Biology Chapter 14

Front 1

character

Back 1

a heritable feature that varies among individuals(ex. peas and flowers in Mendel's experiment)

Front 2

true-breeding

Back 2

referring to plants that produce offspring of the same variety when they self-poolinate.

Front 3

hybridization

Back 3

the mating or crossing of two true-breeding varieties.

Front 4

P-generation(parent generation)

Back 4

true-breeding parents, involved in hybridization.

Front 5

F1 generation(first filial generation)

Back 5

the hybrid offspring of the P generation

Front 6

F2 generation (second filial generation)

Back 6

the offspring of the first filial generation(which self-pollinates)

Front 7

alleles

Back 7

alternative versions of genes. (ex. flower color in pea plants, purple and white)

Front 8

locus

Back 8

a specific place along the length of a chromosome where given gene is located.

Front 9

dominant allele

Back 9

determines the organism's appearance.

Front 10

recessive gene

Back 10

has no noticeable effect on the organism's appearance.

Front 11

law of segregation

Back 11

the two alleles for a heritable character segregate (separate) during gamete formation and end up in different gametes.

Front 12

punnett square

Back 12

a diagrammatic device for predicting the allele composition of offspring from a cross between individuals of known genetic makeup.

Front 13

homozygous

Back 13

an organism that has a pair of identical allesle for a character, said to be this for the gene controlling that character.

Front 14

heterozygous

Back 14

an organism that has two different alleles for a gene

Front 15

phenotype

Back 15

an organism's appearance or observable traits(can be physical ex. color, or physiological ex. the inability to self-pollinate.)

Front 16

genotype

Back 16

an organism's genetic makeup

Front 17

testcross

Back 17

breeding an organism of unknown genotype with a recessive homozygote is called this, because it can reveal the genotype of that organism.

Front 18

monohybrids

Back 18

heterozygous for one character(all the F1 progeny produced in Mendel's crosses of true-breeding partents were this).

Front 19

dihybrids

Back 19

individuals heteroyzgous for two characters(ex. the F1 plants will be this if their parents' genotypes are YYRR and yyrr).

Front 20

law of independent assortment

Back 20

each pair of alleles segregates independently of each other pair of alleles during gamete formation.

Front 21

multiplication rule

Back 21

to determine the probability of two or more independent events occuring together we multiply the probability of one event by the probability of another.

Front 22

addition rule

Back 22

the probability that any one of two ore more mutually exclusive evens will occur is calculated by adding their individual probabilities.

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complete dominance

Back 23

the situation in which the phenotypes of the heterozygote and dominan homozygote are indishtinguishable.

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incomplete dominance

Back 24

in a gene, when neither allele is completely dominant and the F1 hybrids have a phenotype somewhere between those of teh two parental varieties.(ex. red snapdragons crossed with white snapdragons give pink snapdragons.)

Front 25

codominance

Back 25

two alleles both affect the phenotype in separate distinguishable ways. (ex. human blood types.)

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pleiotropy

Back 26

a property revealing most genes have multiple phenotopic effects.(ex. a human's pleiotropic alleles are responsible for the multiple symptoms associated with certain hereditary diseases.)

Front 27

epistasis

Back 27

a gene at one locus alters the phenotypic expression of a gene at a second locus. (ex. two loci, one determines pigment of the fur and the other determines pigment deposition)

Front 28

quantitative characters

Back 28

a heritable feature that varies continuously over a range rather than in an either-or fashion. (ex. human skin color)

Front 29

polygenic inheritance

Back 29

quantitative vartiation usually indicates this, an additive effect of two or more genes on a single phenotypic character(the converse of pleiotropy, where a single gene affects several phenotypic characters.)

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norm of reaction

Back 30

the range of phenotypes produced by a single genotype, due to environmental influences.

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multifactorial

Back 31

many factors, both genetic and environmental, collectively influence phenotype. (ex. skin color)

Front 32

pedigree

Back 32

a diagram of a family tree showing the occurence of heritable characteristics in parents and offspring over multiple generations.

Front 33

carriers

Back 33

an individual who is heterozygous at a given genetic loci, with one normal allele and one recessive allele. The heterozygote is phenotypically dominant for the character determined by the gene but can pass on the recessive allele to offspring.

Front 34

cystic fibrosis

Back 34

strikes one out of 25,000 people of European decent. A human genetic disorder caused by arecessive allele for a chloride channel protein; characterized by an exclusive secretion of mucus and consequent vulnerability to infection; fatal if untreated.

Front 35

sickle-cell disease

Back 35

a human genetic disease caused by a recessive allele that results in the substitution of a single amino acid in a globin polypeptide that is part of the hemoglobin protein; characterized by deformed red blood cells(due to protein aggregation) that can lead to numerous symptoms. One out of 400 African Americans. One out of 10 have the sickle-cell trait.

Front 36

Huntington's Disease

Back 36

a human genetic disorder caused by a dominant allele; characterized by uncontrollable body movements and degeneration of the nervous system; usually fatal 10 to 20 years after the onset of symptoms.

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amniocentesis

Back 37

a technique of prenataldiagnosis in whihc amniotic fuluid, obtained by aspiration from aneedle inserted into the uterus, si analyzed to detect certain genetic and congenital defects in the fetus.

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chorionic villus(CVS)

Back 38

a technique of prenatal diagnosis in which a small sample of the fetal portion of th eplacenta is removed and analyzed to detect certain genetic and congenital defects in the fetus.