Chapter 15: The Chromosomal Basis of Inheritance

Question 1

Chromosomal Theory of Inheritance

Answer 1

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

Question 2

Wild Type

Answer 2

• Phenotype most commonly observed in natural populations

- Refers to the individual with the most common phenotype as well

Question 3

Sex-Linked Gene

Answer 3

• Gene located on either sex chromosome

- Most are located on the X chromosome and show distinctive patterns of inheritance

Question 4

Duchenne Muscular Dystrophy

Answer 4

• Human genetic disease caused by a sex-linked recessive allele
• Characterized by progressive weakening and loss of muscle tissue

Question 5

Hemophilia

Answer 5

• Human genetic disease caused by a sex-linked recessive allele
• Results in the absence of one or more blood clotting proteins
• Characterized by excessive bleeding following injury

Question 6

Barr Body

Answer 6

• Dense object lying along the inside of the nuclear envelope in female mammalian cells
• Represents an inactivated X chromosome

Question 7

Linked Genes

Answer 7

Genes located close enough together in a chromosome that they tend to be inherited together

Question 8

Genetic Recombination

Answer 8

General term for the production of offspring with combinations of traits that differ from those found in either parent

Question 9

Parental Types

Answer 9

• Offspring with a phenotype that matches one of the true-breeding parental (P generation) phenotypes
• Also refers to the phenotype of the parents itself

Question 10

Recombinant Type / Recombinant

Answer 10

• Offspring whose phenotype differs from that of the true breeding P generation parents
• Also refers to the differing phenotype itself

Question 11

Crossing Over

Answer 11

Reciprocal exchange of genetic material between nonsister chromatids during prophase I of meiosis

Question 12

Genetic Map

Answer 12

Ordered list of genetic loci (genes or other genetic markers) along a chromosome

Question 13

Linkage Map

Answer 13

Genetic map based on the frequencies of recombination between markers during crossing over of homologous chromosomes

Question 14

Map Unit

Answer 14

• Unit of measurement of the distance between genes

- One is equivalent to a 1% recombination frequency

Question 15

Nondisjunction

Answer 15

Error in meiosis or mitosis in which members of a pair of homologous chromosomes or a pair sister chromatids fail to separate properly from each other

Question 16

Aneuploidy

Answer 16

Chromosomal aberration in which one or more chromosomes are present in extra copies or are deficient in number

Question 17

Monosomic

Answer 17

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

Question 18

Trisomic

Answer 18

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

Question 19

Polyploidy

Answer 19

Chromosomal alteration in which the organism possesses more than two complete chromosome sets

Question 20

Deletion

Answer 20

• Deficiency in a chromosome resulting from the loss of a fragment through breakage
• Mutational loss of one or more nucleotide pairs from a gene

Question 21

Duplication

Answer 21

• An aberration in chromosome structure due to fusion with a fragment from a homologous chromosome
• Part of a chromosome is seen more than once

Question 22

Inversion

Answer 22

Aberration in chromosome structure resulting from reattachment of a chromosomal fragment in a reverse orientation to the chromosome from which it originated

Question 23

Translocation

Answer 23

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

Question 24

Down Syndrome

Answer 24

• Human genetic disease usually caused by the presence of an extra chromosome 21
• Characterized by developmental delays and heart and other defects that are generally treatable or non-life-threatening

Question 25

Genomic Imprinting

Answer 25

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