA, but participates in the activation of transcription by interacting both with activators and with GTFs.

inhibit the activation of transcription initiation by activators

analogous to the recruitment of coactivators by activators

where the steroid receptor complex binds during gene regulation

regions of DA around transcriptionally active genes that are more highly sensitive to digestion by DNase I.

the process of a chromatin structure being altered in the vicinity of the core promoter

large multiprotein complexes that remodel chromatin by using the energy of ATP hydrolysis

a phenomenon whereby a gene is transcriptionally silent due to its location

an epigenetic phenomenon in which the expression of certain genes is determined by whether the gene is inherited from the female or male parent.

used to produce different pre-mRNA molecules

used to produce different functional mRNA's

when small regulatory RNA molecules silence gene expression in eukaryotes

noncoding, single stranded regulatory RNA molecule about 21-23 nucleotides long derived from an RNA transcript. It regulates the expression of a target mRNA by binding to the 3' UTR causing either inhibition of translation of the mRA or degradation of that molecule, depending on the extent of complementary base pairing between the two molecules.

short double stranded RNAs that function in gene silencing by RNA interference RNAi

the rate of RNA breakdown is regulated

concerned primarily with genetic processes tht occur within individuals and how genes are passed from one individual to another. THE UNIT OF STUDY IS THE INDIVIDUAL

interest is largely in the molecular nature of heredity.

applies to the principles of transmission genetics to large groups of individuals, focusing on the transmission processes at one or a few genetic loci

considers the transmission of traits simultaneously determined by many genes

set of equations that describes the influence of random mating on the allele and genotypic frequencies of an infinitely large population

percentage of individuals within a population that have a particular genotype. the sum of the genotype frequencies at a given locus is 1.

can be calculated in two equivalent ways from the observed number of different genotypes at a particular locus or from the genotype frequencies

if a population is limited in size, chance deviations from expected ratios can result in changes in allele frequency

mating between genotypes occurring in proportion to the frequencies of the genotypes in the population

calculated by dividing the number of polymorphic loci by the total number of loci examined

the average proportion of heterozygous individuals in a population for many loci

the number of individuals in the population that are heterozygous at that locus

the number of heterozygotes expected if the population is in hardy-weinberg equilibrium

different patterns on the gel when the DNA from two individuals is mixed with the restriction enzyme and the resulting fragments are separated on a gel

2-6 base pairs of DNA sequences tandemly repeated a few times up to about 100 times.

the mutation of A to a

a to A

the equivalent number of adults contributing gametes to the next generation

another way in which genetic drift arises. it occurs when a population is initially established by a small number of breeding individuals

form of genetic drift that occurs when a population is drastically reduced in size.

single genes that have effects on different aspects of the life cycle that effect fitness

the simplest type of balancing selection. a form of natural selection that works to maintain genetic polymorphisms in a population

non random mating that occurs when individuals with similar phenotypes mate preferentially

occurs when phenotypically dissimilar individuals mate more often than do randomly chosen individuals

involves preferential mating between relatives

when deviations from hybridization, genetic drift, and migration cause alleles at two loci appear to segregate together

deviations from the expectations of independent assortment and Hardy-Weinberg equilibrium caused either by physical linkage or population demography

techniques designed to estimate how large a population must be to keep from going extinct for a particular period of time with a degree of certainty.

may inclue hybrid sterility, hybrid inviability, or hybrid breakdown

may keep the species apart in many diferent ways

by changing the mating season or the activity periods such that they no longer overlap, the opportunity for mating is removed.

if the ecological niche of the two species is distinct, such that, for example, the two species dietary preferences keep them geographically isolated, even on a small spatial scale, again the opportunity for mating is removed.

if the two species recognize and avoid each other as mates, there is no opportunity for mating

the two species may not be able to discriminate one from another, but if their genitalia do not fit together, zygotes cannot be formed.

even if they mate and gametes come in contact with one another, there still remains a highly complex process of gametic fusion that can fail.

traits that are influenced by both environment and genotype

an explanation that quantitative traits are controlled by many genes.

functional

non functional

allele pairs at a number of loci that have a small effect on the overall phenotype

a summary of a group in terms of the proportion of individuals that fall within a certain phenotypic range.

a statistic that measures the strength of the association between two variables in the same experimental unit, which in genetics is usually an individual.

a measure of how much variation is shared by an individual for both traits.

a measure of all variability for a trait

the genetic contribution to the phenotypic variation

includes any nongenetic source of variation

the proportion of a populations phenotypic variation that is attributable to genetic factors

the individual loci that contribute to a quantitative trait

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