Chapter 15; part 1

Question 1

Several characteristics make fruit flies a convenient organism for genetic studies

Answer 1

• large amount of offspring
• short generation time (2 weeks)
• only 4 pairs of chromosomes

Question 2

wild type

Answer 2

normal phenotype ; RED EYES

Question 3

mutant

Answer 3

recessive WHITE EYES

Question 4

F1

Answer 4

ALL HAS RED EYES

Question 5

F2

Answer 5

3;1 RATIO red;white

Question 6

only males

Answer 6

have white eyes

Question 7

white-eyed mutant allele on

Answer 7

X chromosomes

Question 8

punnett square F1

Answer 8

W Y (sperm) 
W^+( egg)

Question 9

punnet square F2

Answer 9

take the results that you get in F1 and make a new punnet square for F2.

Question 10

genes on Y chromosomes

Answer 10

are called y-linked genes

9 alleles for sperm production+ 1 gene

Question 11

X-linked chromosomes

Answer 11

have genes for many characters

unrelated to sex

Question 12

X inactivation

Answer 12

in female mammals (tortoiseshell cat) ( XX)

Question 13

1 of the 2 X chromosomes in each cell

Answer 13

is randomly inactivated during embryonic development

Question 14

XX and XX

Answer 14

orange fur and black fur

Question 15

Morgan found that wings size and body color

Answer 15

are inherited together in specific combinations ( genes not assorted independently)

Question 16

nonparental phenotypes

Answer 16

phenotypes not inherited from parents

Question 17

genetic recombination

Answer 17

the production of offspring with combinations of traits differing from either parents.

Question 18

recombination of linked genes

Answer 18

crossing over

Question 19

parental types

Answer 19

offspring with a phenotype matching one a parent

Question 20

recombinant types

Answer 20

offspring with a nonparental phenotypes ( new combination of traits)

Question 21

Genes can be linked but it was incomplete

Answer 21

due to crossing over

Question 22

homologous chromosomes

Answer 22

= both equal signs symbolize both homologous chrome

=

Question 23

sister chromatid

Answer 23

= is one of the two pair of homologous chromosomes

Question 24

synapsis

Answer 24

homologous chromosomes loosely pair up, aligned gene by gene

Question 25

crossing over

Answer 25

nonsister chromatids exchange DNA segments

Question 26

random fertilization increases even further the # of

Answer 26

variant combination that can be produced

Question 27

nondisjunction

Answer 27

pairs of homologous chromosomes do not separate normally during meiosis

Question 28

Aneuploidy

Answer 28

fertilization of gametes in which nondisjunction occurs

Question 29

offspring with an abnormal number of chromosomes

Answer 29

aneuploidy

Question 30

monosomic

Answer 30

zygote has only 1 copy of a particular chromosomes

Question 31

trisomic

Answer 31

zygote has three copies of a particular chromosomes

down syndrome - Trisomy 21