Chapter 14

Front 1

blending hypothesis

Back 1

genetic material mixes in a manner like blue and yellow paints blend to make green
-over a period of time there would be uniform individuals
-fails to explain reappearing traits after skipping a generation

Front 2

gene idea

Back 2

parents pass on discrete heritable units(genes) that retain their seperate identities in offspring

Front 3

character

Back 3

heritable deature that varies among individuals

Front 4

trait

Back 4

each variant for a character

Front 5

why peas was a good choice

Back 5

-available in many varieties
-short generation time
-large number of offspring
-able to control mating btwn plants

Front 6

crossing pea plants

Back 6

crossing pea plants that vary in flower calor allows study of patterns in inheritance

Front 7

true-breeding

Back 7

over many generations of self-pollination produced only same bariety as parent plant

Front 8

hybridization

Back 8

mating/crossing of two true-breeding varieties

Front 9

P generation

Back 9

true-breeding parents

Front 10

F1 generation

Back 10

first filial generation, hybrid offspring of P generation

Front 11

alleles

Back 11

alternative versions of genes account for variation in inherited characters

Front 12

mendel's model

Back 12

-for each character, an organism inherits two alleles, one from each parent
-if two alleles at a locus differ, then one will be the dominant allele which determines organism's appearance and the other will be the recessive

Front 13

law of segregation

Back 13

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

Front 14

punnett square

Back 14

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

Front 15

homozygous

Back 15

organism that has a pair of identical alleles for a character

Front 16

heterozygous

Back 16

organism that has two different alleles for a gene
-not true-breeding because produce gametes with different alleles

Front 17

phenotype

Back 17

organism's appearance/observable traits

Front 18

genotype

Back 18

genetic makeup

Front 19

testcross

Back 19

breeding an organism of unknown genotype with a recessive homozygote
-will reveal genotype of that organism

Front 20

monohybrids

Back 20

heterozygous for one character

Front 21

dihybrids

Back 21

individuals heterozygous for two characters (ex: YyRr)

Front 22

law of independent assortment

Back 22

each pair of lleles segregate independently of eachother pair of alleles during gamete formation

Front 23

probbility scale

Back 23

ranges from 0 to 1

Front 24

multipliction

Back 24

to determine probability, multiply the probability of one even by the probability of the other event

Front 25

addition rule

Back 25

probability that ny one of two or more mutually exclusive events will occur is calculated by adding their individual probabilities

Front 26

complete dominance

Back 26

phenotypes of the heterozygote and the dominant homosygote are indistinguishable

Front 27

incomplete dominance

Back 27

neither allele is completly dominant, nd F1 hybrids have a phenotype somewhere between those of two parental varieties

Front 28

codominance

Back 28

two alleles both affect the phenotype in separate distinguishable ways
-ex: blood type (AB)

Front 29

tay-sachs disease

Back 29

inherited siorders in humans where cannot metabolize certain lipids because crucial enyzme does not work properly
-seizures, blindness, degeneration of motor and mental performance and will die with in a few years
-need two copies of Tay-Sachs allele, recessive at organismal level
-however in heterozygotes the lipid-metabolizing enzyme is intermediate
-biochemical level=incomplete dominance (no diseased symptoms)

Front 30

frequency of dominant alleles

Back 30

-affected by natural selection
-not necessarily most popular

Front 31

pleiotropy

Back 31

multiple phenotypic effects
ex: cycstic fribrosis and sickle-cell disease

Front 32

epistasis

Back 32

a gene at one locus alter the phenotypic expression of a gene at a second locus
ex: albino mice

Front 33

qunititative characters

Back 33

characters vary in the population along a continuum (in gradations)

Front 34

polygenic inheritance

Back 34

additive effect of two or more genes on a single phenotypic character (converse of pleiotropy)

Front 35

norm of reaction

Back 35

range of phenotypic possibilities due to environmental influences

Front 36

multifactual

Back 36

many factors, both genetic and environmental collectivly influencing phenotype

Front 37

pedigree analysis

Back 37

pedigree information about a family's history for a particular trait and aseembled info into a family tree describing traits of parents and children cross generations

Front 38

behavior of recessive alleles

Back 38

an allele that causes a genetic disorder codes either for a mlfunctioning protein or for no protein at all

Front 39

carriers

Back 39

heterozygotes that transmit recessive allele to their offspring

Front 40

cystic fibrosis

Back 40

most common lethal genetic disease in U.S.
-strikes 1 out of every 2,500 ppl of European descent
-chloride transport chains defected
-increase mucous

Front 41

sickle-cell disease

Back 41

most common inherited disorder among ppl of African descent
-will clump small blood vessels
-pleitropy->some heterozygotes with symptoms

Front 42

achondroplasia

Back 42

form of dawrfism that occurs in one of every 25,000 people

Front 43

huntington's disease

Back 43

-lethal dominant allele
-degenertive diease of the nervous system

Front 44

multifactorial disorders

Back 44

genetic component plus a significant envrionmental influence
-heart disease, diabetes, cancer, alcoholism, schizophrenia

Front 45

amniocentesis

Back 45

sample of fluid taken t 14th week of pregnancy, biochemical tests, centrifuge, fetal cells cultivated

Front 46

chorionic villus sampling

Back 46

sample of tissue from placent at 8th week of pregnancy -->karyotyping

Front 47

ultrsound

Back 47

sound waves used to produce image of fetus by simple noninvasive procedure

Front 48

fetoscopy

Back 48

needle-thin tube containing viewing scope nd fiber optics is inserted into uterus