Biology Chater 12

Front 1

chromosome map

Back 1

a diagram of allele positions on a chromosome.

Front 2

deletion

Back 2

a mutation in which a segment of DNA breaks off of a chromosome.

Front 3

frame-shift mutation

Back 3

a mutation that results in the misreading of the code during translation because of a change in the reading frame.

Front 4

germ-cell mutation

Back 4

a change in the DNA of a sex cell.

Front 5

inversion

Back 5

a mutation that occurs when a chromosome piece breaks off and reattches in the reverse orientation.

Front 6

lethal mutation

Back 6

mutations that cause death, often before birth.

Front 7

linckage group

Back 7

the group of genes, located on the same chromosome, that are usually inheerited together.

Front 8

map unit

Back 8

a unit in chromosome mapping equal to 1 percent occurrence of crossing-over.

Front 9

nondisjunction

Back 9

the failure of homologous chromosomes to seperate during meiosis or the failure of sister chromatids to seperate during mitosis.

Front 10

point mutation

Back 10

the change of a single nitrogen-containing base within a codon.

Front 11

sex linkage

Back 11

the presencce of a gene on a sex chromosome.

Front 12

sickle cell anemia

Back 12

a genetic disorder caused by a point mutation that sustitutes adenine for thymine in a single DNA codon.

Front 13

somatic mutation

Back 13

a mutation that occurs in a body cell.

Front 14

substitution

Back 14

a point mutation in which one nucleotide in a codon is replaced with a different nucleotide.

Front 15

translocation

Back 15

a mutation in which a broken piece of chromosome attaches to a nonhomologous chromosome; movement of organic molecules in plant tissues.

Front 16

X-linked gene

Back 16

a gene found on the X chromosome.

Front 17

Y-linked gene

Back 17

a gene found on the Y chromosome.

Front 18

amniocentesis

Back 18

a procedure used in fetal diagnosis in which fetal cells are removed from the amniotic fluid.

Front 19

carrier

Back 19

individuals who have one copy of a recessive autosomal allele; they usually do not express the recessive allele, but they can pass it along to their offspring.

Front 20

chronic villi sampling

Back 20

a procedure involving the analysis of the chronic villi to diagnosis fetal genotypes.

Front 21

colorblindness

Back 21

a recessive X-linked disorder in which an individual cannot distinguish between certain colors.

Front 22

Down syndrome

Back 22

a disorder caused by an extra twenty-first chromosome and characterized by a number of physical and mental abnormalities.

Front 23

Duchenne muscular dystrophy

Back 23

a form of muscular dystrophy that weakens and progressively destroys muscle tissue.

Front 24

genetic counseling

Back 24

the process of informing a couple about their gentic makeup, which has the potential to affect their offspring.

Front 25

genetic disorder

Back 25

a disease that has a genetic basis.

Front 26

genetic marker

Back 26

a short section of DNA that indicates the presence of an allele that codes for a trait.

Front 27

genetic screening

Back 27

an examination of a person's genetic makeup.

Front 28

hemophilia

Back 28

a trait in which the blood lacks a protein that is essential for clotting.

Front 29

Huntington's disease (HD)

Back 29

a human genetic disorder caused by a dominant allele resulting in involuntary movements, mental deterioration, and eventual death.

Front 30

monosomy

Back 30

a condition in a diploid cell in which one pair is missing as a result of nondisjunction during meiosis.

Front 31

pedigree

Back 31

a diagram of the gentic history of an individual; can show how a trait is inherited over several generations.

Front 32

phenylketonuria (PKU)

Back 32

a genetic disorder in which the body cannot metabolize phentlalanine.

Front 33

polygenic trait

Back 33

a trait controlled by multiple genes.

Front 34

sex-influenced trait

Back 34

a trait that is influenced by the presence of male or female sex hormones.

Front 35

single-allele trait

Back 35

trait controlled by a single allele.

Front 36

trisomy

Back 36

a chromosomal anomaly in which an individual has an extra chromosome in any of the chromosome pairs.

Front 37

trisomy-21

Back 37

a human cogenital disorder caused by trisomy of chromosome 21 due to the failure of the sister chromatids to seperate during meiosis.