Chapter 23 Terms Of _Inquiry Into Life_

Front 1

law of segregation

Back 1

-each individual has two factors for each trait
-the factors segregate (separate) during the formation of the gametes
-each gamete contains only one factor from each pair of factors
-fertilization gives each new individual two factors for each trait

Front 2

dominant allele

Back 2

indicated by a capital letter. is shown in the phenotype, even when a recessive allele is present.

Front 3

recessive allele

Back 3

indicated by a lowercase letter. is only shown in the phenotype when two of these are present.

Front 4

autosome

Back 4

any chromosome other than the sex chromosomes

Front 5

codominance

Back 5

pattern of inheritance in which both alleles of a gene are equally expressed

Front 6

dihybrid

Back 6

individual that is heterozygous for two traits; shows the phenotype governed by the dominant alleles but carries the recessive alleles

Front 7

genotype

Back 7

genes of an individual for a particular trait or traits; often designated by letters, for example, BB or Aa

Front 8

heterozygous

Back 8

having two different alleles (as Aa) for a given trait

Front 9

homozygous

Back 9

havign identical alleles (as AA or aa) for a given trait; pure breeding

Front 10

law of independent assortment

Back 10

alleles of unlinjked genes assort independently of each other during meiosis so that the gametes contain all possible combinations of alleles

Front 11

linkage group

Back 11

alleles of different genes that are located on the same chromosome and tend to be inherited together

Front 12

monohybrid

Back 12

individual that is heterozygous for one trait; shows the phenotype of the dominant allele but carries the recessive allele

Front 13

multiple allele

Back 13

inheritance pattern in which there are more than two alleles for a particular trait; each individual has only two of all possible alleles

Front 14

polygenic inheritance

Back 14

inheritance pattern in which a trait is controlled by several allelic pairs; each dominant allele contributes to the phenotype in an additive and like manner

Front 15

phenotype

Back 15

outward appearance of an organism caused by the genotype and environmental influences

Front 16

Punnett Square

Back 16

gridlike device used to calculate the expected results of simple genetic crosses

Front 17

sex chromosome

Back 17

chromosome that determines the sex of an individual; in humans, females have two X chromosomes, and males have an X and Y chromosome

Front 18

sex-linked

Back 18

allele that occurs on the sex chromosomes but may control a trait that has nothing to with sexual characteristics of an individual

Front 19

X-linked

Back 19

allele located on an X chromosome but may control a trait that has nothing to with the sex characteristics of an individual