AP Bio Midterm Key Terms Ch. 15

Question 1

aneuploidy

Answer 1

A chromosomal aberration in which one or more chromosomes are present in extra copies or are deficient in number.

Question 2

Barr body

Answer 2

A dense object lying along the inside of the nuclear envelope in female mammalian cells, representing an inactivated X chromosome.

Question 3

chromosome theory of inheritance

Answer 3

A basic principle in biology stating that genes are located on chromosomes and that the behavior of chromosomes during meiosis accounts for inheritance patterns.

Question 4

crossing over

Answer 4

The reciprocal exchange of genetic material between nonsister chromatids during prophase I of meiosis.

Question 5

cytologenetic map

Answer 5

Chart of a chromosome that locates genes with respect to chromosomal features.

Question 6

deletion

Answer 6

(1) A deficiency in a chromosome resulting from the loss of a fragment through breakage. (2) A mutational loss of one or more nucleotide pairs from a gene.

Question 7

Down syndrome

Answer 7

A human genetic disease caused by presence of an extra chromosome 21; characterized by mental retardation and heart and respiratory defects.

Question 8

Duchenne muscular dystrophy

Answer 8

A human genetic disease caused by a sex-linked recessive allele; characterized by progressive weakening and a loss of muscle tissue.

Question 9

duplication

Answer 9

An aberration in chromosome structure due to fusion with a fragment from a homologous chromosome, such that a portion of a chromosome is duplicated.

Question 10

genetic map

Answer 10

An ordered list of genetic loci (genes or other genetic markers) along a chromosome.

Question 11

genetic recombination

Answer 11

General term for the production of offspring that combine traits of the two parents.

Question 12

genomic imprinting

Answer 12

Phenomenon in which expression of an allele in offspring depends on whether the allele is inherited from the male or female parent.

Question 13

hemophilia

Answer 13

A human genetic disease caused by a sex-linked recessive allele; characterized by excessive bleeding following injury.

Question 14

inversion

Answer 14

An aberration in chromosome structure resulting from reattachment in a reverse orientation of a chromosomal fragment to the chromosome from which the fragment originated.

Question 15

linkage map

Answer 15

A genetic map based on the frequencies of recombination between markers during crossing over of homologous chromosomes.

Question 16

linked genes

Answer 16

Genes located close enough together on a chromosome to be usually inherited together.

Question 17

map unit

Answer 17

A unit of measurement of the distance between genes. One map unit is equivalent to a 1% recombination frequency.

Question 18

monosomic

Answer 18

Referring to a cell that has only one copy of a particular chromosome, instead of the normal two.

Question 19

nondisjunction

Answer 19

An error in meiosis or mitosis, in which both members of a pair of homologous chromosomes or both sister chromatids fail to move apart properly.

Question 20

parental type

Answer 20

An offspring with a phenotype that matches one of the parental phenotypes.

Question 21

polyploidy

Answer 21

A chromosomal alteration in which the organism possesses more than two complete chromosome sets.

Question 22

recombinant

Answer 22

An offspring whose phenotype differs from that of the parents; also called recombinant type.

Question 23

sex-linked gene

Answer 23

A gene located on a sex chromosome.

Question 24

translocation

Answer 24

An aberration in chromosome structure resulting from attachment of a chromosomal fragment to a nonhomologous chromosome

Question 25

trisomic

Answer 25

Referring to a cell that has three copies of a particular chromosome, instead of the normal two.

Question 26

wild type

Answer 26

An individual with the normal (most common) phenotype.