Ch 15: Chromosomal Basis of Inheritance

Question 1

Who developed the Chromosome theory of inheritance?

Answer 1

around 1902 Sutton and Boveri and others independently noted the parallels between chroomosme behavior and the behavior of the proposed factors and developed the theory

Question 2

What is a wild type?

Answer 2

normal phenotypes in populations

Question 3

What is a sex-linked gene?g

Answer 3

genes on X and Y chromosomes that code for an individuals sex

Question 4

What are X-linked genes?

Answer 4

genes on the X chromosome, which humans contain about 1,100 genes on their X chromosme

Question 5

What needs to occur for a recessive X-linked trait to be expressed?

Answer 5

a female needs two copies of the allele (homozygous) and a male needs only one copy of the allele (hemizygous)

Question 6

What are some disorders that are caused by recessive alleles on the X chromosome in humans?

Answer 6

color blindness (mostly X-linked), Duchenne muscular dystrophy, and hemophilia

Question 7

What is the inactivated X (in females) condensed too?

Answer 7

a barr body

Question 8

What are linked genes?

Answer 8

genes that are on the same chromosome that tend to be inherited together

Question 9

What is genetic recombination?

Answer 9

the production of offspring with combinations of traits differing from either parent

Question 10

What are parental types?

Answer 10

offspring with a phenotype matching one of the parental phenotypes

Question 11

What are recombinant types (recombinants)?

Answer 11

offspring with nonparental phenotypes (new combinations of traits)

Question 12

What is crossing over?

Answer 12

when genetic material is swapped between chromosomes during prophase

Question 13

What increases genetic variation?

Answer 13

recombinant chromosomes and random fertilization

Question 14

Who constructed a genetic map?

Answer 14

Alfred Sturtevant, one of Morgan’s student’s

Question 15

What is a genetic map?

Answer 15

an ordered list of the genetiv loci along a particular chromosome

Question 16

What is a linkage map?

Answer 16

a genetic map of a chromosome based on recombination frequencies

Question 17

What can distances between genes be expressed as?

Answer 17

map units

Question 18

What is nondisjunction?

Answer 18

when pairs of homologous chromosomes do not separate normally during meiosis, as a result, one gamete receives two of the same type of chromosome, and another gamete recieves no copy

Question 19

What is aneuploidy?

Answer 19

offspring with an abnormal number of a particular chromosome, resulting nondisjunction

Question 20

What is a monosomic zygote?

Answer 20

a zygote with only one copy of a particular chromosome

Question 21

What is a trisomic zygote?

Answer 21

a zygote has three copies of a particular chromosome

Question 22

What is polyploidy?

Answer 22

a condition in which an organism has more than two complete sets of chromosomes

Question 23

What is triploidy?

Answer 23

three sets of chromosomes

Question 24

What is tetraploidy?

Answer 24

four stes of chromosomes

Question 25

What are the four types of changes in chromosome structure that results from the breakage of a chromosome?

Answer 25

deletion, duplication, inversion, and translocation

Question 26

What is deletion?

Answer 26

the removal of a chromosomal fragment

Question 27

What is duplication?

Answer 27

repetition of a segment

Question 28

What is inversion?

Answer 28

the reverse orientation of a segment within a chromosome

Question 29

What is translocation?

Answer 29

the movement of a segment from one chromosome to another

Question 30

What is down syndrome?

Answer 30

is an aneuploid condition that results from three copies of chromosome 21

Question 31

What are the two exceptions to standard Mendelian inheritance?

Answer 31

genes located in the nucleus and genes located outside the nucleus

Question 32

What is genomic imprinting?

Answer 32

the silencing of certain genes depending on which parent passes them on