Chapter 12 The Chromosomal Basis Of Inheritance

Question 1

Today we know that genes are located on

Answer 1

Chromosomes

Question 2

The chromosome theory of inheritance states

Answer 2

Mendelian genes have specific loci on chromosomes

Chromosomes undergo segregation and independent assortment

Question 3

Morgan I’m the early 1900’s

Answer 3

Work provided evidence of a specific gene with a specific chromosomes

Noted wild type or normal phenotypes with alternate called mutant phenotypes

Concluded that eye color was related to the sex of the fly

Question 4

Humans have two types of sex chromosomes

Answer 4

Larger X and smaller Y

The sry gene on the Y chromosome is required for testes

Ends of Y chromosome have regions that are homologous to corresponding regions of X chromosome

Question 5

A gene that is located on either sec chromosome is called a

Answer 5

Sex-linked gene

Question 6

For a recessive X linked trait to be expressed

Answer 6

A female needs two copies of the allele

A male needs only one copy of the allele

Question 7

Linked genes

Answer 7

Genes located one the same chromosome that tend to be inherited together

Question 8

Genetic recombination

Answer 8

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

Question 9

Parental types

Answer 9

Offspring with a phenotype matching one of the parental phenotypes

Question 10

Offspring with nonparental phenotypes are called

Answer 10

Recombinant types or recombinants

Question 11

Genetic map

Answer 11

Ordered list of the genetic loci along a particular chromosome

Question 12

Linkage map

Answer 12

Genetic map of a chromosome based on recombination frequencies

Question 13

Distance between genes can be expressed as

Answer 13

Map units-one map unit represents a 1% recombination frequency

Question 14

Cytogenetic maps

Answer 14

Indicate positions of genes with respect to chromosomal features

Question 15

Non disjunction

Answer 15

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 receives no copy

Question 16

Aneuploidy

Answer 16

Results from fertilization involving gametes in which non disjunction occurred

Offspring have an abnormal number of a particular chromosome

Question 17

Monosomic

Trisomic

Answer 17

Zygote has only one copy of a particular chromosome

Zygote has three copies of a particular chromosome

Question 18

Polyploidy

Answer 18

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

Question 19

Breakage of a chromosome can lead to four types of changes in chromosome structure

Answer 19

Deletion-removes a segment

Duplication-repeats a segment

Inversion-reverses orientation of a segment

Translocation-moves a segment from one chromosome to another

Question 20

Down Syndrome

Answer 20

Aneuploid condition that results from three copies of chromosome 21

Question 21

Klinefelter syndrome

Answer 21

Extra chromosome in a male producing XXY individuals

Question 22

Turner syndrome

Answer 22

Produces X0 females who are sterile