Ch.15: Chromosomes and Inheritance

Question 1

Mitosis and meiosis were first described in

Answer 1

late 1800s

Question 2

The chromosome theory of inheritance states:

Answer 2

Mendelian genes have specific loci (positions) on chromosomes
Chromosomes undergo segregation and independent assortment

Question 3

The behavior of chromosomes during meiosis was said to account for Mendel’s

Answer 3

law of segregation and law of independent assortment

Question 4

an embryologist
Particular genes are on particular chromosomes
Still didn’t know about DNA

Answer 4

Thomas hunt morgan

Question 5

What did Morgan worked with?? It is a model organisms that has certain characteristics that are easily observed such as eye color

Answer 5

fruit flies

Question 6

Several characteristics make fruit flies a convenient organism for genetic studies:

Answer 6

They breed at a high rate
A generation can be bred every two weeks
They have only four pairs of chromosomes

Question 7

or normal, phenotypes

Types that were common in the fly populations

Answer 7

wild type

Question 8

Traits alternative to the wild type are called

Answer 8

mutant phenotypes

Question 9

In one experiment, Morgan mated male flies with white eyes (mutant) with female flies with red eyes (wild type)
The F1 generation all had red eyes
The F2 generation showed the 3:1 red:white eye ratio, but only males had white eyes
Morgan determined that the white-eyed mutant allele must be located on the ____________

Answer 9

x chromosome

Question 10

A gene located on either sex chromosome is called a

Answer 10

sex-linked gene

Question 11

Some disorders caused by recessive alleles on the X chromosome in humans:

Answer 11

Color blindness
Duchenne muscular dystrophy
Hemophilia

Question 12

For a recessive sex-linked trait to be expressed

Answer 12

A female needs two copies of the allele

A male needs only one copy of the allele

Question 13

sex-linked recessive disorders are much more common in

Answer 13

males than females

Question 14

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

Answer 14

gene recombination

Question 15

Offspring with a phenotype matching one of the parental phenotypes are called

Answer 15

parental types

Question 16

Offspring with nonparental phenotypes (new combinations of traits) are called

Answer 16

recombinant types or recombinants

Question 17

3 types Types of Chromosomal Alterations

Answer 17

Nondisjunction
Aneuploidy
Alteration of Chromosome Structure

Question 18

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

Answer 18

nondisjunction

Question 19

results from the fertilization of gametes in which nondisjunction occurred
Offspring with this condition have an abnormal number of a particular chromosome

Answer 19

aneuploidy

Question 20

zygote has only one copy of a particular chromosome

Answer 20

monosomic

Question 21

zygote has three copies of a particular chromosome

Answer 21

trisomic

Question 22

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

Answer 22

downs syndrome

Question 23

the result of an extra chromosome in a male, producing XXY individuals

Answer 23

klinefelter syndrome

Question 24

Monosomy X, called ______ _______, produces X0 females, who are sterile; it is the only known viable monosomy in humans
Only possible because it occurs on sex chromosomes

Answer 24

Turners syndrome

Question 25

is a condition in which an organism has more than two complete sets of chromosomes
Triploidy (3n) is three sets of chromosomes
Tetraploidy (4n) is four sets of chromosomes
common in plants not animals

Answer 25

polyploidy

Question 26

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

Answer 26

Deletion removes a chromosomal segment
Duplication repeats a segment
Inversion reverses a segment within a chromosome
Translocation moves a segment from one chromosome to another

Question 27

The syndrome cri du chat (“cry of the cat”), results from a specific deletion in

Answer 27

chromosome 5

Question 28

are genes found in organelles

Mitochondria and chloroplasts carry small circular DNA molecules

Answer 28

extranuclear genes or cytoplasmic genes

Question 29

Extranuclear genes are inherited

Answer 29

maternally because the zygote’s cytoplasm comes from the egg.

Question 30

What are some examples of Some defects in mitochondrial genes prevent cells from making enough ATP and result in diseases that affect the muscular and nervous systems

Answer 30

mitochondrial myopathy and Leber’s hereditary optic neuropathy