Biology Chapter 12

Front 1

Thomas Hunt Morgan

Back 1

experimented with fruit fly and discovered sex chromosones

Front 2

sex chromosomes

Back 2

contain genes that determine the siex of an individual

Front 3

autosomes

Back 3

chromosomes that determine body characteristics

Front 4

SRY

Back 4

sex-determining region y

Front 5

sex-linked trait

Back 5

trait that is coded for by an allele on a sex chromosome

Front 6

linked genes

Back 6

pairs of genes that tend to be inherited together

Front 7

linkage group

Back 7

a set of linked genes

Front 8

chromosome map

Back 8

a diagram that shows the linear order of genes on a chromosome

Front 9

map unit

Back 9

the frequency of crossing over of two traits

Front 10

germ-cell mutations

Back 10

mutations that occur in an organisms gametes and affect the offspring but not the organism itself

Front 11

somatic-cell mutations

Back 11

mutations in an organism's body cells that affect the organism but cannot be inherited

Front 12

lethal mutations

Back 12

mutations that cause death, often before birth

Front 13

deletion

Back 13

the loss of a piece of a chromosome due to breakage

Front 14

inversion

Back 14

when a chromosomal segment breaks off, flips around backward, and reattaches

Front 15

translocation

Back 15

when a piece of a chromosome breaks off and reattaches to a nonhomologous chromosome

Front 16

nondisjunction

Back 16

when a chromosome fails to separate from its homologous pair during meiosis

Front 17

point mutation

Back 17

the substitution, addition, or removal of a single nucleotide

Front 18

substitution

Back 18

one nucleotide replaces another

Front 19

frameshift mutation

Back 19

incorrect grouping of remaining codons, caused by point mutations

Front 20

insertion mutations

Back 20

when one or more nucleotides are added to a gene